CASE STUDY -- Improving cycle time with heat transfer technology         I have often been asked to provide some examples ...
CASE STUDY -- Improving cycle time with heat transfer technologyHEAT PIPES DO THE TRICKThe solution Bucher offered to the ...
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Acrolab Thermal Management System - Case study thermoset injection molding

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I have often been asked to provide some examples as to process improvement with the Acrolab thermal management system. Below is an article which was printed some years ago, however it does provide for real data and a definite impact in terms of how Acrolab engineered, manufactured and installed a thermal transfer system which heightened through-put, saved energy and improved quality of the product.

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Acrolab Thermal Management System - Case study thermoset injection molding

  1. 1. CASE STUDY -- Improving cycle time with heat transfer technology I have often been asked to provide some examples as to process improvement with the Acrolabthermal management system. Below is an article which was printed some years ago, however it doesprovide for real data and a definite impact in terms of how Acrolab engineered, manufactured andinstalled a thermal transfer system which heightened through-put, saved energy and improved quality ofthe product. Questions? Comments? Please give me a call. 519 944 5900Thanks and best regards,PeterPeter McCormack, BA, MAGlobal Technical Sales ManagerAcrolab Ltd. Windsor, Ontario CANADAMold-heating technology raises thermoset moldingquality.By Fallon, Michael Publication:As printed in Plastics TechnologyDate: Saturday, December 1, 1990Mold-Heating Technology Raises Thermoset Molding QualityHeat-transfer technology for thermoset molds has enabled a processor to eliminate a problem of unevenmold heating and reduce cycle times by up to 23%. When Squares Ds Columbia, Mo., injection moldingplant took delivery of its second 200-ton Bucher injection molding machine 18 months ago, moldingengineer Gary Emanuel had strong expectations that the new equipment would yield better cycle timesand less waste for the polyester BMC part he had been running on less sophisticated equipment.However, early in the startup process, it became evident that the design of the mold Square D had beenusing was creating problems that even the best of equipment and material couldnt overcome.The Columbia plant molds and assembles circuit breakers for household electrical service lines. The moldused for the breakers plastic housing is both deep and complex in configuration. Production had beenplagued by excessively long cycle times, incomplete curing, and haze and blisters on part surfaces.Through testing, Emanuel discovered a critical 50 [degrees] F differential between the heated mold baseand portions of the core face. Because the cavity was so deep, when the mold was heated to a settemperature of 350 F, the reading on some mold surface registered only 300 F.Process engineer Jeffrey Ison experimented with varying temperatures and preheating routines, with noimprovement. Says Isom, "The hotter the mold, the faster the material cures. If you get too hot, you candamage the part, produce a hazy appearance, or, in the worst case, the mold will lock up on you." AsEmanuel and Ison ran out of ideas, their equipment supplier, Bucher, Inc., Buffalo Grove, III., called tosee how the new machine was performing. Emanuel recalls, "Buchers response when it heard of ourmold heating problems was reassuring. They had experience with other complicated molds and foundsolutions, including a new way to bring heat from the base to the face of the mold directly andinstantaneously."1|P a g e
  2. 2. CASE STUDY -- Improving cycle time with heat transfer technologyHEAT PIPES DO THE TRICKThe solution Bucher offered to the mold-heating problem was a heat-transfer technology for thermosetapplications from Acrolab Instrument, Ltd., Windsor, Ontario. Acrolabs "Isobar" heat-transfer systemconsists of inserting an array of heat-pipe thermal conductors within the cavity and core of the mold toachieve high-speed heat transfer within the mold as well as thermal consistency of the mold faces. Thesystem also employs integrally heated sprue spreader and core pins, which permit active heating andindependent control of specific areas of the mold, such as bosses and sprues.The Isobar system resides completely within the mold itself, and requires no additional external controlhardware, nor any special processing or handling considerations. The principal benefits of the system areexceptional temperature uniformity of all molding surfaces and rapid mold-temperature recovery aftereach clamp opening. Acrolabs Isobar heat-pipe system was custom engineered to suit Square Ds mold.In all, over 150 Isobar heat pipes of 13 different diameters were installed in holes drilled into the variousinserts that make up the cavity and core faces. Acrolab engineers calculated minimum hole depth,location and wall thickness requirements to ensure that the inserts were structurally sound and that theIsobar array would produce the most uniform temperatures at all molding faces. All the heat input for theinserts was conducted by the heat pipes from a bank of cartridge heaters in the mold base.Square Ds mold was sent to Artag Plastics Corp., a Chicago mold builder, for preparatory machining andIsobar installation. Holes had to be drilled, cleaned and dried for precision fitting of the heat pipes.Acrolabs service manager flew to Chicago to inspect the mold and install the Isobar system, a serviceextended to all Acrolab customers.HOW IT PERFORMEDTo evaluate the results of the newly installed heat-pipe system, Emanuel devised initial tests that wouldeliminate all other variables and provide valid comparisons. He took a computer readout produced a yearearlier by the Bucher CNC press controller, and matched the parameters of that process exactly to runthe new tests. He selected the same material, stroke, injection profile and plasticating profile. He pre-heated the mold to the specified temperature, and ran the process. The results were dramatic.Not only was surface appearance improved, the system made it possible to reduce curing time by 13sec. The reduction in total cycle time averaged 22-23% over the old mold design, exceeding Buchersown prediction of at least 15% improvement in cycle rates. And Emanuel says he is certain they can doeven better. Mold heating was totally stabilized through the entire depth of the mold. The face of the moldnow registered the same temperature as the mold base. As a result, Square Ds team was able to reduceset point temperature more than 40 [degrees] F, with a corresponding saving in energy costs.2|P a g e

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