3.4.2 Forging Professes Compared With Alternate Processes

The choice between forging and alternate processes is driven by five factors.

Material and structural requirements Applications that require high operating temperatures or corrosion resistance require alloys such as stainless steel, titanium or superalloys. Applications that require materials with very high strength, ductility, impact toughness and fatigue strength usually require steel, high strength aluminum or titanium alloys. In these cases, the manufacturing process must be one that can utilize the required materials. Pressure die casting is excluded because it is used almost exclusively for alloys of aluminum, magnesium and zinc, which have low melting points, moderate corrosion resistance, and moderate mechanical properties.

Production quantities Manufacturing processes that are characterized by low tooling cost generally require extensive machining operations to develop the shape and achieve the required precision. For very low production quantities, "hogouts" made by CNC machining or weldments will be economical because the high cost of machining and processing is offset by minimal tooling cost. As volumes increase, impression die forgings become more cost effective.

Shape capability Some processes, such as evaporative pattern and investment casting, offer almost unlimited capabilities to produce complicated shapes. However, they tend to be less controlled and more labor intensive, and may be more costly than an assembly of parts made by a less labor intensive process. Tensile and shear strengths are often lower or more erratic than those for forgings.

Weight reduction In some applications, such as automotive and aerospace, minimum weight is essential. Processes that can produce components as close as possible to the required shape, eliminate material in non-critical areas, and provide superior mechanical properties, offer a distinct advantage over components that may cost less to produce but weigh more.

Product integrity Forgings are free from internal porosity and exhibit a high degree of integrity. Processes that may be characterized by internal flaws, such as inclusions or porosity, are difficult to justify when safety is a concern. They often require extensive, sometimes 100% inspection, which significantly increases the cost. Furthermore, there are few 100% inspection processes that are 100% effective.

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The choice between forging and alternate processes is driven by five factors.

Material and structural requirements Applications that require high operating temperatures or corrosion resistance require alloys such as stainless steel, titanium or superalloys. Applications that require materials with very high strength, ductility, impact toughness and fatigue strength usually require steel, high strength aluminum or titanium alloys. In these cases, the manufacturing process must be one that can utilize the required materials. Pressure die casting is excluded because it is used almost exclusively for alloys of aluminum, magnesium and zinc, which have low melting points, moderate corrosion resistance, and moderate mechanical properties.

Production quantities Manufacturing processes that are characterized by low tooling cost generally require extensive machining operations to develop the shape and achieve the required precision. For very low production quantities, "hogouts" made by CNC machining or weldments will be economical because the high cost of machining and processing is offset by minimal tooling cost. As volumes increase, impression die forgings become more cost effective.

Shape capability Some processes, such as evaporative pattern and investment casting, offer almost unlimited capabilities to produce complicated shapes. However, they tend to be less controlled and more labor intensive, and may be more costly than an assembly of parts made by a less labor intensive process. Tensile and shear strengths are often lower or more erratic than those for forgings.

Weight reduction In some applications, such as automotive and aerospace, minimum weight is essential. Processes that can produce components as close as possible to the required shape, eliminate material in non-critical areas, and provide superior mechanical properties, offer a distinct advantage over components that may cost less to produce but weigh more.

Product integrity Forgings are free from internal porosity and exhibit a high degree of integrity. Processes that may be characterized by internal flaws, such as inclusions or porosity, are difficult to justify when safety is a concern. They often require extensive, sometimes 100% inspection, which significantly increases the cost. Furthermore, there are few 100% inspection processes that are 100% effective.

Return to Table of Contents

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The choice between forging and alternate processes is driven by five factors.

Material and structural requirements Applications that require high operating temperatures or corrosion resistance require alloys such as stainless steel, titanium or superalloys. Applications that require materials with very high strength, ductility, impact toughness and fatigue strength usually require steel, high strength aluminum or titanium alloys. In these cases, the manufacturing process must be one that can utilize the required materials. Pressure die casting is excluded because it is used almost exclusively for alloys of aluminum, magnesium and zinc, which have low melting points, moderate corrosion resistance, and moderate mechanical properties.

Production quantities Manufacturing processes that are characterized by low tooling cost generally require extensive machining operations to develop the shape and achieve the required precision. For very low production quantities, "hogouts" made by CNC machining or weldments will be economical because the high cost of machining and processing is offset by minimal tooling cost. As volumes increase, impression die forgings become more cost effective.

Shape capability Some processes, such as evaporative pattern and investment casting, offer almost unlimited capabilities to produce complicated shapes. However, they tend to be less controlled and more labor intensive, and may be more costly than an assembly of parts made by a less labor intensive process. Tensile and shear strengths are often lower or more erratic than those for forgings.

Weight reduction In some applications, such as automotive and aerospace, minimum weight is essential. Processes that can produce components as close as possible to the required shape, eliminate material in non-critical areas, and provide superior mechanical properties, offer a distinct advantage over components that may cost less to produce but weigh more.

Product integrity Forgings are free from internal porosity and exhibit a high degree of integrity. Processes that may be characterized by internal flaws, such as inclusions or porosity, are difficult to justify when safety is a concern. They often require extensive, sometimes 100% inspection, which significantly increases the cost. Furthermore, there are few 100% inspection processes that are 100% effective.

Return to Table of Contents

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