Does More Injection Molding Capacity Require More Pump Capacity?

Q. I have an older central conveying system and my vacuum pumps seem to be maxed out. Now I need to add two more molding machines (with receivers). Do I need to buy a new pump and reconfigure my loading system, or is there an easier (hopefully less costly) solution? - Maxed Out in the Midwest

A. There are a few things you can do to make sure you are getting all the capacity you should from the system you already have. First, make sure the filters in your receivers are clean. If they are not, that can affect your conveying capacity. Just cleaning your filters regularly can boost pump performance dramatically. Second, check all flexible hoses for cracks or splits. Make sure all hose clamps and gaskets are tight and not leaking air.

Next, check to ensure that load times are properly set on the controller. Sometimes an operator will increase the length of loader fill time, expecting the loader to get more material. Actually, this often degrades the overall system performance.

The most severe case would be when the vacuum pump is forced to run beyond the point when the receiver is completely full. Trying to pack a filled loader is wasting valuable pump time. If it takes 20 sec to fill the loader, but the pump is set to run for 25 sec, you are wasting 5 sec of pump capacity because the loader can’t physically hold any more material. It may not seem like much, but if you fill that receiver four times an hour and you have four receivers set up incorrectly, that’s enough wasted pumping capacity to fill a fifth receiver.

If none of the above gives you the extra capacity you need, consider moving your vacuum pumps so that you shorten your vacuum-line length. I’ve seen many systems that have increased pump capacity (measured in inches of mercury) simply by relocating a remote vacuum pump closer to the farthest loader on the line. It takes time and energy to move material over any given distance, and shorter conveying runs will allow your pumps to move more material.

Finally, you might consider replacing some of your older, small receivers with larger-volume receivers to reduce the number of loading cycles they require. It usually takes only a few extra seconds to fill a 1-ft3 receiver compared with a 0.5-ft3 receiver. You don’t need to fill the larger receivers as often, which means your pump is available to fill other receivers.

Doug Brewster, customer service manager
The Conair Group, Cranberry Township, Pa.
(724) 584-5500 • conairgroup.com