FORDWORLDWIDEFASTENERSTANDARD

Date:1993-01-01

WD950

APPENDIXA

MaterialandPerformanceRequirementsforCaseHardenedCarbonSteelThreadCuttingScrews-TypeD

1.SCOPE.

ThisappendixcoverstherequirementsforThreadCuttingScrewsnotspecifiedinthebodyofWD950.

UnlessotherwisespecifiedallotherrequirementsofWD950apply.

1.1REFERENCES.

ISO1502-Generalpurposemetricscrewthreads-Gauging.

2.MATERIAL.

Screwsshallbemadefromcoldheadingquality,killedsteelwiresuitableforcasehardening.

3.METALLURGICALREQUIREMENTS.

3.1COREHARDNESS,SURFACEHARDNESSANDMICROSTRUCTURE.Theseshallbe

specifiedinClauses3.1,3.2and3.4ofthespecification.

3.2TOTALCASEDEPTH.Amicrohardnesstestshallbecarriedoutatthethreadflankmid-point

betweencrestandrootor,inthecaseofsmallerscrewsupto(M)4,intherootofthethread.The

casedepthshallbeatthepointwherethehardnessexceedstheactualcorehardnessbyHV25and

shallbeinaccordancewiththefollowing:

ScrewSizeTotalCaseDepth

(M)2and(M)30.05-0.018mm

(M)4and(M)50.1-0.23mm

(M)6andlarger0.15-0.28mm

4.PERFORMANCEREQUIREMENTS.

4.1DRIVETEST.Threadcuttingscrewsshallmeetthesamethreadformingrequirementsasthe

spacedthreadtappingscrewswhentested