Injection Molding: Get It Set Right

Machine setting is crucial to getting the best part out of an injection molding machine but it is also crucial in minimizing the energy use of the machine. Good molding settings are needed for reproducible part production and this also minimizes the energy used in production.

Optimizing the process through setting will minimize energy use by minimizing cycle times and the cooling required but also by increasing the productive output of the machine. The material in rejected parts may be recovered but the energy used in producing them is lost forever.

Machine energy monitoring (see Energy Saving Tip of the Month #60) can also reveal machines that are incorrectly set. If the cycle is unclear when monitored, then it is likely the machine is not set correctly and is using excess energy. Look at settings such as barrel temperatures, back pressure, clamp forces, cooling times and other variables that can increase the cycle time without improving the quality or reproducibility of the part.

Actions:

Get injection molding machines set correctly by using 'scientific molding' at the start of the job, record the settings and make sure they are always used.
Good setting techniques not only optimize the cycle and give more reproducible results but also reduce the energy costs of operating the machine.
Use SPC to control the process and the product.

Note: Dr. Robin Kent is the author of Energy Management in Plastics Processing, published by Plastics Information Direct, and managing director of Tangram Technology Ltd., consulting engineers specializing in energy management in plastics processing. rkent@tangram.co.uk.