1、 WORLDWIDE FASTENER STANDARD WD954 2015 03 06 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 material and performance requirements for through ha
2、rdened 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, unlubricated finishes should be specified. For example: S437, S424. 1.1 REFERENCES
3、 ISO 6157-3 Fasteners-Surface Discontinuities 2. MATERIALS Screws shall be made from cold heading quality fully killed, fine grain, spherodized annealed steel wire. The following chemical composition is given for guidance only. Table 1. Chemical Composition - Ladle Material and Treatment Chemical El
4、ement 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 and tempered Carbon Phosphorus Sulfur 0.151) 0.40 0.035 Max 0.035 Max 1)In the case of carbon boron alloyed s
5、teel 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 core hardness of 320-380 HV, (32-39 HRC). The surface hardness shall not be more than 30 Vickers points above t
6、he 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 exceeds 390 HV is not acceptable. The tempering temperature shall be 340C minimum. The requirements of WSS-M99A
7、3-A shall apply. WORLDWIDE FASTENER STANDARD WD954 2015 03 06 Material and Performance Requirements for Screws Used in Thermoplastics Materials Printed copies are uncontrolled Copyright 2015 Ford Global Technologies, Inc. Page 2 of 5 3. MECHANICAL PROPERTIES (cont.) 3.2 HEAD SOUNDNESS There shall be
8、 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 screw. The test shall be regarded as satisfactory even if a crack should appear in the first thread, provided that the head d
9、oes 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 diameter +0.05mm up to and including 5mm dia. and +0.1 for 6mm dia. and above in a hardened wedge block, or other suitable dev
10、ice 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 with respect to a plane normal to the axis of the screw. NOTE: It is normal procedure to induce the 6 deformation by a blow o
11、r blows from a hand held hammer. 3.3 SURFACE INTEGRITY For referee purposes, surface integrity shall be in accordance with WA 990. Acceptability of thread discontinuities not applicable to thread forming threads and lead area. 3.4 TORSIONAL STRENGTH TEST The shank of the sample screw (coated, or unc
12、oated, as received) shall be clamped in a mating, split, blind-hole die (Figure 1) or other means, such that the clamped portion 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 wi
13、thin the clamping device. (A blind hole may be used in place of 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
14、 cause failure shall equal or exceed the minimum value shown in Table 2 for the type and size of screw being tested. Figure 1. Typical Test Device for Torsional Tests WORLDWIDE FASTENER STANDARD WD954 2015 03 06 Material and Performance Requirements for Screws Used in Thermoplastics Materials Printe
15、d copies are uncontrolled Copyright 2015 Ford Global Technologies, Inc. Page 3 of 5 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/RemformII/PT Screws Torque Min. Nm 0.30 0.70 1.10 1.70 2.50 3.40 4.70 7.70 17.00 RemformII “HS”/Delta PTScrews Torqu
16、e min. Nm 0.42 0.9 1.5 2.5 3.7 5.2 7.1 12.8 30.0 4. ADDITIONAL DESIGN DETAIL 4.1 REMFORM, REMFORMII and PTTHREAD FORM Figure 2. rr30Detail “X“Detail “X“pYapYdcdcaREMFORM/REMFORMII Screw Thread PTScrew Thread Table 3 Screw Size (Nominal Dia.) mm 3.0 4.0 5.0 6.0 8.0Tolerance of Nominal Dia +0.10 +0.10
17、 +0.15 +0.15 +0.18Pitch, p 1.35 1.75 2.25 2.65 3.50Thread Runout, a max. 1.50 2.00 2.50 3.00 4.00Radius, r max. 0.50 0.60 0.70 0.80 1.00Minor Diameter, dc min. 1.90 2.55 3.19 3.84 5.12Incomplete Thread Length, y 1-2 Pitch LeadREMFORM/REMFORM II Thread DimensionsTable 4 Screw Size (Nominal Dia.) mm 3
18、.0 4.0 5.0 6.0 8.0Tolerance of Nominal Dia +0.14 +0.18 +0.18 +0.18 +0.22Pitch, p 1.34 1.79 2.24 2.69 3.59Thread Runout, a L3d 3.50 4.60 5.70 6.80 9.10L3d 1.50 2.00 2.50 3.00 4.00Radius, r max. 0.40 0.50 0.60 0.80 1.00Minor Diameter, dc min. 1.70 2.20 2.70 3.20 4.20Incomplete Thread Length, yPT Threa
19、d Dimensions1-2 Pitch LeadWORLDWIDE FASTENER STANDARD WD954 2015 03 06 Material and Performance Requirements for Screws Used in Thermoplastics Materials Printed copies are uncontrolled Copyright 2015 Ford Global Technologies, Inc. Page 4 of 5 4.2 REMFORMII “HS” and DELTA PTTHREAD FORM Figure 3. pYdc
20、Detail “X“pYDetail “X“dcar 3020arREMFORMII “HS” Screw Thread DELTA PTScrew Thread Table 5 REMFORMII “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
21、.00 4.00 Radius, r max. 0.05 0.06 0.07 0.08 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 PTThread 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
22、.80 2.14 2.82 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 NOTES: - Reminc specifies “dc“ as a minimum - Reminc does not have an “a“ requirement - Updates are via EJO
23、T Short WORLDWIDE FASTENER STANDARD WD954 2015 03 06 Material and Performance Requirements for Screws Used in Thermoplastics Materials Printed copies are uncontrolled Copyright 2015 Ford Global Technologies, Inc. Page 5 of 5 5. SUMMARY OF REVISIONS 2015 03 06 Updated Table 2 with Remform II data Add
24、ed Section 4.1 header and references to Remform II 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
