Design News for Mechanical and Design Engineers

Strong demand from Asia has stretched supplies of basic metals in the past three years, driving prices higher. The problem has been exacerbated by inadequate expansion after the collapse in pricing in late 2001 and 2002. Lead was $500 a ton in 2003 and went to $3,400 a ton in August. Nickel was $7,000 per ton in May 2003 and then went to 50,000 a ton. It’s now at $28,000/ton. Cobalt went from $1,250/ton in 2004 to $74,000 ton and has settled down to $50,000/ton.

OEM profit margins have suffered as a result, triggering interest in replacement materials as well as alternative processes that could reduce costs. At times, the new strategies have also raised quality and simplified designs.

One of the companies actively exploring new materials strategies is General Motors, whose top supply chain executive, Bo I. Andersson, told reporters in a recent press conference that materials prices are “scary” and GM is exploring opportunities to replace expensive materials.

In an interview with Design News, Andersson said the main strategy is to develop materials options even before vehicles are designed, so GM can shift gears down the road if imbalances develop between materials’ prices. “We typically look at what we can do to create options before the fact,” says Andersson. “In one of our global programs we made it an option (before actual vehicle design) that there will be steel fuel tanks as well as plastic.”

That’s quite a sea change because multi-layered automotive plastic fuel tanks have made tremendous penetration in the last 20 years.

Plastic offered lower weight, more design flexibility and other advantages. Even as long ago as 1993, about a quarter of passenger cars had nonmetallic fuel tanks. There are two reasons for the new strategy. “We have been using plastic fuel tanks for the last 10 years and the resin price has been going up. Secondly, we look at transportation cost, because with everything we buy, we look at best landed cost. So, in short, you can say that a steel fuel tank can be welded together very close to the assembly plant and now you have reduced transportation cost and that is another key driver.”

Companies pushing steel fuel tanks launched a big marketing and technology drive several years ago through the Strategic Alliance for Steel Fuel Tanks and they never really got much traction. Multi-layer plastics systems just kept getting better and better. The steel guys had a story too, including: 1) New steels are increasingly formable, allowing more design freedom and 2) Steel tanks are 100 percent recycleable. And they are increasingly cost competitive. With a landed cost approach and ballooning hydrocarbon prices, they are even preferred on a cost basis.

GM’s Big Four

Andersson says the focus is on four materials under significant price pressure: palladium, aluminum, steel and plastics.

“When you look at our sports cars in general, we are trying to replace steel parts with plastic parts,” says Andersson. “You get better weight and you save on costs. You see some examples with the Chevrolet Corvette and the Pontiac Solstice.”

The Corvette, of course, was the first plastic-bodied car, dating back to 1953. But the commemorative Edition Z06 featured a carbon fiber hood — the first ever use of the material on a painted, Class A exterior body panel. Sheet molding compound (SMC) is widely used on the Solstice. Also new on the Z06 is first-time use of magnesium as a single-piece component in the engine cradle, replacing multi-piece assemblies of aluminum. Corvette is often used as GM’s test bed for new technology and the die casting clearly was a significant breakthrough for a structural load-bearing material.

But are these really good examples of materials’ switches made to save costs? The key driver for the magnesium die casting clearly was weight reduction — Andersson said the magnesium allowed GM to avoid a gas guzzler tax. Except for a simple grade reduction, materials substitutions are really done for a variety of reasons. “We work with design engineering and manufacturing to see what are the things we want to impact. In some cases, it’s costs,” says Andersson. “In some case, it’s mass, and in others, it may be transportation costs or design flexibility. And sometimes, it’s all of the above.”

Higher materials costs are really triggering a concerted effort to provide options, when possible.

“We work together with engineering in what we call our systems management teams,” says Andersson. “Before that, engineering was systems focused and purchasing was commodity focused. Four years ago, Jim Queen (global vice president of global engineering) and myself said, ‘Let’s bring this together.’ So, today, there are seven systems management teams for engineering and purchasing. These leadership teams meet every Tuesday. We’re not where we want to be, but we have made a lot of improvements.” Suppliers are also more involved in the design process and have the benefit of meeting with systems teams made up of engineering and purchasing officials. “We can also explain better (to suppliers) the key drivers for us: mass, quality or cost.” GM is also using new Web-based tools to facilitate communications.

Another strategy is to move bright engineers into purchasing early in their careers so they can develop a better understanding of the company’s cost goals. “They add much more value three years out when they are back in engineering,” says Andersson.

10 Cost-Cutting Tips

Here’s a look at 10 strategies developed by Design News that can be used to reduce exposure to high, and unpredictable, materials prices: As with the examples from Andersson, most of these are not straight materials substitutions for cost purposes, but rather alternative approaches, sometimes involving significant engineering time, that can allow lower costs, in addition to other benefits.

1) Switch from zinc alloy die castings to magnesium die castings. Zinc prices rose more than four fold from 2005 to 2006, then slid some. By comparison, magnesium prices were fairly stable. According to Chicago White Metal, hot-chamber magnesium machines can normally accommodate the identical die casting dies being used for zinc production, allowing rapid production after die examination and sampling.
2) For cosmetic applications, replace stainless steel with porcelain coatings that mimic their appearance. Whirlpool is using the coating on a just-introduced electric range. The porcelain enamel does not show noticeable fingerprints, does not discolor from heat and is resistant to stains, scratching and chemical cleaners.
3) Substitute sheet molding compound (SMC) for flat rolled steel. SMC is a glass fiber-reinforced compound using a thermoset plastic as a matrix material. FRP composites are usually 25 to 35 percent lighter than steel parts and can be fabricated with low cost tooling. In some cases parts can only be shaped with a molding. Downside: Process can be slow and the recycling track record is far inferior to steel.
4) Try a new surface hardening process from Swagelok that boosts hardness of stainless steel. The surface of the metal is activated and is then carburized at a temperature that is low enough that carbides are not formed. As a result, corrosion resistance is not compromised. Ordinary stainless steel has performance characteristics of expensive alloys like Hastelloy or titanium. Target applications include commercial pumps and circulation systems, fasteners, bearings, clutch plates and other industrial parts subject to heavy wear, military applications, aerospace, automotive, and medical devices, such as hip implants.
5) New high-alloy grades from Carpenter Technology are aimed at applications such as titanium replacement in aircraft landing gears and performance enhancement in golf clubs. Custom 465 stainless is a double vacuum-melted, martensetic, age-hardenable alloy that offers corrosion resistance as well as strength and toughness. When aged at 950F, it’s capable of ultimate tensile strength in excess of 250 ksi.
6) Check out emerging nano solutions. A new hybrid structure uses a proprietary process called MetalFuse that applies precise amounts of nanometal to molded plastic components. Parts are said to have the stiffness of aluminum or magnesium, but with better strength. Grain sizes of the metals are 1,000 times smaller than conventional metals. The technology was introduced at K 2007 by DuPont Engineering Polymers and partners Morph Technologies of Toronto, Canada, Integran Technologies of Pittsburgh, PA and PowderMetal Technologies of Carlsbad, CA.
7) Where applicable, metal powder molding is always a good candidate to reduce costs and improve performance. One exotic metal powder part won a grand prize from the Metal Powder Industries Federation this year. Superconducting dipole cryomagenets are made by hot isostatically pressing stainless 314LN powder to full density. The parts have the equivalent mechanical properties of wrought stainless. The parts were designed by Bodycote HIP-Surahammar, Sweden and Metso Materials Technology, Oy, Finland.
8) Take a new look at ceramics, which are increasingly high tech. Example: New Ceralese ceramic materials are said to offer superior dielectric strength, thermal stability, strength and hardness compared to materials traditionally used for laser reflector/pump chamber applications.
9) New injection moldable tungsten/plastic compounds replace lead, solving environmental and other problems. Even though tungsten is more costly than lead, new molded shapes can provide a lower total cost. (Listen to a podcast about this approach)
10) Take a new look at thermoplastic composites that replace structural steel parts on cars and other applications. The Chevy Volt concept car shown by General Motors earlier this year uses an innovative composite for the hood and doors.

There’s no question there is a new push to look at innovative materials technologies. An abundance of emerging processes, ranging from nano to hybrid fabricating, are combining with new materials technologies to make these approaches even more attractive. Add in unpredictable and soaring materials costs and the role of design engineering is becoming even more critical.

Listen to the podcast:
Hear GM executive Bo Andersson explain how the auto giant is building design options into new vehicle programs so that substitutions, such as steel for plastic, can be made. Listen Now

The Rising Tide of Metals Prices

Average metals prices for the past two years are as much as three to four times higher than their levels in the previous five years. Rising demand from Asia put a strain on the global supply base, which for the most part had been stagnant due to weak pricing and lack of demand. No relief is in sight, at least in the short term, leading to heightened efforts to switch to less expensive materials and find less-costly manufacturing processes. Here’s a graphical look at the situation. All data comes from the London Metals Exchange.

		GM is using more sheet molding compound in the Pontiac Solstice.
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