07th February 2012

Twice the pioneering work:

Manufacture and crushing of fibreglass

Glass-fibre-reinforced plastics (GRPs) can be found today in vehicle bumpers and bodies, in aeroplane tails, in wind tur-bines, canoes, and also in waste water pipes and potable wa-ter tanks. These corrosion-resistant, durable and very stable materials are valued highly. However, for these very same reasons, these materials also pose a great challenge when recycling. This is where a QZ 1600 Querstromzerspaner from the German company MeWa Recycling Maschinen und Anlagenbau GmbH is leading the way.

Fibreglass (as glass-fibre-reinforced plastics are informally re-ferred to) was first used in vehicle construction, in the aerospace industry and shipbuilding. The finished material is resistant to chemicals, is highly resistant to corrosion and extremely robust.

It therefore made sense to try out the materials for other uses. With GRP pipes, we can now transport water to and from house-holds, irrigate dry areas, drain water from roads, tunnels and bridges, and use them to hold potable water. One trailblazer in this area is HOBAS, with its headquarters now in Carinthia, Austria. In 1957, an innovative manufacturing process, referred to as the spinning method, was used by HOBAS for the first time to produce pipes made of glass-fibre-reinforced plastics. During this production process, the individual material components (glass fibres, polyester resin and filler materials) are injected into a rotating (i.e. spinning) cylinder. The enormous centrifugal forces compact the materials to such an extent that they are ideal for building up the pipe from the outside in. This creates a cavity-free, gas-tight pipe wall.

The inner layer is finished with a large amount of resin. It is shaped so that it is completely smooth, thereby giving it the best flow conditions for liquids. At the end of the production process, the end pieces of the pipes are cut off, ground and finally fitted with a coupling. The pipes are then stacked and stand ready for dispatch in the grounds of HOBAS Rohre GmbH in Klein Sankt Paul, not far from Klagenfurt. The only waste material from this process are the off cuts and end pieces.

But these production residues are not easy to recycle. “In the past, we were able to shred the pieces and supply them to the cement industry as fuel”, explains Karl Marktl, who works in technical maintenance at HOBAS. “Since then, technology has progressed so far that we can produce pipes with walls up to 100 millimetres thick”. With these material properties, the shredder technology reached its limits.

The Carinthian GRP pioneer found a solution with the Swabian pioneer in crushing technology, MeWa Recycling Maschinen und Anlagenbau GmbH, based in Gechingen/Germany. HOBAS brought together a selection of GRP waste and sent the “most difficult pieces” to the MeWa test centre for testing. This is where, instead of a cutting system, the engineers used the patented QZ 1600 Querstromzerspaner to crush the GRP production waste. After a few tests, adjustments were made to find the right parame-ters, and the machine was soon producing the required fine material.

At the beginning of 2012, the recycling system was installed in Carinthia. The previously broken GRP rings that used to sit in the yard at HOBAS Rohre GmbH are now all fed into the MeWa QZ. Inside the machine, rotating chains whip up a whirlwind, which accelerates the pieces of fibre glass to high speeds. The force of the pieces colliding with one another reduces the material into fine particles. After a matter of seconds, the crushed plastics exit the machine's drum. The material is then passed over a filter and poured into containers that are standing ready. The material is now ready for collection and for supply to the cement industry. Only a few oversized pieces remain, and these are guided back to the conveyor belt to be fed into the QZ a second time.

In this way, HOBAS was able to quadruple the throughput of the high-speed shredders. The wear costs, on the other hand, have been significantly reduced. HOBAS's managing director, Peter Kunze, and his colleague, Karl Marktl, summarise it as briefly and concisely as the work of the MeWa Querstromzerspaner: “The result is exactly what we wanted. The QZ works perfectly.”

Twice the pioneering work in the manufacture and crushing of GRP also leads to innovative solutions.