1/1/2001 | 14 MINUTE READ

The EDM Forecast: Sunny Skies

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Despite the growing popularity of alternative technologies, new trends in EDM automation and product efficiencies guarantee its continued use well into the new millennium.


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The moldmaking industry is in a constant state of change. New materials, faster technologies and more advanced components are being introduced to aid moldmakers in their never-ending quest to shorten delivery times - and EDM technology is no exception to this rule. Below, several major suppliers comment on what's new and why they think that EDM will never be replaced.

What major advancements do you foresee in EDM this year? And how will these advancements affect the mold designer, the moldmaker and the moldmaking process in general?

Gabriele Carinci, president of Agie, Ltd. (Davidson, NC): When I take a look at 2001, I believe that manufacturers will come forward with ways of improving productivity. This comes at a time when moldmakers are having a difficult time staffing competent toolmakers - CNC experts and people who really can take their job and run with it. The question is how to improve utilization of capital equipment with the dilemma and limitations in hiring, skill sets and so forth. The biggest advances are going to come in minimizing floor-to-floor time - getting the job in and out in a minimum amount of time.

The second area is how to simplify the entire process so the moldmaker can maximize production and still maintain the precision and surface finish/surface integrity levels that customers demand on molds that are being produced. Another capability that we're seeing now - which we've seen in Europe for some time - is the implementation of automation cells, where one can achieve productivity by having a mechanical, robotic workhandler stocked with jobs and feeding one, two or several EDM systems at one time. Those automation cells can range in complexity from simply picking and placing parts or electrodes - in the case of sinkers - to very sophisticated systems which are monitoring every job in the backlog, and selecting the job that should be next sequenced into the EDM queue.

Gisbert Ledvon, marketing manager for Charmilles Technologies (Lincoln-shire, IL): We are going to see more automation on EDM machines like pallet and electrode changers, especially on die sinkers. On the wire machines I've already seen more enhancements as far as more flexibility [especially for the moldmakers] and more accuracy in taper cutting. I think moldmakers need this more because not many them use wire EDM in all cases.

I would say that the industry is moving toward more user-friendly controls. I think we will see more machines in the future with industrial PCs inside that will interface with Windows, so it will be easy for the user to run the machine. What's also coming is that parts and maintenance systems will be provided on CDs with the machines. The user can search for a part on the CD, find the information that he needs, then call up and order it. The user needs to have more tools to keep his machine running without needing people to hold his hand or having to call around to find a part. This will improve efficiency.

I think that automation also will change the moldmaker's role a little bit. He needs to get more involved in the planning process - like presetting his mold base on the pallet, for example - and learn how to setup the electrodes. He then needs to make sure he loads the electrodes correctly into the robot to let the machine run automatically overnight.

The mold designer will have more say in the undersizing of the electrode and the electrode design. There will be systems out there where the mold designer can describe his electrode and the system will tell him the best undersize he should make the electrode with. He will put it on the print, so the moldmaker can make it to that size in order to cut the part the most efficient way on the die sinker.

Fritz Wittwer, vice president of engineering for Erowa Technology, Inc. (Arlington Heights, IL): EDM has always been very slow. Every manufacturer is improving its technology - be it on the drives, generator, programming system or flushing - in different steps and approaches. If you look at all of the EDM equipment manufacturers, what is done the same is palletization. This and automation are the EDM trends right now - robotic systems can be seen everywhere. Big tool changers also are prevalent - technology is moving away from the operators changing the tools. Technology puts the operator in the position of being a machine cell manager who is responsible for providing parts, tools, CNC programs and fixtures on time in order to keep the machine productive 24 hours a day.

Jason Habib, EDM application engineer for Makino (Mason, OH): Adaptive technology and high-speed jumping are technologies we need to stay on top of. Adaptive control is important because the main concerns people have are arcing and their final finishes. High-speed jumping and linear motors are becoming more popular.

Automation is big, and what we're promoting with our machines is no man-time. Our customers want the machines to do the work with the minimal manpower possible. For the smaller shops, we are letting them know that they can spend their time doing setup work and then the machine is going to do the rest with things like high-speed jumping, advanced adaptive controls system, etc. The jobs can be set up and then forgotten about - knowing the work is being done.

Greg Langenhorst, product manager of EDM sales for Mitsubishi EDM (Wood Dale, IL): Automation is the biggest innovation overall and it is driven by the global marketplace. Molds and dies are being shipped to China, Portugal, Spain and Brazil because the labor rates are so much lower. In order to get more production and actual spark time out of your existing equipment, you need to put them together in an automation cell. In doing so, the equipment will run longer and be less labor-intensive, thus saving added operator costs.

The key to unattended operation is that the machine must run at the same speeds when no one is there and also be reliable, dependable and have an active adaptive control system that can emulate a good operator's capabilities. Once a machine can run at 100 percent efficiency fully unattended, you can then add a robot and extend that peak efficiency over hours that you normally didn't have available. All EDM equipment manufacturers are moving toward automation, each with a different idea of how to get there.

In general, everyone also is trying to push for higher cutting speeds on wire EDM with more reliability. Auto threading systems seem to be the key element here - everyone is getting better and faster with this technology, improving threading capabilities and reducing maintenance intervals. Sinker-wise, the push is to minimize electrode wear and increase the equipment's intelligence - to keep the machine burning with the right current density amount for whatever electrode size that you are running. Depending on your work type - whether it's little thin rib work or large cavity work - everyone is trying to balance their machine's intelligence and power to give customers the best of both worlds.

P.J. Naughton, marketing manager for Sodick, Inc. (Mt. Prospect, IL): At the past IMTS show, the major advance was automation. System 3R (Totowa, NJ) had robots in just about every EDM manufacturer's booth. More EDM manufacturers are moving toward using robots for their EDM machines. It's a better way to remain competitive in a world market. Also, the process will be quicker and more foolproof - the less operator intervention on a job, the less chance for error - assuming that your setup is correct.

How do you feel about the "buzz" that EDM will someday soon be eliminated?

Carinci, Agie: With high-speed machining and hard milling technologies, there's been a lot of gloom and doom that these technologies are really going to kill EDM and I think that these are really bombastic statements. Certainly in the case of high-speed milling, if you are roughing out a cavity there may be cases where the high-speed milling will be the preferred technology. However, there are certain applications today that are beyond the technical capabilities of high-speed milling that relate to the "tool length" to "depth of cavity" ratio and critical radii that must be achieved.

In my opinion there's a symbiotic relationship between high-speed milling and technology and die sinking EDM where they are necessary and absolutely important to each other, as opposed to being absolutely competitive with each other. There will be application-sensitive changes that occur as a result of the implementation of high-speed milling versus die sinking because in high-speed milling you also have certain technical obstacles. One must be able to select a cutter for a specific application [e.g., cutting depth, cutting speed, material hardness, radii required, cutter cost, etc.] versus the use of EDM technology. In numerous applications both high-speed milling and EDM will be required to achieve the floor-to-floor time and production cost goals needed to be globally competitive.

Ledvon, Charmilles: At this point, I think that these new technologies are not a threat - they are more like complementary technologies for the die sinker. The high-speed milling allows the cutting of multiple electrode shapes onto one block of graphite and one electrode holder. This increases the machine and tool changer capacity because you have multiple electrodes on one tool changer holder. I see the following problems with high-speed milling: you can only cut certain sizes of cavities to a certain depth and if you have small ribs and small details, high-speed milling just can't get in there; and you have to use EDM to achieve the depth, accuracy and the finish the customer requires.

Also, high quality steels need to be used for molds to have a long life and if the material is too hard, high-speed milling is limited. Last but not least, the equipment investment and the operation cost per hour is expensive - the cutters are expensive, and if you want to hold a certain accuracy and get sharp corners with good finishes you need to make sure that you are changing the cutters frequently. Taking all of these factors into consideration, I don't think that high-speed milling will eliminate EDM in the near future. They will be a team to increase productivity and make it easier for moldmakers to be more efficient and to overcome the threat of cheaper overseas moldmakers.

Langenhorst, Mitsubishi EDM: There are great applications for hard milling and terrible applications for hard milling. Trying to achieve sharp corners in cavities that have real fine details with a ball nose endmill or putting a specific texture on a mold surface is not possible with this technology. But it's a great tool to help speed the process. High-speed graphite milling is a terrific innovation - the faster and the less costly you can make the electrodes, the more efficient it makes the rest of the process. Hard milling will definitely never completely replace EDM. If anything, it may help to increase the amount of work that, at a certain level, comes into EDM departments. You will be able to mill something to a point - and then if you need sharp, fine detail in part of the cavity, it will need to be EDM'ed for the final process.

What developments are underway within your company for EDM to combat this "threat?"

Carinci, Agie: Agie has examined how to improve the man/machine interface potential between the die sinking and wire cut systems to the operators, so that they can do their jobs more efficiently with limited EDM knowledge. For example, we recently took a look at the amount of time a customer takes to set up a job in a wire or die sinking system, and depending on the precision, capability and experience of that individual, it can take minutes to hours. So, we developed an on-board measuring system to automatically measure the exact workpiece tilt and skew. The control then automatically adjusts the entire geometry that you programmed into it for that tilt or skew to produce a perfect part.

Ledvon, Charmilles: I think that we will have more specialized application technologies because we have to adapt to the high-speed milling made electrodes and it will go into a direction where customers can automate easier - it doesn't have to be an engineer who runs an automated EDM anymore. One software program will control the robot and the EDM machine, and there will be solutions in the future to run a robot, an EDM machine and a high-speed mill on a PC-based controller. Some mechanical advancement may be made in the future as far as speed for XY movement and things like that. I think linear motors are still limited and not proven yet. To enhance your cutting speed on a die sinker, it still comes down to how good your technology is and how the generator performs.

Wittwer, Erowa: To keep EDM technology competitive, we provide a four-step, modular manufacturing concept that allows the user to run an EDM machine more than 6,000 hours per year. The first step is palletization - tools and pallets can be changed automatically. Step number two is organization - every moldmaker needs to organize the workflow into his EDM machine outside of the machine and we provide presenting stations to set up tools and mold components outside of the machine so that the machine can run constantly without extra setup time.

Step three is robotics - we offer a number of different tool changers and robotic systems to load EDM machines unattended during the second and third shifts or over weekends. Step number four is process control software, which allows the user to manage the workflow through the EDM machines more efficiently. The user can then ensure, before the machine is done the burning of a mold, that all of the CNC programs, offset data and all of the other information needed to burn or machine the next job is complete. These four steps are what we need to keep machining costs low in order to be competitive with the other technologies - also important with time-to-market getting shorter.

Habib, Makino: A key item - besides faster times, accuracy and unmanned machining - is surface finish. The potential customer is always looking for the best surface. One of the up-and-coming trends is an "additive-based" machine. Makino's entire line of EDNC [CNC EDM machines] comes in two forms - the standard machine and the HQSF [High Quality Surface Finish] machines. These machines use an additive in the dielectric fluid in conjunction with low-power settings to achieve superior surface finishes as low as 0.5-fRmax. This process is called DDM or Diffused Discharge Machining.

Langenhorst, Mitsubishi EDM: In 1992, we first came out with an anti-electrolysis power supply on our wire machines, which improves surface integrity, minimizes rust and corrosion and minimizes cobalt depletion when cutting carbide, but we gave up a little bit of cutting speed in order to get that higher quality part. We finally were able to design a way to make that power supply fast again. Wire-machine wise, we're totally focused on reducing maintenance, which creates machine downtime. All of our customers say that they have no time to do maintenance - the machine must be kept running. The big push has been trying to reduce the maintenance areas and create what we call self-cleaning situations. Auto threader maintenance has been a major problem - it has to be done or it won't work. We came out with an auto threader that has some self-cleaning capabilities. The maintenance cycles that have to be performed are fewer and farther between. Another area that has always been a maintenance headache is the seal plate. Dirt can build up on the front of the seal plate and cause drag, which can result in inaccuracy and leakage that increases maintenance. We came up with a stainless steel seal plate that's self-cleaning, adding to overall reliability.

Our biggest innovation in sinker EDM is the silicon powder finishing system. We introduce silicon powder into the oil as slurry - strictly using it during the finishing cycle of the sinker EDM orbiting process. This produces what we call a super-slick, glossy EDM finish that can eliminate a great deal of hand polishing, which can be very time consuming.

Naughton, Sodick: We have come up with something drastically different. Instead of using ball screws on our machine to move the axis tables, we use linear motors - which use magnets. There is no physical contact so the reaction time is much quicker than using a ball screw, and if your reaction time is quicker, your cuts are quicker because it can change your cutting conditions at a faster rate than what you can do on a ball screw driven machine. Also, as the fast reaction time moves the axis at such a high-speed, it generates its own natural flush so you never need auxiliary flushing ports.

We've also designed a high-speed, automatic wire threader that runs approximately 12 seconds AWT (automatic wire threading) - before it was about 65 seconds. Another new development is remote monitoring and remote control capabilities on our machines, where a shop owner can check up on the status of his machine without going into the shop. On a Sodick EDM, the machine is assigned a name and is linked to a modem. The operator - from his remote location - needs a computer, modem, Windows 95 or 98 and a web browser. The operator could view the machine's control on the laptop, send and receive text messages and programs, and enter and execute MDI codes.


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