Analyzing a Product's Working Environment To Aid Part Designs

Design engineers and OEMs can choose from a vast combination of materials and processes to create parts and components for new or existing products. The dizzying array of options can include plastics; die-cast metals; such metals as iron, steel and copper-base alloys; and at the most costly end of the spectrum, specially alloyed or heat-treated ferrous alloys. This front steering knuckle provides attachment for an automotive front wheel, hub end bearing, steering linkage, and suspension control arm and strut, while supporting front-end weight and steering loads. The part is precision squeeze cast from A356-T6 aluminum, reducing machining cost, improving product durability, and substantially reducing the part's weight. Cast as a cargo-container refrigeration unit air-circulating fan, this A380 aluminum evaporator stator is designed to withstand strict environmental requirements, including shock, ambient temperature extremes, humidity, salt, and fog. Obviously, no one material is the best choice for all applications. So how to decide? To help designers make the best selection, the Diecasting Development Council (DDC) has created a systematic plan that focuses on the product's actual working environment. Based on the experience of hundreds of designers and die casters, the DDC recommends that designers carefully evaluate six aspects of every product's working environment before settling on a production method. Those six critical factors are: Like so many things, temperature is not always what it seems to be. Several key questions merit consideration. In a cyclic environment, the maximum temperature often doesn't represent what temperature the part will actually reach. For example, in gasoline engines, die-cast aluminum and magnesium pistons are often exposed to temperatures above 3,000°F (1,648°C). However, the piston is exposed to this extreme for only a brief portion of the cycle. Gas-turbine wheels, on the other hand, operate in an environment of about 2,200°F (1,204°C), yet require high-temperature alloys. Why? Because