B&F srl

Plastic Materials Extrusion

Research and Reconditioning of Plastic Extrusion Machines

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Plastics Extrusion Process

Plastic extrusion is a process used to create artefacts such as pipes, sheets and profiles using materials such as plastic and rubber.

The extruder (Figure 1) is mainly composed of a hopper, a barrel which contains a screw, and a die at the other end which determines the profile of the product to be obtained.

Raw thermoplastic materials such as PVC (in the form of small beads) are fed from the hopper into the barrel, which is heated to the desired melt temperature by resistors. The screw, which contributes to the melting process by applying friction and intense pressure, pushes the material towards the other end where the molten plastic enters the die and takes the wanted shape. The die may have an elaborated section for particular profiles, a flat section for the production of rubber profiles, and may be of circular shape for the creation of pipes such as handles for Long Handle Dustpans, Dustpans and Broom sets, Small Handle Brooms e Window Cleaner & Squeegee.

The extrudate from the die is cooled in a water bath and then automatically sized of the required measure by a cut off device (Figure 3).

In a tube or pipe extrusion line, the extrudate is first cooled in a sealed water bath (Figure 4) which represents a controlled vacuum that keeps the newly formed and still molten tube or pipe from collapsing.

Plastics Coextrusion Process

Coextrusion is a variant of the extrusion production process in which different materials enter a single die for the production of profiles that have both a rigid and a flexible part. Since different materials require different melt temperatures, two extruders positioned perpendicularly are necessary to achieve that result.

The procedure is equivalent to that of extrusion until to the point in which both materials pushed by the screws enter the same die and merge and weld together. The profile created then goes through a calibrator which cools it and determines its final shape. The profile is then automatically sized of the required measure by a cut off device.

Coextrusion is a production process that allows to combine materials of flexible and rigid nature into a single profile and riduce the cost for our customers. Rubber lips for Dustpans are some examples of the products obtained through this process, using the rigid part to assemble the rubber lip to the dustpan and the flexible part to make a tight seal between the dustpan and surface for convinient dust collection.

Injection Moulding Process

Injection moulding is a production process in which plastic material fed from the hopper of the press and melted in the barrel, is pushed by a piston towards a nozzle and injected into a hollow mould cavity under high pressure. The mould is kept mechanically closed until the part is solidified and then opened for the automatic release of the artefact.

This process allows to produce objects with great precision such as the stoppers that we assemble with the handles.