ISO 7045 specifies the dimensions and tolerances for sems screws with captive flat washers. The full dimensional table is reproduced below, followed by the DIN, ISO and ASME parts that match or supersede it.
- Standard
- ISO 7045
- Product
- SEMS Screws with Captive Flat Washers
- Governing standards
- DIN 7985 / ISO 7045 and EN ISO 10644
Equivalence between national standards is dimensional, not always metallurgical. Check the property class separately when substituting.
ISO 7045 is the governing dimensional standard for sems screws with captive flat washers. This page sets out the scope of the standard, reproduces the full size table it specifies, and lists the DIN/ISO/ASME cross-references commonly cited in datasheets and drawings.
ISO 7045 — Scope
ISO 7045 specifies the dimensions and tolerances of sems screws with captive flat washers. Material, property class, surface finish and packaging are governed by separate documents in the same standards family (for example ISO 898-1 for the mechanical property classes of bolts and screws).
Tolerance & Product Grades
ISO 7045, alongside the related DIN 7985 / ISO 7045 and EN ISO 10644 entries on this site, specifies product grades (typically A or B for fine work and C for general engineering) and tolerance classes for the controlling dimensions. Choose the grade against the precision your application requires.
Dimensions Specified by ISO 7045
| Thread size | Pitch (mm) | Washer outside diameter (mm) | Washer thickness (mm) | Property/material options | Drive | Reference standard |
|---|
| M2.5 | 0.45 | 6 | 0.6 | steel 4.8/8.8 or A2 stainless | Phillips | DIN 7985 / ISO 7045 and EN ISO 10644 |
| M3 | 0.5 | 7 | 0.6 | steel 4.8/8.8 or A2 stainless | Phillips | DIN 7985 / ISO 7045 and EN ISO 10644 |
| M4 | 0.7 | 9 | 0.8 | steel 4.8/8.8 or A2 stainless | Phillips | DIN 7985 / ISO 7045 and EN ISO 10644 |
| M5 | 0.8 | 10 | 1.0 | steel 4.8/8.8 or A2 stainless | Phillips | DIN 7985 / ISO 7045 and EN ISO 10644 |
| M6 | 1.0 | 12 | 1.6 | steel 4.8/8.8 or A2 stainless | Phillips | DIN 7985 / ISO 7045 and EN ISO 10644 |
| M8 | 1.25 | 16 | 2.0 | steel 4.8/8.8 or A2 stainless | Phillips | DIN 7985 / ISO 7045 and EN ISO 10644 |
Companion Standards
ISO 7045 controls only the geometry of sems screws with captive flat washers. The mechanical strength is set by ISO 898-1 (bolts and screws) or ISO 898-2 (nuts); the surface finish is governed by separate finish standards (e.g. ISO 4042 for electroplating). For corrosion testing, the relevant document is ISO 9227 (neutral salt spray).
When to Specify ISO 7045
Choose ISO 7045 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for sems screws with captive flat washers.
Applications & Industries
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
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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
