Jan H. Schut
Induction heated barrels are alive and well, but hard to get. The world’s first commercial induction heated barrels were launched by Nordson Xaloy Corp., New Castle, PA (www.xaloy.com) at the K 2007 Show in Germany. Called nXHeat, Xaloy’s patented barrels (U.S. Pat. # 8007709) had compelling advantages, reportedly using roughly 55% less energy than even insulated barrels with resistance heater bands. A 2008 ANTEC paper by Xaloy and Sabic Innovative Plastics, Pittsfield, MA (www.sabic-ip.com), also reported “50% reduction in part weight variability, 25% reduction in dimensional variability,” shorter cycles, and lower maintenance.
Induction is used industrially to melt and temper metals and sinter ceramics. It generates electro-magnetic waves in electrically conductive materials like metals (not in non-conductive plastic). A twisted induction cable, known as a Litz winding, uses low voltage, high amperage, and very high alternating frequency (20-40 kHz) to pulse oscillating eddy currents into a metal object, heating it from outside in. Patents on induction heated barrels go back to the 1940s, but induction wire wasn’t as efficient then, so they weren’t commercialized. Three Japanese machine builders also developed induction barrels in the early 2000s, but didn’t commercialize them.
Xaloy’s induction barrels use a coiled Litz wire in a sleeve, wrapped around the barrel outside of the foamed barrel insulation. Induction heat requires a generator for the specialized high frequency power supply and expensive controls for the pulsing voltage and phase supply. Temperature controls shut the current on and off rapidly, responding to temperature sensors in the barrel, which are installed closer to the melt than sensors for heater bands. Coils are individually controlled, so if one fails, they can be replaced easily without shutting the machine down. All in all, nXHeat cost five times more than conventional resistive heater bands. Even so, Xaloy expected payback from energy savings in 1.5 to 2 years for machines over 400 tons.
In 2008-2009, several injection molding machine makers supported Xaloy’s induction barrels as options. Ferromatik Milacron Maschinenbau GmbH, Malterdingen, Germany (www.ferromatik.com), showed it in-house in 2008 on an EC-300 injection molding machine forming caps and sold a couple of dozen packaging machines with hybrid induction barrels. To keep cost down, Ferromatik put induction only on the feed zone, where heat demand is highest. At NPE 2009 in Chicago, KraussMaffei AG, Munich, Germany (www.kraussmaffei.com), and Engel Austria GmbH, Schwertberg, Austria (www.engelglobal.com), also offered Xaloy induction barrels as options on their energy-saver machines.
But in a recession, expensive barrels were a tough sell, and all three OEMs dropped it. There was also an unspoken liability issue. Because there is no physical limit to how hot induction can make a material, if a temperature sensor on an induction barrel failed and the coils didn’t shut off, they could physically melt the barrel. Resistive heater bands, on the other hand, have an upper limit of around 600 °F, just enough to process PC.
Xaloy sold hundreds of induction retrofits in the U.S. and Europe primarily to high-tech molders with energy-hungry applications for large parts and high temperature plastics. Nordson Xaloy Asia (Thailand) Ltd. in Chonburi, Thailand, sold even more induction barrels in Asia, mostly to large international automotive and electronics molders, where the attraction was both energy saving and better part quality.
In the U.S., molders tried to get energy subsidies for induction retrofits. A custom molder in Wisconsin retrofitted one of the first barrels in 2008 with an energy subsidy and found it saved maintenance and downtime as well as energy. Over the next two years, they retrofitted 24 more presses from 200 to 1000 tons. But often utilities baulked at supporting the new technology. A molder in North Carolina tried hard to get their local electricity co-op to approve subsidies for induction retrofits, but couldn’t and couldn’t afford them. In Europe, hybrid induction retrofits of only zones 1 and 2 of the barrel became more common than full retrofits because of cost.
Then the Chinese jumped in with cheap imitations. There are now over a dozen Chinese induction barrels on the market at very low prices. “Some take induction wire used for cooktops and wind it around barrels, so there is interference between the zones, and no EMF filters to protect workers. Some even put empty boxes along the barrel to look like zone controls, but it’s really one loop, so there’s no energy saving,” complains an Asian salesman for Xaloy.
INDUCTION IS DRIVEN MOSTLY BY KOREA
By 2013 in response to perceived issues with induction (mostly cost), Xaloy launched its SmartHeat barrel technology (U.S. Pat. # 8247747), which heats resistively with fine nickel chrome wires wound directly around the barrel and ceramic coating plasma sprayed over them. Energy saving is similar to induction because SmartHeat barrels also have very low thermal mass compared to heater bands, but SmartHeat costs a third of what nXHeat does.
Xaloy stopped offering induction barrels except to existing customers, for which Xaloy still retrofits 100s of barrels a year. SmartHeat barrel coating is offered to new customers globally. Some big molders in Europe, South America and Asia, however, prefer induction. Logistics are one reason. For a SmartHeat retrofit, a barrel has to be shipped to the U.S., coated and shipped back with a lot of machine downtime. Induction can be retrofitted onto a barrel in place in the factory in a day.
To fill the void left with Xaloy pulling back from induction, the Korean government stepped in to ensure a supply of reliable induction barrels. At the Koplas 2013 plastics show in Seoul, Korea, Purmi Co. Ltd. in Seoul introduced Eco-heater induction barrels from ECO-nomical Heater Co. also in Seoul with Korean government support. Basco Barrel Screw Co. in Seoul (email@example.com), Xaloy’s long-time Korean rep, represents Eco-heater, which has developed smaller induction units than Xaloy, down to 6 kW vs. 8 kW for Xaloy’s smallest.
Basco/Eco-heater barrels are sold primarily to Korean customers. According to published reports, a dozen Eco-heater barrels went to Samsung Group (www.samsung.com), including one for a 4000-ton Mitsubishi press in Kuang-Ju, Korea, and one for a 3000-ton JSW press to mold bumpers also in Korea. Five Eco-heater barrels went to Hyundai Mobis Co. (www.hyundaimotorgroup.com), including one for a 2000-ton LS Mtron press in A-San, Korea.
Eco-heater/Basco induction barrels have also gone to Korean companies outside of Korea to Samsung plants in Poland, India, Mexico and China. Ninety Eco-heater induction barrels went to LG Electronics Inc. (www.lg.com) in the U.S. for LS Mtron presses from 450 to 1800 tons, plus one barrel for a 2500-ton LS Mtron press for LG in Mexico. (Injection molding machine builder LS Mtron in Korea (www.lsmtron.com) is a spin-off from LG.) Certainly having a second source for quality induction barrel retrofits is better for molders than having one reluctant source. But can molders who aren’t Korean and already Xaloy induction customers buy them if they want to? Probably not.