The Seven Wastes (or muda) are categories of unproductive manufacturing practices identified by Taiichi Ohno, the father of the Toyota Production System (TPS). Looking at waste in these seven separate categories helps to unpack and scrutinise processes in a more thorough way than merely trying to eliminate obvious waste.
The Seven Wastes are:
- Transportation: When we look at all the processes in a manufacturing production line that contribute towards the creation of an end-product, transportation isn’t really one of them. Sure, transportation gets products from the production facility into the hands of the consumer and is thus a very important and necessary link in the supply chain. However, transportation doesn’t transform or add to the product. Each time the product is moved (transported), a cost is incurred, and there’s a risk of damaging the product or delaying delivery. It’s therefore important to scrutinise all transportation processes to eliminate unnecessary steps.
- Inventory: The existence of inventory means capital has been spent (in order to acquire the inventory), but income has not yet been realised by the sale of this inventory. Inventory is not only assembled stock items, but can be work in progress (WIP), unassembled parts, or even raw materials. It’s important to look at the various types of inventory to find where non-value-adding work can be eliminated. Perhaps machine breakdowns or changeovers/setups cause large stoppages in WIP. Inventory also takes up storage space, which comes at a cost too.
- Motion: Not to be confused with transportation, motion pertains to workers, equipment or producers. During motion of any of these three, the risk of safety, wear or damage increases. As parts move through the production process, risk of damage, etc. can also add expenses to the production process.
- Waiting: Also known as work in process (WIP), this waste is concerned with goods that are not currently being transported, nor being assembled or processed. These waiting goods are wasteful in much the same way as inventory sitting on shelves – while they are waiting; no value is being added to them. It’s not to say that we can eliminate all waiting, but that these WIP situations should be reviewed to ascertain the cause of hold-ups: can delays or waiting times be decreased? Are we producing too much? Do we have staff or machine shortages that are causing bottlenecks?
- Overproduction: Probably the worst of all waste, overproduction can, in essence, cause all of the other wastes. Overproduction happens when more product (supply) is created than required by customers (demand). This creates excess inventory, which, as stated earlier, comes at an additional cost because inventory must be stored, not to mention the costs associated with the other wastes. Overproduction often occurs when manufacturers produce products in batches. Though batches may make sense in terms of economies of scale, the dichotomy lies in the fact that batch creation can take longer, during which time consumer demand could change.
- Over-processing: This waste occurs when more work, effort or machine investment is used than is actually required/necessary to produce the product. For instance, if one of the machines or tools used in the production process is more complex, sophisticated and expensive than it needs to be, this constitutes waste.
- Defects: A defective product, whether the defect is picked up by the customer, retail outlet/agent, or on your own premises during the quality control process, constitutes waste. There is waste in terms of the time required to repair, disassemble and reassemble the product. In instances where the product is defective beyond repair, or possibly in the instance of the food industry where food standards might dictate that certain defects must result in disposing of the defective product, this constitutes even more waste.
These Seven Wastes force us to look deeper into our processes. By suggesting the various types of waste to look out for (as above), work teams are more likely to pick up more latent wastes and come up with creative ways to eliminate or minimise them. Although the Seven Wastes list was created for manufacturing, the categories can be adapted to apply to most types of workplaces.
Help your employees detect manufacturing wastes with this set of 7 free posters.
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