Compression oven queries

Hey all,
New to this but am looking forward to getting our first compression machine set up. In the video I notice that all the fans and air circulations of the electric oven have been completely stripped. Is it worthwhile to leave one of the fans to help get an even temp throughout the oven? Has anyone experimented with this? I only have a heating element on one side of the oven and I am a little worried that I worried the temp on one side of the mould will be significantly higher than the other and I may cause unnecessary damage to the plastic. Any thoughts would be greatly appreciated.

Welcome to Precious Plastic @barefootwanderer

It doesn’t really matter if you leave the fans or if your oven only has 1 heating element, what truly matters is that you have a well tuned temperature. Plastic won’t get damaged (burned) if you ensure that the temperature of the oven is the appropiate for the plastic you are melting

I would suggest you to add a separate thermocouple and a PID controller to fine-tune the temps inside the oven

I have a fan oven. Going to try keep the fan in as it helps circulate the heat around the oven and makes ovens generally more efficient for cooking and presumably plastic. My element is on top of the oven and fan at the back so may mount my thermocouple nearer the fan to get an accurate/even read. Or possibly on either side.

My one curiousty is about casing and insulting the back, if i insulate should i incase all round – seal any holes and not worry? Will the fan motor/electrics at the back be ok baked in the oven also, there will be more heat than normal installation of the oven(i guess they are designed to withstand some heat but). Or maybe this is a reason to remove it, and just insulate the back and sides?

Hi! May I ask where did you put the thermocouple so it will measure the temperature efficiently?

When I build the compression oven I first removed the fan, but found that the temperature at the top and bottom was significantly different (up to 15°C difference!) which needs to be accounted for. It would be best to have a fan on I think if possible.

Another useful tip – the radiative heat transfer from the heating element also caused the plastic/mould nearest the heating element to reach a higher temperature from the surrounding air which caused it to burn in places. I solved this by placing a piece of foil between and it seems to work fine.
Good luck!

@barefootwanderer Even with insulation the compression machine will get hot but it shouldn’t be an issue unless you are working less than 2 meters away from the machine. Adding plenty glass fiber wool between the internal and external casing of the oven helps but some heat will still escape

Thanks Olivier,

I was a little concerned that the position of the element and thermocouple would mean a considerable differentiation of heat from one side of the mould to the other (possibly being able to burn the plastic on one side and only melting it on the other?). We have bought a K type thermocouple and a PID controller. If that is sufficient, we will leave the fan out.

The other question was about the external casing of the oven and how hot it gets. Though the temperatures of the oven are only up around 200 and they have significant insulation we will be working in a rather busy environment and it is worth knowing ahead of time. Any experience would be greatly appreciated.

Thanks again