ANSI/AGMA 2004-c08 pdf free download.AMERICAN NATIONAL STANDARD Gear Materials, Heat Treatment and Processing Manual.
3.1 Factors in material selection
Many factors must be considered when selecting a gear material, as shown in figure 1.
The specific material selection is often determined by cost and availability factors such as standard industry alloys and procurement time.
For example, standard wrought carbon and alloy SAE steel grades such as 1020, 8620, 4320, 4820, 9310,4140, 4150 and 4340 are available from service centers and steel mills. Service centers can usually furnish these materials in small quantities and with short delivery time from their inventories. Steel mill purchases require mill quantities” and long delivery time. However, the mill quantity cost may be substantially lower, and non-standard steels can be supplied on special request.
When specifying parts with small quantity requirements, standard alloys should be specified or engineering drawings should allow optional materials. Material designations from national or international standards, such as SAE or ASTM, should be used wherever possible.
3.2 Material form
The selection of the basic material form is central to the gear manufacturing process.
Selection of the gear blank producing method for most applications is primarily a matter of economics, with quality becoming increasingly important as tooth loads, down time costs, and safety considerations increase. The gear designer is faced with numerous choices, each with its own advantages and limitations. The choice involves the exploitation of a specific process’ advantage(s) to produce the lowest cost component that meets the performance requirements.
3.2.1 Wrought
Wrought steel is the generic term applied to carbon and alloy steels that are mechanically worked into form for specific applications. The standard wrought steel forms are forgings, round (bar) stock, flat stock, and tubing.
Cast steel ingots may be either bottom poured or top poured. Bottom poured ingots show improved cleanliness and ingot yield (more usable ingot metal after conventional cropping or removal of the top pipe cavity and bottom discard of top poured ingots). Strand casting produces a bloom or billet that is smaller in cross sectional area than an ingot.
Steel manufactured using production methods that improve cleanliness, such as vacuum clegassing and ladle refining, can result in improved transverse ductility and impact strength. Cleanliness for various grades of gearing shall comply with the applicable AGMA standard or AGMA 923-B05.
For additional information on wrought steel manufacture and steel making refining practices, refer to the following sources:
ASM International Handbooks
Iron and Steel Society (ISS), Steel Products Manual.ANSI/AGMA 2004 pdf download.