Can’t Find a Suitable Automation Solution? Invent Your Own

About four years ago, PRD Inc., a busy custom molder in Springville, IN, bought its first robots--Yushin HOP III sprue pickers. The company bought them for the usual reasons: to cut labor costs, cycle times, scrap, and mold damage.

The robots worked well. Maybe too well. PRD's pickers dropped runners into beside-the-press barrels that someone had to haul all the way to the storage area to prevent cross-contamination. Eventually, the runners were fed into a grinder, hand blended with virgin, and hauled back to the molding area. That kind of labor utilization just didn't fit into PRD's short-run JIT way of doing business.

With more than 83 customers in markets ranging from electrical and automotive to others, PRD tried some off-the-shelf auxiliary equipment solutions, but they didn't work. So, two employees at PRD invented their own answer. It's called the P.T. Lightning Loader. And you can buy one.

The "P.T." stands for P.T. Equipment Inc. of Bedford, IN. Paul Pemberton, PRD's processing coordinator, and Darren Tipton, PRD's maintenance manager, invented the Lightning Loader, patented it, and cofounded P.T. Equipment to sell it as their first product. Both men are only moonlighting as auxiliary equipment suppliers, though; they still work at PRD. So do their Lightning Loaders. The systems are installed on almost all of PRD's 44 molding machines (50 to 310 tons). And after some initial minor debugging, they've been operating flawlessly since the fall of 1995. There have been zero failures requiring operating component replacements. All that needs replacing is the filters.

The Guts of the Loaders
Lightning Loaders are key elements to closed loop grinding and blending systems designed from day one to work with robots. The robot drops the runner into the beside-the-press grinder, which feeds the Lightning Loader. The Lightning Loader delivers regrind and virgin at a preset ratio, and then blends them in the machine hopper. The Lightning Loader's materials proportioning system is based on timing rather than air pressure, and the blending itself is performed by air agitation. Pemberton and Tipton have found this method to be more accurate, with blend consistency. The air agitation system also can be used to blend materials right in the molding machine hopper.

PRD uses grinders from MPG Service & Sales Inc. (Hillsboro, TX), but P.T. Equipment can supply you with systems on any grinders with the output capabilities. Systems are available with output capabilities and other specs that are matched to your machine's shot size. A typical system, for say a 200-tonner, ranges from $1000 to $2500, depending on customer specifications and options. PRD's closed loop regrind/blending systems have decreased its scrap rate by 20 percent, while increasing productivity some 15 percent. For more information, try P.T. Equipment's website at www.lightningloader.com.