Condition Monitoring in Injection Molding

Reactive and preventive maintenance practices just don't cut it in modern manufacturing. Predictive maintenance – changing parts and fluids only when their conditions deem necessary is truly the best practice for saving costs and preserving your assets.

That being said, an advanced condition monitoring solution can also be necessary to keep product quality high and scrap low in the injection molding process.

There are several points throughout the injection molding process where changes in an asset’s temperature, pressure, or humidity can compromise product quality. If left unchecked, such changes can lead to:

Part deformity

Stress cracks

Extra flashing

Excess scrap

Increased recall costs

Trapped air or moisture

Shrinkage

Voids in molded parts

Overall poor end result quality

Unmet specifications, like especially tight tolerances

Consistent and accurate condition monitoring is critical to ensure the molding process isn’t costing your company thousands annually in additional operational costs.

Temperature monitoring
If equipment is running too hot or too cold, the two seconds it takes for the initial mold process can be enough to jeopardize product quality. From the resin storage area to the mold itself, there are varying temperatures that must be kept consistent.

For instance, clogged water channels in the injection mold won’t show an increase in water temperature, but cavity temps will rise, hindering the cooling process and leading to product deformations. Being cognizant of changes throughout the system helps operators quickly diagnose and address issues.

Pressure monitoring
From the injection screw that pushes material into the mold to the clamp that holds the mold shut, insufficient pressure can let air and moisture seep into the material, leading to batch defects:

Short shot: A void of material in a portion of the part due to insufficient pressure

Flash: Excess pressure forces mold open just enough to allow material seepage, resulting in defective parts and potentially damaging the mold

Dimensional variation: Packed mold is fully compressed, but cavity pressure changes at a critical point

Warp: Variations in packing pressure (as well as cooling rate/time) that leads to random distortions in part

Maintaining proper working pressure is a vital part of the injection process.

Humidity monitoring
Plastic resin is subject to changes in ambient humidity conditions in storage containers, as well as the process lines. Too much humidity can add moisture to the resin, changing its properties and preventing it from molding like it’s supposed to.

However, measuring ambient humidity isn’t enough. You need to monitor humidity in the plastic itself, as well as the moisture content of the air being blown from your resin dryers.

A solution that makes sense
Parker’s condition monitoring solution of SensoNODE Blue sensors and SCOUT Mobile software scans multiple points of interest throughout the injection molding process simultaneously, quickly giving operators a picture of their assets that is accurate and complete.

SensoNODE Blue sensors monitor your assets for changes in temperature, pressure, and humidity, then wirelessly transmit that data to SCOUT Mobile software’s easy-to-use interface on your mobile device, saving time and reducing labor cost.