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Metric screws and inch screws

A screw is made from various materials such as steel, stainless steel or plastic. DIN standards ensure standardisation in the use of screws on standardised components. DIN 933 defines the basic properties of hexagon head screws from the thread to the head.

Metric screws for steel construction always require a mating thread for retention. Metric screws are also called machine screws or metal screws and use a metric ISO thread with the designation M. The number behind it stands for the nominal diameter. An M8 screw is therefore a steel screw with a nominal diameter of 8 mm.

What is the difference between a metric screw and an inch screw?

A metric screw differs from an inch screw in that the unit of measurement of the thread is specified differently. For a metric screw, it is the distance of one revolution, i.e. the distance between the thread tips in millimetres. For an inch screw, it is the number of thread turns, whereby the distance of one inch is decisive.

What does a thread pitch mean?

For metric threads, a thread pitch is the pitch that is travelled during one revolution. This corresponds to the distance between two thread tips in millimetres.

What types of thread are there?

There are full threads, partial threads, fixing threads and combination threads. With a full thread, the thread extends from the tip to below the screw head. The partial thread has a thread-free part, which is useful when fastening two pieces of wood. The upper wooden part is fixed by the screw head and the lower wooden part by the thread, which is anchored in the wood.
With a fixing thread, there is a further thread underneath the head of the partially threaded screw. This thread guarantees a permanent connection between woods, especially when laying wooden floors or decking boards.

Which screws does our metric screws and inch screws category include?

There are a large number of different screws that we can categorise as metric screws or inch screws. We give you an overview of our categories:

Cap screws
Cylinder head screws are often used in highly visible places for aesthetic reasons. Thanks to the round shape of this screw, the risk of injury is minimised. The cylinder head screw is available with various screw head drives.

Pan head screws
Pan head screws are often used in combination with plugs, as they prevent the plugs from turning.

Countersunk screws
Countersunk head screws are often used for woodwork. The risk of injury with these screws is minimised to almost zero, as the countersunk head screw is completely countersunk into the wood.

Hexagon head screws
The hexagon head screw stands out from other screws in particular due to its screw head drive. It has neither a slot nor a cross, as it is tightened with a hexagon spanner. Hexagon head screws are often used with nuts in metal, wood, machine and vehicle construction.

Concrete screws and stone screws
Concrete and stone screws are moulded into the concrete so that only the threaded part remains visible. The components to be fastened are screwed to this. Concrete and stone screws have special split dowels/hooks that anchor themselves firmly in the concrete. For this reason, heavy components can be fastened to this screw.

Threaded rods
Threaded rods are very long screws without a screw head. In construction and assembly, threaded rods are used as extensions instead of screws.

Threaded pins and stud bolts
Setscrews and studs are used as locking screws. These screws are often fitted in a set collar or in a hole in the workpiece.

Screw plugs
Screw plugs are often used in the automotive and hydraulic industries as well as in plant and mechanical engineering to seal openings

Wing screws
Fl Wing screws are tightened or loosened by hand and are therefore easy to use and versatile.

Coarse and eyebolts and screw hooks
This category includes knurled screws, slotted cup screws, ribbed screws with nuts, suspension hooks, round steel brackets with nuts and more.

Round head screws
Truss-head screws are mainly used in timber construction or for connecting wood to metal. The screw head usually consists of a slotted head.

Eyebolts and eyebolts
Eyebolts are used for lifting and transporting components such as motors, switch cabinets and gearboxes. Eyebolts can hold hooks, bolts, ropes, cables or shackles or can be used to guide rods as they have a special head.

Lug bolts
Lug bolts are characterised by their oval protruding head shape. This large screw head makes lobe screws easy to tighten.

Furniture handle screws
Furniture handle screws are used to attach handles to drawers and cabinets.

Fitting shoulder screws
Fitting screws are often used as stopper screws. These are mainly used in toolmaking for guidance and stroke limitation. The fitting screws are ideal for mounting rod ends and articulated arms.

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Metric screws and inch screws: Frequently asked questions (FAQ)

  • Which screw to use?

    Which screw is used depends on the material that needs to be fastened:

    • Universal screws are used for various materials such as hardwood, chipboard and plastic.
    • Wood screws are used in furniture construction. However, wood construction screws are also used for screwing chipboard.
    • Sheet metal screws are used for materials such as sheet metal, hardboard and plastic panels.
    • Metric screws are used for assembling furniture and components. A tap or thread cutter may be required here.

    If you have any questions about a screw that is not listed, you can contact us at any time.

  • What does a screw fasten?

    A screw holds a connection together, and the screw is designed depending on the nature of this connection and the specific requirements. The holding forces of a screw depend on many different influencing factors.

  • What is the shank of a screw?

    The shank is the unthreaded part of a screw between the head and the thread. If the shank diameter is increased, the screw is able to absorb higher shear forces. If the diameter is reduced, the elastic flexibility of the screw connection also increases.

  • What do the numbers on screws mean?

    The numbers that appear in connection with screws stand for the strength class. The numbers usually consist of two numbers separated by a dot. The first number stands for the tensile strength and the second for the yield strength of the material.

  • What does the term DIN mean for screws?

    DIN stands for the German Institute for Standardisation. The DIN standard for screws therefore refers to the German standard for screws. Its purpose is to create standardisation and simplicity. The difference to an ISO standard is that the ISO standard is internationally recognised.

  • What does the term ISO mean for screws?

    ISO is an abbreviation for International Organisation for Standardisation and defines globally valid standards. The difference to DIN standardisation is that ISO standards apply internationally and DIN standards are only recognised in Germany.

  • What are INOX screws?

    INOX screws are made of stainless steel. These are categorised as stainless steel screws and are mostly used outdoors, where moisture is prevalent and a long service life must be guaranteed. An INOX screw is particularly reliable due to its resistance.

  • What is a metric screw?

    Metric screws are characterised by the thread designation M. It is the most important thread dimension and is given in mm. For example, M10 stands for a metric thread with a nominal size of 10 mm.

  • What is an inch screw?

    The difference between inch screws and metric screws is that the thread diameter of the inch screw is given in inches. This number is usually shown as a fraction.

  • What is meant by HV screws?

    HV stands for high-strength preloaded screw. These are hot-dip galvanised steel construction screws in accordance with EN 1090. Preloaded means that the HV screw can be brought to a defined preload force through standardised handling. They are mostly used for heavy steel connections, especially in safety-relevant buildings. The HV screw has strength class 10.9.

  • Which screws do not rust?

    Stainless screws include screws with the characteristics A2 or A4. The difference is that A2 screws are less sensitive to moisture than normal screws. If the screw is in constant contact with water or an acid, the quality of an A2 screw is not sufficient and an A4 screw must be used. A4 screws are mainly used in shipbuilding, in the chemical industry and in the food industry.

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