PVD coatings for better flow, lower degradation, and greater steel protection.

Improving sliding means avoiding adhesion of the polymer to the screw which can be one of the possible reasons of stagnation of plastic material inside the extruder.

Today we want to tell you about one of our latest projects in which the PVD coatings applied to our screws played a leading role; let's start from the beginning: With Physical Vapor Deposition we mean various coatings whose process is linked to the condensation of vaporized material that generates a thin film on a substrate that can be composed of different types of metal alloys and derivatives. PVD coatings exist in a wide range of technical solutions and have a multitude of applications, in our business they are primarily used to improve component life and function. In this specific case, this optional solution was applied to a Ø85 twin-screw extruder.

Our customer, an international leader in the production of electrical wires, had issues created by polymer “burning” problems and alterations of the extruded melted mass, this was caused by the adhesion of the plastic material (PVC) to the screw. In addition to making minor changes to the screws’ design, to solve the adhesion problems we have chosen to adopt a PVD coating that reduces the coefficient of friction. In this way, in addition to protecting the component from possible chemical attacks, we were able to decrease the surface porosity, reducing friction and improving the sliding of the extruded material.

By doing so, we were able to avoid any alterations in the plastic material while it was being processed, avoiding that it stayed too long inside the extrusion unit, altering its physical characteristics. Protected screw, better melt quality and satisfied customer!