Sems Screws
304 Stainless Steel Black Oxide Sems Screws Button Head Hex Socket Spring Washer Pre Assembled Metric M3 M4 M5 For Electronics-1
What are sems screws?
A sems screw is a screw with a pre‑assembled captive washer. You get one part instead of two. This speeds up assembly and prevents washer loss during maintenance.
Why choose a sems screw?
- Save time – No separate washer handling.
- No lost parts – Washer stays on the screw even when fully loosened.
- Consistent quality – The same washer type on every screw.
Washer types available
- Spring washer – Stops vibration loosening. Ideal for motors, fans, moving machinery.
- Flat washer – Spreads clamping pressure. Perfect for soft materials like plastic or aluminum.
- External tooth lock washer – Teeth bite into the surface. Best for high‑vibration environments.
- Internal tooth lock washer – Teeth grip the screw head. Cleaner appearance, no snagging.
- Double washer – Spring + flat combined. Anti‑vibration + pressure distribution.
Head styles
- Phillips pan head – Most common. Works with any Phillips screwdriver.
- Hex head – Use a wrench or socket. Good for higher torque.
Materials we use
- 304 stainless steel – Corrosion resistant. Ideal for outdoor and wet areas.
- 316 stainless steel – Marine grade. Excellent for saltwater environments.
- Zinc plated carbon steel – Strong and cost‑effective. Good for indoor and light outdoor use.
Sizes & strength
- Metric sizes – M3, M4, M5, M6. Lengths from 6mm to 30mm. Custom sizes on request.
- Strength grades – Class 8.8 (medium‑high), Class 10.9 (higher), Class 12.9 (maximum).
Where are they used?
Electronics assembly, PCB mounting, control panels, industrial equipment, automotive parts, marine enclosures, HVAC units, and general factory assembly.
Quality assurance
Every batch goes through thread gauging and dimensional inspection. ISO 9001 and ISO 10012 certified.
Custom orders
Need a non‑standard size or a special head marking? Send us your drawing or sample. We produce exactly what you need. OEM orders welcome.
Company profile
YH Fastener started in 1998. We make sems screws, self tapping screws, machine screws, shoulder screws, and custom fasteners. Factory direct. Ship to 60+ countries.
- Pre‑assembled washer saves assembly time
- Spring washer for anti‑vibration locking
- External tooth lock washer for high vibration
- Double washer (spring + flat) for demanding jobs
- Phillips pan head and hex head styles
- Stainless steel 304, 316, and zinc plated carbon steel
- Metric M3 to M6, Class 8.8, 10.9, 12.9