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:
Increased recall costs.
Trapped air or moisture.
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.
If the 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.
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.
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.
Parker’s condition monitoring solution of SensoNODE™ Sensors and Voice of the Machine™ Software platforms scan multiple points of interest throughout the injection molding process simultaneously, quickly giving operators a picture of their assets that is accurate and complete.
SensoNODE Sensors monitor your assets for changes in temperature, pressure, humidity, and vibration then wirelessly transmit that data to Voice of the Machine Software’s easy-to-use and understand interface, saving time and reducing labor cost.
Article contributed by Marc Williams, IoT project lead, Parker Hannifin Corporation
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