Moulding Techniques

Extrusion molding is the predominant plastics-forming process used in industry today. In extrusion a heated thermoplastic compound is forced continuously through a forming die made in the desired shape. The process may be compared to squeezing toothpaste from a tube, in that it produces a long, usually narrow, continuous product.
Injection Molding
Most appropriate when high quality has to match high volume, injection molding provides a virtual flash-free finish, eliminating the need for secondary trim work.

Compression Molding
Offers lower tooling and set-up costs for manufacturers seeking short runs or prototypes. Other benefits include larger cavity density and reduced waste.

Transfer Molding
More accurate than compression, thus reducing reject rates on small to medium runs of precision parts. Additional benefits include shorter cure times and reduced labor.

Insert Molding
The process of placing an object, or insert, into the mold cavity and forming rubber around it..

The RPM process first of all involves the manufacturing of tools to produce rubber parts. For each metal part, plaster blocks are cast around these rubber models. The different plaster parts are assembled to form a cavity in which a metal is then cast. Once the metal has solidified, the plaster is broken, leaving a moulded part.
The production of rubber tools consists of the following steps:
1. Stereolithography (positive)
2. Silicone mould with definition of the required parting planes (negative)
3. Rubber copy (to be used several times) (positive)
4. Plaster mould (for once-only use) (negative)
5. Metal copy (positive)

This sequence of conversions results in a small loss of accuracy, which may necessitate post-finishing. The surface structure remains fairly unaffected throughout the sequence and unlike investment casting, rubber plaster moulding must have models free of undercuts.
The use of rapid tooling techniques simplifies this process and raises the quality level.


Standard lead time:
15 days for a first batch of 5 castings.

Standard accuracy:
± 1%

Minimal wall thickness:
1.5 mm.

Typical quantities:
25 copies or less, although larger quantities are also feasible.

Casting material:
Different metals from low melt point tin and zinc alloys to aluminium.

Typical application:
Aluminium and zamac parts with complex smooth surfaces, without undercuts.