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Please help identify mystery material in SMD pre-heater


Tenma pre-heater. What is the stiff, but flexible and flakey material underneath the heater assembly? Some kind of mica thermal insulator or asbestos ;)?

FWIW the earthing of the chassis was poorly done, with the knurled washer in the wrong place.

Interesting. I've never seen that before either. Looks like some kind of cross between 'cowhide' (red or black plasticized cardboard, used as insulator), mica insulating sheet, and silicone based insulating sheet.
Probably being used as a radiant heat shield between the bend in the hot air pipe and the case.
Though I don't know why some fiberglass matting wouldn't have done the job.

Could be useful stuff. I hope someone posts some name/source info.

What do you mean "knurled washer in the wrong place"?
A star washer?
Was it between the ground wire lug and the sheet metal of the case? And you think it should be between the lug and the securing nut?
If it's between the lug and the case, it's there to better puncture the oxide layer on the metal of the case.

The material has a flakey, silvery texture.
The star washer was between the screw and the lug. The chassis is painted. Not how I would design equipment...

But still wonder what the heat shield material is, and whether it's a health hazard.

Sent from my HTC One S using Tapatalk 2

Mica sheet, I buy it for use in repairing microwave ovens, it makes a great replacement cover for the units, and is cheap. Cuts with scissors, but is rather brittle.


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