Translating the manual

[Robin Hewitt]

Opened the leaky gasket and found a sump full of rust gunge. Just waiting for the top to dry out before I remove the last of the old gasket and make with the gasket compound. Type blue I think.

No obvious blockages, no thermostat, the water goes over the top. I can only presume the rust gunge blocked the pipe, it is certainly the gasket eating culprit.

I sat there for 20 minutes stabbing a screwdriver up in to the top cavity until no more great lumps fell out. If it blocks again I should be able to dislodge it with compressed air and let it drop into the sump. Well, it's nice to have a plan

HOW INJECTION MOULDERS WORK

We are looking below where the raw plastic granules enter the screw. In front of the screw is a pool of molten plastic. To inject you advance the nozzle to touch the mould, drive the screw forwards to nearly fill it and then start spinning the screw. The screw winds new plastic forwards out of the hopper, forcing it up hard against the heated barrel and squeezing the air out. As this new plastic moves forwards and melts, the plastic in the mould is cooling and shrinking. It can't take all the new melt arriving in front of the screw so the screw is driven backwards inside the heated barrel building up a new pool for the next shot. By adjusting the rpm of the screw and it's resistance to moving backwards you try to maintain the mould filling pressure and get the perfect fill. They call this notion "backpressure". The plastic entering the mould cavity is about the consistency of treacle. Where it touches the mould walls it thickens so the main flow is as far away from them as it can get, ie: up the middle. The exception to that are the "gates", narrow constrictions where the flow is fast enough to stay molten. Injection ends when the flow stops and the gates freeze. I haven't figured out how to size gates yet.

I suppose it is vaguely possible that someone might have similar problems and find my pictures useful, so here are some buzz words for the search engines to pick up on... Arburg Allrounder 221 221-55-250