Rotational molders at a Society of Plastics Engineers conference heard an update on Hedstrom Plastics' move into a former Wal-Mart and learned why Trilogy Plastics Inc. has invested in computer numerically controlled routers.
They also learned about a new mold-venting technology.
Jim Braeunig, Hedstrom president, said the company should begin operating in October at the Wal-Mart building in Ashland, Ohio. The retail building, with 129,000 square feet of manufacturing space, became vacant when a Wal-Mart Supercenter opened across town in 2006.
Hedstrom is leaving its aging factory space in Ashland. Braeunig outlined investments Hedstrom is making to improve operations in the new building and cut natural gas use on the ovens by up to 30 percent. The company had added gas meters to measure usage.
* Adding rounded panel inserts inside its oven and adding fire brick.
* Installing variable-speed drives on the oven and exhaust blowers, and a compressor.
* Putting Allen-Bradley Panel View controllers on its rotomolding machines.
Braeunig said Hedstrom continues to look at alternative methods to heat its ovens, including infrared and biomass-based fluidized bed combustion. But there isn't a big incentive now, since natural gas prices are low, he said.
Trilogy Plastics bought its first CNC router, a Motion Master, in the early 1990s, according to Daren Balderson, engineering director at the Alliance, Ohio, company. Today 90 percent of Trilogy's parts go through its three routers two Motion Masters and one Quintax and they are in continuous use, he said. Trilogy runs seven rotomolding machines.
The routers can trim and drill holes in parts with complex geometries and large parts that would be difficult to finish by hand. Trilogy likes twin-table routers that allow an operator to load parts onto a fixture while the parts on the other table go through the router. We like to get as many features done in one fixture as possible, to minimize setup time on the router, Balderson said.
Benefits include reduced labor costs, improved safety and higher quality and productivity, Balderson said.
Trilogy also uses the routers to cut its own wood patterns and make models, and to spin-weld some parts.
Only about 35 percent of North American rotomolders use CNC routers, Balderson said. He first learned the power of CNC routers during a college internship at a large Alliance foundry that made steel side-frames for railroad cars. The company employed 125 pattern makers, but cut that number to just 10 people after it invested in routers and computer-aided design/manufacturing.
Trilogy got into CNC routing and CAD/CAM when it got a major job making parts for a lawnmower manufacturer. Officials thought the work would take eight people over two shifts to rout the parts manually using 16 fixtures. Using the new router, the job required only two employees and five fixtures.
The original router paid for itself within six months, he said.
Sandy Scaccia, president of Norstar Aluminum Molds Inc. in Cedarburg, Wis., described the Technovent mold-venting system, made by La Plastecnica of New Zealand. Norstar makes molds for rotomolding. The vent portion of Technovent is based on the firm's Supavent, made of a flexible polymer.
Traditionally in rotomolding, heat passes from the outside of the mold to the inside in the oven, then has to come back out of the mold in the cooling chamber. By allowing for two-way air flow, Technovent enables both internal and external heating and cooling in the mold, which provides better part consistency, a 55 percent reduction in the variation of the cooling rate and an 18 percent decrease in part warpage, Scaccia said.
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