Industrial Casting Applications

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Castings can range in size from a few grams to several tones, shape complexity from simple to intricate and order size one-off to mass production.
The desired dimensional accuracy and surface finish can be achieved by the choice of process and its control. Castings enable many pieces to be combined into a single part, eliminating assembly and inventory and reducing costs by 50% or more compared to machined parts.

Castings can range in size from a few grams (for example, watch case) to several tones (marine diesel engines), shape complexity from simple (manhole cover) to intricate (6-cylinder engine block) and order size one-off (paper mill crusher) to mass production (automobile pistons).

The desired dimensional accuracy and surface finish can be achieved by the choice of process and its control. Castings enable many pieces to be combined into a single part, eliminating assembly and inventory and reducing costs by 50% or more compared to machined parts. Unlike plastics, castings can be efficiently and completely recycled.

Today, castings are used in virtually all walks of life. The following is a partial list of applications, with transport sector and heavy equipment taking up over 50% of castings produced:

  • Transport: automobile, aerospace, railways and shipping
  • Heavy equipment: construction, farming and mining
  • Machine tools: machining, casting, plastics moulding, forging, extrusion and forming
  • Plant machinery: chemical, petroleum, paper, sugar, textile, steel and thermal plants
  • Defense: vehicles, artillery, munitions, storage and supporting equipment
  • Electrical machines: motors, generators, pumps and compressors
  • Municipal castings: pipes, joints, valves and fittings
  • Household: appliances, kitchen and gardening equipment, furniture and fittings
  • Art objects: sculptures, idols, furniture, lamp stands and decorative items.



Figure 1: Metal Casting

Virtually any metal or alloy that can be melted can be cast. The most common ferrous metals include grey iron, ductile iron, malleable iron and steel. Alloys of iron and steel are used for high performance applications, such as temperature, wear and corrosion resistance. Table 1 lists the major metals in use today (by weight) along with their main characteristics and typical applications.

Table 1: The most used metals, characteristics and applications

Metal Use Characteristics Applications
Grey
Iron
54% Heat resistance, damping, low cost,
high fluidity, low shrinkage
Automobile cylinder block, clutch plate,
brake drum, machine tool beds, housings
Ductile
Iron
20% Strength, wear and shock resistance,
dimensional stability, machinability
Crank shafts, cam shafts, differential
housing, valves, brackets, rollers
Steel 9% Strength, machinability, weldability Machine parts, gears, valves

Metal Casting Applications in the United States

The United States are the world leader in the use of rapid prototyping processes (RP) for metal casting applications. Metal casting from RP patterns is widely used by government and industry, cross-cutting numerous markets, including those for automotive, aerospace, medical, and consumer products. The use of RP patterns for investment casting continues to increase as processes evolve and pattern quality improves.

There is already a significant number of U.S. companies applying RP to metal casting, as Table 2 shows. 3D Systems' stereolithography (SL) process is often used to fabricate patterns for investment casting. The QuickCast build style, coupled with CibaTool and other epoxy resins, is now used by many U.S. companies to fabricate complex patterns quickly for investment casting of metal parts.

Table 2: U.S. Rapid Prototyping Manufacturers' Applications for Metal Casting

Rapid Prototyping Process Metal Casting Application
3D Systems Stereolithography QuickCast patterns for investment casting. Epoxy patterns for precision sand casting and soft tooling.
DTM Selective Laser Sintering Investment casting wax, polycarbonate and TrueForm patterns for investment casting. TrueForm, composite nylon, polycarbonate for precision sand casting and soft tooling. Rapid Tool for hard tooling investment casting patterns.
Stratasys Fused Deposition Modeling Wax patterns for investment casting.
Helisys Laminated Object Manufacturing Laminated paper master patterns for send casting, limited use for investment casting.
Soligen Direct Shell Production Casting Ceramic investment casting mold fabricated directly from CAD solid model.
Cubital Solid Ground Curing Patterns for flask mold casting; process for fabricating wax investment casting patterns under development.
BPM Ballistic Particle Manufacturing Wax patterns for investment casting.
Sanders Model-Maker 3D Plotting Wax patterns for investment casting.

Metal Casting Applications in Europe

In Europe the use of RP for investment casting is limited but increasing. As the use of Computer-Aided Design (CAD) solid modeling increases, the application of rapid prototyping for manufacturing metal investment castings will also increase. Table 3 summarizes some German-manufactured rapid prototyping systems.

Table 3: German Rapid Prototyping Manufacturers' Applications for Metal Casting

Rapid Prototyping Process Metal Casting Application
Electro Optical Systems (EOS) Stereos Laser Stereolithography Investment casting patterns fabricated using Skin&Core software and Allied Signal Exactomer resin.
EOSINT P Laser Sintering Investment casting patterns fabricated using polystyrene material developed jointly with the University of Stuttgart IKP.
EOSINT S Laser Sintering Sand Casting molds and cores fabricated directly from CAD solid model using polymer-coated green sand.

Dassault Aviation (France) is a frequent user of RP patterns for investment casting. In the same manner as many U.S. companies, Dassault designs and manufactures complex metal castings using 3D Systems' QuickCast build style to fabricate patterns. Dassault engineers have worked with several foundries to develop process parameters for successfully casting RP patterns. Dassault has certified RP castings for use in testing prototype flight hardware. In addition, some German companies use the expertise of Dassault to get metal castings from RP patterns.

The European automotive industry has also had success using RP castings. Typically, a company sends a CAD solid model of the design to the United States for pattern fabrication, a U.S. foundry does the casting, and the part is delivered back to the company.

Metal Casting Applications in Japan

As in Germany, the use of CAD solid modeling in Japan is lower than in the US. Again, as the enabling technology for rapid prototyping machines, a CAD solid model must be created before a part can be fabricated.

The use of two-dimensional CAD is very common in Japan. Often a 2D CAD file is translated to a 3D CAD solid model, then fabricated on an RP machine, but the extra step of creating the solid model increases the cost of the RP part.

In Japan, rapid prototyping competes with machining for producing prototype parts. In many cases, even complex geometries can be machined as fast as parts can be fabricated using RP. There are hundreds of small machine shops in Japan, and the competition for work makes machining an attractive alternative to RP. Another reason RP competes with machining is the lower accuracy and surface roughness limitations of RP parts.

As the use of CAD solid modeling increases, the use and application of RP is expected to increase. This was evident by the use and application of RP in some of the small progressive companies that the JTEC/WTEC panel visited. Table 4 summarizes some of the RP systems in use in Japan.

Table 4: German Rapid Prototyping Manufacturers' Applications for Metal Casting

Rapid Prototyping Process Metal Casting Application
CMET Solid Object Ultra-violet Laser Plotter (SOUP) Epoxy investment casting patterns fabricated using proprietary software that generates triangle or rectangle hatches to build quasi-hollow patterns. This process is also used to fabricate solid patterns for sand casting.
Design Model Engineering Center (DMEC) Solid Creator Investment casting patterns fabricated in Sony process using JSR polyurethane acrylic resin.
Teijin Seiki Soliform Solid Forming System Teijin Seiki is working with DuPont to develop a new resin (SOMOS 4100) for use in fabricating patterns for investment casting.
Kira Solid Center/Selective Adhesive and Hot Press Process (SAHP) Laminated paper patterns for sand casting.
Meiko Plaster casting patterns for Japanese jewelry industry using a relatively low-accuracy photo-resin system. Process is used to fill void from lack of skilled craftsmen to make patterns.
Denken (There was no mention of use of Denken’s process for metal casting applications)

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