Everything you need to know about parallel keys

Parallel keys: a must-have part for solid connection. In this article, we'll look at how the round-ended parallel key or feather key ensures efficient rotational torque transmission between the shaft and the hub. Find out more about its advantages, the manufacturing process and differences with standard straight-ended keys. We manufacture our round-end parallel keys to DIN 6885 or NFE 22177 standards, and according to our customers' own designs.

‍What are rounded-end parallel keys?

The round-end parallel key, also known as a feather key, is usually made of steel or stainless steel to ensure strength and durability. It is inserted into the recess on the shaft and the hub in such a way that the rounded ends don't damage the contact surfaces of these elements.

Once in place, a key with rounded ends prevents the hub from slipping on the shaft, allowing torque to be transmitted effectively between the two elements. It is commonly used in applications requiring the transmission of high loads with back and forth movements, and where precise alignment is essential to ensure everything operates smoothly without any unwanted vibrations.

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What is the difference between a form A parallel key and a form B parallel key?

The main difference between a form A parallel key and a form B parallel key is the shape of the end of the key.

The form A key has rounded ends, making it easier to insert into the shaft and avoid damage from rough insertion. Potential applications for round end keys include use in rotating machines such as engines and transmission systems, where they are used to connect the shaft to other components.

In most cases, it is preferable to opt for a rounded-end key rather than a straight-end key as it offers better load distribution and reduces shaft wear.

Nonetheless, straight-end keys may be more suitable for certain applications. For example, if the shaft already has a square or rectangular hole or if the machine specifications require a square key, a straight-end key would be necessary. In general, the required key depends on the machine, the shape of the shaft, and the load that will be transmitted.

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How are round-end parallel keys made?

Round-end parallel keys or feather keys are manufactured in a similar way to standard keys, albeit with a different finish. The general manufacturing steps for a round-end parallel key are as follows:

1. Cold rolling & drawing: The raw material, usually steel or stainless steel, is cold-rolled and drawn to achieve a rectangular or square profile.
2. Milling: Once the rectangular or square profile has been obtained, the ends are rounded and the length of the key adjusted via milling using appropriate forming tools.
3. Vibratory finishing: After milling, the keys may have burrs and a rough surface. To improve the parts' surface condition, they undergo a vibratory finishing process for a high-quality finished product.
4. Quality control: Finally, before being used or sold, parallel keys with rounded ends are subject to our quality control procedure to ensure that they meet the required specifications and industry standards. This can involve visual checks, dimensional measurements and other tests to make sure that the keys comply with quality requirements.

It should be noted that the exact manufacturing steps may vary depending on each customer's particular requirements.