Request for Interpretation for ANSI/AGMA 2001-C95, Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear Teeth
Issued November 29, 2018
(Note that while this RFI was originally submitted for ANSI/AGMA 2001-C95, it still applies to the newer revision, ANSI/AGMA 2001-D04).
Question:
Section 1.2 in ANSI/AGMA 2001-C95, states that the formulas of this standard are not applicable when the following condition exists: “Where root fillets of the gear teeth are produced by a process other than generating.”
Does this mean grinding in root fillets violates this standard? Is using a hob an acceptable way of producing root fillets?
Response from AGMA:
Yes, grinding in the root does violates ANSI/AGMA 2001-C95 since AGMA 908-B89 does not apply to non-generated root fillets. Regarding ground root fillets, AGMA 908-B89 applies to gears produced by generating grinding such as threaded grinding wheels, in which case the grinding process is very similar to hobbing. However, AGMA 908-B89 does not apply to non-generated root fillets such as ground root fillets produced by form grinding. Moreover, grinding root fillets can be very risky, and is best left to gear manufacturers with the necessary expertise to avoid the many potential problems inherent in grinding root fillets.