ISO 2702 Mechanical Properties of Tapping Screws
ISO 2702 specifies the mechanical and physical properties of heat-treated steel tapping screws, with requirements intended to ensure reliable performance during installation. The standard addresses key characteristics such as surface hardness, core hardness, and torsional strength, which are important for resisting wear and preventing screw failure when forming or engaging threads in the workpiece. These requirements vary according to screw dimensions and the applicable specification.
The standard provides a basis for evaluating the quality and performance of steel tapping screws used in applications involving sheet metal, plastics, and other suitable materials. By controlling hardness and torsional performance, ISO 2702 helps manufacturers maintain consistent product quality and provides buyers with defined criteria for inspection and acceptance.
Mechanical Property:
ISO 2702 specifies the mechanical and physical requirements for heat-treated steel tapping screws, including hardness, case hardening depth, and torsional strength. Testing requirements also define the applicable test plate thickness and hole diameter for evaluating screw performance. The required values depend on the nominal screw diameter and the relevant test conditions. The following table summarizes the key requirements specified in ISO 2702.
| Thread | ST2.2 | ST2.6 | ST2.9 | ST3.3 | ST3.5 | ST3.9 | ST 4.2 | ST 4.8 | ST 5.5 | ST 6.3 | ST 8 | ST 9.5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Surface Hardness(min) | 450 HV0.3 | 450 HV0.3 | 450 HV0.3 | 450 HV0.3 | 450 HV0.3 | 450 HV0.3 | 450 HV0.3 | 450 HV0.3 | 450 HV0.3 | 450 HV0.3 | 450 HV0.3 | 450 HV0.3 |
| Core Hardness Depth(min) | 0.04 | 0.04 | 0.05 | 0.05 | 0.05 | 0.1 | 0.1 | 0.1 | 0.1 | 0.15 | 0.15 | 0.15 |
| Core Hardness Depth(max) | 0.1 | 0.1 | 0.18 | 0.18 | 0.18 | 0.23 | 0.23 | 0.23 | 0.23 | 0.28 | 0.28 | 0.28 |
| Core Hardness | 270 HV5~370 HV5 | 270 HV5~370 HV5 | 270 HV5~370 HV5 | 270 HV5~370 HV5 | 270 HV5~370 HV5 | 270 HV5~370 HV5 | 270 HV10~370 HV10 | 270 HV10~370 HV10 | 270 HV10~370 HV10 | 270 HV10~370 HV10 | 270 HV10~370 HV10 | 270 HV10~370 HV10 |
| Test Plate Thickness(min) | 1.17 | 1.17 | 1.17 | 1.17 | 1.85 | 1.85 | 1.85 | 3.1 | 3.1 | 4.67 | 4.67 | 4.67 |
| Test Plate Thickness(max) | 1.3 | 1.3 | 1.3 | 1.3 | 2.06 | 2.06 | 2.06 | 3.23 | 3.23 | 5.05 | 5.05 | 5.05 |
| Test Hole Diameter(min) | 1.905 | 2.185 | 2.415 | 2.68 | 2.92 | 3.24 | 3.43 | 4.015 | 4.735 | 5.475 | 6.885 | 8.27 |
| Test Hole Diameter(max) | 1.955 | 2.235 | 2.465 | 2.73 | 2.97 | 3.29 | 3.48 | 4.065 | 4.785 | 5.525 | 6.935 | 8.33 |
| Minimum Torsional Strength | 0.45 | 0.9 | 1.5 | 2 | 2.7 | 3.4 | 4.4 | 6.3 | 10 | 13.6 | 30.5 | 68 |
