Leap Design Hurdles with Materials

Die Casting Changes Shape- Amid their industry ’s largest-ever consolidation, die casting firms are cutting their lead times for die-cast parts, accommodating customer demands for shorter production runs, and expanding the range of services they offer, all to keep pace with domestic and offshore competition. In the early 1960s,approximately 1,250 die casters shared a North American market valued at no more than $2.5 billion, according to Walter G. Treiber, president and chief executive officer of Chicago White Metal Casting, Inc.(Bensenville, IL)and a member of the Board of Directors of the North American Die Casting Association (NADCA).Today, Treiber says, the number of firms is nearer 225,but the market's value has climbed to nearly $10 billion. That may be bad news for many of the “mom and pop ” die-casting shops that have served geographic or niche application markets, but good news for design engineers. The die-casting firms most likely to survive the consolidation and the ongoing market doldrums are highly automated, more knowledgeable, and more efficient than ever before; increasingly like pit crews at an auto race.

Injection Molding Provides Growing Number of Design Options- Dustin Hoffman didn’t take the career advice he received in “The Graduate,” but the plastics industry has fared quite well without him. Injection molding has become the dominant manufacturing technique for myriad industries, giving product designers many different features while keeping costs down. Multi-shot molding is becoming more common, making it possible to make toothbrushes, hand tools, and other products that are durable yet provide a cushioned touch. In applications that don ’t require different types of materials, there’s a big move to thinner walls, which decrease size and weight without sacrificing strength. At the same time, the industry is undergoing a bit of backlash against high-volume production, as more customers opt for some degree of customization.These trends are altering a huge industry. Injection molders dominate the plastics processing industry, with 7,000 U.S. facilities, according to the Society of the Plastics Industry (SPI). That was far more than half of the 12,916 plastics molding plants in operation in 2000,SPI statistics show.

The Right Dimensions- Aluminum plate is specified for countless uses that benefit from the inherent properties of the metal itself. Aluminum ’s reduced weight, easy workability, and thermal/electrical conductivity contribute to the performance of many products. With its versatility and high speed for a variety of machining operations, aluminum tooling plate has advantages that make it a popular choice for shaping intricate components. When selecting aluminum tooling plate for applications where dimensional control is critical, the design engineer must be confident of precise tolerances and dimensional stability. Fixtures and quality control equipment illustrate the need for close tolerances. In such equipment, components may require controlled thickness and flatness to serve as the base for a tool or a measuring device. This type of portable fixture is found in industries ranging from aircraft to automotive, computers to electronics, and printing equipment to food processing machinery. The second consideration, dimensional stability, is an important factor in parts that are machined by removing extensive levels of metal (as much as 85%). Dimensional stability must be considered both before and after processing, as well as in components subject to wide temperature variations.

Selecting the Right Metal for Your Design-  Robert Spana,Product Manager,Mic6 Plate, Alcoa, Pittsburgh, PA  Design News:What are the most important design considerations when selecting metal?

Spana:When it comes to cast tooling, the primary concern is dimensional control and stability, which is not achievable in rolled, stretched, thermally treated product. In the final treatment for rolled plate, there is an artificial aging. That happens in temperatures of 300 to 350 degrees F. In the manufacture of cold plate, some stresses are aligned in a final stretch. But that doesn't eliminate stresses, it just aligns them. The thermal temperature isn't high enough to eliminate stresses. So, when you process the material there is the potential for releasing the stresses, and the wrought plate will distort. For maintaining precise tolerances, cast tooling is the alternative. Also, you can do more high-speed machining with cast than with a wrought product. But don't use cast plate for structural strength. It has limited mechanical properties and is soft and weak.

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