Plastic injection mold temp control

[LARGrizzly]

We are trying to control the temperature of our plastic injection mold. We have struggled with contamination and corrosion using water. We have decided to use a thermal oil.

The problem is that there seem to be no companies that offer mold temp control units capable of running oil. When I say I'm using oil people are trying to push me to a hot oil unit like those used for rubber injection cold runner blocks. These units have very little cooling capacity at the temperatures necessary for platic mold cooling.

My experience with pumping oil is that as long as the pump seals are compatible with the fluid, the pump should be oversized by 50 to 100% to compensate for the viscosity and maintain flow and pressure.

Does anyone else use thermal oil for cooling a plastic injection mold?

 

[Pud]

Hi,

Have you tried using corrosion inhibitors in your cooling system (water)

I would suggest a good flush out and refill with inhibitor added (the stuff used for domeastic central heating systems works quite well) Alternatively, if you are going really cold, use automotive antifreeze as that has good inhibitor systems in it.

I would guess the heat transference properties of oil may not be adequate if you are currently having problems - you may have to open up the cooling channel diameters to increase the surface are available for heat transfer. We have used oil heaters on "cold" tools (e.g. less than 50 deg) and the cooling is not good.

Rgds

Harry

 

[patprimmer]

Mould temperature controllers which use water are available from many plastics moulding ancillary equipment manufacturers. I just got a few pages full of hits on google. Why don't you try it.

The only really valid reason for exposing your plant to the mess and hazard of oil used in mould temperature control is if you need a temperature above the point at which water will boil and induce cavetation in the pump.

Methods of reducing corrosion have already been clearly described by PUD.

There is one more method which is patented, so there is only one source, so I cannot make several recommendations. It is called ritetemp and is marketed by Comtec. Their url is

http://www.comtecipe.com

I have no affiliation with them.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[LARGrizzly]

Pud,
Thank you but we have decided to use oil and water is not an option. I agree with you, we struggle with the lower temperatures too with our oil heaters. We have many of these. In fact, these were originally intended to be used as hot water machines but we converted them for use with oil.


patprimmer,
ummm... yesterday was my first day on this intarweb thingy but NOW I am familiar with Google and I HAVE tried it, thanks.

 

[injectionmolder]

Oil should only be used for resins such as Polysulfone, Ryton, Ultem, polymers that require high heat. Processing ABS even with lower heat, but running oil just don’t seem right. I know water is no longer an option in your company however, seems to me your problem with corrosion was originated due to the lack of inhibitors in your cooling system just as Pud mentioned, and perhaps because the set-up technicians were not carefully enough to “fully blow the water out” of the channels before storing the tool.

Even better then oil you could get electrical heater cartridges. Installed properly onto the tool you are just a plu in a way.

Regards

 

[BradJH]

Use of oil has its own set of problems. It is much lower in thermal conductivity, very messy and dangerous, tends to creep leak from tooling, and it is generally a source of part contamination. It should be used as a last resort for resins requiring very high mold temperatures.
If you have problems with corrosion in your tooling it is because your water treatment is not sufficient.
If you simply insist on using oil...Mokon makes a nice temperature control unit. I would also recommend that you use a synthetic heat transfer oil.