"Top half not forming - using cokers J100 - anyone had this?" Topic

so 6 times in a row now the top half of the mould hasnt formed – nothings changed on my vulcaniser, Im doing the exact same process thats worked perfectly hundreds of times before – the only difference is Im into a new box of discs

Has anyone (in the UK using cokers) ever had a 'dud' box before?

Whats happening is the Bottom half is forming perfectly, whereas the top half isnt 'flowing' at all. The top disc itself is swelling up hugely with air pockets – I have no idea how to solve that? I dont know if this is the cause or symptom of why its not forming properly?

This is really odd that only the top half should do this – the vulcaniser is absolutely fine. Checked it both electronically and using a handheld laser thermometer.

I tried just now to make a mould using just two 'bottom half' discs together – that worked absolutely fine – so right now Im thinking 'dud top halfs in this box' – but Im loath to keep cracking on in case Im missing something someone more experienced can tell me whats going on?

The top half of the discs were exposed to some heat and maybe have semi cured (you said your vulcaniser was top so not that) take one set of the rounds reverse it and see if the discs does the same thing.
Cheers hope it helps

Are the top discs the same thickness? I had an instance in the past where the top did not form properly because I was given a thinner disc and the plates could not press them together properly. The company buyer, i.e. the arrogant owner, decided to try something new and not inform anyone.

I double checked on the thickness against the spacers and can – no change there.
Tried making one the other way up. (The 'top' rubber-disc on the bottom) – same thing.

So Im almost totally sure that the discs from the top halves have been partly cured – this is odd as I'd imagine Cokers would just cut them all from the same sheet? I'll have to ask.

Its moot anyway as at this point Ive wasted the entire box and only got a single workable mould out of it! (From when I put two bottom pieces in the can) Pretty much an entire weeks evenings wasted for me :(