en
nl
de
it
es
A manufacturer of rigid PVC pipes for the construction industry was experiencing a recurring problem: every 18–24 months, one of the two extrusion screws fractured in the same area.
Although the screw pair consistently delivered the required product quality, these repeated failures compromised long-term process reliability. The customer therefore asked Maxi Melt to identify the root cause and develop a targeted engineering solution.
🔧 Challenge
The customer supplied a used screw pair for detailed engineering analysis. The objective was not simply to replace the damaged component, but to determine why the failure repeatedly occurred in the same section of the screw.
🌟 Looking beyond the visible damage
The screw geometry was reconstructed and analysed using engineering software. The investigation revealed an unbalanced compression profile: the material travelled through a long section of the screw without receiving enough energy to begin the gelation process.
As a result, the PVC reached the critical section in a partially gelled state. The preceding elements were therefore forced to act as mixers, generating heat but also causing intense localised abrasive wear on the screw core and flights.
Over time, this progressive wear weakened the critical area, creating the conditions for the failure to recur.
🎯 A redesigned screw profile
To address the root cause, Maxi Melt redesigned the screw geometry, distributing material compression progressively over a longer section.
The new profile allows the PVC to reach the critical area with a higher and more uniform degree of gelation, promoting smoother material flow and more evenly distributed pressure.
Engineering out the root cause
Rather than addressing the visible damage alone, the analysis identified the process conditions behind the recurring wear. This led to the development of an application-specific screw profile designed to address the underlying cause of failure.
