Woodruff Keys | Definition, Types, Applications, Advantages, Disadvantages

What is Woodruff Key?

A woodruff key is a half-moon key, it is a semi-circular machine shaft key which prevents gears, hubs or other components from moving independently of a rotating shaft or a spindle. Woodruff key is a semi-circular disc which fits into circular recess in a shaft and machined by woodruffs keyway cutter.

Woodruff keys are semi-circular pockets that are driven into shafts to hold woodruff keys. This pockets in the shaft can directly cut by using woodruff keyway cutters. The bottom circular part is hammered into the shaft and top flat part is inserted into the hub. The key is actually easy to remove but difficult to install. A light force of hammer can make the woodruff key to installed properly.

How to Install a Woodruff Key?

The process of installation of a woodruff key is, pressed the semi-circular key way provided in the shaft manually by applying force. If it doesn’t fix with the keyway, then manually hammer the key with light force, but make sure it doesn’t break the keyway.

When the woodruff key is fitted into the shaft, after that you need to align the top, the flat side of the key is parallel to the host shaft.

Sometimes the woodruff keys pop out of their grooves as the mating components are pressed during installing the keys, it can make the installation process of woodruff keys difficult. Make sure to hammer slightly by applying light force to make it perfectly installed.

Types of Woodruff Keys:

The woodruff keys are manufacture with a full radius and flat radius. Bot types of keys perform similar functions but used to different types of applications. Some of the main types of woodruff keys are as follows,

  1. Full Radius Key
  2. Flat Radius Key
  3. Hi-pro Key
  1. Full Radius Key: A full radius key is similar to full half-circular like a half moon and can make full contact with a groove seat. A full radius key has high precision as well as tight fit tolerances.
  2. Flat Radius Key: A flat radius key has same profile as standard woodruff keys. The bottom portion of the key is cut flat, so that it can easily adjust in a groove and becomes compact with less weight.
  3. Hi-pro Key: A high-pro woodruff keys are a modification of woodruff keys in which a full radius half-circular shape with added features of two legs. The high-pro key has a full half-circular shape at bottom and a slightly different profile at the top.

Applications of Woodruff Keys:

Woodruff keys are used for light duty applications and for mounting taper bored components. The applications of woodruff keys are,

  1. It is used in machine tools like crankshafts, flywheels and internal combustion engines.
  2. It is used for locking gears and for pulleys and shafts.
  3. It is used for eliminating milling around shaft shoulder.
  4. It is used for automotive applications.

What is a Use of Woodruff Key?

Woodruff keys are commonly used in the machine tools, flywheels, crankshaft of internal combustion engine, where the drive depends on the fit between the shaft and flywheel hub.

The main advantage of woodruff key is the elimination of milling near the shaft shoulders, where stress concentration and concentration would be affected.

Some of the common applications include machine tools, automotive applications, marine propellers, snow blowers, etc.

Woodruff Key Materials:

Woodruff keys are made from alloy steel, carbon steel and stainless steel. Alloy steel woodruff keys and carbon steel woodruff keys are durable and they are plated to prevent from corrosions. Stainless steel woodruff keys are way better in terms of corrosion resistance but not as strong as alloy steel and carbon steel woodruff keys.

Advantages of Woodruff Keys:

Some of the advantages of woodruff keys are as follows,

  1. Woodruff keys are used to reduces the stress concentration and improves the safety of the shaft.
  2. These keys are easy to remove and simple to use.
  3. It can provide more precise fit while reducing movement in the key seat.
  4. It is an easily adjustable key.
  5. A woodruff keys are perfect for high-speed operating systems.
  6. The keys minimize the risk of rolling over shaft.
  7. It is ideal for high speed rotating assemblies.

Disadvantages of Woodruff Keys:

Some of the disadvantages of woodruff keys are as follows,

  1. Woodruff keys are not used for carrying high load capacity.
  2. It is quite difficult to install.
  3. It reduces the stress of concentration, if the key has an extra depth of keyway in the shaft.
  4. Woodruff keys are not used for transmission of heavy torque.
  5. The depth of keyway weakens the shaft.
  6. The keys do not allow axial motion between shaft and hub.

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