Revolutionary Tape Reinforcement: Shedding Weight from Moulded Enclosures

Can Fibre Reinforcement Improve Injection Moulded Parts?

Plastic and fibre is a well-known combination for making strong lightweight specialist enclosures, but can a little bit of fibre reinforcement usefully improve mass-produced injection moulded parts?

That is the question a German consortium asked itself late in 2021, and its interim results are out.

The short answer is: yes, it can be done technically, and pilot manufacture has been started to better estimate the economic side.

"The use of only a small quantity of thin unidirectional tape to increase the properties of an injection-moulded part has not yet become established," according to Aachen University. "This is because the potential of this process is not yet adequately known, and the practical implementation of this technology has not yet been adequately researched."

Differential Thermal Expansion has to be Compensated

It was Aachen University's Institute for Plastics Processing (IKV) that started the project - called T3-Hub (tape technology transfer hub).

So far, an optimization technique for designing parts with sparse reinforcement has been created, and an algorithm based on this has been tested on a common folding plastic logistics crate design (sketch right), of which over 20 million all-plastic versions are in circulation, said the university.

The proof-of-concept brief was to increase crate flexural rigidity around the crate handles by 50%, while keeping thermal warpage within the crate's original specification - as the tape has a different rate of thermal expansion than the bulk plastic.

Modelling indicates that it will take only 4g of tape near the handles (top diagram), made from glass fibre bound together with polypropylene, to hit the target - around 1% of the total crate weight.

"With this design method, it should be possible to integrate such tapes into injection-moulded parts without extensive technical know-how," said IKV. "The next step in the project will be to validate the simulation results by integrating optimized tape structures into the production process."

Bending Stiffness near the Handle was Improved by 50%

In parallel, a pilot melt-impregnation plant has been designed and built from scratch to estimate how far the cost of now-expensive unidirectional tapes can be reduced, and discover "what tape quality is sufficient to obtain the best results at the end of the process chain in the component, taking account of ecological, economic and technological requirements," said the university.

Consortium partner AZL (Aachen Centre for Integrative Lightweight Production) is the specialist in injection moulding, and AVK-TV, Simcon Software, and Conbility are the remaining partners. Funding has come from the German Federal Ministry for Economic Affairs and Climate Action.

Detailed interim results will be presented at the 32nd International Colloquium Plastics Technology in February in two sessions: "Injection Moulding Process Technology for Lightweight Products" and "Cost-efficient Lightweight Design of Tape Reinforced Mass-production Parts". The colloquium is to be held at IKV, where tape production will be demonstrated live.