'Polymech Designs' is a research project that investigates the viability and feasibility of using post-industrial waste for market-ready products. We currently explore furniture, mechanical elements with strong focus on repeatability and quality with limited resources.

Using an Extruder

Our tests with extruders showed promising results creating acceptable feedstock but with limited scope due to air voids. Furthermore the stock had to be faced to achieve surface finishes needed for assembly and customer expectations.

Tests with a 25mm bench top extruder, using a mould with back pressure

Follow-up tests

Footage for milling and precision testing, exploring the idea of mechanical components

Beams as quality feed stock

After extensive trials we settled on 60x60mm square beams. Air voids are still present but the overall quality was sufficient for some applications such as furniture. Recommended minimum extruder motor power is 4kW @ 400V with a 1:15 ratio, capable of overcoming most problems during that process.

Using a sheetpress

To address common problems with the process, we redesigned the machines for strength, repeatability, and quality results under safe conditions. We discovered different process types, such as one to three-stage pressing, added advanced monitoring interfaces as well as adaptive pressure, and also used the extruder to combat air voids and surface defects.

First tests using a 'traditional' one stage process with medium sized flakes. We managed to go up to 4 cm in thickness ( 5 hours ).

2 Stage process

To overcome problems related to shrinkage ( up to 25% ) such as warping and surface problems, we introduced a die technique. This involves flipping the mould ( up to 40 kg ) after initial heating and inserting a die with slight re-heating close to the softening point. Adding support for pressure profiles enabling controlled pressure over time enabled good results ( 0.5mm tolerance across 50cm ).

This involves a lot of time and labor and poses safety risks to the operator without proper lifting equipment.

Average processing time for a 3cm sheet is around 2-3 hours, before cooling. More productive and versatile thickness of 15mm takes up to 90 minutes depending on material.

Extruder to the rescue

By incorporating an extruder into the process, we finally achieved safe and predictable results, with up to 6 cm of consistent and dense feedstock. It also eliminated all the hassle related to mold filling and handling.

Our test machines

Software interface (see Polymech Controller)

Status Quo & Conclusions

We are still investigating better processes to speed up production and increase quality with reasonable investment and labor. Designing a fully automatic mold system (carousel) using an extruder as a feeder seems to be the most promising solution, ideally handled by a robot.

In the meantime, please enjoy a few ideas using generative AI.