Extrusion Equipment

1Q. What is extrusion equipment?

1A. This can be a screw type device such as used in processing polymers. The screw consists of a shaft with flights that forces the product through a die with holes, slots or some other pattern. The screw is contained in a barrel that may be water cooled. A motor is used to drive the extruder screws though a gearbox. Reductions can be 20:1 to achieve the low speed and high torque required in the extruder during processing.

2Q. What tends to be the biggest problem with extruders?

2A. There are many, but mechanically, controlling the wear of the flights and the barrel are certainly high on the list. The correct hard surfacing at the correct locations are key to a long operating life and to minimize product quality issues. Every industry and product have their unique problems that must be worked out. New products or higher throughputs can create a new series of problems.

3Q. Our extrusion machines keep getting bigger and some are Serial #1. Should we be concerned?

3A. You should always be concerned with Serial #1. By concerned I mean involved with the manufacturer in the early stages of the design during development of the design specifications. With a knowledgeable and well established manufacturer your concerns are minimized, especially if your company has a history with them. Your people usually know your equipment in certain areas better than the manufacturer. Working with them and challenging design modifications are not unusual. Many times changes which may reduce manufacturing time or machine costs can greatly influence long term reliability. It is better to find out about this at an early "cold eyes specification review" stage than after start up.

4Q. A shaft failed in our large polymer extruder. The laboratory report came back that the shaft had sheared due to excessive load. What happened?

4A. This is why analytical analysis are good. Since you now have valuable information and know the mode of failure (shearing) and the material properties and there is no corrosion you can model the system. Include horsepower, RPM, shaft geometry etc. and see what load it takes to fail. Then figure out where you could have gotten this much load and make sure it doesn't happen again. As you can see it will take analytical knowledge and practical knowledge to determine the cause in this way.