Complete Guide for Press-In Nut: Selection, Plate Matching, Installation Process & Failure Troubleshooting

Complete Guide for Press-In Nut: Selection, Plate Matching, Installation Process & Failure Troubleshooting

Press-in nuts are internal thread fasteners specially for thin sheet metal, no welding required and flat back surface, widely used in chassis, new energy battery packs, photovoltaic inverters and medical equipment. yamaoluomu supplies full range S carbon steel, CLS stainless steel, SP ferritic stainless steel, CLA aluminum & copper press nuts. This guide complies with ISO14579 and GB/T17880 standards.

1. Four Series Material & Application Classification

• S Series Carbon Steel: High tensile strength, for cold rolled steel sheets, indoor electrical cabinets with zinc plating;
• CLS Stainless Steel (304/316): Excellent salt spray resistance, for aluminum, copper, outdoor PV & medical devices;
• SP Ferritic Stainless Steel: High hardness, matched with 304/316 stainless thin plates;
• CLA Aluminum/Brass: Lightweight & conductive, for lightweight electrical grounding parts.

Model Code Example: CLS-M4-2 ZI CLS=304 stainless steel; M4=thread size; 2=min plate thickness 1.5mm; ZI=zinc passivation finish.

2. Sheet Metal Matching Standard: Hole Size, Plate Thickness & Minimum Edge Distance

Standard pre-hole & edge distance for metric nuts (mm): M2: hole 4.0, min thickness 0.8~1.0, min edge 3.2 M2.5: hole 4.3, min thickness 1.0~1.2, min edge 3.6 M3: hole 4.3, min thickness 1.2~1.5, min edge 4.0 M4: hole 5.4, min thickness 1.5~2.0, min edge 4.8 M5: hole 6.4, min thickness 2.0~2.5, min edge 5.5 M6: hole 7.8, min thickness 2.5~3.0, min edge 6.5

Design rules: Punch raw hole without deburring; keep enough distance from hole to edge; avoid over-hard stainless sheets with carbon steel nuts.

3. Standard Press Riveting Process

1. Punch standard raw holes, clean metal debris;
2. Place nut through sheet with knurl side down on lower mold;
3. Apply uniform vertical pressure by hydraulic/servo riveting machine, no hammer impact;
4. Inspect flat surface, torsion & pull-out force after pressing.

4. Common Failures & Solutions

4.1 Nut rotating / low torsion resistance

Causes: Oversize hole, hard plate, insufficient pressure. Solution: Reduce hole diameter, soften sheet, increase riveting force.

4.2 Sheet cracking near hole edge

Causes: Insufficient edge distance, thin plate, over pressure. Solution: Enlarge edge margin, select smaller nut, slow pressing.

4.3 Thread slipping

Causes: Thread damage, nut deformation during pressing. Solution: Inspect thread gauges, control riveting stroke.

4.4 Rust under outdoor environment

Solution: Replace S carbon steel with CLS 316 stainless press nuts for coastal & outdoor projects.

5. Special Selection for EV Battery Pack

CLS-M4/M5 304 stainless black passivation for 2.0~3.0mm 6061 aluminum shell, salt spray ≥720h, anti-loosening under vibration, non-magnetic, RoHS compliant for new energy vehicles.

6. Service Advantages of yamaoluomu

Full stock of metric & imperial press nuts M2-M12; custom blind sealed & thin press nuts available; provide riveting parameter drawings, torsion & pull-out test reports; professional process support for PV, EV, medical & communication mass production.