SEMS Machine Screws with Captive Washer Pre-Assembled
SEMS Machine Screws
Screw-and-washer assemblies — machine screws shipped with one or more captive washers pre-assembled under the head. Eliminates separate washer handling and guarantees the washer is always installed, even on high-volume automated lines.
Selected across automotive electronic modules, ECU enclosures, harness brackets, dashboard components, and mixed-material joints where a specific washer type — flat, tooth-lock, or split-lock — is required without risk of loss or substitution on the line.
Why source through Way Fast
We serve Tier 1 and Tier 2 automotive suppliers — primarily to North American OEM programs, including platforms shared with European and Japanese brands — with day-to-day experience handling the documentation and tolerance standards these projects demand.
01 · Multi-source capacity
Working with multiple qualified manufacturing partners — we match each order to the best-fit production line, stabilizing lead times and cost when single-source capacity tightens.
02 · Submission-grade documentation
Full support for PPAP (Levels 1–3), IMDS submission, and RoHS / REACH documentation.
03 · Audited special-process chain
Partners certified to AIAG CQI-9 (heat treat), CQI-11 (plating), and CQI-12 (coating) — covering the full post-processing chain under audited special-process controls.
04 · Multilingual drawing review
Technical drawing review in English, German, Japanese, and Chinese — including ISO 8015 GPS callouts, JIS standards, thread tolerance classes, and coating specifications.
05 · Washer-to-application matching
Washer type, material, and size matched to substrate hardness, coating, torque spec, and vibration profile — drawing-reviewed against customer joint requirements and PPM target.
Family coverage · 4 forms
Selecting across SEMS washer configurations
Plain / Flat
Most common · bearing distribution
Flat washer captive under the head — distributes clamp load and protects soft surfaces from indentation. Most common baseline SEMS configuration across automotive electronic assemblies, harness brackets, and industrial joints. Non-locking; paired with chemical thread-lock, lock nut, or prevailing-torque feature where retention is critical.
External Tooth
Anti-rotation · exposed teeth
Teeth on the outer rim provide maximum grip against the mating surface and the largest torsional resistance. Selected where loosening under vibration is the primary concern and the joint tolerates visible tooth marks.
Internal Tooth
Concealed teeth · clean surface
Teeth face inward — used where tooth marks must be hidden (visible assemblies, painted panels). Requires tight mating-hole diameter to prevent tooth miss-engagement.
Split Lock (Helical Spring)
High-vibration · spring tension
Split-ring geometry provides spring tension against the joint. Selected where the assembly sees continuous low-amplitude vibration. Paired with carbon or hardened spring-steel washers.
Sizes
M1.4 – M20 · #0 – 3/4″
Lengths
3 – 120 mm · 1/8″ – 4 3/4″
Material
Carbon steel, alloy steel, stainless steel, or brass — or to customer specification.
Finishes
Zinc, zinc-nickel, Delta-Seal®, Geomet®, black oxide, nickel, or to customer specification.
Head types
Pan, flat, hex washer, cheese, or per drawing.
Drive
Phillips, Pozidriv, Torx®, slotted, hex socket, or per drawing.
Lead times
Quotation and production
Quotation
Within 5–7 business days from receipt of drawing and specifications.
Sample & production
Schedules issued per project.
Send your drawing, SEMS part reference, or assembly joint requirement with specified washer type and size.
Supplied through qualified manufacturing partners. PPAP / IMDS / RoHS / REACH documentation per customer program. Quality levels to 50 PPM standard; tighter levels (25 PPM) available on request.
