Heating Strips

[RB202]

Hello,

I work in a compression moulding facility moulding phenolic resin composites. Recently I have noticed that the heater bands in the top and bottom platens of the presses are not all working even though the temperature controller is reading correct. Our setup is 11 bands on both top and bottom platens. I have counted up to 4 bands not working at any given time. How important is it to have all heater bands working? I have worked with extruders before and having all heater bands working is critical but is it the same when heating a platen?

Thanks

 

[patprimmer]

When you say not working at any given time, are they cycling on and off, or do they stay off until repaired.

Do you have a number of temperature controlers or just one for each plattern, ie are all elements in one plattern hooked up to one controller.

Regards

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[RB202]

Thank you for the reply.

Our setup on our presses is that we have 3 amp meters each, for both top and bottom platens. The heater bands are connected in the following groups for both top and bottom platens,

Amp Meter 1 - 4 bands connected
Amp Meter 2 - 4 bands connected
Amp meter 3 - 3 bands connected

Yes they do cycle on and off but what I observed was that the amp meters are not pulling enough amps to indicate that all 3 or 4 heater bands are working.

 

[Pud]

You will get:

a) Uneven heating across the platens - try spot readings with a surface contact probe.

b) With some heaters off, the others will be working more and this will reduce their life - you will eventually get a "cascade" of failures.


Cheers


Harry