---
title: "What Are Slotted Adjusting Screws (DIN 551) Used For?"
description: "Slotted Adjusting Screws (DIN 551) (DIN 551) are used for threaded assemblies where the head drive and seating style matter. Catalogued M3 to M10."
url: https://engineeringhardware.com/applications/slotted-adjusting-screws-din-551/
source: Engineering Hardware & Fasteners
---

# What Are Slotted Adjusting Screws (DIN 551) Used For?

Screws · DIN 551 · Application guide

Typical applications, the industries that specify slotted adjusting screws (din 551), and how to choose the right size, material and finish for the joint.

Slotted Adjusting Screws (DIN 551) are used for threaded assemblies where the head drive and seating style matter. They are manufactured to DIN 551, 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 551
- **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 Slotted Adjusting Screws (DIN 551) Used For? application image](https://engineeringhardware.com/wp-content/uploads/2026/08/Adjusting-Screws.webp)

Slotted Adjusting Screws (DIN 551) (DIN 551) are specified where the joint requires threaded assemblies where the head drive and seating style matter. The sections below cover the typical end-uses by industry, the size and material decisions for each, assembly practice, and the applications this fastener type is not suited to. Stocked across roughly M3 to M10, they cover general to heavy-duty work.

## Typical Applications for Slotted Adjusting Screws (DIN 551)

The most common settings where these are specified:

- **Appliances & consumer goods:** high-volume assembly with power tools and consistent seating.
- **Machine guarding & panels:** removable access covers that are opened for service.
- **General machine building:** fastening covers, brackets, motors and sub-assemblies on production equipment.
- **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.

Product catalog

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## How to Specify Slotted Adjusting Screws (DIN 551) 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 551. 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 Slotted Adjusting Screws (DIN 551)

- 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 Slotted Adjusting Screws (DIN 551) 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.

Custom manufacturing · Made to drawing

## Need a slotted adjusting screws (din 551) outside the standard range?

Thread size and pitch, length, property class, drive form, head geometry and head marking are all specifiable — the standard part is where it starts, not where it stops. Made by cold heading or warm forging.

Minimum order from 2,000 pieces; samples within 7 days of drawing approval.

[Custom screw manufacturing](https://engineeringhardware.com/custom/screws/)[Send a drawing](https://engineeringhardware.com/custom/screws/#rfq)

## Technical Drawing

Dimensioned line drawing of M3 Slotted Adjusting Screws (DIN 551) to DIN 551. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.

- **Pitch (mm):** 0.5
- **Slot width n (mm):** 0.4
- **Slot depth t (mm):** 0.8
- **Point form:** Flat
- **Common length range (mm):** 3~16
- **Property class:** 14H

## Dimensions & Specifications (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 |

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](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 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](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 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](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 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](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 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

### What material should Slotted Adjusting Screws (DIN 551) 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.

### Are Slotted Adjusting Screws (DIN 551) made to a recognized standard?

Yes — they are manufactured to DIN 551, so dimensions are interchangeable between suppliers when you quote the standard on your order.

### What are Slotted Adjusting Screws (DIN 551) used for?

Threaded assemblies where the head drive and seating style matter. They are supplied to DIN 551.

### Which industries use Slotted Adjusting Screws (DIN 551)?

They are commonly specified in fabrication & metalwork, electronics & enclosures and appliances & consumer goods, among other sectors.

### Can I get a quote for Slotted Adjusting Screws (DIN 551) 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.

## Related Pages

Product page: [Slotted Adjusting Screws (DIN 551) — specifications & sizes](https://engineeringhardware.com/fastener/slotted-adjusting-screws-din-551/)

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