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Injection Molding Innovations

New Single-Step In-Line Compounding

With the development of the new Husky 300-ton injection molding/Werner & Pfleiderer compounding system, a 30 percent glass-filled polypropylene plate, with a maximum fiber length of 20mm, can now be produced in-line in a single step.
Editor’s note: PM&F presents a new column highlighting innovative products and methods for the injection molding industry.

A new system that allows for in-line compounding with injection molding — in a single step — is now available to the plastics market.

Husky Injection Molding Systems and Werner & Pfleiderer developed the machine concept in order to produce long glass fiber filled parts in a one-step process. According to Husky, the design operates like a standard injection system, allowing for fast cycle times with low energy consumption.

In-line compounding offers cost reductions over pre-compounded polymers by integrating the pre-compounding step into the injection molding process, says Husky. This process results in longer fiber lengths in parts than pre-compounded resins can achieve.

At its recent open house in Luxembourg, Husky demonstrated a 300-ton injection molding machine equipped with a Werner & Pfleiderer ZSK40 twin screw extruder and produced a 30 percent glass fiber filled polypropylene plate with a fiber length of up to 20mm in the final part.

During the manufacturing process, a mixture of polypropylene resin and compatibilizer are gravimetrically fed into the feeding zone of a co-rotating intermeshing twin screw extruder. Endless glass fiber rovings are then actively pulled into the melt in a second barrel opening. The compounded material is transferred to a shooting pot before injection into the mold, which eliminates the need for a check valve. According to Husky, standard injection or injection compression molding can be used depending on the applications.

The company says upcoming developments include the use of natural fibers, talc, calcium carbonate and wood powder with resins, such as PP, PA, ABS and PET.

For more information on this system, contact Husky at (905) 951-5000 or visit

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