Pan Head Hex SEMS Screw Pre Assembled Captive Washer Fastener

Main Product Description

SEMS Screw – Pre-Assembled Captive Washer Fastener Factory Supply

Browse our full range of industrial SEMS Screw series widely used in electronics, automotive and machinery assembly. Our factory produces complete SEMS Screw integrated with flat washers, spring lock washers or customized plastic gaskets. It solves the troubles of separate washer matching and vibration loosening, perfectly matching high-efficiency automated production lines.

What Is a SEMS Screw?

A SEMS Screw is a pre-assembled captive washer fastener. Flat and spring washers are permanently locked onto screw threads during cold forging, which will never fall off during transportation, storage and high-speed assembly. Compared with separate screw and washer kits, our SEMS Screw cuts assembly labor cost by over 30% and reduces inventory varieties for manufacturers.

We supply multiple head types of SEMS Screw, including Phillips pan head, external hex flange head, hex socket button head and square captive head. Standard metric sizes M2/M2.5/M3/M4/M5/M6/M8 are in stock, and custom inch thread specifications are acceptable for OEM orders.

Core Strengths of Our SEMS Screw

1. 1
   Dual Washer Anti-Vibration Lock Design

   The flat washer prevents scratches on metal and plastic workpieces, while the spring washer maintains continuous elastic tension to offset vibration stress, effectively avoiding screw loosening on long-running equipment.

2. 2
   Diversified Material & Surface Finishes

   Optional raw materials: Grade 4.8/8.8 carbon steel, SUS304, SUS316 stainless steel. Available finishes: color zinc plating, black zinc, black oxide and stainless steel passivation to meet different anti-corrosion requirements.

3. 3
   Customizable Washer Combinations

   Support single flat washer, flat+spring double washers, external tooth lock washers and waterproof plastic sealing washers for electronic enclosures.

4. 4
   Standard & Non-Standard Customization

   All products comply with DIN, ISO, ANSI industrial standards. We customize thread length, head thickness, washer thickness and laser marking based on customers’ engineering drawings.

5. 5
   Strict Batch Quality Control

   Every batch of SEMS Screw passes thread tolerance test, neutral salt spray test, vibration anti-loosening test and tensile test. Complete inspection reports can be provided upon request.

Wide Industrial Applications of SEMS Screw

Our versatile SEMS Screw serves multiple manufacturing industries:

• Consumer Electronics: PCB boards, monitor housings, smart robot plastic shells, home appliance control panels
• New Energy Industry: Energy storage cabinets, charging pile panels, photovoltaic auxiliary brackets
• Auto Parts: Car interior plastic trim, battery fixing frames, vehicle sensor housings
• Industrial Machinery: Motor casings, electrical control boxes, automation equipment frames
• Precision Instruments: Micro testing equipment, communication terminal shells

Complete Product Specifications

• Drive Type: Phillips cross, external hex, inner hex socket
• Thread Standard: Metric M2-M8, UNC/UNF inch customizable
• Raw Material: Carbon Steel, SUS304 Stainless Steel, SUS316 Stainless Steel
• Surface Treatment: Color zinc plating, black zinc, black oxide, passivation
• Matching Washer: Flat washer, spring lock washer, plastic sealing washer
• MOQ: Small trial orders supported, bulk orders delivered within 5–15 working days

Company Introduction

We are a professional precision fastener manufacturer with over 10 years of production experience, specializing in the R&D, production and customization of SEMS Screw and various non-standard screws. Our factory covers a standardized production workshop equipped with full sets of cold forging, thread rolling and precision testing equipment. We have passed ISO9001 quality management system certification, and all production links implement strict quality control.

We have stable monthly mass production capacity to support long-term framework orders from global buyers. Our professional foreign trade team provides one-stop service covering technical consultation, drawing optimization, sample production and after-sales support. We have cooperated with hundreds of manufacturers from Europe, North America, Southeast Asia and other regions, winning consistent recognition for stable product quality and competitive factory direct prices.

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