Keys

Keys are steel bars that transmit torque and prevent parts from rotating relative to each other. Due to their strength and reliability, keys are used in virtually all branches of machine-tool building and mechanical engineering.

A key connection consists of a shaft, a hub and a key. Depending on the type of key, two types of connections are distinguished:

• stressed (segment, parallel, cylindrical keys);
• unstressed (taper, tangential keys).

An unstressed connection is used to transmit a small torque. It is most often used in small-batch production.

In a stressed connection, all parts are under stress from the spreading force after the taper key is installed in the hub and shaft keyway. In this case the hub can deform and shift relative to the shaft, causing runout. For this reason taper keys are used in low-speed assemblies, and their use is generally declining. Tangential keys are the most reliable, so they are used in heavy machine building under severe dynamic loads.

Manufacturing standards

As with most fasteners, the production of keys is governed by the domestic GOST and its foreign counterparts — the German DIN and the international ISO.

Parallel keys

Manufactured to DIN 6885-1, with counterparts GOST 23360-78, the American standard ANSI B17.1 and ISO 773. Dimensions: length from 10 mm to 280 mm, cross-section from 5×5 mm to 22×14 mm, ends rounded with a radius from 0.25 mm to 0.6 mm. Keys with length deviations outside the specified ranges are permitted. Under GOST 23360-78, applying protective coatings to such keys is not allowed.

Material of manufacture — key steel, cold-drawn, to GOST 8787-68. Other steel may be used provided the tensile strength is at least 590 MPa.

Segment keys

Comply with DIN 6888, with counterpart GOST 24071. Unlike parallel keys, segment keys are installed in shaft keyways and have a technological advantage: a semicircular shape, greater cutting depth, and a more stable fit. However, they weaken shafts, so they are mainly used only on heavy-duty shafts. The key cross-section dimensions for a given shaft diameter are determined per GOST 8794-68. Side-face fits are the same as for parallel keys.

Made from stainless steel grade A2/A4.

Taper keys

The manufacturing standard for the gib head taper key is DIN 6887, with counterparts GOST 24068-80, ISO 774. The DIN 6887 key has a head for convenient installation. A taper of 1:100 ensures a secure connection fit. Width 6-16 mm, height 6-10 mm, length 32-100 mm.

Material — stainless steel A2/A4, plain finish, no protective coating.

How to order and buy

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