1、 WORLDWIDE FASTENER STANDARD WA 971 Date: 2011 12 23 Copyright 2011, Ford Global Technologies, LLC Page 1 of 5 Dimensions, Material and Physical Properties and Performance Requirements of Through Hardened and Carbon Restored POWERLOKand KLEERLOK Bolts with a Special Crest Configuration 1. SCOPE This
2、 standard covers the dimensions, material and physical properties, and performance requirements of through hardened and carbon restored POWERLOKand KLEERLOK bolts with a special configuration at the crest of the threads which for Ford purposes shall be known as a “CREST INTERFERENCE” thread. As part
3、ial or complete decarburization of the thread or thread form seriously impairs the locking properties of the bolt, this condition is not permitted. Decarburization as permitted by ISO 898/1 is replaced in this standard by a requirement for carbon restoration as detailed in Clause 4.2. NOTE: These bo
4、lts are designed to be used in normal ISO metric threaded holes in the range M6 to M12 inclusive. 1.1 REFERENCE ISO 6157-3 Fasteners-Surface Discontinuities ISO 6507-1 Metallic Materials - Vickers Hardness, Part 1: Test Method ISO 898/1 Mechanical Properties of Fasteners - Part 1: Bolts, Screws and
5、Studs SAE/USCAR-8 Grain Flow Pattern for Bolts and Screws 2. DIMENSIONS The dimensions of the Crest Interference thread shall be as specified in Figure 1 and Table 1 prior to application of a protective coating. Parts already coated shall be checked with the protective coating removed. These parts s
6、hall be inspected and areas of thread damage avoided. Figure 1. See Note 2.3C PITCHa+1“C“ MajorActual3060Form as RolledThread CrestPOWERLOK Thread Form Profile“D“ Major “C“ MajorPOWERLOK KLEERLOKPrinted copies are uncontrolled WORLDWIDE FASTENER STANDARD WA 971 Date: 2011 12 23 Copyright 2011, Ford
7、Global Technologies, LLC Page 2 of 5 Printed copies are uncontrolled Table 1. Bolt Diameter and Pitch Nominal 1)C MajorD MajorPitch Diameter Cp Point Max. a 6.30 6.10 0.189 (M)6 x 1.00 6.15 5.95 6.00 0.100 8.35 8.10 0.227 (M)8 x 1.25 8.20 7.95 8.00 0.100 10.40 10.10 0.274 (M)10 x 1.50 10.25 9.95 10.
8、00 0.180 12.45 12.10 0.300 (M)12 x 1.75 12.30 11.95 The bolt pitch diameter measured atthe “C” lobes has dimensions that are Max. C = 4h max Min. C = 6g min. in accordance with ISO 965/3 12.00 0.230 1) NOTE: Although the designations for these bolts are M6, M8, etc., the thread form dimensions vary
9、from ISO metric threads. 2.1 Point Taper POWERLOK point tapered threads may be sharp crested or underfilled at the discretion of the manufacturer. KLEERLOK tapered lead threads as per shown in Fig. 1. 2.2 Method of Measurement The method of measuring the dimensions is at the discretion of the manufa
10、cturer but for referee purposes a direct measurement system shall be used. Tri-Roll gauges are necessary for the direct measurement of pitch diameter. 2.3 Minor Diameter Minor diameter must not interfere with 6H nut minor diameter. 3. MATERIALS Screws shall be made from cold heading quality fully ki
11、lled, fine grain, spherodized annealed steel wire. Material shall meet the chemical composition limits for PC10.9 per ISO 898 Part 1. 4. MECHANICAL PROPERTIES 4.1 BREAKING FORCE NOTE: POWERLOKand KLEERLOK screws have reduced tensile breaking loads as compared to ISO 898/1 due to reduced cross sectio
12、nal areas. See table 2 below. When tensile tested under wedge loading in line with ISO 898/1, the performance requirements identified in Table 2 must be met. Table 2. Size kN min. (M)6 x 1.00 19 (M)8 x 1.25 34 (M)10 x 1.50 55 (M)12 x 1.75 80 WORLDWIDE FASTENER STANDARD WA 971 Date: 2011 12 23 Copyri
13、ght 2011, Ford Global Technologies, LLC Page 3 of 5 Printed copies are uncontrolled Fracture shall occur in the threaded area, except for bolts with special heads which are weaker than the threaded section. The above requirements apply to head diameters up to 1.7d. For products with head diameter ab
14、ove 1.7d, the head may be machined to 1.7d prior to test. For products too short for tensile testing, a 6 head soundness test in accordance with ISO 898/1 will apply. 4.2 DECARBURIZATION During the hardening process the carbon potential of the atmosphere shall be maintained at a level slightly in ex
15、cess of the carbon content of the screws being processed. This process of carbon restoration is designed to eliminate partial and total decarburization of the bolt thread form. Partial or complete decarburization of the bolt thread form would seriously impair the locking properties of the bolt. Carb
16、on enrichment up to 0.1mm maximum from the surface of the bolt is permitted as a result of the carbon restoration process when tested in accordance with Clause 5.4. 4.3 SURFACE HARDNESS The minimum tempering temperatures specified in ISO 898/1 shall apply (See Table 1). When tested in accordance wit
17、h Clause 5.5, the surface hardness shall not be more than 30 Vickers points above the measured core hardness on the product when readings of both surface and core are carried out at HV 0.3. 4.4 CORE HARDNESS HV 320 380 The core hardness shall be determined at the mid-radial position on a cross secti
18、on taken at a distance equal to the screw nominal diameter from the threaded end. 4.5 GRAIN FLOW Grain flow shall be verified in accordance with SAE/USCAR-8. This verification should be conducted at job setup, or whenever tooling or raw material changes are made that affect grain flow. The sample si
19、ze and frequency should be identified in the manufacturers Control Plan. All records, test specimens or photographs for this requirement shall conform to QS9000 record retention requirements. 4.6 SURFACE INTEGRITY Acceptability of thread discontinuities per ISO 6157-3, except not applicable to taper
20、ed threads in lead area. WORLDWIDE FASTENER STANDARD WA 971 Date: 2011 12 23 Copyright 2011, Ford Global Technologies, LLC Page 4 of 5 Printed copies are uncontrolled 5. TEST METHODS Performance shall be accessed on parts as received by Ford. 5.1 DRIVEABILITY TEST The sample bolt shall be driven int
21、o a test plate (see Clause 5.3) until a minimum of one pitch of the bolt, excluding the tapered lead threads, extends beyond the test plate. For referee purposes the speed of driving shall not exceed 30 r.p.m. The maximum torque value occurring during this test shall be regarded as the drive torque
22、and shall not exceed the figures specified in Table 3. Table 3. Size Drive Torque Max. Nm 1stPrevailing Off Torque Min Nm (M)6 4 0.45 (M)8 10 0.90 (M)10 14 1.80 (M)12 25 2.60 5.2 PREVAILING OFF TORQUE TEST The sample bolt, after conducting the drive test per clause 5.1, shall be tested for the minim
23、um prevailing off torque. For referee purposes the speed of driving shall not exceed 30 r.p.m. The maximum torque value occurring during the first 360 degrees of removal in this test shall be regarded as the 1stprevailing off torque and shall not be less than figures specified in Table 3. These valu
24、es are applicable to finishes with an approximate 0.15 coefficient of friction. Finishes that may result in the bolt not meeting these torque values should have applicable torque values specified on the release drawing. 5.3 TEST PLATE The test plate shall be low carbon rolled steel having hardness o
25、f 115 to 150 HV30. Plate thickness shall be equivalent to the nominal bolt diameter. The hole shall have an appropriate ISO metric thread with a 6H tolerance. The test plate shall be clean and dry. 5.4 DECARBURIZATION Longitudinal sections shall be taken through the thread axis approximately on nomi
26、nal diameter from the end of the bolt. The specimen shall be suitable mounted and prepared for metallographic examination at not less than 100% magnification. Prior to examination, the sample shall be etched in 2% Nital solution. WORLDWIDE FASTENER STANDARD WA 971 Date: 2011 12 23 Copyright 2011, Fo
27、rd Global Technologies, LLC Page 5 of 5 Printed copies are uncontrolled 5.5 SURFACE HARDNESS TEST The surface hardness shall be measured using the Vickers Hardness Testing Procedure in accordance with ISO 6507. The surface hardness shall be performed on the head after removal of any finish and suita
28、ble preparation (1200 grit grinding or better). Care should be taken to remove as little material as possible. For referee purposes, a micro-hardness instrument with a Vickers indenter and a 300g load shall be used. In such cases, measurements shall be made on the thread profile of a suitably prepar
29、ed longitudinal metallographic specimen. 6. SUMMARY OF REVISIONS 2011 12 23 Added KLEERLOK to description, deleted minor diameter in Fig. 1 and replaced with “See note 2.3”, added POWERLOK and KLEERLOK drawings to Fig. 1. In Table 1, replaced C Minor with Cp Point Max. and revised the dimensions. Revised note 2.1 and added note 2.3. Added KLEERLOK to notes 1 and 4.1 and deleted 6 from note 4.1. 2010 07 20 Clause 3 deleted minimum tempering temperature 2009 12 08 Completely revised.
