For many years, fastener manufacturers have struggled with the concept of "zero defects". The evolution of this concept proved to be a more formidable task than first realized. Today, with the onset of PPM (parts per million) many suppliers are still looking for answers. There were many reasons for this conundrum, but several glaring thoughts demand high consideration:
- Late response to the evolution of sophisticated customer automation and assembly techniques.
- The disparity between what zero defects meant to the customer and the supplier.
- Not realizing that reduction of process variation was paramount to reducing all kinds of customer complaints.
A case could be made for poor up-front quality planning on all counts by the supply base, but each customer must also share in the failure. After all, isn't Advanced Quality Planning supposed to be a partnership? In any event, a serious problem ensued which must be, and is being dealt with.
First of all, let's examine what zero defects might mean. A defect, by Webster's definition, is something, which contains a flaw or is deficient in nature. How does this relate to fasteners? For example, the customer could deviate if the fastener met its functional requirements; function described as the task which the fastener has been designed and manufactured to perform. Assuming that the manufacturing process has a Cpk of 1.33, consider the fact that one single dimensional characteristic is within specification 99.97% of the time. Based on one million pieces, the out-of-specification range could be between 0 and 63 parts per million. Multiply this by all dimensional characteristics and the numbers become quite staggering.
Do these statistics mean that all out-of-specification parts become defects? Not necessarily - there are times when the 0 to 63 parts will function and times when parts within specification might not function satisfactorily due to stack-up tolerances, mating threads or other assembly issues. Those aren't the only issues. Traditionally, manufacturers focused on defects, which could render a fastener unfit for use, including mechanical, and performance characteristics as well as dimensional characteristics. Very rarely did other items, such as, appearance, documentation or packaging issues make the list, unless extremely severe in magnitude. They just weren't dealt with in-the same fervor.
Therefore, for the sake of defining a defect, we must change our thinking from tangible discrete data to the true identity of fastener defects. These are the tangibles as well as the intangibles. The true definition of a defect must be associated with "Customer Contentment". Whatever makes the customer dissatisfied with the overall experience of dealing with the manufacturer must be included into the defect equation. In other words, give the customer ease of doing business and no perceived problems to contend with. Today, more than ever, manufacturers must double and re-double their efforts to anticipate and prevent such problems.
Recently, fastener manufacturers have taken great strides forward in defining and understanding basic principles and actions required to reduce defects/PPM and increase customer contentment. Initially, the focus has been on promoting dramatic improvement in mixed parts/foreign material. Also, there has been an overall longer term action aimed at standardizing and consolidating data on common areas of PPM causal factors, planning and defining corrective/preventive action(s) based on Pareto logic, and ultimately uniting customers, manufacturers, and sub-contractors to work together to incrementally reduce defects. To this end, the manufacturer must enlist support from all sub-contractors with the ultimate goal being to improve the overall performance of the supply chain. The following actions must be clearly communicated:
- Inform sub-contractor(s) of your customers', requirements and expectations.
- Inform sub-contractor(s) of your requirements and expectations.
- Identify areas of redundancy and cost improvements.
