CAD/CAM Software: A new productivity tool?
Does CAD/CAM software make a difference in EDM productivity? The definitive answer is, YES. The wire EDM marketplace is more competitive today than ever before. To be competitive your machines must be running at peak efficiency. The proper CAD/CAM software package is a significant part of the machine efficiency equation. If a new machine purchase is planned, then a system that can take advantage of the latest generation technology will be needed. However, if older model machines are being used then it is equally important that they be operating at maximum efficiency
CAD/CAM software may seem insignificant as a part of the total package since the total software price is probably well below 5% of the total purchase. This fact many times relegates CAD/CAM software review to a cursory study at best. Inadequate software is perhaps the largest reason for machine idle time. With that said, letís examine several situations.
Four distinct situations will be discussed:
Each of these situations is unique, yet CAD/CAM software plays an important role in each. Most CAD/CAM software systems are sold in situations 1 and 2, this is understandable since most companies with existing machines will likely have some type of software in place. This does not make the purchase of new CAD/CAM software less necessary, simply less likely.
A Company with no existing wire EDM machines is planning to purchase a new machine. In this instance some provision will need to be made to create programs for the machine. If a company has no existing CAD/CAM software then the purchase of a new system will be needed. The distributor who is selling the machine may make a recommendation as to which CAD/CAM system will work best with their equipment. This recommendation should be given some significance, however you should be aware that many machine tool distributors have little if any experience in advanced software such as CAD/CAM. Many factors should be weighed in determining which product is best for your needs. Any product that is purchased should be capable of utilizing the advanced capabilities of a specific wire EDM machine. It would be unwise to purchase a package that specializes in a single manufacturer; this will limit the choices when it comes time to purchase additional machines. If there are any doubts concerning support for other manufacturers simply ask the distributor for a users list of companies using the software with other types of equipment. Donít hesitate to call these users, and be specific in questioning them when they contacted. Another good source of information may be the applications department at the machine manufacturer. The applications engineers will likely have experience with customers with a variety of software packages.
A Company with no existing wire EDM machines is planning to purchase a used machine. In this case the software decision may become more critical. The reason being that older machines have less sophisticated controls and are sometimes awkward to program, requiring special codes and programming techniques not required by newer controls. Once again the dealer who is selling the equipment may suggest a system, but beware; they may know little about the programming requirements of a specific machine as they may deal in a number of different manufacturers and models. If it were possible to contact the manufacturer, this would be a good source of information. When purchasing an older used machine it is best to consider only well established companies with a long history in the EDM marketplace, as they are more likely to have post processors already developed for your machine. A Company trying to implement a new type of technology does not need the added headache of becoming the test site for software development.
A Company with an existing wire EDM machine is purchasing a new machine. In this situation there is most likely already some type of programming system in place. It is only natural to assume that by simply purchasing a new post processor for the current system the problem will be resolved with a minimum of time and expense. This may be true if the existing system is relatively current and supports the new equipment. The evolution of CAD/CAM systems has been accelerated in recent years due to the competitive nature of the marketplace and the advancements in computer hardware. If the system that is in place is lagging behind the technology, serious consideration should be given to updating to a newer version or perhaps an entirely new package. This will not only insure support for the advanced features of the new equipment but may increase productivity on the older equipment.
A Company has an existing machine in place and is planning no new purchases. This situation represents a classic example of "If itís not broken, then donít fix it" mentality. If the current system and machine are producing parts with few if any errors then why spend the time and money to purchase a new system. Additionally, staff will have to be retrained and there will be a learning curve. The simple answer is Productivity. If the current system makes it difficult and tedious to program parts to run unattended then chances are they are not programmed that way. If programming complex parts such as: gears, cams, and 4-axis work is impossible or extremely difficult, then work is probably being turned away that could be cut if there were a method to efficiently program it. A further concern may exist if the company no longer supports the version of the software, or worse, is no longer in business.
Now that we have reviewed these situations letís take a look at the criteria that should be used to determine which software package if any will provide the productivity needed to allow the wire EDM equipment to perform to its designed capacity.
I. General Criteria
Compatibility. To insure compatibility with current and future trends in computer hardware, a system must operate in any of the current Windowsģ operating systems (95/98 or NT). It should be a native Windows program which means that it was designed specifically to run in Windows and takes full advantage of the features of the operating system. Even though Windows has been the standard for years, there are still systems available that claim to run in Windows, but were really designed to operate in DOS or UNIX. When viewing these products a disjointed feeling will be noticed when the system is operating. This is due to the fact that it is actually a collection of different programs that do not run from the same interface. With a true native Windows product, all functions should be available from within the same program. As the Windows product line continues its evolution these older programs will find it increasingly difficult to function in an environment they werenít designed for.
Hardware Requirements. Any package under consideration should be capable of performing well on a mid-range PC. Special hardware requirements such as: specific network adapter cards or high-end graphics cards should be avoided. These items not only increase the price and limit your choices in computer hardware, they can create problems in the future if they are discontinued or can no longer be serviced. With the amazing power of todayís off-the-shelf computers any system requiring more should be viewed with suspicion.
Ease of Use. It would seem that if a system were designed to operate in Windows then it would necessarily be easy to use. This is not always the case. A system should have an intuitive feel to it, where you naturally understand what to do. To achieve this, a systemís menus should be organized in a logical progression, there should be a limited number of questions in each dialog box, picture icons should be used in addition to text menus whenever possible. A powerful system that is difficult to learn and use is of little value.
Capability. When evaluating systems capabilities, consideration should be given to current needs as well as future requirements. The system that is purchases should have the ability to take advantage of the complete range of functions of the machine tool. Even if only the components that are necessary to program your existing parts are purchased, the ability to add features as the complexity of your work increases should be available. A common mistake is to purchase a system that will handle the present work, but is limited in its capacity to expand, as needs inevitably will.
Price. Although price is almost always a factor in any purchasing decision, it should not be given significant weight. The price of a CAD/CAM system is a fraction of the total cost of the complete package (machine, tooling, and software); it should therefore receive an appropriate amount of consideration. It should be noted that more expensive does not always mean better. Having said that the old rule of "You get what you pay for" generally applies If a package is unbelievably inexpensive it is probably lacking capability, customer support or may simply be a product that is obsolete.
II. Situation Specific Criteria
Machines equipped with automatic wire threading. If a machine is equipped with automatic wire threading then it will be necessary to insure that the system will automatically generate the necessary codes for threading and cutting the wire. It should not be necessary to instruct the software each time one of these codes is needed. This adds to program time and increases the possibility for errors. The system should also have the capability to program for unattended machining. This typically involves cutting openings and leaving the slug attached until all roughing cuts have been completed. Then the slugs will be removed using a reverse cut from the original start hole. After the slugs have been removed the trim cuts can be performed automatically. If the CAM system does not automate this process it can be a tedious chore to program it manually and will likely result in this type of machining being ignored.
Machines with submerged cutting capability. Typically extra codes are needed to fill and drain the tank for this type of machine. If the post processor does not automatically generate these codes they will have to be manually added to the program.
Machines with OEM cutting conditions. Most modern wire EDM machines have a set of predetermined cutting conditions for specific materials and wire sizes. It will make programming more efficient if the system has a database of these conditions included. This eliminates the need to look up this data and manually enter it for each program.
Machines with programmable Z-axis. If the machine has a programmable Z-axis then the system should be capable of implementing a Z move during the program. Typically this is used to enable programming of different height work in a common job or to raise the upper guide away from the work during trim cuts on non-submerged machines.
Machines with special equipment (start hole drill, automatic slug removal, etc.). If the machine is equipped with any special equipment it should be confirmed that this equipment is supported. If not, the necessary codes will have to be manually added to the program.
Extrusion Die and Mold shops. These applications obviously will require 4-axis programming capability. However there are several other considerations: Does the system offer variable land heights within the same shape. Does the system offer automatic synchronization of the two shapes? How easy is it to create and edit synchronization points between the two shapes. Many systems only allow you to use points that have been predefined as part of the shape for sync points, this can be limiting if additional points have to be added after the job has been initially programmed. If 4-axis work will be programmed careful scrutiny should be given to how easily this type of work can be can be programmed and more importantly edited after a program is complete.
III. Machine Specific Criteria
Agie 100 & 123 controls. These machines are perhaps the most difficult to post process for. If one of these Agie controls is to be programmed, insist on a test program which can be loaded into the control for a test cut. In this case it is probably wise to choose a software company that has had a long history of programming Agie controls. The newer Agie 123 controls require 3 distinct and different programs to machine a part. The first file type is the technology file, which is a set of cutting parameters. This file is supplied with the machine. This file can be selected at the machine using the Agie control. The second file type is the JOB file, which is a set of instructions pertaining to job setup and execution. Z heights, offset direction and which technology file is to be used are some of the settings necessary for a common job. This file is normally created at the machine using the JOB editor. The third file type is the geometry (GEO) file. This is the actual NC code file that causes the machine to cut the part.
AgieVision controls. This control is the latest control from Agie. In many ways it is improved from the Agie 123, but it does have unique requirements of its own. This control uses a separate NC code file (ISO) for each shape to be cut. Any system that is being considered for this control should automatically generate the multiple files needed within a single program. This control also uses a script file (SBL) which gives the control basic information about how to machine the part. Separation cut amount, Z heights, quality target, trimming direction and approach types are some of the parameters used in the script file. If a system does not generate the script file these items can be set at the machine. This will increase time required to setup a program at the machine as these parameters will need to set by the operator.
Mitsubishi machines. Mitsubishi has produced a large number of machine models over a considerable period of time. As the machines have progressed the capabilities have increased. It is important to clarify if a post processor for a specific machine is available. Mitsubishi machines require that a lower power setting be used during the entry move with the full power setting being activated once the cut has been started. The programming system should be capable of outputting 2 sets of E-packs for the initial roughing cut. It would also be helpful if a specified distance for the insertion of the second E-pack could break the contour automatically. Another requirement for certain Mitsubishi machines is the output of a dwell (G04) command after the lead out move when cutting outside shapes. This is necessary due to the wire lag created during a roughing cut under certain conditions. A wire break can occur if this dwell is not programmed. Machines equipped for submerged machining need tank drain and fill commands output when automatic wire threading is to be used. All of these commands could be manually inserted if necessary but it would be best if the software could output them automatically when needed.
Charmilles machines. Modern Charmilles machines use two different file types to cut a part. The first file type is the CMD file which is the master instruction file. This file is used to call onboard technology, to specify tapering on or off, to activate program stops and other secondary functions. The second file type is the ISO file which is the actual NC code file. The Charmilles control has options for tapering and corner modes. These features are activated by "G" codes and your programming system should support these different modes if you are to be able to take full advantage of the machines capabilities.
Sodick machines. Sodick has also produced a wide variety of machines with different controls. It should be verified that a post processor is available for a specific control. On older Sodick controls it is necessary for the wire offset to be applied and canceled in two stages. This avoids the offset being applied to the entry and exit moves, which will leave a small scallop on the part. The Sodick offset register (H) is programmed using a 3 place non-decimal number that actually represents the amount of the offset. This is a unique format and the system must be capable of outputting it in this format to utilize the Sodick preprogrammed offset values. The latest Sodick machines can have the wire speed (WS), wire tension (WT), and PIKA selection (WC) output in the NC code. These machines no longer have manual adjustments for speed and tension so it is convenient to have them included in the program. The WC register is used to activate specific modes of the PIKA circuitry for different finish requirements.
Japax machines. These machines were offered with two different series of controls in the US market. The 3 series is the older of the two and the most peculiar to program. It does not support true 4-axis programming but was capable of using different tapering and corner modes during a 2-axis program. The tapering (T value) on this control is not output directly as an angle but rather as a factor of the angle. All of the tapering values must be declared at the head of the program before any cutting takes place. These unique requirements will need a specialized post processor to properly generate the necessary codes for the Japax 3F series control. The 4G is the newer model control and it programs similar to most of the other Japanese controls. It also has full 4-axis capability. If the system is being considered for an older Japax machine with a 3 series control it should be confirmed that a post processor is available.
Charmilles/Andrews machines. These machines were some of the first wire EDM machines ever produced. The control is very simplistic, however the fact that it requires leading zeroes, does not accept decimal points, and programs in incremental may cause problems for some systems.
IV. Programming Productivity Tools
Automatic Skim Cuts. If multi-pass machining will be used on your EDM then this feature is a must. A system with automatic skim cuts will program all necessary passes using a single command. This saves both time and possibility for errors.
Associative Tool Paths. This feature associates the tool path with the geometry. If the geometry is updated then the tool path will automatically reflect the change.
Operations Editor. A comprehensive operations editor should allow editing of existing operations, insertion of new operations and reordering of current operations.
OpenGLô viewing. This feature is a graphics-viewing tool, which allows for dynamic zoom, rotation and panning of wire frame and rendered geometry. In complex 4-axis parts the ability to zoom and rotate a rendered part without having to redraw the screen can save time and allow for better verification.
Graphical creation and editing of mode change points, taper change points, corner modes, and 4-axis sync points. If you intend to do variable taper or 4-axis parts then it is important to consider how easily you can create and edit these taper change points and sync points. The most flexible method would be to allow creation of these points at any location on the shape.
A modern CAD/CAM system may be the most important factor in the productivity of wire EDM equipment. Invest the time, and thoroughly investigate the systems available. A general-purpose CAD/CAM system may be acceptable, but will it allow for the most efficient use of the machine. A specialized wire EDM CAD/CAM system may be an additional expense, but it is certainly one that can be justified. The penny saved today, may be the pound of productivity lost tomorrow.
About the author
Randy Mell is the President of CAM-1 Inc. In his current position he is involved in product development as well as sales and support of the Esprit CAD/CAM software product. He has been involved in machining since 1976 when he began as an NC programmer for a small manufacturing company in his home state of Illinois. He worked as Senior NC Applications Engineer for KGK International from 1980 through 1985 where he was involved in customer training and support as well as custom turnkey projects. He was a self employed CAD/CAM consultant from 1986 until October of 1998 when he joined an American subsidiary of a European software company as National Sales Manager. During this time he focused his attention primarily on the programming of wire EDM machines and has been involved in the development of several CAM systems specializing in wire EDM. In January of 2002 he left his position as National Sales Manger to form CAM-1 Inc.
You may contact Randy directly at the following e-mail link rmell@CAM-1.com with any further questions you may have.