Using Process Monitoring Systems

Process monitoring systems are a great resource for the Scientific Molder.


We already have a {brand-name} production monitoring system and are now considering using it to also monitor the process.

My Response:

In practice most companies use such systems helpful to look for individual short shots or analysis of past problems. This is essentially quality control and is an important use for the system, but not its highest potential.

The important factor is to have a good basic scientific molding process than compensates for normal variation. With this in place, you can then use your process monitoring to identify a process shift. This allows your technician to then go to the machine and determine what changed and its effect on the quality of the process and parts. If used in conjunction with a good process, monitoring can be effectively used to provide quality assurance as well as quality control.

For example, you would rather your system to indicate a change such as a shift in transfer pressure and have your process tech head to the machine to determine the cause. It could be problem such as a blocked cavity, dying nozzle heater band, or it could also be something simple like a material lot change with a lower melt flow. You want your tech to understand what a high transfer pressure could signify, locate the cause, and then determine its significance.

If the change above was due to an equipment problem, the tech would then go about either fixing it or having it fixed.

If the change was due to a lot change in our example above, the tech might need to adjust the transfer to make the short shot the same weight as the standard, verify the quality of the part, and then adjust the process limits (such as +/-5%) to accommodate the new lot of material. The key in Scientific Troubleshooting is the change has been identified and a knowledge-based action was made using actual data with the intent of maintaining a good process known to make good parts for your customer.

Additional Thoughts:

The key to the above situation is to first ensure the tech has a good understanding of Good Scientific Documentation, Basic Scientific Processing, and Scientific Troubleshooting. Without this, the tech tends to just turn off or change the alarm because the parts look good, though the process may be different and thus producing suspect parts.

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