Gear Materials

Today there is a great variety of materials that are available to a gear designer. The designer can choose from a plethora of choices. Further, there are many ways to modify or process the materials. This improves the properties and side by side helps to minimize the cost of production. Actually the production process also plays a decisive role in the type of Gear Material. For example take the case of Machined gears they are most precise. Now to manufacture them only that materials could be used that show good strength characteristics.

Type of Gear Material
These can be divided into two types:

 

Metallic Gears Cast Iron Gears Steel Gears Aluminium Gears Bronze Gears Brass Gears Ductile Iron Gears

Non Metallic Gears Plastic Gears

 

Selection of Gear Materials:
There are some very critical matters that needs to be given a consideration before selecting a gear material. They are the following:

• Allowable bending and hertz stress
• Wear resistance
• Impact strength
• Water and corrosion resistance
• Manufacturing cost
• Size
• Weight
• Reliability
• Lubrication requirements
• No Moisture Absorption
• Dimensionally Stable
• Stress-Free structure
• Environmental and surface temperature-
• It has been found that if there is friction the surface temperature of the gear shows a tendency to rise.

Die Cast Alloy
The process is capable of producing high-volume low-cost gears. Mostly they are produced in aluminium and zinc alloys, while others in bronze and brass.

Material Quality
As it is well known that material quality has a strong influence on factors like pitting resistance and bending strength. So for getting a high quality material, the following metallurgical variables should be properly controlled.

• Chemical composition
• Hardenability
• Material Toughness
• Hardness of Surface and core
• Micro structure of surface and core
• Cleanliness and inclusions
• Surface defects like flanks and root fillets
• Structure and size of grain
• Residual stress pattern
• Internal defects
• Decarburization