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Monday, November 29, 2010
Electrical Discharge Machining And Injection Mold Making
Electrical discharge machining, or EDM, is such an integral part of injection mold making that they are inseparable. In the eons ago, before EDM, injection molds were milled, filed, turned, ground and handworked to obtain the same results as today, with the newer technology.
The fits and finishes are much better, as are the designs, thanks to this amazing process. Many of the molds made today would simply be impossible if done the old way. With computers playing such a critical role in the design and manufacture, parts have become very complex and expensive.
For example: rather than make many small inserts to create a plastic part, now there may be only one steel part with all the details machined. This makes the process simpler, but also more risky in the event of a mistake. Now you are throwing away a very expensive component instead of a small part of that component.
Then there is the wire EDM! This remarkable tool is like an electrical bandsaw that cuts to extreme accuracies, regardless of the steel hardness or type. Hardened tool steel is extremely difficult to machine, but the WEDM makes it look easy!
Randy Hough writes about electrical discharge machining.
The fits and finishes are much better, as are the designs, thanks to this amazing process. Many of the molds made today would simply be impossible if done the old way. With computers playing such a critical role in the design and manufacture, parts have become very complex and expensive.
For example: rather than make many small inserts to create a plastic part, now there may be only one steel part with all the details machined. This makes the process simpler, but also more risky in the event of a mistake. Now you are throwing away a very expensive component instead of a small part of that component.
Then there is the wire EDM! This remarkable tool is like an electrical bandsaw that cuts to extreme accuracies, regardless of the steel hardness or type. Hardened tool steel is extremely difficult to machine, but the WEDM makes it look easy!
Randy Hough writes about electrical discharge machining.
Sunday, November 1, 2009
EDM Machining, Precision Tooling and Mold Repair
Have you ever noticed how everyone is nice to the mold repair guy who is also able to do micro welding or laser welding? No wonder, when a mistake is made with EDM machining, you need help, now!
The use of precision tooling helps immensely, when operating a sinker EDM or a WEDM. If you have sub-par electrode holders or ineffective set-up and inspection equipment, you job becomes vastly more difficult.
Hard as it is to believe, there are still shops out there that are using vises, angle plates or homemade tooling to hold electrodes. This might make sense in some remote case where nothing else works, or if your application is so specialized that it is the best approach.
Actually, I did work in a high precision mold making shop that machines graphite blanks and held them in little fixtures they had made. Because the product line was so limited and the machining was always the same but different, this worked quite well.
Whenever we got outside of that little box, it was different though. When I suggested that we invest in System 3R, they looked at me as if I was crazy. I also wanted to get a high speed milling machine and use the automatic tool changer, but this was not to be. They are no longer in business.
Randy Hough has a website: http://CompleteEDM.com that talks about EDM machining and how to get the best results.
The use of precision tooling helps immensely, when operating a sinker EDM or a WEDM. If you have sub-par electrode holders or ineffective set-up and inspection equipment, you job becomes vastly more difficult.
Hard as it is to believe, there are still shops out there that are using vises, angle plates or homemade tooling to hold electrodes. This might make sense in some remote case where nothing else works, or if your application is so specialized that it is the best approach.
Actually, I did work in a high precision mold making shop that machines graphite blanks and held them in little fixtures they had made. Because the product line was so limited and the machining was always the same but different, this worked quite well.
Whenever we got outside of that little box, it was different though. When I suggested that we invest in System 3R, they looked at me as if I was crazy. I also wanted to get a high speed milling machine and use the automatic tool changer, but this was not to be. They are no longer in business.
Randy Hough has a website: http://CompleteEDM.com that talks about EDM machining and how to get the best results.
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