Case history: reducing costs by linking heat treating with other operations.

Plant 10 of Superior Industries International, Van Nuys, Calif., was looking to reduce labor, energy, maintenance and inventory. For the low-pressure permanent mold casting facility, it made sense to integrate and automate its in-house T-6 heat treatment process with the upstream casting operations and the downstream inspection and machining processes. So, the company called on CleanCast technologies from Consolidated Engineering Co., Kennesaw, Ga.

The fundamental principal of CleanCast is to remove the casting from the mold shortly following solidification and insert it into the furnace before the casting spends substantial time below the process critical temperature (PCT). At Superior Industries, pick and place mechanisms and high speed conveyors transfer the castings from the casting decks into the solution furnaces within a few minutes of casting extraction from the mold. This arrests the cooling of the casting and allows for greatly reduced thermal cycles in both the solution and age cycles. And, because the castings are charged from the casting machines directly onto parallel chains in the solution furnace and then carried through the solution and age treatments, no racks or fixturing is required.

Vision systems identify the castings prior to charging into the solution furnaces, so the optimum thermal cycle can be selected for a particular casting, adding much-needed versatility for Superior Industries, which manufactures hundreds of different aluminum wheel castings. The entire process, from casting pickup after mold extraction through the T-6 treatment is totally automated with no labor and manual handling.

Castings are processed through solution and age in a four-by-four arrangement on the parallel chains and separated by airspace to allow hot uniform air and quenchant to pass for optimum heat transfer in the heat and quench. High velocity jets heat the castings from the PCT threshold to solution temperature, further enhancing metallurgical properties. High volume airflow in the soaking zones provides uniform part temperatures in both the treatment and the age. The individual part heat up promotes better part to part uniformity. Automatic robotic quenching minimizes distortion of the as-quenched castings because it can control the speed of entry and orientation of the casting into the quench, the temperature and thermal uniformity of the quench, the agitation rate and direction of the quench, and the method of supporting the casting during cooling and contraction.

Prior to aging, castings are cooled to a uniform, near-ambient temperature, allowing them to stabilize and achieve uniform properties. Once again, the vision systems are used prior to age in order to determine the most effective age cycle. The age oven is heated using exhaust from the solution furnace in order to conserve energy.

Superior Industries has been able to keep its reject and scrap rates low while boosting productivity and reducing production costs with the CleanCast technologies.

Visit www.cec-intl.com for more information.

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