posted March 02, 2004 06:57 AM               

Regardless of carbon or glass breakage during the extrusion operation, you must also be aware of the final pellet size once the compounding is done - that is to say, when it enters and leaves the chopper.

Once it leaves, the pellets are usually set and dropped onto a shaker bed, which then allows the size of pellets you want to drop through the holes. In this case, both "fines" and larger pellets are off-shooted to a box.

The majority of glass breakages occur there at the chopper, and not in the extruder.

Glass filled PP for example requires a coupling agent as well, so that the sizing (coating) of the glass will bond to the PP. It is very common to see competitive materials that are weak, which are attributable to this.

If a coupling agent is not added properly to the mix, this too will cause more severe breakage both in the extruder and out of the chopper.

Relative to "screw profiles", are you looking for screw and barrel designs, clearances, or temperature settings? The greatest majority of glass filled PP here in the USA are compounded on twin screws.

You'll also going to require an anti-oxidant -perhaps a UV inhibitor, a lube and other additves to finalize your glass PP pellets.

In essense then, what one ought to do is to ask for a written DEFINITION OF REQUIREMENTS for the finished product.

Simply stated, "Glass Filled PP" is a very specialized field of compounding.

Think about what you really need. A simple answer is hard to achieve without answering some questions that may appear complex to you.

There too, are so many different glass fibers (or carbon fibers) to select from. This is a big world.

Above all else, cost is one of the major driving forces for the majority of applications. Conversion costs can be high or low - depending on the complexity of the mix.