Ejection Pins and Cores
EDM Productions of ejection pins and cores for molds
Ejection pins and cores are used in nearly all molds and dies. Sometimes 20, 30 or more of these pins and cores are necessary to produce a mold. Especially microextrusion, which often require pins and cores which are very difficult or not possible to produce by conventional machine.
The Challenge
It is often necessary to produce very precise ejection pins and cores. Normally they are produced by grinding. But unfortunately grinding has some problems. Grinding wheels have to be structured and aligned from one wheel to the other. A further problem is the sideforce against the workpiece during the grinding process. All production processes with tools (like grinding wheels or turning tools) normally exert a force against the side of the workpiece. Side force is a problem when machining very small diameters.
Another problem is that cores often do not fit in the first step. But it is nearly impossible, with the normal grinding process, to make such a diameter 0,01-0,05mm smaller.
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The Solution
The one and only process which is the ideal one has to be made with a wirecut machine in combination with a rotation spindle of JS JS. Wirecutting does not cause sideforce against the parts. No special toolings are necessary. For the parts you see on the photos you need only a machining program. If the first shut of the extrusion shows that the cores are to big in diameter, you only have to make a correction in the program. Now you can immediately go into the erosion grinding process and lower the diameter of the cores 0,01-0,02mm.
The Example
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The first photo shows an ejection pin for micro extrusion with a diameter of 0,05mm, produced with erosion grinding. With this process this job is absolute “no problem”. |
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The second photo shows free programmable contoures which are also “no problem” to manufacture with the erosion grinding technology. |
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The third picture is made from a measurement machine and shows ball structures which are difficult to produce with normal grinding. Look at the excellent surface quality made from the wirecut machine. It doesn`t matter if you have to produce ball structures, angels or combination of different contoures. A wirecut machine, equipped with a JS rotary spindle (RR, RP or RS) can achieve it easily. |
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