EDM electrodes made by RP&T techniques + variable offsetgenerator on STL files, results available now

From: b.kooijmans@ind.tno.nl
Date: Wed Oct 23 2002 - 18:16:46 EEST

Dear list,
As promised the results of this project are made available to the
listmembers now, after being presented first at TCT2002 in Manchester UK
this year. Underneath a short summary, those interested can reply to me
personally and I will send you PDF files of summary and presentation.

Regards to all from a rainy Holland,


Working in RPD, the tendency to expand the possibilities of RP techniques is
obvious. Numerous surveys have been conducted to try to use RP, in order to
make electrodes for EDM (Electral Discharge Machining). Electroplating
RP-models, casting Cu, trying to SLS a whole variety of materials. TNO
decided to see whether any of those had become applicable yet and discovered
some new interesting and important facts regarding EDM along the way! The
presentation brings together modern and conventional techniques with a
funded view on technologic developments.

Using a market scan, the different possibilities of making EDM electrodes
using RP&T techniques were traced. Also the ones that are still in
development or have not made it past development. Any possible lead has been
explored. They will be discussed in the presentation. A special testing
geometry included all features important for EDM electrodes such as
measurements and tolerances, smallest possible detail etc. All the offered
test pieces were admitted. EDM tests were run on all different offered
techniques. The results of these tests and experiences will be shared.

During the project the need for an offset-generator became clear. EDM
electrodes have to be compensated for the spark gap. Generally this is done
by deliberately programming the milling tool diameter in CAM with a smaller
diameter than the actual milling tool. RP machines however use STL files for
input. They must already incorporate the gap distance. Manually editing the
CAD-file proved way too cost-inefficient. Thus TNO developed software to
make a good offset on an STL file. While making the software an important
feature was discovered which had not been noticed and identified before.
This will be revealed and explained in the presentation. The solution, a
variable (angle dependent) offset generator, has been patented.

Ing. N.M.J.P. Kooijmans

Prototyping and Tooling engineer, projectleader
TNO Industrial Technology
Department Industrial Prototyping Project:
P.O. Box 6235
5612 AP Eindhoven (Netherlands)
Tel. (+31) 040-26 50 128,
Fax (+31) 040-26 50 678
E-mail b.kooijmans@ind.tno.nl <mailto:b.kooijmans@ind.tno.nl>

Visit TNO-Industrial Prototyping and Tooling at:

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