Hydraulic cylinders get their power from pressurized hydraulic fluid, which is typically oil. The hydraulic cylinder consists of a cylinder barrel, in which a piston connected to a piston rod  moves back and forth. The barrel is closed on one end by the cylinder bottom and the other end by the cylinder head where the piston rod comes out of the cylinder. The piston has sliding rings and seals. The piston divides the inside of the cylinder into two chambers, the bottom chamber and the piston rod side chamber .

A hydraulic cylinder is the actuator or “motor” side of this system. The “generator” side of the hydraulic system is the hydraulic pump which delivers a fixed or regulated flow of oil to the hydraulic cylinder, to move the piston. The piston pushes the oil in the other chamber back to the reservoir.

Parts of a Hydraulic cylinder

A hydraulic cylinder has the following parts:

Cylinder barrel

The main function of the cylinder body is to hold cylinder pressure. The cylinder barrel is mostly made from honed tubes. Honed tubes are produced from Suitable To Hone Steel Cold Drawn Seamless Tubes (CDS tubes) or Drawn Over Mandrel (DOM) tubes. Honed tubing is ready to use for hydraulic cylinders without further ID processing. The surface finish of the cylinder barrel is typically 4 to 16 microinch.Honing process and Skiving & Roller burnishing (SRB) process are the two main types of processes for manufacturing cylinder tube.The piston reciprocates in the cylinder.The cylinder barrel has features of smooth inside surface,high precision tolerance, durable in use etc.

Cylinder base or cap

The main function of the cap is to enclose the pressure chamber at one end. The cap is connected to the body by means of welding, threading, bolts, or tie rod. Caps also perform as cylinder mounting components [cap flange, cap trunnion, cap clevis]. Cap size is determined based on the bending stress. A static seal/o ring is used in between cap and barrel (except welded construction).

Cylinder head

The main function of the head is to enclose the pressure chamber from the other end. The head contains an integrated rod sealing arrangement or the option to accept a seal gland. The head is connected to the body by means of threading, bolts, or tie rod. A static seal/o ring  is used in between head and barrel.

Piston

The main function of the piston is to separate the pressure zones inside the barrel. The piston is machined with grooves to fit elastomeric  or metal seals and bearing elements. These seals can be single acting or double acting. The difference in pressure between the two sides of the piston causes the cylinder to extend and retract. The piston is attached with the piston rod by means of threads, bolts, or nuts to transfer the linear motion.

Piston rod

The piston rod is typically a hard chrome-plated piece of cold-rolled steel which attaches to the piston and extends from the cylinder through the rod-end head. In double rod-end cylinders, the actuator has a rod extending from both sides of the piston and out both ends of the barrel. The piston rod connects the hydraulic actuator to the machine component doing the work. This connection can be in the form of a machine thread or a mounting attachment. The piston rod is highly ground and polished so as to provide a reliable seal and prevent leakage.

Seal gland

The cylinder head is fitted with seals to prevent the pressurized oil from leaking past the interface between the rod and the head. This area is called the seal gland. The advantage of a seal gland is easy removal and seal replacement. The seal gland contains a primary seal, a secondary seal / buffer seal, bearing elements, wiper / scraper and static seal. In some cases, especially in small hydraulic cylinders, the rod gland and the bearing elements are made from a single integral machined part.

Seals

The seals are considered / designed as per the cylinder working pressure, cylinder speed, operating temparature , working medium and application. Piston seals are dynamic seals, and they can be single acting or double acting. Generally speaking, Elastomer seals made from nitrile rubber, Polyurethane or other materials are best in lower temperature environments, while seals made of Fluorocarbon  Viton are better for higher temperatures. Metallic seals are also available and commonly use cast iron for the seal material. Rod seals are dynamic seals and generally are single acting. The compounds of rod seals are nitrile rubber Polyurethane, or Fluorocarbon Viton . Wipers / scrapers are used to eliminate contaminants such as moisture, dirt, and dust, which can cause extensive damage to cylinder walls, rods, seals and other components. The common compound for wipers is polyurethane. Metallic scrapers are used for sub zero temperature applications, and applications where foreign materials can deposit on the rod. The bearing elements / wear bands are used to eliminate metal to metal contact. The wear bands are designed as per the side load requirements. The primary compounds used for wear bands are filled PTFE , woven fabric reinforced polyester resin and bronze

Other parts

There are many component parts that make up the internal portion of a hydraulic cylinder. All of these pieces combine to create a fully functioning component.

• Cylinder base connection
• Cushions
• Internal Threaded Ductile Heads
• Head Glands
• Polypak Pistons
• Cylinder Head Caps
• Butt Plates
• Eye Brackets/Clevis Brackets
• MP Detachable Mounts
• Rod Eyes/Rod Clevis
• Pivot Pins
• Spherical Ball Bushings
• Spherical Rod Eye
• Alignment Coupler
• Ports and Fittings

Single acting vs. double acting

• Single acting cylinders are economical and the simplest design. Hydraulic fluid enters through a port at one end of the cylinder, which extends the rod by means of area difference. An external force, internal retraction spring or gravity returns the piston rod.
• Double acting cylinders have a port at each end or side of the piston, supplied with hydraulic fluid for both the retraction and extension.

Designs

There are primarily two main styles of hydraulic cylinder construction used in industry: tie rod style cylinders and welded body style cylinders.

Tie rod cylinder

A tie rod cylinder

Tie rod style hydraulic cylinders use high strength threaded steel rods to hold the two end caps to the cylinder barrel. They are most often seen in industrial factory applications. Small bore cylinders usually have 4 tie rods, and large bore cylinders may require as many as 16 or 20 tie rods in order to retain the end caps under the tremendous forces produced. Tie rod style cylinders can be completely disassembled for service and repair, and they are not always customizable.

The National fluid power assotation  (NFPA) has standardized the dimensions of hydraulic tie rod cylinders. This enables cylinders from different manufacturers to interchange within the same mountings.

Welded body cylinder

Welded body cylinders have no tie rods. The barrel is welded directly to the end caps. The ports are welded to the barrel. The front rod gland is usually threaded into or bolted to the cylinder barrel. That allows the piston rod assembly and the rod seals to be removed for service.A Cut Away of a Welded Body Hydraulic Cylinder showing the internal components

Welded body cylinders have a number of advantages over tie rod style cylinders. Welded cylinders have a narrower body and often a shorter overall length enabling them to fit better into the tight confines of machinery. Welded cylinders do not suffer from failure due to tie rod stretch at high pressures and long strokes. The welded design also lends itself to customization. Special features are easily added to the cylinder body, including special ports, custom mounts, valve manifolds, and so on.

The smooth outer body of welded cylinders also enables the design of multi-stage telescopic cylinders.

Welded body hydraulic cylinders dominate the mobile hydraulic equipment market such as construction equipment and material handling equipment (forklift trucks, telehandlers, and lift-gates). They are also used by heavy industry in cranes, oil rigs, and large off-road vehicles for above-ground mining operations.

Piston rod construction

The piston rod of a hydraulic cylinder operates both inside and outside the barrel, and consequently both in and out of the hydraulic fluid and surrounding atmosphere.

Coatings

Wear and corrosion resistant surfaces are desirable on the outer diameter of the piston rod. The surfaces are often applied using coating techniques such as Chrome (Nickel) Plating, Lunac 2+ duplex, Laser Cladding, PTA welding and Thermal Spraying. These coatings can be finished to the desirable surface roughness (Ra, Rz) where the seals give optimum performance. All these coating methods have their specific advantages and disadvantages. It is for this reason that coating experts play a crucial role in selecting the optimum surface treatment procedure for protecting Hydraulic Cylinders.

Cylinders are used in different operational conditions and that makes it a challenge to find the right coating solution. In dredging there might be impact from stones or other parts, in salt water environments there are extreme corrosion attacks, in off-shore cylinders facing bending and impact in combination with salt water, and in the steel industry there are high temperatures involved, etc. There is no single coating solution which successfully combats all the specific operational wear conditions. Every technique has its own benefits and disadvantages.

Length

Piston rods are generally available in lengths which are cut to suit the application. As the common rods have a soft or mild steel core, their ends can be welded or machined for a screw thread.

Distribution of forces on components

The forces on the piston face and the piston head retainer vary depending on which piston head retention system is used.

If a circlip (or any non preloaded system) is used, the force acting to separate the piston head and the cylinder shaft shoulder is the applied pressure multiplied by the area of the piston head. The piston head and shaft shoulder will separate and the load is fully reacted by the piston head retainer.

If a preloaded system is used the force between the cylinder shaft and piston head is initially the piston head retainer preload value. Once pressure is applied this force will reduce. The piston head and cylinder shaft shoulder will remain in contact unless the applied pressure multiplied by piston head area exceeds the preload.

The maximum force the piston head retainer will see is the larger of the preload and the applied pressure multiplied by the full piston head area. The load on the piston head retainer is greater than the external load, which is due to the reduced shaft size passing through the piston head. Increasing this portion of shaft reduces the load on the retainer.

Side loading

Side loading is unequal pressure that is not centered on the cylinder rod. This off-center strain can lead to bending of the rod in extreme cases, but more commonly causes leaking due to warping the circular seals into an oval shape. It can also damage and enlarge the bore hole around the rod and the inner cylinder wall around the piston head, if the rod is pressed hard enough sideways to fully compress and deform the seals to make metal-on-metal scraping contact.

The strain of side loading can be directly reduced with the use of internal stop tubes which reduce the maximum extension length, leaving some distance between the piston and bore seal, and increasing leverage to resist warping of the seals. Double pistons also spread out the forces of side loading while also reducing stroke length. Alternately, external sliding guides and hinges can support the load and reduce side loading forces applied directly on the cylinder.

Repair

Hydraulic cylinders form the heart of many hydraulic systems. It is a common practice to dissemble and rebuild an entire device in the case of hydraulic cylinder repair. Inspection of the leakage issue and scrutinizing cylinder parts (especially the seals) is helpful in recognizing the exact problem and choosing the repair options accordingly. Steps involved in the repair of hydraulic cylinders:

Disassembly

First of all, you should place the cylinder in a suitable location, which has sufficient space to work. If you are working in a cluttered space, it will be difficult for you to keep track of opened up parts. After bringing the cylinder to an appropriate spot, open the cylinder ports and drain out all the hydraulic fluid. The cover of cylinder can be removed by unscrewing the bolts. Once you take off the cover, remove the piston by loosening the input valves.

Diagnosis

Once the piston is completely removed, you will be able to see multiple seals on different parts that are connected to the piston rod . First of all, you need to examine the piston rod to see if there is any damage. If the shaft of the rod is bent or if the cylinder bore has scratches, then get them repaired at a professional repair shop. If the damage is permanent, then you can order or manufacture a new piston rod for your hydraulic cylinder. Piston seals can get damaged, be distorted, or worn. Such damaged seals can cause leakage of hydraulic fluid from the cylinder leading to lower overall pressure or inability to hold pressure. When such events occur, you know that these seals need to be replaced.

Repairing or replacing damaged parts

The parts of the hydraulic cylinder that are distorted (piston rod, rod seal, piston seal and/ or head of rod), need to be either repaired or completely replaced with new parts. The seals can be repacked with the help of a hydraulic cylinder seal kit. These kits will have seals and suitable o-rings. Remember the size and type of old seal while removing them and fix the new ones accordingly. Make sure that you handle the new seals with utmost care so that they do not get damaged in any way.

Rebuilding

Before reassembling all the parts of your cylinder, you should clean and dry the cylinder barrel completely. Also clean the piston rod, shaft, and other parts of the cylinder. Get the broken and damaged seals repacked. Then assemble the parts back on the piston rod. The assembly needs to be done in a reverse order. Once you have assembled all the parts back, put the rod into the soft-jaw vise and screw back the bolts onto the piston rod.

Important tip

If the parts of the hydraulic cylinder are severely damaged, then it is advisable to replace them with new parts with the help of a professional repair expert. Trying to replace/ repair too many parts on your own can lead to faulty reassembly. By following the above steps, you can accomplish the task of hydraulic cylinder repair. Make sure that you prevent ingress of moisture or dirt after assembly of the parts is done.

Cylinder mounting methods

Mounting methods also play an important role in cylinder performance. Generally, fixed mounts on the centerline of the cylinder are best for straight line force transfer and avoiding wear. Common types of mounting include:

Flange mounts—Very strong and rigid, but have little tolerance for misalignment. Experts recommend cap end mounts for thrust loads and rod end mounts where major loading puts the piston rod in tension. Three types are head rectangular flange, head square flange or rectangular head. Flange mounts function optimally when the mounting face attaches to a machine support member.

Side-mounted cylinders—Easy to install and service, but the mounts produce a turning moment as the cylinder applies force to a load, increasing wear and tear. To avoid this, specify a stroke at least as long as the bore size for side mount cylinders (heavy loading tends to make short stroke, large bore cylinders unstable). Side mounts need to be well aligned and the load supported and guided.

Centerline lug mounts —Absorb forces on the centerline, and require dowel pins to secure the lugs to prevent movement at higher pressures or under shock conditions. Dowel pins hold it to the machine when operating at high pressure or under shock loading.

Pivot mounts —Absorb force on the cylinder centerline and let the cylinder change alignment in one plane. Common types include clevises, trunnion mounts and spherical bearings. Because these mounts allow a cylinder to pivot, they should be used with rod-end attachments that also pivot. Clevis mounts can be used in any orientation and are generally recommended for short strokes and small- to medium-bore cylinders. 

Special hydraulic cylinders

Telescopic cylinder

The length of a hydraulic cylinder is the total of the stroke, the thickness of the piston, the thickness of bottom and head and the length of the connections. Often this length does not fit in the machine. In that case the piston rod is also used as a piston barrel and a second piston rod is used. These kinds of cylinders are called telescopic cylinder. If we call a normal rod cylinder single stage, telescopic cylinders are multi-stage units of two, three, four, five or more stages. In general telescopic cylinders are much more expensive than normal cylinders. Most telescopic cylinders are single acting (push). Double acting telescopic cylinders must be specially designed and manufactured.

Plunger cylinder

A hydraulic cylinder without a piston or with a piston without seals is called a plunger  cylinder. A plunger cylinder can only be used as a pushing cylinder; the maximum force is piston rod area multiplied by pressure. This means that a plunger cylinder in general has a relatively thick piston rod.

Differential cylinder

A differential cylinder acts like a normal cylinder when pulling. If the cylinder however has to push, the oil from the piston rod side of the cylinder is not returned to the reservoir, but goes to the bottom side of the cylinder. In such a way, the cylinder goes much faster, but the maximum force the cylinder can give is like a plunger cylinder. A differential cylinder can be manufactured like a normal cylinder, and only a special control is added.

The above differential cylinder is also called a regenerative cylinder control circuit. This term means that the cylinder is a single rod, double acting hydraulic cylinder. The control circuit includes a valve and piping which during the extension of the piston, conducts the oil from the rod side of the piston to the other side of the piston instead of to the pump’s reservoir. The oil which is conducted to the other side of the piston is referred to as the regenerative oil.

Position sensing “smart” hydraulic cylinder

Position sensing hydraulic cylinder  eliminate the need for a hollow cylinder rod. Instead, an external sensing “bar” using Hall effect  technology senses the position of the cylinder’s piston. This is accomplished by the placement of a permanent magnet within the piston. The magnet propagates a magnetic field through the steel wall of the cylinder, providing a locating signal to the sensor.

Terminology

In the United States, popular usage refers to the whole assembly of cylinder, piston, and piston rod (or more) collectively as a “piston”, which is incorrect. Instead, the piston is the short, cylindrical metal component that separates the two parts of the cylinder barrel internally.

You depend on hydraulic cylinders to help you deliver essential goods and services to your customers. Faulty cylinders translate into downtime. That’s lost money and time that you and those who depend on you can’t afford. When you need hydraulic cylinder repair, it makes sense to count on a company with a track record of high-quality repairs, reliable service and effective solutions. We delivers: dependable, rigorously-tested hydraulic repair, hydraulic pump repair and more that end downtime and return your production processes to peak efficiency.

• Single or double end
• Repair / replacement of rods, seals, piston heads, gland nuts, and tubes
• Any diameter up to 14″ and lengths to 18′
• Pressure testing after repair to 3,000 psi
• Replacement seals rated up to 6,000 psi and 500 deg F

All hydraulic cylinders received for repair are disassembled, all components cleaned and inspected, rods are measured for straightness and wear. tubes are measured for wear and the seal / wear band grooves are measured and inspected.

All hydraulic cylinder repairs are dynamically tested to verify proper operation and leak free performance.

Expert Hydraulic Cylinder Repair

Cylinders are what is known as a “linear” actuator. Their basic operation is to move something in and out or up and down. The particular cylinder below is a “tie rod” type cylinders with “trunions” so that it can can pivot in it’s application. This cylinder is also an “oil or hydraulic” cylinder. The two basic cylinder configurations are “tie rod” and “mill” types. A tie rod cylinder has it’s end cap and seal gland cap held to the tube via tie rods. A mill cylinder has no end cap because it is a welded construction with the seal gland normally a screw in configuration. Cylinders can be used with oil, air, or water depending on their application and design. They also come in numerous shapes and sizes (bore and stroke) depending on their application.

You can find cylinders in virtually all industries. Another place to look in in the mobile industry. Large cylinders are used as shock absorbers on the large Quarry or Mining trucks, and on bulldozers, endloaders, etc. for various functions. They can also be found in the entertainment industry.

Accountability and Reliability

From the moment you contact K+S Services for hydraulic cylinder repair services, we dedicate our efforts to ensuring that you receive your parts back in exceptional working condition. The result is a cylinder that meets or exceeds OEM specifications and performs according to its original pressure rating. Our included Repair and Testing Report is complete with several key details for your review:

• Problems identified
• Parts repair or replaced
• Testing details, duration and results
• Probable root cause of failure
• Recommended installation instructions

Some of the Hydraulic Cylinder and Servo Actuator brands we service and repair include: Anker-Holth, Boxtel-Holland, Caterpillar, Graco, Hanna, Hydroline, Instrom, Kress, Komatsu, Lynair, Miller Milwaukee, MTS, Moog, Nopak, Rexroth, Sheffer, Tomkins and more.Contact Us

Top 5 Hydraulic Cylinder Repair Tips

Hydraulic cylinders are an integral part of the hydraulic system. They are a mechanical actuator that provides the unidirectional force. Integration of hydraulic cylinders will eliminate the presence of levers and gears. Both mobile(hydraulic presses, cranes, forges, and packing machines) and industrial systems(agricultural machines, construction vehicles, marine equipment) utilize hydraulic systems. Among them, most of the application use hydraulic cylinders for lifting, picking and gripping. 

Every hydraulic system will contain basic components like pumps, cylinders, valves, filters, etc.. Hydraulic cylinder is one of the least complicated components in the list. So, they are easy to repair and maintain. A person having basic knowledge about the hydraulic system can perform hydraulic cylinder repairing. Before explaining the repairing of cylinders, I will give you brief details on the causes of hydraulic cylinder failure. Damage of seals is a common reason that creates hydraulic cylinder damage. Seal damage occurs as a result of the incorrect fitting, corrosion, inappropriate metalwork clearance, etc. Fluid contamination will damage the piston rod or seal surface. Improper alignment of cylinder and load will damage the rod bearings or piston rods. An internally corroded barrel will contaminate the fluid inside it. Extreme temperature and chemical attack are the other reasons for failure.

Before performing the repairing, clean the surface properly and disconnect the hoses and plugs attached to it. After disconnecting the parts, drain all the fluid present inside the cylinder. Now, let’s begin the repairing of the hydraulic system. For that we need tools. Proper seal kit, rubber mallet, screwdriver, punch, pliers, emery cloth, and torque wrench are the tools required for repairing. Leaking hydraulic cylinder is the most common issue that results in cylinder repair. Disassembly of the cylinder, diagnosing the cause of failure, repairing or replacing faulty components, and rebuilding the cylinder are the steps involved in cylinder repairing. During the process of hydraulic cylinder repairing, always consider the below-mentioned cylinder repair tips.

1. If you disassemble the hydraulic cylinder as a part of repairing, inspect not only the failed part also perform a thorough inspection of all other components.
2. Hydraulic wear bands(also called wear bush or guide ring) are used for guiding pistons. So, don’t forget to assemble the wear band because this will reduce the metal-to-metal contact. 
3. Premature failure of rod seals indicates the bend on the rod. 
4. Metal tools will scratch the surface of the cylinder and will create problems like corrosion. So always choose the best-fit tools for repairing.
5. Larger hydraulic cylinders use high tension springs to perform operations. So, if you are an inexperienced worker, be careful while handling such cylinders.
6. For replacing seals, don’t measure the existing size of the seal. It will expand or compress according to the environmental condition.

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CNC Turning Machine

CNC Turning is a manufacturing process in which bars of material are held in a chuck and rotated while a tool is fed to the piece to remove material to create the desired shape. A turret , with tooling attached is programmed to move to the bar of raw material and remove material to create the programmed result. This is also called “subtraction machining” since it involves material removal. If the center has both tuning and milling capabilities, such as the one above, the rotation can be stopped to allow for milling out of other shapes.

• The starting material, though usual round, can be other shapes such as squares or hexagons.
• Depending on the bar feeder, the bar length can vary. This affects how much handling is required for volume jobs.
• CNC lathes or turning centers have tooling mounted on a turret which is computer-controlled. The more tools that that the turret can hold, the more options are available for complexities on the part.
• CNC’s with “live” tooling options, can stop the bar rotation and add additional features such as drilled holes, slots and milled surfaces.
• Some CNC turning centers have one spindle, allowing work to be done all from one side, while other turning centers, such as the one shown above, have two spindles, a main and sub-spindle. A part can be partially machined on the main spindle, moved to the sub-spindle and have additional work done to the other side this configuration.
• There are many different kinds of CNC turning centers with various types of tooling options, spindle options, outer diameter limitations as well as power and speed capabilities that affect the types of parts that can be economically made on it.

While a lot of factors go into determining if a part can be made most cost-effectively on a specific CNC turning center, some things we look at are:

• How many parts are needed short-term and long-term?
• What is the largest OD on the part ?
• Price of machine
• Easy avaliablity of machine

When it comes to machining parts, there are a lot of variables. Lot of Service providers can help you determine the best way to have your parts made.

We are dedicated, to provide, high quality products combined with excellent service. Thank you for your time and consideration. We hope you find the above in line with your requirement and eagerly look forward to serving you.

We are providing cnc repairing service  in .Amritsar,Batala, Chandigarh ,Jalandhar,Ludhiana ,Mandi Gobindgarh ,Mohali ,Patiala,Phagwara,Tarantaran ,Goraya,Hoshiarpur and in Punjab(India).

We are repairing CNC,VMC ,HMC spindle in punjab area 

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CNC turning machine

Conveyor system

A conveyor system is a common piece of mechanical handling equipment that moves materials from one location to another. Conveyors are especially useful in applications involving the transportation of heavy or bulky materials. Conveyor systems allow quick and efficient transportation for a wide variety of materials, which make them very popular in the material handling and packing industries. They also have popular consumer applications, as they are often found in supermarkets and airports, constituting the final leg of item/ bag delivery to customers. Many kinds of conveying systems are available and are used according to the various needs of different industries. There are chain conveyors (floor and overhead) as well. Chain conveyors consist of enclosed tracks, I-Beam, towline, power & free, and hand pushed trolleys.

Industries that use conveyor systems

A line shaft roller conveyormoves boxed produce at a distribution center

A Conveyor conveys papers at a newspaper print plant

Roller conveyor for carton transport in the apparel industry

Conveyor systems are used widespread across a range of industries due to the numerous benefits they provide.

• Conveyors are able to safely transport materials from one level to another, which when done by human labor would be strenuous and expensive.
• They can be installed almost anywhere, and are much safer than using a forklift or other machine to move materials.
• They can move loads of all shapes, sizes and weights. Also, many have advanced safety features that help prevent accidents.
• There are a variety of options available for running conveying systems, including the hydraulic , mechanical and fully automated systems, which are equipped to fit individual needs.

Conveyor systems are commonly used in many industries, including the Mining, automotive, agriculture, computer , electronic, food proccesing , aerospace , pharmaceutical, chemical, bottling and canning, print finishing and packing. Although a wide variety of materials can be conveyed, some of the most common include food items such as beans and nuts, bottles and cans, automotive components, scrap metal, pills and powders, wood and furniture and grain and animal feed. Many factors are important in the accurate selection of a conveyor system. It is important to know how the conveyor system will be used beforehand. Some individual areas that are helpful to consider are the required conveyor operations, such as transportation, accumulation and sorting, the material sizes, weights and shapes and where the loading and pickup points need to be.

Care and maintenance of conveyor systems

A conveyor system is often the lifeline to a company’s ability to effectively move its product in a timely fashion. The steps that a company can take to ensure that it performs at peak capacity, include regular inspections and system audits, close monitoring of motors and reducers, keeping key parts in stock, and proper training of personnel.

Increasing the service life of a conveyor system involves: choosing the right conveyor type, the right system design and paying attention to regular maintenance practices.

A conveyor system that is designed properly will last a long time with proper maintenance. Here are six of the biggest problems to watch for in overhead type conveyor systems including I-beam monorails, enclosed track conveyors and power and free conveyors. Overhead conveyor systems have been used in numerous applications from shop displays, assembly lines to paint finishing plants and more.

Poor take-up adjustment: this is a simple adjustment on most systems yet it is often overlooked. The chain take-up device ensures that the chain is pulled tight as it leaves the drive unit. As wear occurs and the chain lengthens, the take-up extends under the force of its springs. As they extend, the spring force becomes less and the take-up has less effect. Simply compress the take-up springs and your problem goes away. Failure to do this can result in chain surging, jamming, and extreme wear on the track and chain. Take-up adjustment is also important for any conveyor using belts as a means to power rollers, or belts themselves being the mover. With poor-take up on belt-driven rollers, the belt may twist into the drive unit and cause damage, or at the least a noticeable decrease or complete loss of performance may occur. In the case of belt conveyors, a poor take-up may cause drive unit damage or may let the belt slip off of the side of the chassis.

Lack of lubrication: chain bearings require lubrication in order to reduce friction. The chain pull that the drive experiences can double if the bearings are not lubricated. This can cause the system to overload by either its mechanical or electrical overload protection. On conveyors that go through hot ovens, lubricators can be left on constantly or set to turn on every few cycles.

Contamination: paint, powder, acid or alkaline fluids, abrasives, glass bead, steel shot, etc. can all lead to rapid deterioration of track and chain. Ask any bearing company about the leading cause of bearing failure and they will point to contamination. Once a foreign substance lands on the raceway of a bearing or on the track, pitting of the surface will occur, and once the surface is compromised, wear will accelerate. Building shrouds around your conveyors can help prevent the ingress of contaminants. Or, pressurize the contained area using a simple fan and duct arrangement. Contamination can also apply to belts (causing slippage, or in the case of some materials premature wear), and of the motors themselves. Since the motors can generate a considerable amount of heat, keeping the surface clean is an almost-free maintenance procedure that can keep heat from getting trapped by dust and grime, which may lead to motor burnout.

Product handling: in conveyor systems that may be suited for a wide variety of products, such as those in distribution centers, it is important that each new product be deemed acceptable for conveying before being run through the materials handling equipment. Boxes that are too small, too large, too heavy, too light, or too awkwardly shaped may not convey, or may cause many problems including jams, excess wear on conveying equipment, motor overloads, belt breakage, or other damage, and may also consume extra man-hours in terms of picking up cases that slipped between rollers, or damaged product that was not meant for materials handling. If a product such as this manages to make it through most of the system, the sortation system will most likely be the affected, causing jams and failing to properly place items where they are assigned. Any and all cartons handled on any conveyor should be in good shape or spills, jams, downtime, and possible accidents and injuries may result.

Drive train: notwithstanding the above, involving take-up adjustment, other parts of the drive train should be kept in proper shape. Broken O-rings on a Lineshaft, pneumatic parts in disrepair, and motor reducers should also be inspected. Loss of power to even one or a few rollers on a conveyor can mean the difference between effective and timely delivery, and repetitive nuances that can continually cost downtime.

Bad belt tracking or timing: in a system that uses precisely controlled belts, such as a sorter system, regular inspections should be made that all belts are traveling at the proper speeds at all times. While usually a computer controls this with Pulse Position Indicators, any belt not controlled must be monitored to ensure accuracy and reduce the likelihood of problems. Timing is also important for any equipment that is instructed to precisely meter out items, such as a merge where one box pulls from all lines at one time. If one were to be mistimed, product would collide and disrupt operation. Timing is also important wherever a conveyor must “keep track” of where a box is, or improper operation will result.

Since a conveyor system is a critical link in a company’s ability to move its products in a timely fashion, any disruption of its operation can be costly. Most downtime can be avoided by taking steps to ensure a system operates at peak performance, including regular inspections, close monitoring of motors and reducers, keeping key parts in stock, and proper training of personnel.

Impact and wear-resistant materials used in conveyor systems

Conveyor systems require materials suited to the displacement of heavy loads and the wear-resistance to hold-up over time without seizing due to deformation. Where static control is a factor, special materials designed to either dissipate or conduct electrical charges are used. Examples of conveyor handling materials include UHMW, nylon, Nylatron NSM, HDPE, Tivar, Tivar ESd, and polyurethane.

Growth of conveyor systems in various industries

As far as growth is concerned the material handling and conveyor system makers are getting utmost exposure in the industries like automotive, pharmaceutical, packaging and different production plants. The portable conveyors are likewise growing fast in the construction sector and by the year 2014 the purchase rate for conveyor systems in North America, Europe and Asia is likely to grow even further. The most commonly purchased types of conveyors are line-shaft roller conveyors, chain conveyors and conveyor belts at packaging factories and industrial plants where usually product finishing and monitoring are carried. Commercial and civil sectors are increasingly implementing conveyors at airports, shopping malls, etc.

Types

Belt driven roller conveyor for cartons and totes.

Flexible conveyor

• Aero-mechanical conveyor

• Automotive conveyor

• Belt conveyor

• Belt-driven live roller conveyor

• Bucket conveyor

• Chain conveyor

• Chain-driven live roller conveyor

• Drag conveyor
• Dust-proof conveyor
• Electric track vehicle system
• Flexible conveyor
• Gravity conveyor
• Gravity skatewheel conveyor
• Line shaft roller conveyor
• Motorized-drive roller conveyor
• Over head I beam conveyor
• Overland conveyor
• Pharmaceutical conveyor
• Plastic belt conver
• Pneaumatic conveyor
• screw or auger conveyor
• Spiral conveyor
• Vertical conveyor
• Vibrating conveyor
• Wire mesh conveyor

Pneumatic

Every pneumatic system uses pipes or ducts called transportation lines that carry a mixture of materials and a stream of air. These materials are free flowing powdery materials like cement and fly ash . Products are moved through tubes by air pressure. Pneumatic conveyors are either carrier systems or dilute-phase systems; carrier systems simply push items from one entry point to one exit point, such as the money-exchanging pneaumatic tubes used at a bank drive through window. Dilute-phase systems use push-pull pressure to guide materials through various entry and exit points. Air compressors or blowers can be used to generate the air flow. Three systems used to generate high-velocity air stream:

1. Suction or vacuum systems, utilizing a vacuum created in the pipeline to draw the material with the surrounding air. The system operated at a low pressure, which is practically 0.4–0.5 atm below atmosphere, and is utilized mainly in conveying light free flowing materials.
2. Pressure-type systems, in which a positive pressureis used to push material from one point to the next. The system is ideal for conveying material from one loading point to a number of unloading points. It operates at a pressure of 6 atm and upwards.
3. Combination systems, in which a suction system is used to convey material from a number of loading points and a pressure system is employed to deliver it to a number of unloading points.

Vibrating

A vibrating conveyor is a machine with a solid conveying surface which is turned up on the side to form a trough. They are used extensively in food-grade applications to convey dry bulk solids  where sanitation, washdown, and low maintenance are essential. Vibrating conveyors are also suitable for harsh, very hot, dirty, or corrosive environments. They can be used to convey newly-cast metal parts which may reach upwards of 1,500 °F (820 °C). Due to the fixed nature of the conveying pans vibrating conveyors can also perform tasks such as sorting, screening, classifying and orienting parts. Vibrating conveyors have been built to convey material at angles exceeding 45° from horizontal using special pan shapes. Flat pans will convey most materials at a 5° incline from horizontal line.

Flexible

The flexible conveyor is based on a conveyor beam in aluminium or stainless steel , with low-friction slide rails guiding a plastic multi-flexing chain. Products to be conveyed travel directly on the conveyor, or on pallets/carriers. These conveyors can be worked around obstacles and keep production lines flowing. They are made at varying levels and can work in multiple environments. They are used in food packaging, case packing, and pharmaceutical industries and also in large retail stores such asWal mart  and K mart .

Spiral

Like Vertical conveyors , spiral conveyors raise and lower materials to different levels of a facility. In contrast, spiral conveyors are able to transport material loads in a continuous flow. A helical spiral or screw rotates within a sealed tube and the speed makes the product in the conveyor rotate with the screw. The tumbling effect provides a homogeneous mix of particles in the conveyor, which is essential when feeding pre-mixed ingredients and maintaining mixing integrity. Industries that require a higher output of materials – food and beverage, retail case packaging, pharmaceuticals – typically incorporate these conveyors into their systems over standard vertical conveyors due to their ability to facilitate high throughput. Most spiral conveyors also have a lower angle of incline or decline (11 degrees or less) to prevent sliding and tumbling during operation.

Vertical

Vertical conveyors, also commonly referred to as freight lifts and material lifts, are conveyor systems used to raise or lower materials to different levels of a facility during the handling process. Examples of these conveyors applied in the industrial assembly process include transporting materials to different floors. While similar in look to freight elevators, vertical conveyors are not equipped to transport people, only materials.

Vertical lift conveyors contain two adjacent, parallel conveyors for simultaneous upward movement of adjacent surfaces of the parallel conveyors. One of the conveyors normally has spaced apart flights (pans) for transporting bulk food items. The dual conveyors rotate in opposite directions, but are operated from one gear box to ensure equal belt speed. One of the conveyors is pivotally hinged to the other conveyor for swinging the attached conveyor away from the remaining conveyor for access to the facing surfaces of the parallel conveyors.^[3] Vertical lift conveyors can be manually or automatically loaded and controlled.^[4] Almost all vertical conveyors can be systematically integrated with horizontal conveyors, since both of these conveyor systems work in tandem to create a cohesive material handling assembly line.

Like Spiral conveyors , vertical conveyors that use forks can transport material loads in a continuous flow. With these forks the load can be taken from one horizontal conveyor and put down on another horizontal conveyor on a different level. By adding more forks, more products can be lifted at the same time. Conventional vertical conveyors must have input and output of material loads moving in the same direction. By using forks many combinations of different input- and output- levels in different directions are possible. A vertical conveyor with forks can even be used as a vertical sorter. Compared to a spiral conveyor a vertical conveyor – with or without forks – takes up less space.

Vertical reciprocating conveyors are another type of unit handling system. Typical applications include moving unit loads between floor levels, working with multiple accumulation conveyors, and interfacing overhead conveyors line. Common material to be conveyed includes pallets, sacks, custom fixtures or product racks and more.

Heavy-duty roller

Heavy-duty roller conveyors are used for moving items that weigh at least 500 pounds (230 kg). This type of conveyor makes the handling of such heavy equipment/products easier and more time effective. Many of the heavy duty roller conveyors can move as fast as 75 feet per minute (23 m/min).

Other types of heavy-duty roller conveyors are gravity roller conveyors, chain-driven live roller conveyors, pallet accumulation conveyors, multi-strand chain conveyors, and chain and roller transfers.

Gravity roller conveyors are easy to use and are used in many different types of industries such as automotive and retail.

Chain-driven live roller conveyors are used for single or bi-directional material handling. Large, heavy loads are moved by chain driven live roller conveyors.

Pallet accumulation conveyors are powered through a mechanical clutch. This is used instead of individually powered and controlled sections of conveyors.

Multi-strand chain conveyors are used for double-pitch roller chains. Products that cannot be moved on traditional roller conveyors can be moved by a multi-strand chain conveyor.

Chain and roller conveyors are short runs of two or more strands of double-pitch chain conveyors built into a chain-driven line roller conveyor. These pop up under the load and move the load off of the conveyor.

In machine tool, a spindlehttp://https://www.youtube.com/watch?v=7Qah4iledMQ is a Rotating axis of the machine, which often has a Shaft at its heart. The shaft itself is called a spindle, but also, in shop-floor practice, the word often is used metonymically to refer to the entire rotary unit, including not only the shaft itself, but its bearings and anything attached to it

A machine tool may have several , such as the headstock and tailstock on a bench lathe. That is usually the biggest one. References to “the spindle” without further qualification imply the main . Some machine tools that specialize in high-volume mass production have a group of 4, 6, or even more main .

Contents 

High speed spindle

High speed spindles are used strictly in machines, like CNC mills designed for metal work. There are two types of high speed , each with different designs:

Belt-driven spindle

Consisting of spindle and bearing shafts held within the spindle housing, the belt-driven spindle is powered by an external motor connected via a belt-pulley system.

Integral motor spindle

• Internal Motor: limited power and torque due to restricted space within the  housing
• Speed Range: 20,000-60,000 RPM
• Advantage: high top speed expands application use
• Disadvantage: sensitive life range according to use

Both types, the belt-driven and the integral motor , have advantages and disadvantages according to their design. Which one is more desirable depends on the purpose of the machine and product(s) being produced.

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 Spindle

Milling is the process of machining using rotary cutters to remove material by advancing a cutter into a work piece. This may be done varying directionon one or several axes, cutter head speed, and pressure. Milling covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations. It is one of the most commonly used processes for machining custom parts to precise tolerances.

Milling can be done with a wide range of machine tools. The original class of machine tools for milling was the milling machine (often called a mill). After the advent of CNC  in the 1960s, milling machines evolved into machining centers: milling machines augmented by automatic tool changers, tool magazines , CNC capability, coolant systems, and enclosures. Milling centers are generally classified as vertical machining centers (VMC) or horizontal machining centers (HMC).

Milling Process in a milling machine

Milling is a cutting process that uses at milling cutters  to remove material from the surface of a work piece. The milling cutter is a rotary cutting tool, often with multiple cutting points. As opposed to drilling, where the tool is advanced along its rotation axis, the cutter in milling is usually moved perpendicular to its axis so that cutting occurs on the circumference of the cutter. As the milling cutter enters the work piece, the cutting edges (flutes or teeth) of the tool repeatedly cut into and exit from the material, shaving off chips from the work piece with each pass. The cutting action is shear deformation; material is pushed off the work piece in tiny clumps that hang together to a greater or lesser extent to form chips. This makes metal cutting somewhat different from slicing softer materials with a blade

The milling process removes material by performing many separate, small cuts. This is accomplished by using a cutter with many teeth, spinning the cutter at high speed, or advancing the material through the cutter slowly; most often it is some combination of these three approaches. The speeds and feeds used are varied to suit a combination of variables. The speed at which the piece advances through the cutter is called feed rate, or just feed; it is most often measured in length of material per full revolution of the cutter.

There are two major classes of milling process:

• In face milling, the cutting action occurs primarily at the end corners of the milling cutter. Face milling is used to cut flat surfaces (faces) into the work piece, or to cut flat-bottomed cavities.
• In peripheral milling, the cutting action occurs primarily along the circumference of the cutter, so that the cross section of the milled surface ends up receiving the shape of the cutter. In this case the blades of the cutter can be seen as scooping out material from the work piece. Peripheral milling is well suited to the cutting of deep slots, threads, and gear teeth.

Milling cutters

Many different types of cutting tools are used in the milling process. Milling cutters such as end mill may have cutting surfaces across their entire end surface, so that they can be drilled into the work piece (plunging). Milling cutters may also have extended cutting surfaces on their sides to allow for peripheral milling. Tools optimized for face milling tend to have only small cutters at their end corners.

The cutting surfaces of a milling cutter are generally made of a hard and temperature-resistant material, so that they wear  slowly. A low cost cutter may have surfaces made of high speed steel. More expensive but slower-wearing materials include cemented carbide. Thin film coatings may be applied to decrease friction or further increase hardness.

There are cutting tools typically used in milling machines or machining centers to perform milling operations . They remove material by their movement within the machine or directly from the cutter’s shape

As material passes through the cutting area of a milling machine, the blades of the cutter take swarfs of material at regular intervals. Surfaces cut by the side of the cutter therefore always contain regular ridges. The distance between ridges and the height of the ridges depend on the feed rate, number of cutting surfaces, the cutter diameter. With a narrow cutter and rapid feed rate, these revolution ridges can be significant variations in the surface finish

The face milling process can in principle produce very flat surfaces. However, in practice the result always shows visible trochodial marks following the motion of points on the cutter’s end face. These revolution marks give the characteristic finish of a face milled surface. Revolution marks can have significant roughness depending on factors such as flatness of the cutter’s end face and the degree of perpendicularity between the cutter’s rotation axis and feed direction. Often a final pass with a slow feed rate is used to improve the surface finish after the bulk of the material has been removed. In a precise face milling operation, the revolution marks will only be microscopic scratches due to imperfections in the cutting edge.

Gang milling refers to the use of two or more nilling cutters  mounted on the same arbor   in a horizontal-milling setup. All of the cutters  may perform the same type of operation, or each cutter may perform a different type of operation. For example, if several workpieces need a slot, a flat surface, and an angular groove, a good method to cut these would be gang milling. All the completed workpieces would be the same, and milling time per piece would be minimized.

Gang milling was especially important before the CNC  era, because for duplicate part production, it was a substantial efficiency improvement over manual-milling one feature at an operation, then changing machines (or changing setup of the same machine) to cut the next op. Today, CNC mills with automatic tool change and 4- or 5-axis control obviate gang-milling practice to a large extent.

Equipment

Milling is performed with a milling cutter in various forms, held in a collett or similar which, in turn, is held in the spindle of a milling machine.

Types and nomenclature

Mill orientation is the primary classification for milling machines. The two basic configuration are vertical and horizontal. However, there are alternative classifications according to method of control, size, purpose and power source.

Mill orientation

Vertical milling machine

In the vertical mill the spindle axis is vertically oriented. milling cutters  are held in the spindle and rotate on its axis. The spindle can generally be extended (or the table can be raised/lowered, giving the same effect), allowing plunge cuts and drilling. There are two subcategories of vertical mills: the bed mill and the turret mill.

• A turret mill has a stationary spindle and the table is moved both perpendicular and parallel to the spindle axis to accomplish cutting. The most common example of this type is the Bridgeport, described below. Turret mills often have a quill which allows the milling cutter to be raised and lowered in a manner similar to a drill press. This type of machine provides two methods of cutting in the vertical Zdirection: by raising or lowering the quill, and by moving the knee.
• In the bed mill, however, the table moves only perpendicular to the spindle’s axis, while the spindle itself moves parallel to its own axis.

Turret mills are generally considered by some to be more versatile of the two designs. However, turret mills are only practical as long as the machine remains relatively small. As machine size increases, moving the knee up and down requires considerable effort and it also becomes difficult to reach the quill feed handle . Therefore, larger milling machines are usually of the bed type.

A third type also exists, a lighter machine, called a mill-drill, which is a close relative of the vertical mill and quite popular with hobbyists. A mill-drill is similar in basic configuration to a small drill press, but equipped with an X-Y table. They also typically use more powerful motors than a comparably sized drill press, with potentiometer-controlled speed and generally have more heavy-duty spindle bearings than a drill press to deal with the lateral loading on the spindle that is created by a milling operation. A mill drill also typically raises and lowers the entire head, including motor, often on a dovetailed vertical, where a drill press motor remains stationary, while the arbor raises and lowers within a driving collar. Other differences that separate a mill-drill from a drill press may be a fine tuning adjustment for the Z-axis, a more precise depth stop, the capability to lock the X, Y or Z axis, and often a system of tilting the head or the entire vertical column and powerhead assembly to allow angled cutting. Aside from size and precision, the principal difference between these hobby-type machines and larger true vertical mills is that the X-Y table is at a fixed elevation; the Z-axis is controlled in basically the same fashion as drill press, where a larger vertical or knee mill has a vertically fixed milling head, and changes the X-Y table elevation. As well, a mill-drill often uses a standard drill press-type Jacob’s chuck, rather than an internally tapered arbor that accepts collets These are frequently of lower quality than other types of machines, but still fill the hobby role well because they tend to be benchtop machines with small footprints and modest price tags.

Horizontal milling machine

The choice between vertical and horizontal spindle orientation in milling machine design usually hinges on the shape and size of a workpiece and the number of sides of the workpiece that require machining. Work in which the spindle’s axial movement is normal  to one plane, with an endmill as the cutter, lends itself to a vertical mill, where the operator can stand before the machine and have easy access to the cutting action by looking down upon it. Thus vertical mills are most favored for diesinking work (machining a mould into a block of metal).Heavier and longer workpieces lend themselves to placement on the table of a horizontal mill.

Computer numerical control

Most cnc milling machines (also called machining centers) are computer controlled vertical mills with the ability to move the spindle vertically along the Z-axis. This extra degree of freedom permits their use in diesinking, engraving applications, and 2.5D surfaces such as relief sculptures. When combined with the use of conical tools , it also significantly improves milling precision without impacting speed, providing a cost-efficient alternative to most flat-surface hand-engraving  work.

Five-axis machining center with rotating table and computer interface

CNC  machines can exist in virtually any of the forms of manual machinery, like horizontal mills. The most advanced CNC milling-machines, themulti axis , add two more axes in addition to the three normal axes Horizontal milling machines also have a C or Q axis, allowing the horizontally mounted workpiece to be rotated, essentially allowing asymmetric and eccentric center. The fifth axis  (B axis) controls the tilt of the tool itself. When all of these axes are used in conjunction with each other, extremely complicated geometries, even organic geometries such as a human head can be made with relative ease with these machines. But the skill to program such geometries is beyond that of most operators. Therefore, 5-axis milling machines are practically always programmed with cam

The operating system of such machines is a closed loop system and functions on feedback. These machines have developed from the basic NC machines. A computerized form of NC machines is known as CNC machines. A set of instructions is used to guide the machine for desired operation

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Milling machine

Numerical control

Numerical control (also computer numerical control,http://https://www.youtube.com/watch?v=mzMYlG4RQfIand commonly called CNC) is the automatic control  of Machinig  tools (drills, boring tools, lathes,Spindle ) and 3d printers  by means of a computer. A CNC machine processes a piece of material (metal, plastic, wood, ceramic, or composite) to meet specifications by following a coded programmed instruction and without a manual operator.

A CNC machine is a motorized maneuverable tool and often a motorized maneuverable platform, which are both controlled by a computer, according to specific input instructions. Instructions are delivered to a CNC machine in the form of a sequential program of machine control instructions such as G codes  and then executed. The program can be written by a person or, far more often, generated by graphical computer added design  (CAD) software. In the case of 3D printers, the part to be printed is “sliced”, before the instructions (or the program) is generated. 3D printers also use G-Code.

CNC is a vast improvement over non-computerized machining that must be manually controlled (e.g. using devices such as hand wheels or levers) or mechanically controlled by pre-fabricated pattern guides (cams ). In modern CNC systems, the design of a mechanical part and its manufacturing program is highly automated. The part’s mechanical dimensions are defined using CAD software and then translated into manufacturing directives by computer added programming (CAM) software. The resulting directives are transformed into the specific commands necessary for a particular machine to produce the component, and then are loaded into the CNC machine.

Since any particular component might require the use of a number of different tools – drills, etc. – modern machines often combine multiple tools into a single “cell”. In other installations, a number of different machines are used with an external controller and human or robotic operators that move the component from machine to machine. In either case, the series of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD.

History

The first NC machines were built in the 1940s and 1950s, based on existing tools that were modified with motors that moved the tool or part to follow points fed into the system on punched tape. Those earlyservo mechanism were rapidly augmented with analog and digital computers, creating the modern CNC machine tools that have revolutionized machining processes.

Description

Motion is controlling multiple axes, normally at least two (X and Y),and a tool spindle that moves in the Z (depth). The position of the tool is driven by direct-drive stepper motors or servo motors in order to provide highly accurate movements, or in older designs, motors through a series of step-down gears. Open loop control works as long as the forces are kept small enough and speeds are not too great. On commercial metalworking machines, closed loop controls are standard and required in order to provide the accuracy, speed, and repeatbility  demanded.

Parts Description

As the controller hardware evolved, the mills themselves also evolved. One change has been to enclose the entire mechanism in a large box as a safety measure, often with additional safety interlocks to ensure the operator is far enough from the working piece for safe operation. Most new CNC systems built today are 100% electronically controlled.

CNC-like systems are used for any process that can be described as movements and operations.

Examples of CNC machines

Tool / machine crashing

In CNC, a “crash” occurs when the machine moves in such a way that is harmful to the machine, tools, or parts being machined, sometimes resulting in bending or breakage of cutting tools, accessory clamps, vises, and fixtures, or causing damage to the machine itself by bending guide rails, breaking drive screws, or causing structural components to crack or deform under strain. A mild crash may not damage the machine or tools, but may damage the part being machined so that it must be scrapped.

Many CNC tools have no inherent sense of the absolute position of the table or tools when turned on. They must be manually “homed” or “zeroed” to have any reference to work from, and these limits are just for figuring out the location of the part to work with it, and are not really any sort of hard motion limit on the mechanism. It is often possible to drive the machine outside the physical bounds of its drive mechanism, resulting in a collision with itself or damage to the drive mechanism. Many machines implement control parameters limiting axis motion past a certain limit in addition to physical limit switches . However, these parameters can often be changed by the operator.

Many CNC tools also do not know anything about their working environment. Machines may have load sensing systems on spindle and axis drives, but some do not. They blindly follow the machining code provided and it is up to an operator to detect if a crash is either occurring or about to occur, and for the operator to manually abort the active process. Machines equipped with load sensors can stop axis or spindle movement in response to an overload condition, but this does not prevent a crash from occurring. It may only limit the damage resulting from the crash. Some crashes may not ever overload any axis or spindle drives.

If the drive system is weaker than the machine structural integrity, then the drive system simply pushes against the obstruction and the drive motors “slip in place”. The machine tool may not detect the collision or the slipping, so for example the tool should now be at 210mm on the X axis, but is, in fact, at 32mm where it hit the obstruction and kept slipping. All of the next tool motions will be off by −178mm on the X axis, and all future motions are now invalid, which may result in further collisions with clamps, vises, or the machine itself. This is common in open loop stepper systems, but is not possible in closed loop systems unless mechanical slippage between the motor and drive mechanism has occurred. Instead, in a closed loop system, the machine will continue to attempt to move against the load until either the drive motor goes into an overload condition or a servo motor fails to get to the desired position.

Collision detection and avoidance is possible, through the use of absolute position sensors (optical encoder strips or disks) to verify that motion occurred, or torque sensors or power-draw sensors on the drive system to detect abnormal strain when the machine should just be moving and not cutting, but these are not a common component of most hobby CNC tools.

Instead, most hobby CNC tools simply rely on the assumed accuracy of stepper motors  that rotate a specific number of degrees in response to magnetic field changes. It is often assumed the stepper is perfectly accurate and never missteps, so tool position monitoring simply involves counting the number of pulses sent to the stepper over time. An alternate means of stepper position monitoring is usually not available, so crash or slip detection is not possible.

Commercial CNC metalworking machines use closed loop feedback controls for axis movement. In a closed loop system, the controller monitors the actual position of each axis with an absolute or incremental encoders. With proper control programming, this will reduce the possibility of a crash, but it is still up to the operator and programmer to ensure that the machine is operated in a safe manner. However, during the 2000s and 2010s, the software for machining simulation has been maturing rapidly, and it is no longer uncommon for the entire machine tool envelope (including all axes, spindles, chucks, turrets, tool holders, tailstocks, fixtures, clamps, and stock) to be modeled accurately with 3d solid models, which allows the simulation software to predict fairly accurately whether a cycle will involve a crash. Although such simulation is not new, its accuracy and market penetration are changing considerably because of computing advancements.

Numerical precision and equipment backlash

Within the numerical systems of CNC programming it is possible for the code generator to assume that the controlled mechanism is always perfectly accurate, or that precision tolerances are identical for all cutting or movement directions. This is not always a true condition of CNC tools. CNC tools with a large amount of mechanical backlashcan still be highly precise if the drive or cutting mechanism is only driven so as to apply cutting force from one direction, and all driving systems are pressed tightly together in that one cutting direction. However a CNC device with high backlash and a dull cutting tool can lead to cutter chatter and possible workpiece gouging. Backlash also affects precision of some operations involving axis movement reversals during cutting, such as the milling of a circle, where axis motion is sinusoidal. However, this can be compensated for if the amount of backlash is precisely known by linear encoders or manual measurement.

The high backlash mechanism itself is not necessarily relied on to be repeatedly precise for the cutting process, but some other reference object or precision surface may be used to zero the mechanism, by tightly applying pressure against the reference and setting that as the zero reference for all following CNC-encoded motions. This is similar to the manual machine tool method of clamping a micrometer onto a reference beam and adjusting the Vernier dial to zero using that object as the reference.

Positioning control system

In numerical control systems, the position of the tool is defined by a set of instructions called the part programes.

Positioning control is handled by means of either an open loop or a closed loop system. In an open loop system, communication takes place in one direction only: from the controller to the motor. In a closed loop system, feedback is provided to the controller so that it can correct for errors in position, velocity, and acceleration, which can arise due to variations in load or temperature. Open loop systems are generally cheaper but less accurate. Stepper motors can be used in both types of systems, while servo motors can only be used in closed systems.

Cartesian Coordinates

The G & M code positions are all based on a three dimensional Cartesian coordinate system. This system is a typical plane often seen in mathematics when graphing. This system is required to map out the machine tool paths and any other kind of actions that need to happen in a specific coordinate. Absolute coordinates are what is generally used more commonly for machines and represent the (0,0,0) point on the plane. This point is set on the stock material in order to give a starting point or “home position” before starting the actual machining.

M-codes

[Code Miscellaneous Functions (M-Code)]. M-codes are miscellaneous machine commands that do not command axis motion. The format for an M-code is the letter M followed by two to three digits; for example:[M02 End of Program][M03 Start Spindle – Clockwise][M04 Start Spindle – Counter Clockwise][M05 Stop Spindle][M06 Tool Change][M07 Coolant on mist coolant][M08 Flood coolant on][M09 Coolant off][M10 Chuck open][M11 Chuck close][M13 BOTH M03&M08 Spindle clockwise rotation & flood coolant][M14 BOTH M04&M08 Spindle counter clockwise rotation & flood coolant][M16 Special tool call][M19 Spindle orientate][M29 DNC mode ][M30 Program reset & rewind][M38 Door open][M39 Door close][M40 Spindle gear at middle][M41 Low gear select][M42 High gear select][M53 Retract Spindle] (raises tool spindle above current position to allow operator to do whatever they would need to do)[M68 Hydraulic chuck close][M69 Hydraulic chuck open][M78 Tailstock advancing][M79 Tailstock reversing]

G-codes

G codes are used to command specific movements of the machine, such as machine moves or drilling functions. The format for a G-code is the letter G followed by two to three digits; for example G01. G-codes differ slightly between a mill and lathe application, for example:[G00 Rapid Motion Positioning][G01 Linear Interpolation Motion][G02 Circular Interpolation Motion-Clockwise][G03 Circular Interpolation Motion-Counter Clockwise][G04 Dwell (Group 00) Mill][G10 Set offsets (Group 00) Mill][G12 Circular Pocketing-Clockwise][G13 Circular Pocketing-Counter Clockwise]

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CNC control

We cover all CNC systems in mainstream use in the industryhttp://https://www.youtube.com/watch?v=SZtLtfS_LCA. As always, repaired units are dynamically tested under load in real world closed loop applications.

CNC Machine Repair Services

Computer numerical control (CNC) controllers are essential for the fine and delicate work required to make the specialized parts needed for more complex machinery. If something goes wrong with one of these devices, it can spell disaster for the production process. There are numerous parts of the system of a CNC controller that could potentially develop issues, including the power controls, limit switch interfaces, servo motor drivers, protection circuitry or even the power source itself.

When it turns out that one of the more uncommon problems is what is affecting a device, it can be difficult to diagnose and even harder to conduct CNC machine repair services. Our technicians are familiar with all types of CNC controller issues whether common or unique.

Stuck Axis

One situation that can cause a CNC controller to fail is a mechanical hangup to the proper movement of one or more axis of the CNC machine itself. In order to perform all of the correct cuts, the device needs to be able to smoothly move on all three planes (x, y and z). If the CNC controller is reporting, for example, that the z-axis is stuck, this indicates that the machine is unable to properly move along that plane.

Even the slightest obstruction could be the cause of this tricky error. It may be that there is something stuck between the nut and the screw. Another possible cause of this problem is that the slides are out of alignment. Even a small issue could cause the entire cutter to freeze up, but it may be possible to narrow down the issue by running the device through the whole range of motion. Trust the our experts to identify any axis errors you’re experiencing.

Broken Emergency Stop Loop

The emergency stop loop on a CNC controller is designed to halt the operation of any machinery in case of a potential safety hazard. This is normally a good functionality to have, but occasionally the emergency stop loop will be running through the CNC system when there is no actual cause for it to be doing so, and this is known as a broken emergency stop loop.

If the controller is not enabled, and the ready light is blinking, it is possible that a broken emergency stop loop is the issue. One way to diagnose this is to disengage all emergency stop switches, and then attempt to enable the controller. It might be helpful to have one person click to enable the device while someone else watches the LED display. If the ready light blinks once after the controller is enabled, it indicates a broken emergency stop loop.

There could be numerous causes for this issue. There may be broken or detached wiring in the emergency stop box. It is also possible that there is an issue with bent or dislodged pins in the control board itself. Determining the specific cause is an involved process that requires carefully removing jumpers one at a time and turning the machine off and on again to narrow down where the problem is coming from.

Runaway Axis

When this error occurs, one axis of the machine travels too far and may even crash, which is known as “taking off.” Sometimes a damaged cable is the cause of this problem, but it may also be that the encoder needs to be replaced. One indicator of this problem is if the Positional Display numbers do not accurately reflect the change in position when the axis is moved by hand.

Complicated Issues Require Expert CNC Repair

The above issues are just a few examples of complex situations where diagnosing and repairing the cause of an error can take a lot of time, and may not have a cut and dry solution. When times like these arise, the specialized team of technicians Services is here to help solve the problem quickly and affordably. For assistance, call +91 7888776715,9915759967.

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