7 Tips for an Energy Efficient Extrusion Process
Extrusion, a plastics manufacturing process that consumes a significant amount of energy, means many things in the plastics industry. It is both a final forming process as well as an intermediate stage for other techniques such as injection molding, blow molding and film blowing. To make an energy efficient extrusion process, the extrusion screw is essential to obtaining maximum productivity, as well as maintaining a good-quality product.
Most of the energy used during the extrusion process is directly related to the extruder operation. For profile extrusion, for example, 50 percent of the total energy used to create the part goes toward driving the extruder. Even without a major capital investment, implementing best practices and more efficient equipment can reduce energy use by roughly 10 percent. Energy efficient extrusion processing is well within grasp.
The main energy drains in the extrusion process are the motors, drives, heaters, cooling systems and lighting systems. It’s also worth taking stock of how extra energy may be used—and often wasted—throughout the day. For example, are extruders, heaters or compressors being run when they are not being utilized?
Here are seven tips for making an energy efficient extrusion process for maximum output with minimum energy.
1. Maximum load. Motors run most efficiently when running at full load, so it’s better to use a small motor at full tilt than a larger motor at partial capacity. Set the extruder to run at its maximum design speed, but control the screw speed to maintain the quality of your product.
2. Accurate temperature. Right-size your motor to match the torque needed by the screw—optimal speed generates maximum heat from mechanical work and reduces the electrical energy needed. Just by doubling the rotational speed of your motor, you can cut energy consumption almost in half.
3. Make standby your friend. Since standby operation can steal energy from heaters, cooling water, vacuum and lights, make sure you always set the standby setting to minimum.
4. Insulate. Barrel insulation ensures that the polymer is kept close to the optimum processing temperature. It has a quick payback period of less than a year and is well worth the effort and expense.
5. Turn it off. Barrel heaters and cooling fans, if they are turned off between runs, will save you a surprising amount of energy.
6. Go lean. Parison, which means the unshaped product, is much bigger than the final version. Improved control of how much needs to be trimmed off (the trimmings can be recycled) will be a huge boon to overall efficiency.
7. Timing is everything. Optimize your start-up and shutdown procedures to align with your peak demands. Startup times can be scheduled to have a cascade effect (e.g., heaters until stabilized, followed by hydraulics and then finally the extruder drive). Shutdown can be timed to switch off the most energy-intensive areas of the machine as quickly as possible.