I used to only injection mould my plastic backings, but now i am starting to injection mould the rubber pad, will post some pics when are totally finished.
Here's what i do:
Heat rubber granules in kiln for 4 hours @ 90 degrees, to release mositure which the rubber absorbs, which can effect mould quality as when heated it starts to bubble as mositre evaoprates.
Switch on injection moulder, let it warm up for 15 mins. Then purge the moulder to remove any old rubber from moulder and flush it though with new dry plastic.
Fill hopper with dry rubber. Insert rubber pad mould into moulder, tighten. And press go.
Every 30 seconds roughly. The mould will be released, extract pad from mould using extraction pins to push it out of mould, close mould up and repeat the process over and over again. :P
Once pad has been moulded, let it cure and reabosorb moisture.
Then put backing into glueing jig, fill with glue, put pad on top and clamp down. Then leave to dry, and again repeat the process thousands of times.
The whole process gets very boring after a while, espeicailly when you have done it a couple of thousand times. (Y)
I hope some people will find this interesting. :)