why when vacuum heating. suction power of vacuum pump is reduced???Why heat the vacuum plating chamber? during heating to 150 degrees the value of the vacuum chamber is at 3.0x10-2 pa , when stopping heating the value drops to 2.0x10-2 pa??
Heating the chamber will drive off any substances (fingerprint oils, atmospheric water, cleaning agents, etc.) that might be stuck to the chamber walls. The pressure will rise when the chamber is heated - but should slowly fall after an initial 'spike'.
When you turn off the heater, the chamber walls become very attractive places for these fugitive gases to stick - so the pressure falls.
This is always a problem with plating chambers - they have to be exposed to air to allow the article to be plated inside (!). So the walls of these chambers tend to be quite 'dirty' and it's hard to achieve really good vacua without prolonged heating to 'bake-out' the condensed agents.
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