Re: Vacuum Pump

From: Rudolf Schenker (rudis@ibi.co.za)
Date: Tue Aug 10 1999 - 20:01:25 EEST


"M.C. MOOLMAN" wrote:

> Dear List, I am busy putting together a low cost vacuum chamber to
> de-air RTV silicon.At present I am using Wacker Elastosil M4640
> transparent RTV. It is extremely tacky and with the vacuum pump I am
> using now, I have difficulty releasing the bubbles from the RTV.Can
> anybody give me a pressure rating of a vacuum pump that I will need to
> de-air most RTV's? Thanks M.C.MoolmanFreeplay EngineeringCape
> TownSouth Africa

DEAR MC

I WHILE BACK I HAD A SIMILAR PROBLEM. THIS SPECIFIC TYPE OF SILICONE
WAS SO TACKY THAT I COULD NOT GET IT INTO THE MOULD. AT THAT POINT I
WAS ADVISED TO ADD A SPECIFIC TYPE OF (MAXIMUM 15%) OIL TO THE MIXTURE
TO GET A LOWER VISCOSITY. THIS HELPED AND THE AIR BUBBLES ESCAPED MUCH
EASIER.
ADDING OIL DID AFFECT THE SHORE HARDNESS SLIGHTLY THOUGH.

CAN SUPPLY MORE DETAIL IF SO REQUIRED.

REGARDS
RUDOLF SCHENKER [Pr.Tech.(Eng.)]



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