DIN 551 specifies the dimensions and tolerances for slotted adjusting screws (din 551). The full dimensional table is reproduced below, followed by the DIN, ISO and ASME parts that match or supersede it.
- Standard
- DIN 551
- Product
- Slotted Adjusting Screws (DIN 551)
- Governing standards
- DIN 551
Equivalence between national standards is dimensional, not always metallurgical. Check the property class separately when substituting.
The table below lists the dimensions catalogued for slotted adjusting screws (din 551) under DIN 551. The scope of DIN 551 itself is not summarised here — where a figure matters, confirm it against the published document.
DIN 551 — Scope
The table below lists the dimensions catalogued for slotted adjusting screws (din 551) under DIN 551. The scope of DIN 551 itself is not summarised here — where a figure matters, confirm it against the published document.
Tolerance & Product Grades
Product grade is a concept from dimensional fastener standards and does not apply to DIN 551. Tolerances for this part are the limits shown against each dimension in the table.
Dimensions Specified by DIN 551
| Thread size | Pitch (mm) | Slot width n (mm) | Slot depth t (mm) | Point form | Common length range (mm) | Property class | Reference standard |
|---|
| M3 | 0.5 | 0.4 | 0.8 | Flat | 3~16 | 14H | DIN 551 |
| M4 | 0.7 | 0.6 | 1.1 | Flat | 4~20 | 14H | DIN 551 |
| M5 | 0.8 | 0.8 | 1.3 | Flat | 5~25 | 14H | DIN 551 |
| M6 | 1.0 | 1.0 | 1.5 | Flat | 6~30 | 14H | DIN 551 |
| M8 | 1.25 | 1.2 | 2.0 | Flat | 8~40 | 14H | DIN 551 |
| M10 | 1.5 | 1.6 | 2.5 | Flat | 10~50 | 14H | DIN 551 |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Slotted Adjusting Screws (DIN 551) page.
Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
When to Specify DIN 551
DIN 551 is still widely used in European mechanical engineering and as a cross-reference on legacy drawings; its ISO equivalent is preferred for new designs.
Custom manufacturing · Made to drawing
Need a screw to this standard in a non-standard size?
Parts built to DIN 551 are already in the catalog, so a special is usually a variation on existing tooling rather than a new design — which is what keeps the cost down. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
Custom screw manufacturingSend a drawing
Applications & Industries
The sectors that buy Slotted Adjusting Screws to DIN 551, and the duty each one buys them for. Stocked from M3 to M10.
Industries that specify Slotted Adjusting Screws
-
Energy & infrastructure
Tower, pipework, switchgear and plant fixings specified for long service life and inspectable joints.
-
Maintenance & MRO
Stocked replacements matched to an existing property class, thread and finish.
-
Food, pharma & cleanroom
Stainless assemblies that are washed down, where the finish matters as much as the strength.
-
Machine building & OEM
The default fastener on production equipment: covers, brackets, motor mounts and sub-assemblies tightened to a specified torque.
-
Automotive & transport
Chassis, driveline and body fixings that see vibration and are assembled to a controlled preload.
-
Steel fabrication
Bolted connections in frames, enclosures, walkways and weldments, on the bench and on site.
Typical applications
- bolting brackets, motors and gearboxes to a frame
- assemblies that are dismantled for service and re-torqued
- joints where the property class is stated on the drawing
- clamping two machined faces to a calculated preload
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 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 Slotted Adjusting Screws are used, how to specify them, and the cases they are wrong for
