Computer Numerical Control

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CNC Machines

What is a CNC Machine? CNC stands for Computer Numeric Control. Sounds complicated, but it isn’t. Years ago, it was just NC, or Numeric Control. Since, they’ve added computers to control the machine.

In the simplest of terms, think of a drill press. It’s a machine that drills holes. But before you can drill the hole, you have to loosen the chuck, install the correct drill bit, drill the hole in the correct place, turn off the drill, and remove the drill bit. Manually, this could be time consuming and cause fatigue over the course of numerous parts. This is a simple example, but throw in some lathe or milling machining and you have a greater chance for error.

With the CNC machine, all of this drilling can be done automatically instead of the manual process listed above. Machining has to be precise, and whether you use a CNC lathe or milling machine, you have to make sure the part is right. The computer takes a lot of the guesswork out of the machining of these parts. In fact, a CNC programmer can sometimes get bored watching the machine do all the work.

But there is more programming for the machine than you would think. The operator has to enter a set of instructions. The programming uses about 50 words and tells the machine how fast, how deep, and location for machining.

What can you do with a CNC machine? In manufacturing, you can use this tool for milling, drilling, reaming, boring and counter boring. You can also groove and thread parts in a CNC turning center. You may have several setups including CNC lathes, CNC drill and tap area, CNC milling, or even CNC grinding.

EDM (electrical discharge machining) can also take advantage of CNC operations. EDM can be either vertical or wire. A vertical EDM machine uses an electrode to make a cavity for a plastic injection-molding machine. A wire EDM machine uses a wire to cut metal for a tooling operation for fabrication. EDM is more closely related to making tooling for other machines, people often overlook the use of CNC with these machines.

CNC machines can also be used with routers in the wood industry. CNC can also be used with lettering and engraving.

I hope this gave you some basic information about what a CNC machine is and what they are used for.

Stuart Simpson

http://www.cnc-machine-review.com

CNC Rotary Tables

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A CNC Rotary table is a piece of CNC milling equipment used for precision metalworking. It is similar than a dividing head or indexing head except that it is fixed to be used in only two planes, the horizontal plane and the vertical plane. A CNC Rotary table is used for CNC milling and is made up of a solid base that has proper provisions for clamping metal material on tables and other kinds of equipment. The table of this CNC milling equipment is a precision machined disc that also has provision to clamp materials in it, that is aided with a T slot. This CNC milling equipment can rotate by itself or be controlled by a worm or a handheld operational control.

1. Extreme Accuracy

A graduated dial and a vernier scale allow this rotary table to be positioned to a high degree of accuracy. The center of CNC milling equipment has hole that allows a morse taper center or fixture to be inserted. A tailstock is usually provided if the rotary table can be mounted from its end, so that the axis will be horizontal. The most common use of this CNC milling equipment is on it vertical axis that in this mode is on the same plane as the cutter when it is used on a milling machine.

2. Coaxial Design

If the CNC rotary table is mounted on a secondary table the work piece is adjusted in the center around the rotary tables axis, in this position the work piece is centered around the cutting tools axis; this make all three axis coaxial. Making a way for the secondary table to be offset in either the x or y plane so that the cutter is pitched at a distance from the work piece's center allowing a simultaneous operations on the work piece.

3. Specialized Or General?

There are literally hundreds of CNC milling equipments available on the market today with different specifications and different additional features. They come in all types of shapes and sizes. Some are designed for specific applications, while others are more of general purposes in nature. When looking for the right CNC rotary tables, try to talk to people who already using this kind of equipments from them you can learn how this things work. The good thing about talking to this people is that you will gain information not based on industrial propagandas but on experience and uses of there CNC milling equipments. You can also visit a shop in your area so that you will ly see on how CNC rotary tables work. You can eve try to use one CNC milling equipment to know how it feels. You can also attend CNC seminars to be able to gain professional views about his matters and also do not forget to check online information sites.

4. Setting Up Shop

When setting up your CNC rotary tables make sure that the platform is stable and your CNC milling machine secure. Setting up your CNC milling machines is a critical issue to early success, the less movement that occur the better. The right material to be used should also be thought about when using this kind of CNC milling machines. Determine the right thickness and sizes of your materials. Also look for proper fixtures for your CNC milling machines, for this will save time, money and frustration when using your CNC rotary tables.

Before going into production, make a plan to test the different variables you need to work with for a period of time. Getting familiar with your machine is also a critical issue for success. Try to make familiar with the different types of cut, type of materials to be cut, the table type, the depths of cut, the feed rates and the type and sizes of bits that you will be utilizing. Feel around the machine but not literally though for it may I injure you.

5. Satefy

Make sure to read your manuals and have a thorough understanding about the safety measures and the different features of your CNC milling machines. Have a good idea on how this things works. On what it can do to make your business prosper and also on how it can harm your employees.

Article Source: http://www.articlenorth.com

For more great cnc rotary table related articles and resources check out www.onlyrotary.com

CNC Milling Machine Buying Tips

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CNC stand for Computer Numerical Control, and refers specifically to the computer control of machine tools. The main purpose of CNC Milling Machines is to repeatedly manufacture complex parts in metal as well as other materials, using a specially coded program. This specially coded program that is used by CNC Milling machines is written in a notation called G-code. G-codes represent specific CNC Milling functions in alphanumeric format. CNC Milling was developed in the late 1940's and early 1950's by the MIT Servomechanism Laboratory.

1. About CNC

- Computer Numerical Control (CNC) Milling is the most common form of CNC
- CNC mills can perform the functions of drilling and often turning
- CNC Milling machines are classified according to the number of axes that they possess
- Axes are labeled as x and y for horizontal movement, and z for vertical movement
- The evolution of CNC milling machines drastically changed the manufacturing industry
- Curves are as easy to cut as straight lines, complex 3-D structures are relatively easy to produce, and the number of machining steps that required human action is way down.

2. The Fabrication Process

With the use of CNC milling machine the fabrication process of the materials have been trimmed down to just a couple of steps. CNC Milling machines now days are driven directly from computer softwares crated by CAD software packages. With the use CNC Milling machines the assembly of parts can go from brief designs without any intermediate paper drawing works being required. In one sense, with the use of CNC milling machines industrials tasks are done must easier and much faster and the production cost of the company is also lessening out. CNC machines may be said to represent special industrial robot systems, as they are programmable to perform any kind of machining operation, within certain physical limits, like other robotic systems.

3. Buying Tips

Before buying a CNC milling machine it is a must that you should have knowledge about the CNC milling machines basic parts. A CNC milling machine is basically composed of a Safety shield that is usually a clear plastic cover that cover and protects the cutting area. The Tool bit, this part of the CNC milling machines is the one that do the cutting. Spindle Shaft, is the part that holds the tool bit. Spindle Motor, is the part of the CNC milling machine that drives the cutter. The Vertical Column, the part that holds the spindle and all of its part. The Cross Side, a moveable support where the work piece is being cut. The axis motors, which moves the cross side into different axis and the Controller box.

When purchasing your milling machine make sure to check that you have all of this part intact on your CNC milling machine, for if one of this parts is not there it will not surely work or will produce an undesirable end product. Also see to it to check out for safety features, never buy a CNC milling machine without an emergency stop button, this button automatically stops machining when it is pressed. Human, hardware or software errors could mean big losses if the CNC cannot be stopped quickly enough to correct the problem. Also check out the control panel part, it is advisable to buy one with a big control guide sticker so you can clearly see it.

Also check out the screws and tools with long overhangs and adapters, be more observant about cracks and breaks on this CNC milling tools. Make sure that the plastic shield that you are purchasing with your CNC milling machine is made up of high impact polycarbonate plastic. An insert break loose from a 35 mm diameter CNC milling cutter at a spindle speed of 45,000 rpm will be thrown out at a speed of 90 meters per second - equivalent to a bullet that is being shot out of a pistol!

Article Source: http://www.articlenorth.com

For more great cnc milling machine related articles and resources check out www.cnc-advisor.com

Computer Aided Manufacturing Applications

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Computer Aided Manufacturing (CAM) refers to an automation process, which accurately converts product design and drawing or the object into a code format, readable by the machine to manufacture the product. Computer aided manufacturing complements the computer aided design (CAD) systems to offer a wide range of applications in different manufacturing fields. CAM evolved from the technology utilized in the Computer Numerical Control (CNC) machines that were used in the early 1950s. CNC involved the use of coded instructions on a punched paper tape and could control single manufacturing functions. CAM controlled computer systems, however, can control a whole set of manufacturing functions simultaneously.

CAM allows work instructions and procedures to be communicated directly to the manufacturing machines. A CAM system controls manufacturing operations performed by robotic milling machines, lathes, welding machines and other industrial tools. It moves the raw material to different machines within the system by allowing systematic completion of each step. Finished products can also be moved within the system to complete other manufacturing operations such as packaging, synthesizing and making final checks and changes.

Some of the major applications of the CAM system are glass working, woodturning, metalworking and spinning, and graphical optimization of the entire manufacturing procedure. Production of the solids of rotation, plane surfaces, and screw threads is done by applying CAM systems.
A CAM system allows the manufacturing of three-dimensional solids, using ornamental lathes with greater intricacy and detail. Products such as candlestick holders, table legs, bowls, baseball bats, crankshafts, and camshafts can be manufactured using the CAM system. CAM system can also be applied to the process of diamond turning to manufacture diamond tipped cutting materials. Aspheric optical elements made from glass, crystals, and other metals can also be produced using CAM systems.
Computer aided manufacturing can be applied to the fields of mechanical, electrical, industrial and aerospace engineering. Applications such as thermodynamics, fluid dynamics, solid mechanics, and kinematics can be controlled using CAM systems. Other applications such as electromagnetism, ergonomics, aerodynamics, and propulsion and material science may also use computer aided manufacturing.

Computer Aided Manufacturing provides detailed information on Applications of Computer Aided Manufacturing, Cam And Computer Aided Design, Computer Aided Design , Computer Aided Design Scanners and more. Computer Aided Manufacturing is affiliated with Computer Aided Design and Manufacturing

Article Source: http://EzineArticles.com/?expert=Kevin_Stith

CNC Milling Machine Buying Tips

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1. About CNC

- Computer Numerical Control (CNC) Milling is the most common form of CNC - CNC mills can perform the functions of drilling and often turning - CNC Milling machines are classified according to the number of axes that they possess - Axes are labeled as x and y for horizontal movement, and z for vertical movement - The evolution of CNC milling machines drastically changed the manufacturing industry - Curves are as easy to cut as straight lines, complex 3-D structures are relatively easy to produce, and the number of machining steps that required human action is way down.

2. The Fabrication Process

With the use of CNC milling machine the fabrication process of the materials have been trimmed down to just a couple of steps. CNC Milling machines now days are driven directly from computer softwares crated by CAD software packages. With the use CNC Milling machines the assembly of parts can go from brief designs without any intermediate paper drawing works being required. In one sense, with the use of CNC milling machines industrials tasks are done must easier and much faster and the production cost of the company is also lessening out. CNC machines may be said to represent special industrial robot systems, as they are programmable to perform any kind of machining operation, within certain physical limits, like other robotic systems.

3. Buying Tips

Before buying a CNC milling machine it is a must that you should have knowledge about the CNC milling machines basic parts. A CNC milling machine is basically composed of a Safety shield that is usually a clear plastic cover that cover and protects the cutting area. The Tool bit, this part of the CNC milling machines is the one that do the cutting. Spindle Shaft, is the part that holds the tool bit. Spindle Motor, is the part of the CNC milling machine that drives the cutter. The Vertical Column, the part that holds the spindle and all of its part. The Cross Side, a moveable support where the work piece is being cut. The axis motors, which moves the cross side into different axis and the Controller box.

When purchasing your milling machine make sure to check that you have all of this part intact on your CNC milling machine, for if one of this parts is not there it will not surely work or will produce an undesirable end product. Also see to it to check out for safety features, never buy a CNC milling machine without an emergency stop button, this button automatically stops machining when it is pressed. Human, hardware or software errors could mean big losses if the CNC cannot be stopped quickly enough to correct the problem. Also check out the control panel part, it is advisable to buy one with a big control guide sticker so you can clearly see it.

Also check out the screws and tools with long overhangs and adapters, be more observant about cracks and breaks on this CNC milling tools. Make sure that the plastic shield that you are purchasing with your CNC milling machine is made up of high impact polycarbonate plastic. An insert break loose from a 35 mm diameter CNC milling cutter at a spindle speed of 45,000 rpm will be thrown out at a speed of 90 meters per second - equivalent to a bullet that is being shot out of a pistol!

For more great cnc milling machine related articles and resources check out http://www.cnc-advisor.com

Cycle Time Reduction Principles for CNC Machining Equipment

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What is the definition of cycle time?

Cycle time is defined to be the time that happens from the time a task or series of tasks is initiated to the time a task is completed. Example, the cycle time is the time a shipping order is printed to the time it is loaded on the truck and the system is updated. An alternate definition would be is the time it takes to load, run, and unload on workpiece.

Cycle time of a machine can be simply measured by timing how long it takes from pressing the button to start the cycle for the first workpiece to the pressing the next button for the next workpiece.

Production quantities in an industry dictate that the more workpieces you run, the more important it is to achieve the goal of lowering the cycle time.

Everything and anything that happens in a Computer Numerical Control (CNC) machining equipment can be divided into four categories:

1.) On-line, productive tasks:

These are the actual machining operations that occur during a CNC cycle. These are the milling, drilling, tapping, reaming, and any other machining operation that in some way furthers the completion of the workpiece. To minimize the cycle time in these areas, there are two ways in which this can be achieved. One would be through careful process planning.

The process engineer must select an appropriate machine tool, cutting tools, fixturing, and machining order in a way that it matches the number of workpieces to be machined that will be based on the production quantity. The cycle time will be a reflection of the processes being used to machine workpieces.

If in the many times that your company’s processes have already been developed and implemented before you begin your cycle time reduction program, then your second alternative is to optimize cutting operations for this would involve properly selecting cutting tool materials, feeds, and speeds to machine workpieces as efficiently as possible with the current process.

2.) On-line, non-productive tasks:

These are tasks that occur during the machining cycle that do not actually further the completion of the workpiece. The first thing Computer Numerical Control people often target for improvement is wasted program execution time. These are the things like rapid movements, tool changes, M-code execution and spindle acceleration/deceleration. Reducing program execution time in this area is usually easy.

It often takes nothing more than carefully monitoring the production run for a few workpieces to find those times when the program can be modified to eliminate noticeable pauses during the cycle. Although keep in mind that the worker for these machines must not overlook other processes for they may be so concerned with minimizing program execution that they overlook other operations, resulting in severe wastes of cycle time.

3.) Off-line, non-productive tasks:

These are the tasks performed in the machining cycle that do nothing to further the completion of the workpiece. Since these types of tasks are done while the machine is producing workpieces, they do not actually add to the cycle time. It is possible to free the operator of the machines of performing off-line productive tasks if they have little, or nothing to do during lengthy machine cycles.

4.) Off-line, productive tasks:

These are the tasks done away by the CNC machine, while the machine is producing workpieces, which would further the completion of the workpiece. This is extremely helpful during lengthy CNC cycles, tasks in this category can reduce the time it takes to complete the production run dramatically, which would effectively reduce cycle time.

CNC Milling Machine Buying Tips

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Source: Free Articles

Autor: infocus

CNC Milling Machine Buying Tips

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Source: Free Articles

Author: infocus

Practical Applications of CNC

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Manufacturing anything that requires exact measurements requires cutting edge precision and nimbleness from the worker. Most of the time manufacturing these kinds of products requires weeks or months to finish therefore slowing down productivity as well as consistency of the manufacturers.

Computer Numerical Control or more commonly called as CNC’s are the new trend in machine shop manufacturing and practice. Any manufacturing environment owns one or is basically acquainted to this kind of device because of its capability to increase productivity as well as consistency on the products being produced.

Benchmarked from Numerical Control (NC) during the late 50’s, Computer Numerical Control incorporate the functionality of a Programmable Logic Controller (PLC), meaning you could program it to execute different functions depending on the type of manufacturing that the industry needs.

Given this kind of quality what does the Computer Numerical Control do in the practical application concept? CNC can do a variety of things depending on how the machine operator would program the system. The more acquainted the machine operator is to the CNC machine the more complex applications as well as programming can be made. Practical applications of CNC range from drilling, lathes, multi-axis spindles, milling machines, laser cutting machines, and wire electrical discharge machines.

Let’s discuss some of these common applications further. In Metal fabrication, Computer Numerical controlled Lathe’s are used to fabricate metal sheet by shearing, flame or plasma cutting, punching, laser cutting, forming and welding. Most CNC Lathe’s are used for designing modern carbide tooling. The design could be created with the Computer Aided Manufacturing (CAM) process, and when done, the CNC could start creating the product automatically with little supervision from the machine operator.

Electrical discharge machining (EDM) is the process of removing metal with the use of electrical sparks to take away the metal. These Electrical Discharge Machine has two types, the vertical EDM and wire EDM. Vertical EDM uses an electrode that is the shape of the cavity to be machined into a work piece. Wire EDM is used to create punch and die combinations in the fabrication industry. Computer Numerical Control EDM’s are not usually known because it is mostly incorporated to other CNC process.

Drilling is the most common machine process. Computer Numerical Controlled Drilling is used to create precise right circular cylinders over a certain material, the CNC could be programmed to create holes on different standards, most of the time this is the gaps between these holes. Drilling is commonly used in wood working manufacturing process in which other process is also involved such as milling, turning and grinding.

Several tools for creating holes with CNC’s involve varied hole sizes as well as drill press for creating different depths on its holes. CNC drills are equipped depending on the type of hole that the machine operator is drilling.

Applications stated above are just a few examples on what the Computer Numerical Control could execute. Depending on how you want it to perform, more complex designs can be made and a lot of things can be made in a shorter period of time, therefore the key concept for the proper use of CNC’s is that the machine operator must know what he or she wants to do.

This makes the CNC an indispensable tool for the Manufacturing Industry nowadays.

The Different CNC Machines

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CNC has different applications depending on the machines that operate on it. So if you're a budding operator, you should know the most common machines that can operate on CNC.

Milling

Milling machines are common CNC machines. These devices are used in the shaping of metal and other solid materials. It is basically a rotating cutter and a table. Milling machines are capable of complex toolpaths as the cutter is not limited to a sideways movement but allows for an “in and out” motion. This movement is precisely controlled by moving the table and the cutter relative to each other. Cutting fluid is then pumped in to lubricate and cool the cut and to remove any swarth that is generated by the cut.

Lathes

Lathes are machines that perform different operations such as sanding, cutting, knurling, deformation, or even drilling. These machines work by spinning various solid objects and then using tools that are symmetric to the axis of rotation. A lathe machine has a single tool in which the workpiece is worked against the tool. The tool is then worked alongside or into the workpiece in order to generate the feed.

Lathes can be used for different operations.

Machining Centers

These are more complex CNC machines that combine milling and turning. As milling was described earlier, turning will be the focus of this section.

Turning is the process by which a central lathe is used in conjunction with the rotation of the material to be turned. The cutting tool is then moved along the two axes of motions to produce accurate dimensions.

Combining turning and milling can produce extremely precise components. And that is what these machines are used for. However, due to the complexity of these machines, operators have to be specialists in order to be able to operate with maximum efficiency.

Electrical discharge machine

An electrical discharge machine (EDM) creates cavities in metals by emitting electric sparks. This process requires an electrode, coolant, a power source, and a tank. The cycle is accomplished by connecting the workpiece to one side of the power supply and then placing it in the tank. An electrode (made in the shape of the cavity required) is then connected to the other side of the power supply.

The tanks is then filled with coolant and the electrode is lowered until a spark jumps between the work and the electrode. As the coolant is a dielectric substance (resists electric currents), it requires a smaller difference in distance in order for a spark to jump through. This means that when the spark appears, the dielectric property has been overcome. The spark then dislodges material thereby creating a cavity in the shape of the electrode.

CNC systems

CNC systems are complex machines that transfer and store data regarding the operation mechanism of the machines. Motion programs include point to point control, straight cut control, and contouring control.

Point to point control means the control of the tools from one point to another in the coordinate plane. This method of control is commonly used in drilling and boring operations.

Straight cut control is the method by which a tool is moved in all axes of the machine. The tool also has the ability to move in a 45 degree angle.

Contouring control is the means to create a toolpath. It moves the tools by interpolating points or coordinates that make up the path for the tool to follow.

3 Basic Motion Types in a CNC Machine

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A Computer Numerical Controlled (CNC) machine may have more than one motion type that it uses, but there are three most common motion types that are easy to remember. These are the Rapid Motion, the Straight Line Motion, and the Circular Motion.

All of these motion types may seem different but they share two things in common, which would be that they are all modal and the endpoint of each motion is specified in motion command. By being modal it means that the motion type would be in effect until changed otherwise.

3 common motion types:

1.)Rapid Motion Type

Rapid motion type is also called Positioning. The way this motion type is used is through utilizing the fastest rate possible of the command motion of the machine. Example uses of rapid motion are moving to clear obstructions, placing cutting tools to and from the desired position, and any program that provides non-cutting in their schemes.

The command that is usually programmed to a CNC machine is G00 because in this command, the end point for the rapid motion would be specified.

The CNC machine, with most controls given, will be able to move as fast as possible in all commanded axes. In the case of rapid motion, one axis may be able to reach its end point before other axes. Straight line movement will not occur with type of rapid command function and the programmer of the machine must take into account that there are no obstructions to avoid. Straight line motion will happen even during rapid motion commands when done with other controls.

2.)Straight Line Motion

This type of motion would allow the programmer of the machine to command perfectly straight line movements within the machine. Unlike the rapid motion type, the straight line motion would allow the programmer to vary the rate of the motion or feed rate to be used during the movement. Examples of using straight line motion would be turning a straight diameter, taper, when milling straight surfaces, and when drilling for this is because these examples require straight cutting movement.

The common word to specify a straight line motion into a machine would be G01, for within this command the programmer will include the preferred end point within each of the axes.

3.)Circular Motion

This motion type would cause the machine to move in the direction of a circular path and is used to generate the radii in machining. When talking about points on circular motion feed rate, it is equal to that of straight line motion.

Other than that of straight line motion and rapid motion, there are two G codes that are commonly used when programming a circular motion into a machine. These are G02 and G03. G02 is used when the programmer desires a clockwise motion into the machine while G03 is used to make an anti-clockwise motion. To know which of the commands to use, the programmer must view the movement with the same perspective as to what the motion of the machine will be, may it be clockwise or anti-clockwise.

Another requirement that would be programmed into a machine that would be using circular motion is that the programmer must specify the radius of the arc that is to be generated. With brand new technological advances in CNC, an “R” word is now used to specify the radius.

For older controls in CNC machinery, an “I”, “J”, and “K” are used to specify location of the center point of the arc.