Sources of Waste: Waiting

by | Jan 5, 2021 | Continuous improvement

Waiting is one of the seven sources of waste considered in lean manufacturing or Muda (無駄), the latter a Japanese word meaning “wastefulness; uselessness”. It is the “act” of doing nothing or working slowly while waiting for a previous step of a process to be completed. How many times have you seen operators wait for a previous operation or a product delivery or just work slowly so as not to find out that they are out of a material?

The Costs of Waiting

Companies pay for the time spent by all of their employees, even the time they spend adding no value to a product or process, waiting. The time spent waiting is not something that the client will want to pay for. The cost of this time spent on standby will come directly from the profits. Every penny that can be saved is a penny reinvested directly into profit.

Often, time spent on standby is caught up later during overtime at a premium rate which is good for the employee but not so good for the profits.

The Causes of Waiting

Imbalanced processes are a cause of waiting in the workflow. If one process takes longer than the next, operators will either be on hold or complete their tasks at a speed that makes it seem like they have work to complete.

Unreliable processes also cause waiting times. For example, the next process is waiting for the previous one because of jams, breakdowns, quality or information problems, or a lengthy conversion.

Waste due to overproduction and inventory also causes waste from waiting. This is because the material has to be transported (other form of waste) from one place to another usually in large quantities. Material handling is often a limited resource and processes are left waiting for the forklift to arrive or for another worker to finish using the pump truck etc.

Information, or the lack thereof, can also cause waiting time, either due to unclear or missing information on how to complete an operation or waiting to know which process needs to be executed next.

Examples of Waste Caused by Waiting

  • Inactive operators/machines awaiting sorting from a previous process due to quality issues with its output,
  • Operators on standby or working slowly while waiting for a previous operation to complete its cycle,
  • Waiting for a previous process to complete a batch of material before movement,
  • Waiting for the forklift to deliver a batch of components,
  • Waiting information from the engineering department,
  • Waiting for the resolution of a jam or breakdown,
  • Waiting to know which product is required next.

How to Eliminate or Reduce Waiting

  • Balancing your production processes using Takt time and Yamazumi Chart will help you ensure that the processes are better suited in terms of cycle times.
  • Improving machine reliability and quality using Total Productive Maintenance (TPM) and quality tools
  • Reducing overproduction and inventory to minimize transport and motion between and within cells. Implement standard operating procedures (SOPs) to ensure standards and methods are clear
  • Using visual planning methods combined with daily in-cell meetings to make sure everyone is clear on what is required for the day.

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