RUBBER MOULDING

RUBBER MOULDING

Our custom rubber mouldings are manufactured in a wide variety of compounds. 
All with the common feature of an elastomer. Namely: deforming under load and then snapping back to almost original shape when the force is removed.

All rubber components require vulcanization or curing. A process of heating and pressure in a mould. There are three types of moulding processes to achieve the vulcanization. All of the three below a carried out using mould tools.

Compression moulding
Transfer moulding
Injection moulding

rubber moulding 2
rubber moulding 5
rubber moulding 1
rubber moulding 3
rubber moulding 4

COMMON MATERIALS -

We Specialize in Small Rubber mouldings.

Common materials used :

  • Silicone
  • EPDM
  • Nitrile
  • Neoprene
  • FKM (Fluorocarbon)

services -

  • Single cavity prototype tooling
  • Sand blast or shiney finish
  • Multi cavity high volume production moulding
  • Food Grade material available
  • Fire retardant material and to London underground specs. available
Sample Pack

COMPRESSION MOULDING

Involves placing a properly shaped blank from the unvulcanized compound in each cavity of the mould. The mould is then closed and placed in a hydraulic press. Under the applied pressure and heat the rubber will flow and completely fill the mould cavity. The slight excess flows out through special groves. This excess is known as flash. The mould remains closed under pressure for a prescribed period of time at a particular moulding temperature. Once this process is complete the mould is opened and the rubber moulding is removed.

TRANSFER MOULDING

Differs from compression moulding in that the stock is transferred through a hole into the mould cavity. In its simplest form a transfer mould consists of three parts: a piston, a cylinder (pot) and the mould cavity.

A piece of the unvulcanized material is placed in the pot and covered by the piston When the press is closed the piston forces the stock through a hole into the actual mould cavity. This allows shorter cure times because of the heat generated as the material is forced to flow through the hole. After the compound has been cured, the mould is disassembled. The residual cured rubber is removed from the pot and the cavities are unloaded.

INJECTION MOULDING

Is similar to transfer moulding in that the rubber compound is forced into a closed mould cavity through a nozzle. 

A strip of the compound is fed into a heated cylinder and masticated by a screw, which then moves forward like a ram and forces this preheated stock through a nozzle into the mould cavities (Fig. 2.5c). As a result rubber mouldings can be vulcanized in very short times, usually reported in seconds (typical time is 30 seconds). Other advantages of injection moulding are reduced stock preparation costs and low cured scrap. However, both the moulds and the equipment are much more expensive than those used for compression and transfer moulding.

POSTCURE

Some elastomer types require two curing steps: a primary vulcanization in the press followed by a postcure in circulating hot air ovens with a constant
fresh air supply. The postcure process usually lasts several hours (up to 24 hrs) at a considerably higher temperature than the vulcanization temperature in the press.
Postcure is carried out to improve one or more properties of the vulcanizate. Furthermore the decomposition products of the compounding ingredients are removed during the process.