Fitness for Use Categories
Dr Juran defined a non-conformance or reject or defect as “unfit for use”. Parts could be broken into one of four categories:
- Fit for use and conforming to specification
- Fit for use but not conforming to specifications
- Not fit for use but conforming to specifications
- Not fit for use, not conforming to specifications
| Conforming to Specifications | Not conforming to specifications | |
| Fit for use | These are no problem – no action is required | This causes seriousInternal communications problems |
| Not fit for use | This causes serious External communications problems | These are no problem – no action is required |
Fitness for Use = Specifications
In two of the four categories, the specifications are useful. The supplier and the customer agree and the customer always get product that they want. When the parts are fit for use and conform to specifications product ships and everyone is happy. In the same way, if the product is not fit for use and does not meet the specification, the supplier will incur a cost but not lose a customer. Everyone is in agreement.
Fitness for Use≠ Specifications
Two of the categories generally lead to a level of (sometimes) controlled chaos. When the parts are fit for use but fail to meet the specification the specifications need to be changed. Understand fitness for use does not mean a product that will function but is cosmetically unsatisfactory. This product meets all the needs of the customer and they see no difference between these products and what they normally receive. Internal communications and conflict will occur until the specifications are revised.
The other category should be considered catastrophic for the supplier. The product does NOT meet the customer’s needs but the supplier views it as conforming to specification, or satisfactory product. It is here that a root cause analysis and long term preventive action is needed.
Controlling Specifications Controls Fitness for Use
Specifications are key documents for training and communication. The customer either sends their specifications or orders a catalog cut which defines the product performance. The first key step to controlling quality starts at Sales. When they take the order, they must understand and communicate the customer needs. If the customer does not what variations in color greater than .5 microns, sales must communicate this back to engineering. Engineering and manufacturing must look at the specifications and their process capability and decide of the specifications can be met. If not they must communicate back to Sales to negotiate a solution.
Clear communication at the start of the process which defines what can and cannot be done is the first step to good quality product, a satisfied customer, and a profit for the supplier.