Pre-extrusion Systems

Wide range of options - from manual to fully automatic

The final quality of the product depends to a large extent on the raw materials that are used.

Unfortunately, however, the proper selection and preparation of raw materials for the extrusion process is often overlooked. We believe that this is a critical factor for ensuring a good and stable product during extrusion.

Though Schaaf specializes in working with local raw materials as much as possible, it is necessary to monitor and properly control the quality and specifications of the raw materials within a given range to ensure uniform product quality. Proper systems need to be set up for performing this quality control.

The pre-extrusion processing of the raw material usually involves 2 main steps: blending and moisturising.

Blending - the blending of various extrusion components according to a preset recipe is an essential prerequisite for the extrusion process. Although the majority of raw materials used in the Schaaf extrusion systems are in grit form, the proper blending of components in smaller proportions is paramount. Schaaf recommends the use of a specially designed ribbon blender type of horizontal mixers for the blending of various extrusion components.

Moisturising - the amount of moisture that is added to the extrusion mix usually ranges from 4% to 8% depending on various factors such as the dry mix moisture level, the final product texture desired, and so on. The moisturisation system must guarantee uniform distribution of the added moisture in the raw material mix. Non-uniform distribution of the moisture in the mix will lead to inconsistent extrusion conditions and consequently an inconsistent extruded product.

The pre-extrusion processing equipment offered by Schaaf ranges from simple manual systems, where only minimal processes are performed by the machines, to fully computerised automatic systems, where the operator only has to program the system according to the set recipe and the entire raw material preparation is executed automatically. The choice of the system ideally suited for a certain product depends on the range and variety of mixes required, the quantity of mix needed per hour as well as the financial budget available.

Major models of raw-material preparation system components: