1、 WORLDWIDE FASTENER STANDARD WB 980 Date: 2007-08-01 Printed copies are uncontrolled Copyright 2007, Ford Global Technologies, LLC Page 1 of 2 PAINT CLEARING SCREWS - PERFORMANCE FOREWORD During the November 2005 update, Table 2 and the design variant diagrams were revised. Designation characters we
2、re lined up with ISO convention. Dimension M was included for all variants, dimension Lp (formally X) was aligned with WA 900. Notes were added to clarify the diagram and table requirements. Variant G was added. 1. SCOPE This specification covers the performance requirements of ISO metric screws wit
3、h a paint clearing feature incorporated at the screw point and with physical properties in accordance with WA 950. 1.1 REFERENCES WSK-M64J29-C1-C3-Waterborne electrocoat WSK-M6J160-A1 Primer surfacer, colored, PU modified polyester, medium solid, 165 oC baking temp. WSK-M50J111-A Paint, medium solid
4、 polyester, baking, exterior topcoat. 2. GENERAL Preferred designs of paint clearing feature are shown in Clause 5. Other designs shall only be used if approval is obtained from the Worldwide Fastener Standards Committee prior to their introduction. 3. PERFORMANCE TESTING (Only for initial design ap
5、proval and as a referee test in cases of dispute) 3.1 CROSS THREADING TEST The screw must be initially misaligned with the center-line of the test nut thread by 5 +/- 1 and when assembly is attempted using a 20 +/- 1 N end load the screw must not cross thread. The tendency towards self-alignment mus
6、t not be prevented. 3.2 DRIVE TEST The screw must be driven into the test nut with 20 +/- 1 N axial load until a minimum of 3 full form threads of the test screw protrude through the nut. The torque required to drive the screw (paint clearing torque) must be measured and must not exceed the values s
7、pecified in Table 1. 4. TEST PIECES Test pieces must be ISO metric nuts or tapped holes with a 6H tolerance. Thread length must be 0.6D to 0.8D where D is the nominal diameter of the screw to be tested. The test piece must be grey electrocoated 25 to 30 micrometers thickness in accordance with WSK-M
8、64J29-C1-C3 and baked at 175 C min. followed by primer surfacer 20 to 30 micrometers thickness in accordance with WSK-M6J160-A1 baked at 165 C min., and enamel paint 40 to 50 micrometers thickness in accordance with WSK-M50J111-A baked at 130 C min. Baking time must be 10 minutes minimum, with the m
9、etal at heat, for each process. Thickness must be measured on a flat surface of the test piece. The test pieces must be coated in the horizontal position (See Figure 1). Figure 1 - Axis of the Thread WORLDWIDE FASTENER STANDARD WB 980 Date: 2007-08-01 Printed copies are uncontrolled Copyright 2007,
10、Ford Global Technologies, LLC Page 2 of 2 Table 1 - Paint Clearing Torque Nominal Size M4 M5 M6 M8 M10 M12 M14 Torque, max, Nm 0.6 1.1 1.9 4.3 9.1 15.7 27.0 Table 2 - Dimensions Nominal SizeM Max Lp Dp Min W, min (B only) W min (D only) M4 4 2.0 +/1 0.25 2.38 - 2.5 M5 7.1 2.5 +/- 0.25 3.09 3.4 3.3 M
11、6 8.2 3.0 +/- 0.25 3.68 4.1 3.9 M8 10.5 4.0 +/- 0.30 5.28 5.8 5.5 M10 13.2 5.0 +/- 0.30 6.73 7.5 7.2 M12 14.7 6.0 +/- 0.30 8.40 9.1 - M14 18.2 7.0 +/- 0.40 10.0 9.5 9.3 Dimension M is the maximum permitted protrusion of the paint clearing feature. Dimension Y is at the discretion of the manufacturer to meet the performance of section 3. Variants C and D may be tapered within dimensions M and Dp. 5. DESIGN VARIANTS. For variant F the flutes may be parallel to the axis or at an angle to the axis at the discretion of the manufacturer.
