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Drum Bearing Drum Bearing

Summary

  • Failure mode Poor quality bearing (or under spec for load) and water ingress lead to failure.
  • Durability feature Use of better quality/better specified bearings and seals.
  • Cost

Good practices

  • Good practicesCompliance with specified machine tests
  • Good practicesSealed bearings with separate water tight outer seal
  • Good practicesDocumented quality control

Bad practices

  • Bad practicesNo testing of machine bearing
  • Bad practicesNo separate bearing seal
  • Bad practicesNo documented quality control inspection

Key facts

  • Around 40% of washing machines purchased in 2012 were to replace a product under 6 years old.
  • 80% of customers want guarantees of 2 years or longer on major appliances.
  • Design reviews identified cost savings of £550k per 100,000 units could be achieved.
  • Consumer research indicates reliability as the most important product attribute for washing machines.

Icon key

  • Failure mode Failure mode
  • Durability features Durability features
  • Cost saving Cost saving
  • Low cost Low cost
  • Cost neutral Cost neutral
  • High cost High cost

Key failure modes

Early Life

  • Bearing faults typically occur later in life, however some warranty claims are beginning to make this an early life issue if low quality parts are used.
  • This can be accelerated by water getting into the bearings from the tub and uneven loading that cause vibration at high spin speeds.  

Later in lifetime

  • In later life the bearing can collapse altogether, stopping the drum from rotating. 
  • Water getting into bearings during wash cycle.

Specification for improved performance

The specification below provides the recommended improvements needed to improve product durability. They are ranked from bronze to gold based on the effectiveness of the change in improving durability, with bronze being the minimum and gold being the maximum.

Tub not to be welded; available parts; specified for 1,300 cycles

  • Quality control procedures to be in place and documented for the bearings as supplied parts to the washing machine manufacturer.
  • Tub to be bolted or screwed together or fastened to allow separation of the two halves to facilitate replacement of the bearing without the use of special tools.
  • Replacement parts to be available in the UK at reasonable cost (less than 10% of machine cost) for at least 5 years after the machine was last manufactured.
  • Bearing to be specified to last at least 1,300 wash cycles *

Bearings sealed to prevent water ingress; specified for 1,800 cycles

  • Bearings (inner and outer) to be of the sealed/submersible type to prevent water ingress into ball race itself. Separate rubber bearing seal used in-front of the outer bearing.

  • Bearing to be specified to last at least 1,800 wash cycles

Paddles integral part of steel drum; specified to last 2,300 cycles

  • Bearing to be specified to last at least 2,300 wash cycles

Testing to demonstrate performance

Ask for clear evidence of requirements listed above, e.g.: technical specifications, drawings, photographs; test data (ideally from an independent test house), quality control data.

* Bearings on 10 randomly selected production machines to be tested without failure or increased noise in 100% of cases. Test to be for the full number of test cycles specified, on a 40 degree cotton cycle, with a mixed clothing load of 50% of the maximum weight and to encompass the highest spin speed. Details of the actual test method is to be  declared.

Cost implications

Improved reliability of components can reduce early returns and improve brand reputation which, in turn, can lower business costs and increase long-term sales.

To calculate overall cost savings for your business, use the WRAP cost/benefit analysis tool (currently in draft form and available on request).

Saving

Neutral

Low cost

Better / shielded seal 

Better quality seal (e.g. precision made, deeper, abrasion resistant) with shielding  to prevent the ingress of water into the bearing is expected to add a small amount of cost.  

Better bearings 

Numerous types of bearing, race and cage configurations are available. Higher quality materials or the use of needle rollers, rather than ball bearings for example, will add a small cost. 

Testing  

A simulated test as described, although accelerated, will require a significant number of man hours, hence adding cost per unit.   

High cost

Overload / load distribution sensor

‘Wear free’ load and motion sensors would potentially add significant cost to the machine.