 Die casting is a century old process that today is at the forefront of providing innovative solutions for many industries. The modern die casting process includes long lasting die materials, automated process controls, high precision casting machines and custom alloys. These advances have allowed die casters to produce precision and high-strength products at a rapid production rate. No other metal casting processes allow for a greater variety of shapes, intricacy of design or closer dimensional tolerance.
Die casting is a major part of America's most fundamental industry - metal casting - a production process used in parts for everything from aerospace/defense to kitchen implements. In fact, metal castings are used in 90 percent of all finished manufactured products globally, with the die casting process being used for more than one-third of all castings. The die casting process involves injecting molten metal into a steel die under high pressure. The metal, either aluminum, zinc, magnesium and sometimes copper, is held under pressure until it solidifies into a net shape metal part.
Today, more than 550 die casters in North America manufacture thousands of non-ferrous castings ranging from automobile engine and transmission parts, to intricate components for computers and medical devices, or something as simple as a desk stapler. Die casters contribute over $7.3 billion to the nation's economy annually and provide more than 63,000 jobs directly and indirectly. The die casting industry is a microcosm of American manufacturers. Nearly 60 percent of these companies have fewer than 100 employees, while the larger firms are world leaders.
Dispelling Myths
Despite the benefits that die-casting has provided to many industries, a number of designers, engineers and purchasing decision makers still labor under several myths and misconceptions about the use of die-casting. These mistaken beliefs fall into four general categories:
- Time to Produce Tools
- Casting Strength
- Volume Requirements
- Tooling Costs
The North American die casting industry has addressed each of these issues in a number of ways: through research conducted by the North American Die Casting Association (NADCA); studies sponsored by industry and academic partners; and field work conducted by progressive, industry-leading firms. Here are some of the ways the industry is addressing these misconceptions.
Time to Produce Tools
Lead-time to create a tool - the die used for casting a part - was typically measured in months. Now, using new rapid tooling methods, that time has been cut significantly. For example, there are 12 different tooling production methods for low volume work (1,000 parts or less) with lead times from 19 weeks to as low as seven days! Designers can learn more about these methods in the "Design Knowledgebase and Rapid Tooling Selection Tool," developed by NADCA in conjunction with the Department of Defense and the Defense Logistics Agency. The knowledgebase assists designers in selecting an appropriate rapid tool production method based on the volume of the required cast part and the production timeframe.
Casting Strength
Another myth is that the mechanical and physical strengths of die casting alloys are insufficient for critical applications. NADCA-sponsored research work at the Worchester Polytechnic Institute created a database of several thousand data points identifying the influence of key elements on the chemistry-microstructure-property relationships of aluminum alloys. As a result, designers have the ability to customize aluminum die casting alloys to meet special property requirements. One example of expanding applications is the Jaguar steering knuckle, one of the winners in the 2006 NADCA International Die Casting Competition. Using custom alloys and new production methods, a cast part was created to withstand severe operating conditions. While aluminum is one of the most predominant casting alloys, research is also identifying more creep resistant, economical zinc alloys, creating potential new applications for these alloys in commercial components.
Volume Requirements
Die casting is typically linked with only high volume production. But in today's industry, low volume work can be easily and economically achieved. The "Rapid Tool Selection Tool" can be used to identify methods of producing "limited use" tooling for low volume production. The equation of volume requirements compared with costs can also be changed if the design includes more than the original cast part. If a element or an extrusion can be economically combined into one cast part, suddenly the cost of tooling appears minimal when looking at a low volume final cast component versus an assembly. The zinc stabilizer link for an automotive suspension system that is among the Casting
Competition winners is a good example of using die casting to eliminate production steps.
Tooling Costs
The "alleged" high cost of tooling has been reduced dramatically in recent years through a number of changes that have increased tool life by 50 percent to 75 percent over the past decade. The increased quality and enhanced chemistry of tool steels, combined with improved techniques of heat treating the steel permit tools to be used for 150,000 to 175,000 shots, compared with barely 100,000 10 or 15 years ago. Add to that better heat management by the die caster of the dies once in production, and tooling life can be extended even more, which further lowers the cost over the entire production life of the die.
Collaborating for Success
Collaborative engineering is one of the primary ways that die casters are extending their knowledge of the benefits of die casting to OEMs. Working together helps dispel myths and leads to production efficiencies. Designers are finding that they can achieve further cost savings and product improvements by engineering products in conjunction with their die caster. Consulting with the die caster during the design phase helps resolve issues affecting tooling and production, while identifying the various trade-offs that could affect overall costs.
Examples of the benefits of collaboration and innovative thinking were displayed by the die casting industry during the 2006 International Die Casting Competition sponsored by the North American Die Casting Association (NADCA). From using new alloys in automotive components to producing miniature designs, this year's award winners provided outstanding examples of the versatility, quality, innovation and cost savings that can be achieved with aluminum, zinc and magnesium die cast components.
The entrants in this year's competition showcased numerous applications for die casting in today's global marketplace. Several winners used new processes or alloys to create parts that previously were not suitable for die-casting. These initiatives will continue to expand the market for the die casting process. Submissions ranged from the U.S. and Canada, to Japan to Wales, proving that advances in die-casting know no boundaries.
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