Jewellery Trouble Shooting Mould Rubber problems


Cut mould does not seal Evenly (warping)
Cause	Remedy
Rubber used in packing has begun to vulcanise.	Use new rubber.
Mould under packed.	Ensure the work time is fully used. Normally 8 minutes.
Mould over packed.	Review mould packing procedure. Lay strips in same direction.
Voids in mould (air entrapment)
Cause	Remedy
modle not filled in with rubber.	Pack rubber pieces into and around modle.
Platen not at curing temperature.	Preheat vulcaniser to 155 °C.
Mould not cured for recommended time.	Tighten vulcaniser ½ turn past first resistance. Repeat every two minutes until platens are in contact with frame and handle cannot be turned without resistance. Allow 15 minutes at 155 °C for every 6 mm. for intricate moulds allow 20 minutes at 145 °C for every 6 mm.
Mould delaminates after curing
Cause	Remedy
Surface of strips not clean.	Use new strips. Do not contaminate surfaces with hands and protect from extraneous dirt or dust.
Rubber is old.	Use new rubber.
Mould not cured long enough.	Use correct times and temperatures.
Mould soft and sticky in centre
Cause	Remedy
Under heated.	Check temperature of platens.
Cure cycle too short.	Cure for 15 minutes for every 6 mm.
Mould has pebbly surface.Mould is sticky and scorched. Excessive shrinkage. Lack of flexibility.
Cause	Remedy
Overheated.	Check calibration of vulcaniser.