Turkish PUR processor uses LFI procedure in series production

The Turkish processor Pürplast (Kocaeli) is a specialist in manufacturing polyurethane (PUR) components for commercial vehicles. The company produces glass fiber-reinforced component using the long fiber injection (LFI) technology from KraussMaffei (Munich, Germany).

"The critical advantage of the LFI procedure is that the endless glass fibers are not cut into filaments until right before processing," explains Erich Fries, head of the Business Unit Composites & Surfaces at KraussMaffei. "Therefore, there is no need to insert a preformed glass mat into the mold," continues Fries. "This is the reason that prompted Pürplast to decide to invest in an LFI system from KraussMaffei."

"The LFI system from KraussMaffei with its process-technology advantages fits in exceedingly well with our strategy," says Mehmet Sismanoglu, managing director and owner of Pürplast. One of the Turkish company's uses for the procedure is increasing quality when producing large-surface cosmetic parts for commercial vehicles, including overhead compartment cover panels for coaches, and to reduce manufacturing costs.

Uniform fiber wetting
The LFI process unit consists of a cutter and a mixing head. The cutter draws in the roving, chops it into fibers of the preset length, and charges the fibers into the mixing head. The mixing head mixes the reaction components and discharges the PU resin into the mold simultaneously with the fibers. In this way, the chopped fibers are uniformly wetted and their distribution in the mold is isotropic.

Consequently, the manufactured components demonstrate high strength and low thermal expansion. Both the length and amount of fibers in the mixture can be varied during processing to produce zones capable of withstanding higher loads.

A thermoformed film can be inserted into the lower mold half in order to impart a high-quality exposed surface to LFI components. The mixture of PUR and glass fibers is then applied to this film and pressed. "Due to the excellent visual properties of the component surface, there is no need for any subsequent finish. Another variant of the procedure uses what are called honeycomb structures in combination with the LFI technique. This produces components with very low weight and yet at the same time high rigidity,"  adds Fries.

Partner to the commercial vehicle industry
Pürplast employs about 290 employees in the Turkish city of Kocaeli approximately 100 km east of Istanbul. The company possesses a 42.000-m² production area spread across four buildings

Founded in 1981, the company specializes in manufacturing PUR components for the commercial vehicle industry. The product line includes instrument panels, seat pads, exterior body parts, armrest, partition walls, handles and steering wheels.

Annual turnover is approximately 25 million euros. Pürplast ships more than half of its production value to Turkish-based companies including Mercedes Benz, MAN, and Turkish bus and coach builder Temsa and Otokar; the company also exports about 40% of its production to 38 different countries. Major customers include Daimler AG, Evobus, MAN, BMW, VDL, Van Hool, and Volvo.

In addition to the LFI processing, production at Pürplast also makes use of classic high-pressure PUR processing and thermoforming. The company also operates its own toolmaking shop.