Mixing / Compounding

We are proud that we are self-sufficient when it comes to the materials we use in rubber molding.

Already when HGF was founded in the 40s, we had our own mixing department and this is something we have taken notice of and which we see as a great advantage for our customers. The mixing department gives us full traceability while we are not dependent on external suppliers. These factors together with the fact that our technicians develop customized materials based on their specifications and wishes mean that HGF is often seen as a comprehensive supplier.

The mixing department is the very heart of HGF's operations. Here, the semi-finished product is mixed and then vulcanized into finished rubber products. The basic principles of mixing rubber materials have not changed much since people once started mixing rubber. Development and modernization have mainly taken place regarding machine capacity and control as well as environmental improvement measures.

The mixing department is made up of different parts which are presented below.

Weighing: The first operation in mixing is weighing based on predetermined recipes. Rubber polymer is weighed directly from the pallet on a belt scale. Carbon black, oil and any light fillers are automatically weighed as you mix rubber. Ingredients in smaller quantities are weighed manually.

Chamber mixer: A chamber mixer consists of two rotors in a chamber. The rotors have a design that gives a kneading effect. At the bottom of the chamber there is an openable hatch and at the top a "lid" that can be raised and lowered between open and closed position.

When mixing, the ingredients are added via the upper hatch or through separate tubes. The speed of the rotors can be varied steplessly during the ongoing mixing cycle. The speed can, for example, be increased when plasticizers are added and the viscosity and degree of processing otherwise decrease.

When the mixture is ready, the hot mass is emptied through the bottom hatch in the form of a lump. The pulp needs to be quickly flattened and cooled to reduce the risk of the pulp starting to vulcanize. This is done by first letting the mass pass through a rolling mill and then being transported through a water bath.

After this, the semi-finished product is coated with an anti-stick agent and the rubber is largely cooled and can be placed on a pallet for further transport and processing in the form of moulding.

HGF has the opportunity to mix materials both in the laboratory and in our mixing department, which gives us a high degree of flexibility during all project and production phases. Everything from material development and prototype manufacturing to series production.