I recently came across this patent application.
Apparently several people are making apex seals using the
EDM process. Any metallic material will work.
One can start with chrome molly 4340 pre hardened steel or any
other cast iron or steel alloy. Even some of the new high temp NASA
cast aluminum or BeAl alloys might be used and MAY work.
Don't breathe the fumes. The problem is the seals can run
over 500 degrees F destroying the lubrication. They must be
kept cool by an adequate quantity of oil. This is the
main reason charged cooled rotors don't work in heavy duty
rotary engines. The rotor temp. can run up to 650 F.
http://www.rotaryeng.net/OMC-heat-release.pdf
This is probably what caused the demise of the charged cooled
Rotamax engine.
I can see two problems with home made apex seals and I noticed
this with after market seals I have inspected with a mass
spectrometer and a microscope.
Problem number one: Mazda stock apex seals have a slight crown.
Read http://www.rotaryeng.net/seals.html Hard to do with EDM.
The first thing you will notice is a reduction in compression
pressures. This is because the seal is leaking.
Two: The finish on the seal is not mirror smooth as it
is on the stock seals. Stock seals are heated with laser
and chilled in liquid nitrogen. A less than mirror finish
in conjunction with hard steels is death on rotor housings.
EDM does NOT give a mirror finish.
Acicular cast iron used by Mazda is porous and retains lubrication.
Mazda spent millions on apex seal R&D so my advice is to stick
with the stock seals.
http://steel.keytometals.com/default.aspx?ID=CheckArticle&NM=21

Paul Lamar


I wonder what Aixro is using as apex seals, other than the ceramic model.

Marc Joseph