约翰迪尔公司JDV21X1标准

Issued: 2005-09-21

Revised: Term Code: Design Control: DT Page 1 of 2 Supersedes:

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JDV 21X1

APPROVED FOR SUPPLIER DISTRIBUTION Annex X1: Neutral Axis Hardness Evaluation of Case

Hardened Gears

1 Scope

JDV 21X1 describes a test procedure for determining neutral axis hardness on gear teeth. It also

provides a method to evaluate the subsurface quench response.

2 Procedure

2.1 Prepare a specimen as shown in Figure 1 with parallel sides. Sand or grind both sides to a 50 grit

minimum finish to facilitate accurate hardness testing. The specimen must be large enough to clearly

identify the root diameter.

Figure 1 Specimen for Gear Neutral Axis Hardness Evaluation

2.2 Draw a line (AB in Figure 1) to locate the approximate location of the root diameter.

2.3 Draw a line (CE in Figure 1) perpendicular to line AB through the centerline of the tooth.

2.4 Perform a Rockwell C (HRC) hardness test (or equivalent) at the intersection of lines AB & CE

(Point D in Figure 1), which is defined as the “core at root hardness ”.

JDV 21X1 APPROVED FOR SUPPLIER DISTRIBUTION 2.5 Perform a series of HRC hardness tests (or equivalent) at 1.5 mm intervals measured from core at root toward the tooth tip. Also test two positions below core at root location at the same interval. The first position below core at root is defined as “core critical hardness”

2.6 Record all hardness measurements and circle the core at root measurement. The format of reporting shall be:

HRC 56–52–47–43–40–(37)–34–30

The first reading is nearest the tooth tip and the reading identified “()” is the core at root. Other hardness tests such as Vickers (HV) may be used for reporting data.

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