Sems Screws
Phillips Pan Head Sems Machine Screws Double Washer Flat And Spring Metric M3 M4 M5 For PCB Mounting
Sems screws are different from regular screws because they already have a washer on them. You pick up one part instead of two. This makes assembly faster and you never lose the washer.
How They Work
The washer sits right under the screw head. It spins freely but stays on the screw. When you drive the screw in, the washer is already where it needs to be.
What Kind of Washers Do We Offer
Spring washer It flexes under pressure and keeps the screw from backing out. Good for machines that shake or vibrate.
Flat washer It spreads the force over a larger area. Good for soft materials like plastic or thin aluminum where you do not want to dent the surface.
External tooth lock washer The teeth dig into the work surface. Stops rotation even under heavy vibration.
Internal tooth lock washer The teeth grip the screw head. Looks cleaner on the outside because nothing sticks out.
Double washer Spring plus flat together. Gives you both anti vibration and pressure distribution.
Head Shapes
Phillips pan head is the standard choice. Works with any Phillips screwdriver. The flat underside presses down evenly.
Hex head needs a wrench or socket. You can get more torque than a screwdriver. Good for tight spaces where you need a strong clamp.
Materials, Sizes & Strength
Materials We Use:
304 stainless steel. Does not rust. Good for outdoor use and wet areas.
316 stainless steel. Extra rust protection. Good for boats and salt water.
Carbon steel with zinc plating. Strong and affordable. The zinc coating gives basic rust protection.
304 stainless steel. Does not rust. Good for outdoor use and wet areas.
316 stainless steel. Extra rust protection. Good for boats and salt water.
Carbon steel with zinc plating. Strong and affordable. The zinc coating gives basic rust protection.
Sizes:
Metric M3, M4, M5, M6. Lengths from 6mm up to 30mm. Need a different size We can make it.
Metric M3, M4, M5, M6. Lengths from 6mm up to 30mm. Need a different size We can make it.
Strength:
Class 8.8 for most jobs. Class 10.9 for heavier loads. Class 12.9 for the toughest applications.
Class 8.8 for most jobs. Class 10.9 for heavier loads. Class 12.9 for the toughest applications.
Where Do People Use These
Electronics assembly. Putting together circuit boards. Control panels. Factory machines. Car parts. Boat enclosures. HVAC units. Anywhere you want to move fast and not worry about loose washers.
Quality Control
We check every batch. Threads get gauged. Dimensions get measured. ISO 9001 and ISO 10012 certified.
- Pre assembled washer saves assembly time
- Spring washer for anti vibration locking
- External tooth lock washer for high vibration
- Double washer spring plus flat combination
- Phillips pan head and hex head styles
- Stainless steel and carbon steel options
- Metric M3 to M6 Class 8.8 10.9 12.9
YH Fastener has been making precision fasteners in Guangdong, China for over 10 years. We focus on sems screws, machine screws, self tapping screws, and custom fasteners. ISO 9001 and ISO 10012 certified. Every batch is inspected. Factory direct. Ship to over 60 countries.
For inquiries, please send us your drawing or sample. We will reply with a competitive quote within 24 hours. OEM and custom orders are welcome.