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Screws · DIN 6900-4 · Application guide

What Are SEMS Screws with Captive Spring Washer Used For?

Typical applications, the industries that specify sems screws with captive spring washer, and how to choose the right size, material and finish for the joint.

SEMS Screws with Captive Spring Washers are used for threaded assemblies where the head drive and seating style matter. They are manufactured to DIN 6900-4, and the choice of size, property class and finish is driven by the load in the joint and the environment it sits in.

Primary duty
Threaded assemblies where the head drive and seating style matter
Governing standard
DIN 6900-4
Thread size range
M3 to M10
Category
Screws

Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation.

What Are SEMS Screws with Captive Spring Washer Used For? application image

SEMS Screws with Captive Spring Washers are used primarily for threaded assemblies where the head drive and seating style matter. This page lists the industries and assemblies where they are specified, the selection criteria that matter for each application, installation practice, and the cases where a different fastener type is the correct choice. Parts are supplied to DIN 6900-4. Stocked across roughly M3 to M10, they cover general to heavy-duty work.

Typical Applications for SEMS Screws with Captive Spring Washer

The most common settings where these are specified:

  • Maintenance & repair (MRO): a stocked size for servicing existing plant where the original fastener spec must be matched.
  • Fabrication & metalwork: bench and on-site assembly of steel frames, enclosures and weldments.
  • Electronics & enclosures: mounting PCBs, panels and lids where the drive style and head height matter.
  • Appliances & consumer goods: high-volume assembly with power tools and consistent seating.
  • Machine guarding & panels: removable access covers that are opened for service.

How to Specify SEMS Screws with Captive Spring Washer for Your Application

  • Size: Match the nominal size to the mating thread or hole. This product spans M3–M10; check the full table below for the exact dimensions of each size.
  • Drive & head: Pick the drive (socket, cross, slot) and head style for the tool access and seating surface; a recessed drive resists cam-out under power tools.
  • Environment: For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
  • Standard: This product is supplied to DIN 6900-4. Quoting the standard on your order guarantees interchangeable dimensions between suppliers.

Installation & Assembly Practice

  • Match the driver exactly to the recess (PH ≠ PZ; hex key sizes per ISO 2936) and keep the tool axial — side load is the main cause of stripped drives.
  • In tapped holes, engage a thread length of at least 1× the nominal diameter in steel, 2× in aluminum.
  • Set power tools to a torque that seats the head without embedding it into the mating surface.

Common Selection Mistakes with SEMS Screws with Captive Spring Washer

  • Under-sizing the drive for the installation torque — a small recess at high torque strips before the screw is seated.
  • Using a countersunk head in thin sheet where the countersink removes most of the load-bearing material.
  • Specifying stainless in high-strength duty: A2-70 is roughly class 7 steel, not a 10.9 substitute.

Where SEMS Screws with Captive Spring Washer Are Not the Right Choice

Not for high-preload structural joints (use a property-class bolt and nut), and not in thin sheet where a self-drilling or self-tapping type suits better.

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Sends the selected values to the quote form below.

Request a Quote

The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.

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Specification
Business Information

Dimensions & Specifications (DIN 6900-4)

Thread sizePitch (mm)Head diameter dk (mm)Head height k (mm)Washer outer diameter (mm)Cross recessCommon length range (mm)Reference standard
M30.55.62.46.2PH1 / PZ15~30DIN 6900-4
M40.78.03.18.0PH2 / PZ26~40DIN 6900-4
M50.89.53.710.0PH2 / PZ28~50DIN 6900-4
M61.012.04.612.2PH3 / PZ38~60DIN 6900-4
M81.2516.06.015.4PH4 / PZ410~60DIN 6900-4
M101.520.07.518.4PH4 / PZ412~60DIN 6900-4

Video: What Are SEMS Screws with Captive Spring Washer Used For? in use

Third-party video, selected automatically for this topic. It is not produced by Engineering Hardware and is not a specification source — use the tables on this page for dimensional data.

Inside the plant

Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

  1. Wire rod feeding into a cold heading machine
    01

    Cold heading

    Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.

    Head dimensions and under-head radius checked at set-up and per shift.

  2. Thread rolling machine producing bolt threads
    02

    Thread rolling

    Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.

    Go / no-go ring gauges to ISO 965 tolerance class 6g.

  3. Baskets of bolts staged for heat treatment
    03

    Heat treatment

    Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.

    Core hardness and tensile tested per lot to ISO 898-1.

  4. Zinc plated bolts in a treatment basket
    04

    Surface treatment

    Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.

    Coating thickness and neutral salt spray hours to ISO 9227.

Frequently Asked Questions

Which industries use SEMS Screws with Captive Spring Washer?

They are commonly specified in electronics & enclosures, appliances & consumer goods and machine guarding & panels, among other sectors.

How do I choose the right size of SEMS Screws with Captive Spring Washer?

Match the nominal size to the mating thread or hole. This product is available from M3 to M10; the full dimension table on this page lists each size.

What drive type do SEMS Screws with Captive Spring Washer use?

Drive depends on the head style — socket (hex key), cross (Phillips/Pozi) or slot. A recessed drive resists cam-out when driven with power tools; check the product head style on this page.

What material should SEMS Screws with Captive Spring Washer be for outdoor use?

For damp, coastal or chemical environments specify A4 (316) stainless or a suitably coated steel. For indoor or dry use, A2 (304) stainless or zinc-plated steel is normally adequate.

Can I get a quote for SEMS Screws with Captive Spring Washer in the size and material I need?

Yes. Use the technical drawing and quote form on this page to set the size and options, then send the exact configuration to our team for pricing and lead time.