1、 WORLDWIDE FASTENER STANDARD WD954 2016 11 02 Dimensional, Material and Performance Requirements for Screws Used in Thermoplastics Materials Printed copies are uncontrolled Copyright 2015 Ford Global Technologies, Inc. Page 1 of 5 1. SCOPE This standard covers dimensional, material and performance r
2、equirements for through hardened carbon steel tapping screws. In normal use, these screws produce mating threads in thermoplastic materials, without deforming their own threads. NOTE: Some lubricants may degrade the mating materials therefore, dry film or integral lubricants should be specified. Exa
3、mples of acceptable finishes include S437, S451 and S450B. 1.1 REFERENCES ISO 6157-1 Fasteners-Surface Discontinuities WSS-M99A3-A Embrittlement Avoidance 2. MATERIALS Screws shall be made from cold heading quality fully killed, fine grain, spherodized annealed steel wire. The following chemical com
4、position is given for guidance only. Table 1. Chemical Composition - Ladle Material and Treatment Chemical Element Composition Limits (% by weight) Carbon steel quenched and tempered Carbon Phosphorus Sulfur 0.20 0.40 0.035 Max 0.035 Max Carbon Steel with additives (e.g. Boron or Mn or Cr) quenched
5、and tempered Carbon Phosphorus Sulfur 0.151) 0.40 0.035 Max 0.035 Max 1) In the case of carbon boron alloyed steel with a carbon content below 0.25% (ladle analysis), the minimum manganese content shall be 0.7%. 3. MECHANICAL PROPERTIES 3.1 HEAT TREATMENT Screws shall be hardened and tempered to a c
6、ore hardness of 320-380 HV, (32-39 HRC). 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. Any increase in hardness at the surface which indicates that the surface hardness e
7、xceeds 390 HV is not acceptable. The tempering temperature shall be 340C minimum. The requirements of WSS-M99A3-A shall apply. WORLDWIDE FASTENER STANDARD WD954 2016 11 02 Dimensional, Material and Performance Requirements for Screws Used in Thermoplastics Materials Printed copies are uncontrolled C
8、opyright 2015 Ford Global Technologies, Inc. Page 2 of 5 3. MECHANICAL PROPERTIES (cont.) 3.2 HEAD SOUNDNESS There shall be no fracture at the head/shank intersection when a permanent deformation of 6 is induced between the plane of the underhead bearing face and a plane normal to the axis of the sc
9、rew. The test shall be regarded as satisfactory even if a crack should appear in the first thread, provided that the head does not snap off. This test does not apply to countersunk head screws. The sample screw shall be inserted into a drilled hole of a diameter equal to the maximum major thread dia
10、meter +0.05mm up to and including 5mm dia. and +0.1 for 6mm dia. and above in a hardened wedge block, or other suitable device and an axial compressive load applied against the top of the screw. Loading shall be continued until the plane of the underhead bearing face is bent permanently through 6 wi
11、th respect to a plane normal to the axis of the screw. NOTE: It is normal procedure to induce the 6 deformation by a blow or blows from a hand held hammer. 3.3 TORSIONAL STRENGTH TEST The shank of the sample screw (coated, or uncoated, as received) shall be clamped in a mating, split, blind-hole die
12、 (Figure 1) or other means, such that the minor or root diameter of the thread is not damaged and at least two full threads project above the clamping device and at least two full form threads exclusive of point and end slot are held within the clamping device. (A blind hole may be used in place of
13、the clamping device, providing the hole depth is such to ensure that breakage will occur beyond the point. By means of a suitable calibrated torque measuring device, apply torque to the screw until failure occurs. The torque required to cause failure shall equal or exceed the minimum value shown in
14、Table 2 for the type and size of screw being tested. Figure 1. Typical Test Device for Torsional Tests Table 2 Shank Torsion by Thread Form Screw Size, mm 2.0 2.5 3.0 (3.5) 4.0 (4.5) 5.0 6.0 8.0 Remform/Remform II/PT Screws Torque min. Nm 0.3 0.7 1.1 1.7 2.5 3.3 4.7 7.7 17.0 Remform II “HS”/Delta PT
15、 Screws Torque min. Nm 0.42 0.9 1.5 2.5 3.7 5.2 7.1 12.8 30.0 WORLDWIDE FASTENER STANDARD WD954 2016 11 02 Dimensional, Material and Performance Requirements for Screws Used in Thermoplastics Materials Printed copies are uncontrolled Copyright 2015 Ford Global Technologies, Inc. Page 3 of 5 4. SURFA
16、CE INTEGRITY For referee purposes, surface integrity shall be in accordance with ISO 6157-1. Acceptability of thread discontinuities not applicable to thread forming threads and lead area. 5. SCREW AND WASHER ASSEMBLIES Washer must be retained and free spinning. The use of an annular ring or shoulde
17、r is permitted at the manufacturers option provided the torsional strength is maintained. If an annular ring or shoulder is used, the outer diameter must be no larger than the diameter of the fastener thread. 6. ADDITIONAL DESIGN DETAIL 6.1 REMFORM, REMFORM II and PT THREAD FORM Figure 2. REMFORM/RE
18、MFORM II Screw Thread PT Screw Thread Table 3 S c r ew S i z e (Nom i na l Di a.) m m 3.0 4.0 5.0 6.0 8.0T ol eranc e o f Nom i na l Di a + 0.1 0 + 0.1 0 + 0.1 5 + 0.1 5 + 0.1 8P i tc h, p 1.35 1.75 2.25 2.65 3.503.00 4.00 5.00 6.00 8.001.50 2.00 2.50 3.00 4.00Radi us , r m ax . 0.50 0.60 0.70 0.80
19、1.00Mi no r Di am ete r , d c m i n. 1.90 2.55 3.19 3.84 5.12Inc om pl ete T hread Le ng th, y 1-2 P i tc h L ea dRE M F O RM /RE M F O RM II T h r ea d Dimen sion sT hread Runo ut, a L 3dm ax . L 3dTable 4 S c r ew S i z e (Nom i na l Di a.) m m 3.0 4.0 5.0 6.0 8.0T ol eranc e o f Nom i na l Di a +
20、 0.1 4 + 0.1 8 + 0.1 8 + 0.1 8 + 0.2 2P i tc h, p 1.34 1.79 2.24 2.69 3.59T hread Runo ut, a L 3d 3.00 4.00 5.00 6.00 8.00L 3d 1.50 2.00 2.50 3.00 4.00Radi us , r m ax . 0.40 0.50 0.60 0.80 1.00Mi no r Di am ete r , d c m i n. 1.60 2.10 2.60 3.10 4.20Inc om pl ete T hread Le ng th, yP T T h r ea d D
21、imen sion s1-2 P i tc h L ea d WORLDWIDE FASTENER STANDARD WD954 2016 11 02 Dimensional, Material and Performance Requirements for Screws Used in Thermoplastics Materials Printed copies are uncontrolled Copyright 2015 Ford Global Technologies, Inc. Page 4 of 5 6.2 REMFORM II “HS” and DELTA PT THREAD
22、 FORM Figure 3. REMFORM II “HS” Screw Thread DELTA PT Screw Thread Table 5 REMFORM II “HS” Thread Dimensions Screw Size (Nominal Dia.) mm 3.0 4.0 5.0 6.0 8.0 Tolerance of Nominal Dia. +0.10 +0.10 +0.15 +0.15 +0.18 Pitch, p 1.12 1.46 1.80 2.14 2.82 Thread Runout, a max. 1.50 2.00 2.50 3.00 4.00 Radiu
23、s, r max. 0.50 0.60 0.70 0.80 1.00 Minor Diameter, dc min. 2.01 2.73 3.43 4.16 5.58 Incomplete Thread Length, y 1 2 Pitch Lead Table 6 DELTA PT Thread Dimensions Screw Size (Nominal Dia.) mm 3.0 4.0 5.0 6.0 8.0 Tolerance of Nominal Dia. +0.10 +0.10 +0.15 +0.15 +0.18 Pitch, p 1.12 1.46 1.80 2.14 2.82
24、 Thread Runout, a max. 1.50 2.00 2.50 3.00 4.00 Radius, r max. 0.50 0.60 0.70 0.80 1.00 Minor Diameter, dc min. 2.01 2.73 3.43 4.16 5.58 Incomplete Thread Length, y 1 2 Pitch Lead WORLDWIDE FASTENER STANDARD WD954 2016 11 02 Dimensional, Material and Performance Requirements for Screws Used in Therm
25、oplastics Materials Printed copies are uncontrolled Copyright 2015 Ford Global Technologies, Inc. Page 5 of 5 7. SUMMARY OF REVISIONS 2016 11 02 Added dimensional to scope Changed reference from 6157-3 to 6157-1 Added Section 5 note for screw and washer assemblies Changed Figure 2 and Figure 3 threa
26、d runout dimension Added thread runout L3d to Table 3 Corrected Table 4 with PT thread runout L3d Corrected Table 4 with PT minor diameter Corrected Table 5 Radius Miscellaneous editorial correction 2015 03 06 Updated Table 2 with Remform II data Added Section 4.1 header and references to Remform II
27、 Added Section 4.2 with Figure 3 and Tables 5 and 6 2012 09 28 Updated Tables 3 and 4 2009 12 08 Para 1 (note) changed S309 to S437 Added para 1.1 References Para 2 added Table 1 Para 3.1 added minimum tempering temperature Added Para 3.3 SURFACE INTEGRITY Table 2 added Remform/PT requirements Para 4 added Remform/PT design details and Tables 3 and 4
