SEMS Combination Bolts (Pre-Assembled Screw & Washer Assemblies)
SEMS combination bolts are pre-assembled fasteners with a captive flat washer, spring lock washer, or both permanently attached to the screw. This integrated design eliminates loose washers during assembly, speeds up production line installation, and prevents washer loss in automated feeding systems. Widely used in automotive, electronics, appliance manufacturing, and high-volume assembly operations where efficiency and reliability are critical.
Technical Specifications
| Parameter | Specification |
|---|---|
| Standard | DIN 6902, DIN 6903, ASME B18.13 |
| Thread Type | Metric Coarse / Fine Thread |
| Size Range | M3 – M16 |
| Length Range | 6mm – 150mm |
| Material — Screw | Carbon Steel (Grade 4.8, 8.8, 10.9) |
| Material — Washer | Carbon Steel, Spring Steel, Stainless Steel |
| Washer Type | Flat Washer (FW), Spring Lock Washer (LW), Flat + Spring (FW+LW), Conical/Toothed |
| Head Type | Pan Head, Hex Head, Truss Head, Flat Countersunk |
| Surface Finish | Zinc Plated, Zinc Flake (Geomet), Black Oxide, Nickel Plated |
| MOQ | 5,000 pcs (standard), 20,000 pcs (custom) |
| Lead Time | 10-20 days (standard), 25-35 days (custom) |
| Packaging | Bulk cartons / Inner boxes / Reel packaging for automated feed |
Available Combinations
SEMS Screw + Flat Washer | SEMS Screw + Spring Lock Washer | SEMS Screw + Flat Washer + Spring Lock Washer | Internal Tooth Lock Washer SEMS | External Tooth Lock Washer SEMS
Applications
- Automotive assembly lines and sub-assemblies
- Home appliance manufacturing (washers, dryers, refrigerators)
- Electronics and PCB mounting
- HVAC equipment assembly
- Power tool manufacturing
- Metal furniture and shelving
- Automated robotic assembly systems
Certifications
ISO 9001:2015 certified manufacturing. Material test certificates (EN 10204 3.1/3.2) available. RoHS and REACH compliant. PPAP documentation available for automotive supply.
Frequently Asked Questions
What are SEMS screws and what are their benefits?
SEMS are pre-assembled screw-and-washer combinations: the washer is permanently captured on the screw. Assembly lines save a handling step per joint, and the washer cannot be forgotten or dropped — ideal for high-volume production.
What sizes are available?
Available sizes range from M3 – M16. Contact us with your required sizes and quantities for a quick quote.
What is the MOQ and lead time?
The MOQ is 5,000 pcs (standard), 20,000 pcs (custom). Lead time is 10-20 days (standard), 25-35 days (custom). Mixed-size containers and larger orders are negotiable — send us your requirement for a quick quote.
Do you provide material certificates?
Yes. Material test certificates per EN 10204 3.1 are available on request, and our manufacturing is ISO 9001:2015 certified. RoHS and REACH compliance documentation can also be provided.
