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The Advantages & Disadvantages Of Extrusion PVC Moulding
Jan 29, 2018

The Advantages & Disadvantages of Extrusion PVC Moulding

Advantage–Low Cost

Extrusion PVC muolding has a low cost relative to other molding processes.This stems, in part, from the efficiency of the process. Most extrusion molding uses thermoplastics, which can repeatedly undergo melting and hardening. Leftover materials, normally discarded as waste in other processes, can be reused. This lowers raw material and disposal costs. Barring mechanical failure or planned downtime, plastic extrusion machines operate continuously. This reduces the chances of inventory shortage and allows for 24 hours-a-day manufacturing.

Advantage - Flexibility

Extrusion PVC mulding provides considerable flexibility in manufacturing products with a consistent cross-section. To picture a consistent cross-section, imagine cutting straight through a block of cheese in several places. No matter which pieces you pick up, they all maintain the rectangular block shape. So long as the cross-section remains the same, extrusion PVC moulding can produce complex shapes, such as decorative trims. With minor alteration to the process, manufacturers use extrusion molding for plastic sheets. Variation on the extrusion process also allow for the manufacturing of products that mix plastic attributes, such as hard and soft surfaces.

Advantage – Post-Extrusion Alterations

The plastic remains hot when it leaves the extruder, which allows for post-extrusion manipulation. Manufacturers take advantage of this and use a variety of rollers, dies and shoes to alter the shape of the extruded plastic to fit their needs.

Disadvantage – Size Variances

When the hot plastic exits the extruder, it frequently expands. The expansion of the plastic at this stage of the process is called die swell. Predicting the exact degree of expansion remains problematic as it arises from different factors in the process. Due to unpredictable expansion, manufacturers must often accept significant levels of deviation from the product dimensions or tolerance. While methods exist to limit this issue, the tolerance problem largely disqualifies extrusion PVC moulding as a method for precision parts manufacturing.

Disadvantage – Product Limitations

The nature of the extrusion PVC moulding process places limits on the kinds of products it can manufacture. For example, plastic soda bottles narrow at one end to accommodate a cap, which normal extrusion molding cannot achieve. Alternatives, such as extrusion blow molding do provide an option for these types of products, but require investment in a different type of extrusion equipment.