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Using a keyway cutter for in-situ repairs

Posted by Alan Hillier on Jun 15, 2016 11:00:00 AM


    

 

 

What is a keyway?

A keyway is the slot created in a shaft to accept a ‘key’ that connects a rotating machine element to a shaft. The key prevents relative rotation between the two parts, enabling torque transmission. Commonly used machine components using a keyed shaft include gears, pulleys, couplings, motor pumps and turbines.

The keyway method has been used commonly in the power transmission industry for many years. When used correctly, this method guarantees that virtually no relative motion can take place between a shaft and its respective connected component.

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The keyway method has been used commonly in the power transmission industry for many years. When used correctly, this method guarantees that virtually no relative motion can take place between a shaft and its respective connected component.

Problems with keyways

Over time, gradual wear can cause the keys to loosen, leading to damage of the keyway. ‘Keyway backlash’ is a major problem area causing this problem and has a negative effect on the performance of the assembly.

Precise fitting and machining carried out at the time of assembly helps to reduce the clearance between the key and the shaft or hub keyway, but the risk of backlash can rarely be eliminated completely. Ongoing usage such as frequent machine starts, stops, and load reversal all increase keyway wear with the backlash increasing at an accelerated rate over time.

How to repair worn keyways

If a keyway becomes problematic it is possible to mill a new keyway into the same shaft. Keyway cutters such as the MINI-MILL (2 - 20") 3 Axis Key Way Milling Machine are designed specifically for projects such as this within various industries both in a workshop and for site specific applications.

Mounting the machine is straightforward, as different sized clamps are available for mounting onto the shaft or pipe in situ. (For large diameters from 5” to 20” a chain clamp is used, and for the smaller shafts a vice clamp is available for mounting diameters 2” to 5”).

The machine is moved into position using a single sling mounting point and the relevant clamp is then attached around the job onto the underside of the machine.

Mini-Mill (2-20”) specification

  • Available as pneumatic or hydraulic drive
  • X axis Stroke: 0.0 - 8.0" Y Axis stroke: 0.0 - 2.0" Z axis stroke: 0.0 - 2.0"
  • Maximum cutter diameter: 2”
  • Lightweight 3 axis construction
  • Direct drive milling spindle
  • Chain and vice clamp quick mounting options available
  • Hand feed at 2mm per revolution (optional auto feed also available)
  • Spindle RPM 50 to 640
  • Machine weight: 95kgs
  • Shipping dimensions: L – 95cm – (37”) W- 48cm (19”) H- 63cm (25”)

Find out more about Mirage machines in action by downloading the Power Generation Case Study Packor if you have a potential project needing this product right now  please click here to get in touch.

Topics: On-site machining, milling, keyway cutting

   

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