Author Options:

recommend an electric switch plastic casting material? Answered

Trying to figure out which plastic to use to cast the insulation insides around the brass metal contacts of a vintage DC rotating switch that does carry a lot of amps.  So the plastic has to be wear resistant against the brass contacts sliding across and resistant  to the heat created from the current being drawn thru the contacts.

4 Replies

iceng (author)2014-01-25

Try "Halar® (ECTFE)
- Ethylene-Chlorotrifluorethylene copolymer exhibits better mechanical
properties than many other fluoroplastics. But like other
fluoroplastics, its flame retardance, chemical resistance and low
dielectric constant remain constant over a wide temperature range. These
qualities make it suitable for use in such products as electrical
insulation, monofilament, tank linings, housings, and electrical
components. It may be usefully employed at temperatures from the
cryogenic range to about 330ºF."

Personally I like use Delrin because I can afford the cost and have access to scrap pieces.

Select as Best AnswerUndo Best Answer

Veewee111 (author)iceng2014-01-25

Thank you. Will put Halar on the list, but have not found it in a room temperature castable form to keep it from costing too much with low production.
We have Delrin also at work, will start picking up the scraps, but either way looks like will need CNC machining.

Select as Best AnswerUndo Best Answer

verence (author)2014-01-25

> "heat created from the current .. thru the contacts."

If there is any heat, your contacts are not good enough.

Select as Best AnswerUndo Best Answer

Veewee111 (author)verence2014-01-25

Totally agree, but if the switch gets a bit of corrosion in it, I do not want the switch to just melt down if some heat is generated.
Have seen same problem with repro fuse boxes vs originals. The originals hold up much better to heat.

Select as Best AnswerUndo Best Answer