With ever-shortening delivery times being the primary goal of moldmakers today, EDM technology is a vital part of achieving this goal. Still, day-to-day equipment operation is not without its trials and tribulations. At our recent trade show - MoldMaking 2001 - we asked a number of our readers what questions they would like to ask EDM experts. In response to these questions, we discovered that equipment manufacturers are designing easier-to-use equipment with sophisticated components and accessories to help moldmakers do their machining more quickly while maintaining quality. Features like automatic tool changers, palletization and efficient vacuum systems also aid in allowing moldmakers to run their equipment 24/7 - maximizing equipment use and virtually eliminating downtime. The following were the most frequently asked questions and responses.
What are you doing to make EDMs easier to operate and program so that mold shops can train more moldmakers to use them in their shop?
John Foster, national sales manager, Current EDM, Inc. (Plymouth, MN), a small hole EDM manufacturer: Since the release of our special controller unit, high-quality holes can be achieved with less effort and guesswork. This unit enables precise control of the electrode to ensure consistent results at optimum feedrates.
Ken Nelson, senior applications engineer, EDM Solutions (Elk Grove Village, IL), a manufacturer of EDM sinker machines, wire EDM machines and drills: Our R&D department has developed user-friendly software specifically designed for the moldmaker. We also have a very easy-to-use operator manual - with many illustrations - that anyone who can read will understand.
Bud Guitrau, director of operations, Gisco Equipment Corp. (Hauppauge, NY), a high-performance EDM wire supplier: In response to the increasing shortage of skilled EDM users, machine tool builders have compensated by building 'smarter' machines, ones that can be operated by less skilled or inexperienced people. This strategy is solving the industry's immediate problem of the shortage of skilled EDM'ers, but ironically, these 'smart' machines could indirectly allow even less emphasis to be placed upon the need for experienced moldmakers. My concern is that without this emphasis on complete moldmaking training, we will be producing more and more 'compartmentalized' operators and fewer craftsmen - complicating an already difficult situation. Smart machines are good but are only part of the solution. More emphasis on apprenticeship programs and vocational training need to be made by everyone involved in moldmaking. In this way, a trained and experienced 'all-around' moldmaker operating a 'smart' machine will have far greater insight into job planning and execution and be much more capable than an inexperienced or compartmentalized operator.
What are you doing to prevent problems related to the software/interface controlling the machine, which often requires service technicians to update or reinstall the software completely?
Foster, Current EDM: In the rare event that we do need to re-initialize our controller - after a significant power surge for example - all it takes is a five-second sequence at the controller by the operator. Our controller software is stored in non-volatile memory, not on a hard drive, so hardware problems are extremely rare. The operator can make software updates in five minutes by changing one memory chip.
Nelson, EDM Solutions: Our PLC software updates are supplied on E-Proms and the customer can change these. The customer also can change the system software; however, he needs to have a computer and communication software.
What are you doing to speed up the flow-through of work on an EDM?
Foster, Current EDM: We have offered automatic electrode (tool) changing (AEC) since 1995 to enable unattended drilling. In 1996 we first introduced a power supply 'booster' to double machining power, which greatly increases production of large diameter and extremely deep holes.
Nelson, EDM Solutions: We have our own tool changers available that can handle most after-market tooling systems to decrease downtime. But the biggest thing we do is supply specialized cutting technology for specific applications, not the one-size-fits-all mentality that some manufacturers use.
Guitrau, Gisco Equipment: In today's market, moldmakers aren't making as many capital equipment purchases as in the past; instead they are looking for creative solutions to make their existing equipment operate more efficiently. This would include better tooling to aid setup, palletization, robotics, automation, etc. This makes throughput more efficient, as more work is being accomplished in the same amount of hours. Shop owners are busy upgrading their machines and software and augmenting existing equipment to run unattended for longer periods. Perhaps the simplest example of increasing the autonomy of a wire EDM is the use of an automatic wire threader. Depending on the job, planning and programming, you can run in a 'lights out' mode - automatically threading hole-to-hole or in the event of a wire-break, the machine will automatically recover and continue machining.
Wayne Wagner, president, JT Die & Mold Group (Elk Grove Village, IL), a plastic injection mold and die casting die builder of everything from farm implements to connectors: We try to run 24/7 as much as possible with very little operator intervention. One of the ways we've accomplished this is by making our electrodes on a graphite cutting machine. Everything is worked from the center and programmed offline. We basically put the blocks in and the machine does all of its pickups - picking up everything right from the design data - and then we burn. There's no operator standing there manually positioning electrodes like it used to be. The only thing we haven't done is palletization, which will probably be our next step. We're getting closer, but it's a big step.
Joe Genc, engineering coordinator of PM Mold (Schaumburg, IL), a total service toolmaking company that engineers and builds plastic injection molds, compression molds and die cast dies: We run our shop 24 hours a day and we are doing as much unattended EDM work as possible - setting up jobs and letting them burn unattended. The idea is to keep these machines running as much as possible. In order to do that, we're doing a lot of concurrent engineering, which means that we make sure that when we are designing the molds, we are keeping certain key pieces of equipment in mind at all times so that we are maximizing the amount of hours we can put on those machines. Many times when you design a mold, it's up to the designer on how he wants to proceed through that designing procedure. If you are doing concurrent design, you can plan your designing time in such a way that you are making certain parts within that design more important than others. For example, making sure that your EDM work and CNC work gets addressed first as far as detailing and databases go. By planning and outlining these jobs very carefully, we've been able to make much greater utility of our EDMs. The other thing we're looking into is palletization; it's just a matter of deciding whether or not we are going to spend the money. This would save mind-boggling amounts of time because your setup time is done from the machine, of course. Also, to save time with setup we use many different types of EDM holders.
What are you doing to prevent carbon dust during the manufacture of electrodes? Do you know of any alternatives to carbon for electrodes?
Guitrau, Gisco Equipment: With graphite dust, anybody that isn't machining electrodes in an enclosed machining-center-type environment needs a very efficient vacuum system throughout the shop. I don't believe this dust is toxic, but it does need to be contained and collected. Besides the obvious aesthetic and housekeeping issues, this dust is abrasive and will cause premature wear of machine bearings and slideways. Alternatives to graphite electrodes are copper and copper tungsten, but in most cases, they don't EDM as fast or wear as well as graphite does. And except in the instances of producing electrodes by discharge dressing or wire cutting, metallic electrodes are usually more costly to fabricate.
Wagner, JT Die & Mold Group: We use graphite and in some instances copper - especially if we have some very intricate shapes that we would cut on our wire EDM or a very high finish is required. For the most part, we prefer graphite. We can machine it much faster and easier than copper electrodes. To prevent dust, we have a very large dust collecting system hooked up to all of our grinders. It also is hooked into the case of our machine that we use for graphite machining. It has a number of different filters on it, and it pretty much takes care of just about all of the dust.
Genc, PM Mold: We have two systems - a very sophisticated vacuum system on all of the surface grinders and we also have air filtration in the shop where the air is turned over completely every 10 minutes. When you walk into our EDM shop you don't smell EDM oil or anything. We use carbon the most because it is more cost-effective. We use copper electrodes depending on the job. It is much cleaner to work with, but it is more time consuming to cut because it is a harder material.
Rich Spurling, marketing manager, Saturn Industries (Hudson, NY), electrode manufacturer and distributor of electrode materials: We have dedicated vacuum, which a lot of shops don't have. Sufficient vacuum is necessary, although there is no total control. There is still graphite dust everywhere, which is the nature of machining a lot of graphite. The only way to completely eliminate the dust is to have someone else machine your electrodes.
How are you addressing surface consistency after EDM'ing?
Foster, Current EDM: Hole quality is extremely important to our customers since we often drill into finished parts and mold cavities. We design our machines to have as little effect on the part as possible. This means that there is a minimum of etching or corrosion in and around the hole, hole diameters are consistent from top to bottom, and recast and the heat affected zone are kept to absolute minimums.
Nelson, EDM Solutions: Our process optimization controller prevents inconsistent surface finishes and produces a softer EDM surface than many of our competitors. We do not handle after-market products for removing this surface.
Guitrau, Gisco Equipment: With today's technology, moldmakers can often get press-ready finishes right out of the machine, but sometimes economics or time doesn't allow you to get the machine finish that the print calls for. If the shape is simple and easily accessible, it's sometimes more economical to stop EDM'ing and manually polish the detail or cavity to the specified finish.
Wagner, JT Die & Mold Group: Most of the inserts we either send to the polisher or polish in-house. About one-third of the tools we produce leave with an EDM finish, which is fine. Other tools we either stone polish or diamond polish.
Genc, PM Mold: This issue has been addressed by the use of CNC EDMs - the consistency and finish seem to be a lot better by using these machines. We weigh that simply by the amount of complaints we don't get anymore - either from the polisher or the end user.
Is five-axis EDM'ing to handle the workpiece better a possibility?
Genc, PM Mold: I know that there has been talk about it, but I question its cost-effectiveness because five-axis machine tools in general are extremely expensive. Add to that the extra delicacy you would have to envision in such a machine design being that it's an EDM, and I would wonder whether you would realize a return on your investment. It would work though and be fantastic!
Spurling, Saturn Industries: Five-axis EDM'ing will be happening over the next few years, but it's a mindset and a change of direction for most. People need to commit to it and buy fairly expensive machines and software to run the machines.