Demand may be down, but not for long. A series of notable designs illustrate the advantages of a time-tested process.

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Investment casting, which has existed for thousands of years as the "lost wax" process, became a force in the industry during the Korean War. At that time, the Department of Defense launched a variety of initiatives, primarily to support gas-turbine jet engine development. As the process matured, it extended its contribution into land-based gas turbines, sporting goods, automotive, and general industrial applications. Today, global sales of investment castings are in the annual range of $6.5 billion.

Notwithstanding the current economic conditions, the outlook for investment casting is positive. Investment castings have increased sales almost every year in the past 50 years. However, many factors have combined to ensure there will be a decrease in sales in 2002: the 9/11 aftereffects, the commercial aviation down-cycle, the Enron factor, MidEast tension, economic uncertainty, etc. In addition to the economic and geopolitical factors that impact all industries, investment casters also face increased global competition and the need to adapt to rapid technological change.

Market watch

A quick look over the major markets served by investment casting underscores why the outlook is positive. Population is increasing, and the global demand for air travel will reassert itself soon, as will the demand for more electrical power. Other industries - medical, automotive, recreational and general industrial - will also increase as populations grow and consumers demand better and more affordable products. Let's take a look at how these individual market segments are faring right now.

In aerospace, 2001 was one of the strongest years in history. However, 2002 will not be as healthy, as the cycle for building new commercial aircraft of 50 or more seats has peaked and commercial air travel is adjusting to the threat of terrorism. Last year also was extremely strong for industrial gas turbines (IGT) that serve the power-gen market. New installations kept the market booming through most of 2001. However, like aerospace, IGT casting activity began tapering off sharply in 2002 due to the above-mentioned factors.

In automotive the signs are pointing up. The investment casting industry is now routinely supplying components as large as eight- cylinder aluminum engine blocks for high-performance Formula 1 racing cars, and sophisticated valve train components such as valve- train levers and titanium valves. Where competitive performance is critical, automotive design engineers are showing an increased preference for investment castings.

The medical segment is a bright spot for investment castings, particularly in North America and Europe. Prosthetic devices for knees, hips, and other applications are being ordered in increasing quantities. This segment is expected to grow for years to come, as North America's "baby boomers" age and seek to take advantage of advances in medical technology related to joint replacement.

In summary, while two large segments of the investment casting industry are slowing, two relatively smaller segments are exhibiting growth. At some point in the future all four of these segments will be in a growth mode at the same time and the demand for investment castings will resume its steady upward trajectory.

All winners

Despite the temporary difficulties outlined above, we expect the long-term growth of investment casting to continue because of the number of benefits available by utilizing the process. The seven finalists in the Investment Casting Institute's 2002 Casting Contest exemplify these benefits. One look at these seven castings offers a glimpse of the range of benefits the process offers. Here, a single benefit of each of the finalists will be presented here, but most of the full range of benefits the process offers were delivered for each of the casting buyers in the examples below.

Reduce Costs. A manufacturer of a high-speed medical centrifuge was frustrated by the need to find a low-cost way to produce a critical mounting bracket. An attempt to produce the part as a weldment failed and the hog-out under consideration was prohibitively expensive.

However, for the investment casting process to be selected it would have to meet a stringent straightness requirement. Flatness had to be held to within 0.020 TIR and the two upright arms (Figure 1) had to remain parallel to within 0.020 inches. Vestshell Inc., which has operations in Montreal and St. Albans, VT, met these requirements by casting the 17- X 14- X 5-inch part using 304L stainless steel. This success "significandy" reduced component production cost compared to a hog-out.

Although cost reduction benefits vary depending upon the part under evaluation, typically, by converting a hog-out to a casting, it is possible to cut costs in the range of 20% to 50%, sometimes more.

Eliminate Assembly. An airframe manufacturer was burdened by a 50- - hour assembly requirement for a rudder assembly. Previously, this 36- X 24- X 14-inch component (Figure 2) was produced from three aluminum castings, sheet metal assemblies, aluminum hogouts, and related aircraft fastening hardware.

Now the part is cast as a single piece from A 357 and exhibits mechanical properties of 41,000 T, 31,000 Y 2.5% E. In addition to eliminating assembly, this unitized casting streamlines procurement, inspection, and administrative costs to a single part number, rather than the multitude of part numbers required by the previous assembly. The ability to consolidate multiple detail parts into a single casting is one of the chief attractions to design engineers.

This component was manufactured by Howmet Bethlehem Casting, in Bethlehem, PA.

Improve Performance. Automotive manufacturers are struggling to find better ways to improve the performance of their vehicles. Reducing fuel consumption and emissions are two areas of perennial concern. The flexibility of the investment casting process helped make possible the production of a fully variable valve train for an automotive engine. Cast by Hitchiner Manufacturing Co., in Milford, NH, these levers are located between the camshaft and the inlet valves. They convert the movement of the cams into a lesser or greater valve stroke, providing a reduction in fuel consumption between six and 16%. In addition, the design also improves emission performance.

The ability of the investment casting process to pour virtually any alloy facilitates the change to a more desired alloy, in this case 30CrMov9.

As-Cast Finishes. The centerpiece of the torch that athletes carried across the country prior to the 2002 Winter Olympics is an investment casting (Figure 4) produced by SeaCast Inc., which has operations in Seattle and Marysville, WA.

The casting is the primary structural component and is noteworthy for its consistent surface finish. The process provided excellent control of dimensions and eliminated the need for machining. It also permitted easy assembly by mating perfectly with the torch's glass top and chrome-plated plastic handle.

This A356 aluminum casting met customer demand for light weight, good looks, and speedy delivery. The casting was able to satisfy customer requirements for tight dimensional tolerances, excellent surface finish, and superior definition on the lettering, logo, and other details.

Cast-In Features. Ruger Investment Casting, Phoenix, wanted to produce a framing hammer (Figure 5) that would meet demand for a lightweight, fatigue-- reducing tool with improved striking velocity. The alloy choice of titanium and the design features moved Ruger and its design partner Stilletto Tools in the direction of an investment casting.

Cast-in features include a "skeletonized" head and handle, as well as logo, website address and safety warning. The hammer is 17- X 6.5- X 1.5-- inches. It is manufactured from ASTM B367 grade 5 titanium alloy with a removable ASM 8640 low alloy steel striking face.

Shorten Lead Time. Depending on the situation, converting a fabricated assembly to a casting can cut lead time anywhere from 20 to 80%. Practicing what it preaches, Tech Cast Inc., of Myerstown, PA, applied the benefits of investment casting in its own shell room. The tree coupler (Figure 6) this caster's in-house designers produced allows quick attachment of a wax assembly to the handle of the shell-building robot. The new coupling device has slashed the time it takes to attach wax trees to handles by an average of 53%, which translates into a monthly labor saving for Tech Cast of $2,235.

Simplified Manufacturing. The transition duct bracket plate (Figure 7) is an ideal part to conclude the argument that the investment casting process will continue to expand its application throughout industry. The customer, a producer of industrial gas turbines, was able to convert a component that previously required several metalworking processes, including welding. The investment casting designed by Triumph Precision Castings Co., Chandler, AZ, delivered a savings of approximately 140% to the customer, compared to the previous production approach.

Freedom first

Design engineers are turning to investment castings for a variety of reasons, first among them expanded design freedom. The investment casting process gives \engineers significantly greater design flexibility. For example, engineers can design components with thin- and thick-walled sections in the same component, as well as serpentine passageways for liquids or gases. In addition they can design parts in near-net shapes and with sculpted surfaces.

Moreover, investment castings can deliver extremely high alloy properties. This capability opens the door for designers to use a variety of alloys in applications, such as airframe structures, where castings have never been used before. Also, investment castings can be produced in large shapes with asymmetrical geometries. Lastly, castings can consolidate dozens, sometimes scores, of detail parts, reducing procurement, raw material, part count, machining, assembly, and administrative requirements.

These characteristics of the investment casting process enhance design freedom, improve product performance and cut cycle time, cost, and a host of nonvalue-added tasks.

Why design engineers like investment castings

Complex shapes:

Components can be manufactured with intricate geometries

Large shapes:

Six-foot long castings are being routinely produced

Near-net shapes:

Minimize raw material and finishing requirements

Asymmetrical designs:

Significantly reduces machining and assembly

Cast-in features:

Contribute to product performance and manufacturability

Parts consolidation:

Streamlines part count and program administrative chores

Multi-wall configurations:

Increases options, puts thin and thick walls in same piece

Cored passageways:

Improves flow of liquids or gases in countless products

As-cast features:

Enhances component value and speeds machine setup

Sculpted surfaces:

Better aesthetics, reduced finishing tasks, faster production

Uses any alloy:

Material selection is optimized due to almost no restrictions

Michael C. Perry, Executive Director, Investment Casting Institute

Michael C. Perry is executive director of the Investment Casting Institute. Contact him at Investment Casting Institute, 136 Summit Avenue, Montvale, NJ. Tel. 201-573-- 9770. Or, e-mail him at mperry@ investmentcasting.org