UK CNC machine tool company has developed close associations with autosport suppliers and teams in aiding them to making manufacturing lead times as short as possible.

Yamazaki Mazak UK, the world's largest manufacturer of Computer Numerical Controlled (CNC) metalcutting machine tools, has developed extremely strong links with the autosport engineering industry. This reflects its long-standing status as official supplier of CNC lathes and machining centres to Formula One's Team McLaren Mercedes and its support for the numerous sub-suppliers to the many facets of the autosport sector. The machine tools available from Yamazaki Mazak are at the pinnacle of manufacturing technology and, irrespective of component type or company size, the Worcester-based company has a machine to suit most metalcutting applications.

These range from entry level 2-axis Nexus lathes through to multi-function/multi-axis Integrex machines, which will deliver productivity improvements even on the smallest batch sizes.

The extensive autosport related customer base of Yamazaki Mazak UK supplies components to competitors from clubman level to Formula One.

The common denominator with all of these customers is that they are able to rely, not only on the machine tool but also on the technology and engineering support provided by Yamazaki Mazak UK.

Given the demands placed on suppliers to the racing teams, whereby components have to be delivered in short lead times to the highest standards of consistency and quality, the knowledge that the world's largest manufacturer of machine tools is supporting those efforts makes the machine tool purchasing decision a much easier one.

The engineering support provided by Yamazaki Mazak is the key to reducing lead times for all of its customers, irrespective of industry sector.

However, in developing its Done in One strategy Mazak is eliminating much of the expense of set-up, work in progress and the number of machine tools required.

CNC machines are used in a variety of industrial settings and in woodworking shops. Most are out of the price range for the individual user, but can be purchased used for about half the price. These machines increase speed and accuracy when doing large jobs or repetitive tasks.

How CNC Machines Work

CNC machines are used in a variety of industry, manufacturing processes and woodworking shops. CNC routers are used for drilling holes. Some machines have the capability of holding several tools. This allows them to perform more than one operation at a time. They save time and improve accuracy.

CNC stands for Computer Numerated Control. This technology was first seen in the 1970s. The machines need to be programmed and set up properly before operation. Once the initial set up is completed, they are fairly easy to operate and keep running.

In CNC routers, they can be programmed to drill holes in an automatic fashion. This is faster and more accurate over several pieces than in manual drilling. The results are more uniform. This method is very beneficial for larger jobs that require a lot of drilling. Manual drilling can become tiring and when the operator becomes tired, the results can become inconsistent.

Types of CNC Machines

A CNC lathe is a good piece of equipment for cutting wood. These come in models ranging from fifteen to forty horsepower. The amount of power you need depends on the amount of wood you will use with the lathe. The best models operate in several different modes, from completely manual to all CNC. This allows you to tailor the machine’s operation for each project.

A Bridgeport mill is the best in milling technology. Mills are used in many industries, both large and small shops. They are efficient and reliable. Bridgeport mills are built to last a lifetime. However, they are very expensive. The price is out of the range that most people can afford.

The CNC mill is a specialty piece of equipment. It uses computer programming and robotics for accurate operation. The results are more accurate than any person could ever achieve. For this reason, Bridgeport mills are often used in the airline industry. Once the specs are entered, the CNC decides which tools need to be used and automatically changes the tools as needed.

Engraving equipment is made to engrave a variety of materials including glass, stone, metal, wood, composites and many others. The machines mark and engrave with more accuracy than could ever be achieved by hand. Everything from large signs to small lettering can be done, depending on your needs.

Buying Used units

CNC equipment is very expensive and out of the price range of most people. Buying used CNC electronics is an affordable option for some people. You can save nearly 50% or more on some equipment. Be careful when buying used, you want to be sure the equipment is in good condition.

A better option is to look for refurbished equipment. These machines have been inspected at the factory. Any broken or damaged components are replaced. In many cases, the machine is painted and new decals are applied. It’s like getting a new machine for a significantly reduced price. Often, you will get a one year warranty with reconditioned equipment. This gives you time to be sure it is working properly and if not, you can get it fixed for free.

A CNC machine is used in woodworking shops and some other industrial settings. They are very expensive, so most individuals do not buy them, although used ones can be obtained more cheaply. They are important for speed and accuracy in large, repetitive tasks.

There are many uses in industry for CNC machines. Routers drill holes, for example. Many CNC machines can perform a number of tasks at once, improving efficiency in the manufacturing process.

The technology behind these machines is Computer Numerated Control. This technology was developed in the seventies and it allows for a machine to be programmed in advance so the operations are set up to work almost automatically. The initial setup is a little complicated, but once that is done the machine is easy to operate.

A CNC router would be programmed to drill a hole repeatedly at certain intervals. This is much more efficient than manual calculation and drilling and eliminates inconsistency due to human error or fatigue.

A CNC lathe would be used to cut pieces of wood of uniform size and shape. Lathes can have horsepower ranging from 15 to 40 HP, and how much power is needed depends upon the job being done. A good CNC lathe will allow you to work at various levels of automation, so that you can work all manual, or all automated, or any combination in between.

The best mill available is the Bridgeport mill. Mills are designed to be used in both large industries and small milling shops, and the Bridgeport mill is built to last in any situation. The price is prohibitive, however, for individual use.

A CNC mill is considered specialty equipment. The concept is to use computer programming and robotic operation for speed and accuracy. This kind of speed and accuracy would be impossible to achieve for an individual. The airline industry frequently uses the CNC technology of Bridgetown mills; specifications are entered, and the mill automatically determines which functions to perform and how.

Engravers can also be CNC machines. Engraving can be done on many materials, including wood or wood composite, metal, stone or glass. These machines can do very exact engraving on materials from the smallest to the largest, and have the same result over and over.

Since CNC machines are so expensive most individuals cannot afford them, there may be individuals who do a lot of repetitive machine work and would like to obtain one. An option in this case is a used CNC machine, which can be as low as half the price of a new one. It is important to make sure the used machine is in good condition, so you may be better off looking for a rebuilt machine. This is one that has had the major components replaced so it is almost a new machine. Frequently, rebuilt machines have a warranty of at least one year, so that you can be assured that it will be working, or you can get it repaired if it does not.

Modern articulated arm robots are precise, capable of repeatedly making movements within a few thousandths of an inch day after day. That precision is one reason why engineers like them. Precision, however, has a downside too. In the real world, dimensions and surfaces can vary enough from part to part to throw off a robot whose movements have been programmed relative to nominal size or surface. So would finishing or assembly operations that require a sense of "feel," such as assembling finely meshed gears, polishing a metal component, and some types of machining operations.

If you've ruled out assembly or finishing robots for these reasons, it may be time to take another look at them. Over the past couple of years, robot vendors have developed two technologies that improve robots' tolerance of the variability found in real-world assembly and finishing operations. One of these technologies gives robots a sense of "feel" by adding force control capabilities. The other uses machine vision systems to let robots "see" and adapt to variation in part dimensions and locations.

Taken together, force control and vision not only raise the technical capabilities of robots but also improve the economics of using them. Here's a closer look at both technologies and at some applications where they're starting to make a difference:

Force Control

The addition of force sensors near the end-of-arm tooling and enhanced control software gives some robots the ability to adjust to the forces they encounter as they do their jobs.

ABB Robotics, for instance, has developed a system it calls Advanced Force Control, which can be added as an option to a variety of the company's robot arms. The system uses a force and torque sensor from ATI Industrial Automation at the wrist of the robot. "We feed information from the sensors into our axis controller and adjust force and speed," says Jerry Osborne, vice president & general manager of ABB Robotic Assembly in North America. "There's a lot going on in the controller to make this happen."

According to Osborne, the system can sense forces in six axes with a sensitivity of +/- 2.5 Newtons and with a response time of 4 millisec. The system can also work in conjunction with the robot's speed and position control – for example, by first running a search pattern to locate a feature or object and then switching into force control as the assembly proceeds.

In the past, Osborne says, one option for assembly applications in which the robot's contact force would cause problems was to add a compliant mechanism into a traditional position-controlled robot arm. Mostly, though, these force-sensitive applications literally stayed in human hands or went into complex, dedicated assembly machines.

ABB started to develop its force control system about three years ago, as a way to assemble the spline gear assemblies within automotive torque converters. "This work was manual because you had to feel the meshing of the spline gears," Osborne says, noting that 12 of these systems are now in operation worldwide.ABB is also pitching force control for tricky assembly tasks such as piston stuffing and spark plug assembly. Osborne says the system could make sense "wherever you have a press fit assembly."

Though developed three years ago for automotive assembly, the force control system seems to have even bigger implications for machining and finishing. Osborne says the majority of the systems have gone into finishing operations – such as polishing. "We have about 50 systems involved in finish applications. Some of them are involved in polishing magnesium laptop housings," he says. In these cases, the force control gets the nod for its ergonomic and quality advantages – it can provides a more constant force than a human being and not risk the injuries inherent in a long day of hand polishing.

Controlling forces at the end of the robot arm also have implications for robotic machining. Kuka Robotics Corp., which also has force-torque sensors available for its robots, has delivered systems that perform grinding and milling operations. According to Kevin Kozuszek, the company's marketing director, the force controlled robots are starting to become more popular in "pre-machining" applications--or the use of robots to perform rough machining operations, leaving only a single pass on CNC machine for finish machining. In this case, force control helps the robot close the gap with machine tool feeds and speeds by optimizing the contact forces between the robot-borne tool and the workpiece. Kozuszek says this approach can save significant amounts of money in reduced set-up and fixturing costs as well as in possible avoidance on capital expenses. “If you pre-machine with a robot, you may require fewer CNC machines for a given throughput," he says.

ABB's Osborne makes a similar case for pre-machining and adds that applications without tight tolerances may get away with robotic machining as a replacement for CNC. No one is suggesting that robot arms, which inherently lack the stiffness of a machine tool, will take precision machining operations. But Osborne and others see room for robots with force control to machine to tolerances near robotic repeatability – usually within a few thousandths of an inch

Kuka, meanwhile, currently advocates robotic machining for soft materials--such as aluminum or plastic. "It makes a lot of sense in prototyping and low-volume production applications, especially when you consider the time saved by avoiding complex fixtures and machine set-ups" says Kevin Kozuszek, the company's marketing director.

Still, one of Kuka’s customers has developed a new robotic machining cell that works on a hard material – stone. USMechatronics and the Seis Group, a pair of systems integrators that work on robotic and other electromechanical projects, recently created a stone-cutting robot called RoboJet. This stone cutting robot arm runs an abrasive water jet cutter, rotary saw and 3D milling head. Driven by proprietary control software from USMechatronics and by Kuka's CAMRob robotic machining software, this robot can switch between cutting methods automatically.

The stone industry already uses all three of these cutting methods--but on separate machines. "This is the first time they've had a robotic system like this," says Chris Barbazette, Seis' president. "There's been a tremendous amount of interest in it," he continues, explaining that the system can potentially replace all or some of the conventional, stand-alone cutting machines for a significant savings in capital costs. He adds that there's a utilization advantage associated with the robot. "The robot is always doing something, whether it’s cutting or moving materials into place," he says. That's not always true with stand-alone machines, which would typically have some idle time. And there's an obvious floor space savings, too.

Barbazette foresees the RoboJet approach becoming important in other industries that perform operations on stand-alone machines or processes. He thinks that composites fabrication is one application ripe for more robotic finishing and machining operations.And he's looking at metal machining applications too. "The whole idea of a robot as a machine tool is still in its infancy. I don't see it competing against CNC in precision applications because of the stiffness issue, but there are applications where robotic machining has a bright future," he says.

Robotic Vision

The other key enabling technology starting to gather steam is vision-guided robotics. These systems add a CCD cameras and lighting to the robot's end effector while specialized software translates images from the camera into move commands for the robot. Braintech Inc. has developed just such a system for ABB Robotics. Called TrueView, this off-the-shelf Windows-based vision guidance system can locate objects in 3D space with "sub-millimeter" accuracy, according to Jim Dara, vice president of Braintech.

Braintech has delivered TrueView systems to Ford, GM and various automotive suppliers. The common thread in many of these automotive applications – and in non-automotive uses too--is that vision can eliminate the cost of putting parts in correct position and orientation for robotic assembly. Dara points out that custom fixtures, precision dunnage and other positioning methods that "cost hundreds of thousands of dollars in a typical automotive plant."Robotic vision systems, by contrast, range from $10,000 to about $100,000, depending on their complexity.

CNC machine tools are the multitasking proctors of precision manufacturing, representing mature technology and deployed across industries. However, development and application of new software may enable robots to steal a significant portion of the CNC machine tool market.

Last year saw countless news stories about robots, including here at the IMT blog. On the industrial side, the latest data available fared that the North American robotics industry posted 30 percent growth through the first three quarters. Indeed, manufacturers are changing the ground rules for robots at an amazing pace. Today robots are too successful to ignore and too affordable to overlook.

Typical applications of industrial robots include welding, painting, ironing, assembly, pick and place, palletizing, product inspection, and testing — all accomplished with high endurance, precision and speed. Yet new looks and tricks are being aggregated to industrial robots rapidly. Even now, multi-robot controllers are common, mobility is on the rise, and some units are being built with two arms on the same base. At Honda, Toyota and other companies, there have been huge investments in robots that walk, hop and jump…and may one day stand side-by-side with us in the workplace.

“Side-by-side with us” is likely quite a bit further into the future, perhaps even in later lifetimes…but will they replace our actual machine tools sooner? Specifically, our CNC machine tools sooner?

A recent (punctuation-agnostic) headline at American Machinist dictated the following (punctuation included here): “Move over machine tools. Here come robots.” The article supposes the possibility of robots gaining CNC machine tools’ functionalities.

“Robots are poised to take away a significant portion of the CNC machine tool market,” a Robotics Online article declared in late 2005. “Emerging technology is making it possible for robot systems to perform many diverse manufacturing processes — such as complex cutting and material removal, grinding, mold creation, surface finishing, and drilling and tapping applications — that were previously performed by CNC machines.”

First, why even consider robots in CNC machining? CNC machine tools are the factotums of precision manufacturing, representing mature technology and deployed across various industries and applications. The use of robots in CNC machining saves money in at least three ways. In the typical robotic work handling application, the manufacturer realizes all of these savings simultaneously:

• Improved asset utilization;
• More efficient use of labor; and
• More consistent production.

“Robots are proving to be faster, more flexible and are much more robust and reliable when compared to standard industrial CNC machines,” according to Kevin McManus, president of Robotic Production Technology.

Robots as Alternative
Third-party CAD/CAM packages, in fact, have evolved to use process-specific tools for quick creation of complex cutting and material-removal paths. As such, these CAD/CAM programs have solved issues like drilling metals and rotation speeds, process-specific expertise regarding material-removal rates, cutting angles and optimized cutting paths.

The primary problem for robots as a proper alternative to CNC machine tools has been the lack of industry standards regarding robot manufacturers’ own proprietary programming language. “There is a classic failure to communicate in the machine shop. Robots run on brand-specific languages all their own, while conventional CNC machine tools read G-code generated through CAM software,” American Machinist notes.

As the CNC program standard — universally known as G-Codes — has fragmented and evolved over time, G-codes (motion) and M-codes (functions) used in CNC programs are defined variously. From a machine’s perspective, all of this process-specific knowledge built into the CNC programs ultimately produces a path, a speed and the orientation of the tool relative to the part,” Robotics Online notes.

Robots use the same kind of information in parts processing. To attain the expertise of third-party CAD/CAM packages developed for CNC machine tools, manufacturers found their answer to the lack of a universal proprietary programming language code: in software.

Says Robotics Online:

Individual CNC programs often contain tens of thousands of programming points, representing untold man-hours of program development. However, PC-based software now exists that easily and quickly translates programs written for CNC machine tools, including I/O and other non-motion commands, into robot programs that are ready to run.

This conversion is done offline — all of it, offline — so production remains uninterrupted.

While some translators (sometimes called post-processors) are specific to a particular industry and/or CNC process, other software translators have the capability to handle the variations in format and different G- and M-code meanings among diverse industries with only minor changes to the software configuration files.

In addition to an expected lower overall equipment cost, such CNC machine-tool program-conversion software enables manufacturers increased flexibility that five- or six-axis robots can offer, “as opposed to more expensive CNC machines with only three- to five-axes of motion.” Six-axis robots can perform many of the same tasks more efficiently, with a faster and cleaner process that provides high throughput rates and virtually unlimited flexibility. Some applications still will require the high tolerances and accuracies provided by CNC machines, but many do not require quite the same level of precision.

Currently, most shops do not associate even five-axis contour surface machining with robots, primarily because “it would take a great deal of time to teach a robot all the necessary data points,” says American Machinist:

Instead, shops use CNC machine tools. If the parts are large, they are split into multiple pieces that fit on the machines and reassembled after cutting. Alternatively, shops will remove machine panels and doors to mount the portion of the workpiece that needs cutting on the machine, while the rest of the part hangs out or over the sides.

While CNC technology coupled with CAD/CAM has long helped to introduce flexibility in batch production, there still remain some major inefficiencies inherent in most machining processes.

Present day CNC technology relies on the programmers' input of appropriate cutting parameters - even when sophisticated software systems are used to generate NC programs. The fact is that NC programming is based on predetermined and unchanged conditions.

The control mechanisms of CNC machines are limited to geometry and kinematics. As such, they follow pre-programmed and constant speed and feedrates during each cutting segment. Consequently, they do not have the flexibility required for adapting to the dynamic changes that occur during cutting. This inflexibility would be acceptable if cutting conditions were uniform during machining. In practice, however, cutting conditions tend to continuously vary for many of the following reasons:

* Uneven workpiece surface.
* Gradual tool wear.
* Material hardness varies within each workpiece.
* Workpiece dimensions vary from piece to piece.
* Temperature variations in material during cutting.
* The fixture's stability may be affected during cutting.
* NC programs may contain errors.

Advances in CAD/CAM technology have caused machinists to focus most of their attention to "defining the required geometry" and ignore the need to consider the rest of the previously mentioned conditions. However, with all of the those deviations in mind, NC programmers have no alternative but to be conservative in determining cutting parameters - resulting in safer but more inefficient cutting processes. No matter how optimized NC programs may be, they cannot take into account these dynamic variations encountered during cutting. At best, long NC programs may be created with different feedrates for each segment. However, these programs still cannot modify cutting parameters in real time in order to adapt to unexpected conditions that may occur during cutting.

Dynamic Optimization Solution
CNC machining can be fully optimized through the implementation of add-on adaptive control systems, which continuously monitor cutting conditions in real time. Such optimization and machine automation technology systems are indispensable if expensive CNC machines are ever to run at their full capacity and if cutting tools are to be utilized up to their maximum life rather than incurring in-process catastrophic breakage and production disruption. Similarly, machine operators will not be required to intervene in the machining process to watch and manually fine-tune the process. In this way, true automation is made a reality and programmers may be more aggressive, knowing that the adaptive controls will adjust the feedrate based on the load.

Manufacturers require optimization features that can be added on to their existing CNC machinery. Add-on adaptive control systems connect directly to the CNC machine controller; sense and monitor actual cutting load conditions; and adjust feedrates to optimal levels in real time. This ensures a constant cutting load, which takes into account the variations in the cutting conditions during the cut. In this way, these systems ensure that machine cycle times are minimized and that the machines run at the maximum permissible capacity for each tool.

One of the most attractive features of these systems is that they apply the optimal feedrate in real time based on the most basic parameters for each specific tool and material. These parameters may be input, if necessary, from an external tool library. The operator is not required to know specific load threshold for each tool, as the internal expert system determines these limits for itself.

This enhancement allows NC programmers to be aggressive and program feeds as though the tools are new and sharp. During cutting, the adaptive controls automatically compensate for tool wear since feedrates are automatically and continuously adjusted partly as a function of the extent of tool wear. The system also gives operators a quantitative indication of tool wear during the cut. Based on the system's indication, operators can get ready to replace the worn tools in time without actually incurring costly and disruptive tool breakage or replacing the tool much sooner than necessary.

In addition to detecting tool wear, the devices also protect tools from breakage through their sensitivity to the spindle load. Fewer broken tools also reduce scrap and the need for rework. Breakage protection is provided in the form of an alarm system that alerts the machine operator/supervisor when acute overload conditions occur in the cutting process and, if necessary, automatically stops the machine.

Adaptive control systems ensure automatic optimization of the machining process to reduce cycle times, increase tool utilization and prevent tool breakage, thus lowering machining costs and increasing machine capacity.

These adaptive control systems are applicable on CNC milling, turning and drilling applications. Typical applications include rough milling when the material and workpiece surface hardness vary, die and mold manufacturing, blade manufacturing and helical milling on turning centers. Machining cycle times are typically reduced by 10 to 40 percent, depending upon the application.

CNC machine tools are the workhorses of precision manufacturing. They represent mature technology, and thousands upon thousands of them are deployed in a wide array of industries and applications. To support the myriad of CNC machines, a host of mature third-party CAD/CAM packages have evolved that use highly developed, process-specific tools to quickly create complex cutting and material removal paths. Process-specific expertise about material removal rates, drilling metals and rotation speeds, along with cutting angles and optimized cutting paths, are just a few of the issues that have been solved and encapsulated in these third-party CAD/CAM programs.

CNC programs follow a standard call RS-274D created by the Electronic Industry Association (EIA) in the early 1960s. This standard is almost universally known as ‘‘G-Codes.’‘ Over its history, the standard has evolved and fragmented. Depending on the industry, G-codes (motions) and M-codes (functions) used in CNC programs can have different meanings. Other variations -- such as programs with one or multiple instructions per line, with or without line numbers, and with or without spaces – are also allowed. From a machine’s perspective, all of this process-specific knowledge built into the CNC programs ultimately produces a path, a speed and the orientation of the tool relative to the part.

Robots use the same kind of information to process a part. However, each robot manufacturer uses its own proprietary programming language; no industry standard exists. This lack of standards is the reason that the robot industry has not enjoyed the same kind of third-party CAD/CAM support as the CNC industry. The robot market was too small and fragmented to provide the kind of return on investment needed to make third-party software development efforts worthwhile. Additionally, robot manufacturers were not willing to share their proprietary programming language codes with third parties.

To avoid having to ‘‘reinvent the wheel,’‘ robot manufacturers needed a way to tap into the expertise of third-party CAD/CAM packages developed for CNC machine tools. Software was the answer. Individual CNC programs often contain tens of thousands of programming points, representing untold man-hours of program development. However, PC-based software now exists that easily and quickly translates programs written for CNC machine tools, including I/O and other non-motion commands, into robot programs that are ready to run. This conversion is all done off-line, so production is not interrupted. While some translators (sometimes called post-processors) are specific to a particular industry and/or CNC process, other software translators have the capability to handle the variations in format and different G- and M-code meanings among diverse industries with only minor changes to the software configuration files.

This CNC machine tool program conversion software allows manufacturers to take advantage of the lower overall equipment cost and increased flexibility that six-axis robots can offer as opposed to more expensive CNC machines with only three- to five-axes of motion. Six-axis robots can perform many of the same tasks more efficiently, with a faster and cleaner process that provides high throughput rates and virtually unlimited flexibility. Some applications will still require the extremely high tolerances and accuracies provided by CNC machines, but many do not require quite the same level of precision. Examples of these types of applications are far-ranging. Many applications in the plastics industry require trimming, deburring, drilling and routing of molded parts. Examples include deburring of plastic toys and furniture and the trimming of dental products such as custom dentures and dental alignment inserts. Water-jet trimming and cutting of automotive carpets and headliners are other processes that are being done by robots programmed like traditional CNCs. More traditional applications such as robotic trimming, deburring and drilling of aircraft body panels are currently being evaluated. Today’s robots now have the positioning accuracy, repeatability, and rigidity (mechanical stiffness under load) required to process these slightly less stringent applications.

One automotive supplier was able to use PC-based software -- offline -- to convert a CAD/CAM program for the creation of an automotive door handle mold with more than 27,000 points into a robot program in approximately 10 minutes. As a result, the automotive supplier was able to manufacture the door handle mold with a flexible robotic system that cost less than $150,000 – less than half the price of a $300,000 CNC machine. In this case, the robot system was fast, cleaner and more flexible than a CNC machine would have been.

In another example, this same automotive supplier used a $300,000 CNC machine to create an automotive hood scoop mold. The CNC machine first removed all unwanted material in one plane. The operator then indexed the mold 90-degrees (with respect to the CNC machine). The CNC then removed the unwanted material in the new plane. A more flexible six-axis robotic system costing $100,000-$150,000 could perform the same material removal process, completely automatically, in fewer operations without having to re-index the part. The robot would simply remove the unwanted material in the first plane, reorient its end-of-arm tool automatically, and then use it to remove the unwanted material in the new plane. Since the part does not move during robotic processing, the potential for inaccuracies caused by improper index of the part in conjunction with the CNC machine is eliminated.

PC based CNC machine tool controllers are starting to become the trend in CNC machining. Retrofitters and OEMs are looking toward the PC as the new machine tool controller platform to accommodate today's need for "high-speed" machining. More and more retrofitters and OEMs are starting to switch from a pre-fabricated controller to a PC based CNC controller for a variety of positive reasons. The most common reasons are described below.

PC based CNC machine tool controllers are less expensive than pre-fabricated controllers. You can replace your existing pre-fabricated control with a PC based controller at a fraction of the cost when compared to replacing your control with another pre-fabricated controller. This cost savings is accomplished because a PC based CNC controller uses a standard Windows based 95, 98, ME, NT or 2000 personal computer, motion control board, digital I/O card and CNC machine tool control software, which are relatively inexpensive components.

If you don't want to build your own PC based CNC machine tool controller, you don't have to. Today, there are several different companies manufacturing various ready-to-go, bolt-on professional PC based CNC controller enclosures. Most of these controller enclosures include all the hardware and software necessary to control your machine including the amps and motors. Users can also purchase separate high-quality hardware and software components and use their own personal computer.

PC based CNC machine tool controllers are easy to install. The idea behind advanced PC based CNC machine tool controllers is to eliminate the need for tracing wires to the PLC or write ladder logic. Rather, the computer becomes the PLC and does the logic thus eliminating the need for PLCs and writing ladder logic. PC based CNC machine tool controller software generally comes equipped with several ready-to-go operator screens to choose from and even customize for ease of use and to get you up and going in minimal time. The software generally allows you to mix and match physical buttons, knobs, gauges, switches, lights and displays with virtual ones.

PC based CNC machine tool controllers are also easy to use. A well designed PC based CNC controller software package generally has the ability for a user to fully customize the control's user interface without being a C++ or VB programmer. For example, the control's user interface is able to be designed by dragging and dropping control objects around the operator screen and then setting each control object's size, caption and functions with fill-in-the-blank or check boxes within Windows. The user interface can be as simple or as feature rich as the operator desires. Control operators are no longer subject to the rigid design of pre-fabricated controllers. PC based CNC machine tool controllers also offer various programming styles such as G code, conversational or CAD to motion.

PC based CNC machine tool controllers are quickly retrofitted. Most companies cannot afford to take months off to get a machine on-line and productive. A good PC based CNC machine tool controller's learning curve is only about 1/5 of the time needed when compared to most controllers that still use PLCs. On average, installation is capable of being done in three days for the most common types of knee mills, bed mills, lathes, lasers, water jets, plasmas and punch presses.

PC based CNC machine tool controllers are capable of stilling running a customer's old G code programs. A state-of-the-art PC based machine tool controller, for example, allows flexibility to run a Fanuc G code program in the morning and then an Allen Bradley in the afternoon. Definable G code and M code tables are generally built into the control to allow configuring the new controller to understand pre-existing programs.

Real time solid modeled or wireframe tool path simulation while the machine is cutting is one of the features a good PC based CNC machine tool controller contains. Being able to perform tool path animation and CNC verification prior to pressing Cycle Start is also an important feature. Simulation provides step-by-step control over each move graphically, moving the light source, solid model rotation and viewing angles.

PC based CNC machine tool controllers are user customizable and are considered an open system. The best software allows screens to be customized without having to be a VB or C++ programmer. Typical Windows-style fill in the blanks and check boxes are used on well-organized screens so that even novice Windows users can drag and drop objects into place and set their properties. More advanced users are able to configure the controller routines to support new processes and new technologies with well-documented software application program interfaces (APIs) made available to all customers as well as source code for ActiveX and DLLs.

All good software supports the ability to integrate third-party applications. PC based CNC machine tool controller software contains, at a minimum, machine maintenance software, remote diagnostics via a modem, self-diagnostics and remote machine tool monitoring via RS232, ActiveX or a Network card. This includes automatic collection of manufacturing data in real time without operator intervention as a standard feature.

PC based CNC machine tool controllers are fast and can easily accommodate today's "high speed" machining requirements. With over 200,000 motion cards shipped to date these cards can achieve 62.5 microsecond servo update times per axis, which result in cutting feedrate velocities of up to 122,000 IPM. Some digital I/O cards can detect a change of state at rates in the 10 KHz range. DSP microprocessors close the servo loop using dual 32 bit micro processors to increase productivity, feedrates, accuracy and cut quality. Multiple events and multiple position motions can happen simultaneously. 3D profiles can even be cutting while the tool is changing. The extra processor on the motion card is not only the best way to close the servo loop with the motors, it is also the fastest method known to date to produce the fastest block-to-block cutting speeds.

With PC based CNC machine tool controllers, maintenance and repair are no longer an issue. Machine operators are now the masters of their own machine. Self-diagnostics are generally a part of every system. When it comes to parts, off-the-shelf Windows 95, 98, ME, NT or 2000 personal computers and brand name hardware purchased from local sources can be used. Are your parts now either so proprietary or hard to find that they do not exist anymore? How long can you be down? PC based CNC machine tool controllers eliminate the need to rely on others. Machine operators can learn how to service, support, maintain and upgrade the complete control and replace any part themselves.

PC based CNC machine tool controllers help eliminate downtime. No more waiting for proprietary parts that can only be obtained through the control's manufacturer. Generally, there is a terminal strip and cable that connects the machine wiring to the computer. All that needs to be done is to unplug the cable from the computer. This will not disturb the wiring to the machine. Next, restore the screens, G codes, M codes and logic files within 10 seconds from a saved backup on a floppy disk. The backup file is also small enough to be emailed. If the problem is the motion or I/O card, either of these can be replaced by anyone without disturbing the wires. If a control breaks, swap out another computer to replace any control for any machine type at anytime.

PC based CNC machine tool controllers are easier and quicker to service. Manufacturers of PC based CNC controller software hire qualified technicians to immediately answer technical questions via phone, fax or email. If application assistance or custom logic is needed, the PC based CNC controller software manufacturer has qualified in-house staff and local reps that can fulfill these needs either on-site or via the internet. Also, most PC based CNC machine tool control software manufacturers do not detach themselves from the hardware boards and takes responsibility for all of the hardware boards they sell.

PC based CNC machine tool controllers allow use of your existing motors and amplifiers. This holds down the cost and labor plus ensures that the motors and amps are sized right for the machine. Good hardware can control existing motors that are: Brush or brushless, AC or DC, servo, stepper, PWM or hydraulic. The amps or drives can be either current driven or velocity type. Spindle drives use current mode or inverters. Feedback can be closed or open loop. Closed loop systems use encoders or resolvers. There are a number of companies that also make digital I/O cards. Touch screens are also available.

Tough-to-produce plastic parts used to be something extremely difficult for programmer David Eno at Auburn Vacuum Forming Co. (Auburn, NY); however, he found a way to make them more easily, while giving them a comfort zone for any part that comes through their doors.

Auburn is a manufacturer of vacuum or pressure-formed plastic parts for mid-size and larger companies serving the general industrial, medical and transportation markets. These custom-made parts normally involve secondary CNC machining and further value-added assembly work. Their 40-person staff is supported in these efforts with in-house services including CAD, pattern, mold and fixture construction.

Auburn’s pattern shop has the capability to produce tools using traditional pattern making equipment coupled with CAD/CAM. Fixtures and CNC programs are developed in-house to ensure tight control over the manufacturing process. Three and five-axis CNC machines are used extensively for consistent and productive part processing. They are able to import and export files, to rapidly develop CNC toolpaths, and to assist customers with part design and development.

The Challenge
A problem the company had to solve was how to trim small or large parts from thermoformed-plastic sheets quickly and accurately, and produce molded parts productively. Molds and plastic formed parts could be as small as two inches by three inches or up to 10 feet in length. An average molded thermoformed part is five-feet square using up to one-half-inch-thick plastic sheet.