Upsize / Downsize Conversions for Injection Operations

Ever had the problem that regardless of what you try, there is still degradation in your plastic resin? You have carefully measured the injection unit for material hang-ups, and you have even taken off the heater bands and thermocouples and qualified them. Yet nothing seems to be wrong.

However, someone brings it to your attention that of the 8 inches of stroke available, the process requires only 1 inch of stroke to fill the mold. All of the material that is stored in the injection unit is subject to the heat energy of the barrel, which is referred to as residence time. When a plastic material is subject to heat energy for too long a period of time, it will degrade.

Once degraded, there is little hope that this defect will go unnoticed. Even if the part design is able to hide this degradation, the plastic material has still lost the properties for which the material was originally selected.

The only true solution to this problem is to downsize the injection unit. SFP is able to help processors by re-designing the injection unit of the molding machine to produce less output.

By reducing the amount of plastic contained within the injection unit, we are able to significantly lower residence time and eliminate the effects of degradation due to overexposure to heat energy.

Nothing is worse than setting up a mold in your injection press to find out that you have enough tonnage to clamp the tool, but the machine cannot produce enough plastic to fill the mold.

Typically, the only solution for processors would be to move the mold to another press that could supply the proper tonnage or outsource the project. With SFP’s design engineering team in your corner, we offer another option.

In most cases, molding machine injection units can be engineered to increase the volume of plastic that is injected for every shot. Typically, an engineered solution can expect to yield up to 15% additional shot weight without having to replace feedscrew drive motors or injection cylinders.

The 41-ounce, 500-Ton Cincinnati Milacron press does not have enough material to fill, pack and hold your eight-cavity mold and runner system that required 48 ounces. Generally, there are no other options than to put this mold into an even larger press even when the additional tonnage is not needed. SFP can take your existing injection unit and rebuild it to oversize specifications that will increase the shot size to produce slightly over 48 ounces in every shot.