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Screws · DIN 7985 / ISO 7045 and EN ISO 10644

M2.5 SEMS Screws with Captive Flat Washers Dimensions

Controlling dimensions to DIN 7985 / ISO 7045 and EN ISO 10644, with clearance hole and tapping drill, spanner or drive size and tightening torque.

M2.5 SEMS Screws with Captive Flat Washers are dimensioned by DIN 7985 / ISO 7045 and EN ISO 10644. The controlling dimensions, tolerance classes and assembly data are tabulated below.

Figures are nominal values from the governing standard. Confirm against the tolerance class for your application before machining or ordering.

M2.5 SEMS Screws with Captive Flat Washers Dimensions reference image

M2.5 SEMS Screws with Captive Flat Washers (DIN 7985 / ISO 7045 and EN ISO 10644) are specified by thread size, length and head dimensions. The M2.5 row from the standard is reproduced below, followed by the drill sizes, spanner size and torque values used when installing this size.

M2.5 Dimensional Row (DIN 7985 / ISO 7045 and EN ISO 10644)

Thread sizePitch (mm)Washer outside diameter (mm)Washer thickness (mm)Property/material optionsDriveReference standard
M2.50.4560.6steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644

Spanner & Drive for M2.5 SEMS Screws with Captive Flat Washers

Drive geometry for M2.5 SEMS Screws with Captive Flat Washers is given by the row above; match the tool to the listed values.

Installation Tips for M2.5 SEMS Screws with Captive Flat Washers

  • Pozidriv (PZ) drivers ride out of Phillips (PH) recesses and vice versa — confirm the recess marking on the head before assembly.
  • For automated assembly, an ACR (Anti-Cam-Out Ribs) or torx-equivalent driver gives noticeably longer bit life than plain PH.
  • At M2.5 the joint is sensitive to over-torque — use a torque-limiting driver and check the head doesn't bury into a softer counterpart.

Mating Parts for M2.5

For M2.5, pair with a M2.5 hex nut (ISO 4032 / DIN 934) and, where used, a M2.5 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.

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.

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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 7985 / ISO 7045 and EN ISO 10644)

Thread sizePitch (mm)Washer outside diameter (mm)Washer thickness (mm)Property/material optionsDriveReference standard
M2.50.4560.6steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M30.570.6steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M40.790.8steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M50.8101.0steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M61.0121.6steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644
M81.25162.0steel 4.8/8.8 or A2 stainlessPhillipsDIN 7985 / ISO 7045 and EN ISO 10644

Applications & Industries for M2.5 SEMS Screws with Captive Flat Washers

Where SEMS Screws with Captive Flat Washers are used, and what decides the specification in each case. Stocked from M2.5 to M8.

Industries that specify SEMS Screws with Captive Flat Washers

  • Electrical assembly Captive flat-washer screws for panels, terminals and equipment covers.
  • Appliance production High-volume screwdriving where a separate washer would slow assembly.
  • Sheet-metal enclosures Removable covers that must retain the washer on the screw.
  • Machine guarding Service hardware that stays with the cover during removal.
  • Steel fabrication Bolted connections in frames, enclosures, walkways and weldments, on the bench and on site.
  • Energy & infrastructure Tower, pipework, switchgear and plant fixings specified for long service life and inspectable joints.

Typical applications

  • combining the screw and flat washer into one captive assembly
  • spreading bearing load while preventing washer loss during service
  • using a Phillips drive for controlled production installation
  • selecting the washer outside diameter and thickness with the thread size
  • clamping two machined faces to a calculated preload
  • bolting brackets, motors and gearboxes to a frame

Service conditions to specify against

Marine and coastal
Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
High load
Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
Torque and preload
The joint is designed around bolt tension, so lubrication, coating and the friction coefficient all change the torque figure — state them together.

Where to use something else

  • Do not substitute the captive washer for a hardened structural washer in a high-preload joint.
  • Do not use a machine thread into unthreaded sheet or timber; use a tapping screw, rivet nut or insert made for that parent material.

Full application guide: where SEMS Screws with Captive Flat Washers are used, how to specify them, and the cases they are wrong for

Video: M2.5 SEMS Screws with Captive Flat Washers Dimensions

All About SEMS Screws: Double Washer Pan Head

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

Phillips or Pozidriv for M2.5 SEMS Screws with Captive Flat Washers?

Match the bit to the recess marking on the head — Phillips (PH) drivers cam out of Pozidriv (PZ) recesses and vice versa. The recess type for SEMS Screws with Captive Flat Washers is shown in the spec table.

Is M2.5 SEMS Screws with Captive Flat Washers suitable for electronics and small mechanisms?

M2.5 SEMS Screws with Captive Flat Washers is in the micro range and is widely used in electronics, instrument enclosures and small precision mechanisms. Watch the over-torque margin — micro joints strip easily.

What's the typical proof load behavior of M2.5 class 8.8?

Micro-thread joints are sensitive to plastic deformation in the first turn under load — use a torque-limiting driver and check the bearing surface deformation on softer mating materials.

How do I request a quotation?

Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.