The waste of waiting is any idle time spent by people or machines when materials or information aren’t immediately available to proceed.
In manufacturing, workers may have to wait on equipment such as a forklift to become available or for maintenance to complete if the planned downtime was inaccurate. Alternatively, associates may have to wait for information such as work instructions before proceeding with production.
Unfortunately, overproduction or busy work often obscures waiting, making it one of the most difficult wastes to quickly identify. That said, anytime waiting is noticed, it is vital to ensure that people don’t fill the time with unneeded production just to keep busy since this can cause even more waste in the form of overproduction and inventory.
The Cost of Waiting
Waiting can be extremely costly. In fact, the cost of waiting can be directly correlated to the following:
- Lost capacity
- Wasted operating costs
- Overtime costs (associated with having to meet deadlines)
- Decreased ability to adapt to changing customer needs.
- Overproduction from employees producing more of a product than needed in order to “keep busy”
- Inventory caused by overproduction.
Tools to Prevent Waiting
There are tools and techniques to prevent the waste of waiting:
- Workload Balancing
This is where takt time kicks in. Remember that for us we need to effectively balance each process cycle with takt time so that no operator is left waiting for something to do.
Fig 1. Workload Balancing
- One-Piece Flow
Also referred to as Make One, Move One is a great technique for production lines in ensuring they never have to wait for work because everything is balanced throughout the production line and every process.
- Standard Work Documents
Standard work documents work hand-in-hand with Visual Management best practices. Having clearly defined and followed standard work documents helps all associates know exactly what needs to be done and where they can help in the case, they ever run out of work to complete.
- Heijunka (Production Leveling)
For many manufacturers, demand variation naturally results in occasions when there’s very little work to do, and other occasions there may be so much work that overtime may be necessary. Production leveling can help reduce or even eliminate this bull-whip effect within an organization. Smoothing production processes helps us to plan, schedule, and deliver effectively without the need for waiting or overburdening our workforce.
Fig 3. Heijunka – Production Leveling