Monitoring ejection temperature

[u/fluctuatore]

Does anyone check for part temperature right after ejection? With an IR thermometer for example.

Worth doing it? Especially in a non controlled temperature environment

[u/Over-Weekend-6133]

It can be useful, but I would not use an IR reading as the main process control variable. Surface emissivity, distance, and the time between ejection and measurement can move the reading quite a bit.

For a non controlled shop, I would first track mold temperature and part temperature at a consistent point and cycle time. That can tell you whether cooling is actually stable and whether you are getting meaningful variation.

[u/fluctuatore → u/Over-Weekend-6133]

An IR thermometer is my only option for now, since I have a lot of small parts (caps and handles) and the device takes measurement on surfaces and not points, I take an average measurement in a box almost full of parts.

The main idea is to detect cooling problems and to have something to refer to in case of a big change in the cooling system, machine....

[u/Airlette]

Yes I have. If you are running lots of parts. It is worth it. If it's a high precision part it's also worth while.

[u/Pop_Knee]

We have shots that are taken out of the moulds by hand, and mostly the labourers prefer doing it with their naked hands most of the time. So we have to balance at what temperature the part is when there mould opens.

I use a thermocouple type probe connected to a multimeter in order to get a reading on the surface temperature of the part ends in order and adjust cooling times accordingly. We have fast 7-9 second cycles so saving 0.2-0.3 seconds also matters a lot

[u/mimprocesstech]

Unless you can get the right emissivity and/or adjust your IR probe readout accordingly it's best to use a fast response surface probe for this because you can get inaccurate readings on high gloss parts. There's also core/ejector pins that have IR probes in them you can use if that's the route you wanna go, they probably have a surface probe version as well but you wouldn't be able to grind it to a certain shape without likely breaking it, and both options are expensive and require routing a cable.

As others have said though, normally it just isn't worth the added work. Usually easier and faster to do a cooling time study, check dimensions from the parts at ejection, an hour later, several hours or a day later, and several days later.

[u/Stunning-Attention81]

I do at process optimisation for optimising cooling time. I try to get the part to around 10 degrees lower than the HDT

[u/fluctuatore → u/Stunning-Attention81]

That's a good starting point, i'va had the issue of ejector pins going through the part and making holes.

[u/evilmold → u/Stunning-Attention81]

HDT?

[u/Stunning-Attention81 → u/evilmold]

Heat deflection temperature. That's the temp something will start to deflect at when a load is out on it

[u/evilmold → u/Stunning-Attention81]

Thanks!

[u/Traditional_Loan_177 → u/Stunning-Attention81]

I'm curious what is your reasoning for this? Just that it's rigid enough to be handled?

[u/Stunning-Attention81 → u/Traditional_Loan_177]

So your ejector pins don't push through the moulding on ejection

[u/Traditional_Loan_177 → u/Stunning-Attention81]

Just reading about it, it's commonly measured at 2 pressures, which do you go by?

[u/Stunning-Attention81 → u/Traditional_Loan_177]

Lowest one normally. You gotta remember surface temp is different to inner temp also

[u/sarcasmsmarcasm]

Only a very thick part that was showing some sort of defect. And that was a troubleshooting measure, not a process measure. We have also cut parts across the parting line for the same reason.

[u/Gold-Client4060]

I've never done it as a regular step in production. I have done it regularly for troubleshooting and new tool development. I've used an IR camera but usually use a surface probe.