Chief Delphi sprockets

[archiver]

Posted by Joe Johnson at 03/07/2001 3:43 PM EST


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.


In Reply to: Re: Wire EDM for 150% of SPI Cost!
Posted by Patrick Dingle on 03/07/2001 3:17 PM EST:



EDM = Electo Discharge Machining (approx. words).

Basically, an electrode is used to make a spark. The spark "zaps" a bit of metal and a bit of the electrode (often made from carbon). With time, the electrode burns its way into the metal. A new electrode is used after the rough cut to make the hole look just like the electrode.

This machining technique has revolutionized injection molding (especially for plastic parts).

Enter Wire EDM.

Same idea, but the electrode is replaced by a wire running from a feeder on top to a collection spool on the bottom. This wire gets partially zapped as it "cuts" the metal, but it is not a problem because new wire is constantly feed to do the new cutting.

This vertical wire is walked around a horizontally mounted work piece in the pattern you want. Essentially, the wire is like a hot wire going through butter, only on a much slower scale.

If you add computers and servos to move the top and bottom wire points you can make very complex parts very easily (e.g. gears).

Wire EDM is wonderful.

Every FIRST team should have a source for this type of work. They are usually in small prototype shops. Go knock on their door and ask them for a coupon for next year's build cycle.

Joe J.