Machine Design

Automotive die castings steal the show

Innovative automotive parts took all but one of the top honors at the recent International Die Casting Competition.

The North American Die Casting Association (NADCA), Wheeling, Ill., handed out top honors to automotive OEMs for parts that exemplified performance and fuel economy. The competition aim is to demonstrate the versatility, quality, innovation, and cost savings possible with aluminum, zinc, and magnesium die cast parts.

According to NADCA, several winning components are breakthroughs in casting because of their reduced weight — a significant factor in automobile engineering. A computer component for electronic storage also received an award.

Aluminum, Squeeze/Semi-Solid

An innovative tooling design from Contech, Portage, Mich., made possible a large, complex housing for a rack and pinion steering gear used in Toyota Tundra and Sequoia trucks. A two-cavity die and proprietary P2000 HVSC (high-vacuum squeeze casting) process let Contech meet Toyota's burst test and end cost targets. The parts were cast on a 2,000-ton Prince DMC (die casting machine) that puts a vertical shot into a verticle split die outfitted with horizontally moving die blocks.

Aluminum under 1 lb

Twin City Die Castings, Minneapolis, produced a one-piece exhaust gas recirculating (EGR) valve housing for car and truck diesel engines that has features usually done with multiple die and sand cast components. The ERG positions and houses the valve actuator, maintains alignment, fixes the valve seats, and provides a sealing surface. It was cast in a two-cavity die with two stainless steel inserts per cavity and six core pulls. The stainless steel insert molding weighs less than a stainless steel cast housing, without sacrificing performance or durability.

Aluminum 1 to 10 lb

Shock Towers for suspension mounting and alignment are traditionally made from a series of steel stampings welded together during vehicle body fabrication. With die casting, Contech, Portage, Mich., reduced the number of assembly components and dropped shock tower weight by 40%. Contech used a new casting technology called High-Q-Cast to produce the lighter weight aluminum casting. The heat-treated aluminum shock towers have thin walls, yet give manufacturers the ability to weld and rivet the castings to other components.

Aluminum over 10 lb

A patented insert molded tube technology from Metaldyne, Plymouth, Mich., was used to die cast a front engine module assembly (FEMA) for V-6 and V-8 engines. The tube assembly is made from welded together mandrel bent 304 stainless steel. Each casting is produced from 380 aluminum with a minimum wall thickness of 3.0 mm. The process needs no special tooling or equipment. Compared to sand or semi-permanent mold casting, insert molded tubes are said to improve fluid flow efficiency, eliminate leaks, and reduce weight and cost.

Magnesium under 0.5 lb

Phillips Plastics Corp, Eau Claire, Wis., used a magnesium casting to make an assembly that injects and ejects 3.5-in. hard drives from a server, squelches and dampens vibrations from the disk drives, and protects against EMI. The cast part is the assembly's backbone, holding fiber channels, clips, an EMI shield, hard drive, a locking mechanism and a pin connector. Zinc was previously used, but magnesium better dampens vibration and brings inherent EMI protection.

Magnesium over 0.5 lb

Lunt Manufacturing Co., Schaumburg, Ill., created a die-cast cross-car beam for BMWs E-70. The die cast magnesium part weighs half as much as the steel beam it replaces. The part is cast in a 4,000-ton cold chamber IdraPrince DMC using a two-cavity die. The part reportedly gives the beam and steering column more stiffness as well as crash energy absorption. The die casting also provides attachment points for the instrument panel.

Zinc under 6 oz/nonelectroplated

Cast Products Inc., Norridge, Ill., created a new design for Gentex rearview mirror mounts used in Volvo Autos and SUVs. Zinc gives the mounts good wear resistance and tensile strength. It also easily molds the necessary thin-wall sections. The casting was designed around the mirror mount's humidity sensor to make the smallest possible footprint. This windshield-to-mirror head transition housing eases the mounting of the sensor and related wiring and harnesses. This is important because rearview mirror assemblies are the preferred location for advanced electronic features, such as climate control and automatic dimming to eliminate nighttime glare.

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