Greenslade: Achieving Zero Defects

Jason Sandefur

It�s generally accepted in fastener circles that it�s nearly impossible to ship zero defect parts in production quantities. Despite this, customers are demanding zero defects, leading to a �huge� problem for the industry, according to Joe Greenslade of Fort Worth, TX-based Greenslade and Co.
Greenslade, speaking at the Industrial Fastener & Forming International conference, cited examples of automakers finding a single defect in a pallet of fasteners and having the entire shipment sorted at supplier expense.
The question, he observed, is no longer �if� a supplier can ship defect-free parts, but �when.�
�The penalties for not figuring it out are just huge.�
Greenslade, who has been in the fastener industry since 1970, said the only way to achieve zero defects is to prevent them. Relying on detection is a recipe for failure. Statistical analysis is critical to preventing defects.
The road to shipping zero defect parts begins with a thorough understanding of part requirements. Find out which characteristics (recess quality, thread fit, etc.) are �mission critical� to the customer. Despite what many customers claim, not all features are �show stoppers,� Greenslade advised.
Knowing machine capability and gages is the next step. Greenslade said it�s important to know if the machine can actually make the part with the specified tolerance. Key to this is the quality of the gages used to measure tolerance. Greenslade said old, cheap gaging won�t help manufacturers achieve zero defects.
�If you think you�re going to use analog instruments, you�re kidding yourself.�
Variable gages are best, with a target Gage Repeatability and Reproductivity rate of 10%. To keep gages calibrated for compliance, Greenslade recommends an outside laboratory that is ISO 17025 accredited. Likewise, a manufacturer must use the same instrument as the customer to measure compliance. Different gages give different readings, adding to confusion.
Also needed for zero defect parts is consistent raw material from a single vendor with a registered ISO 9000 quality system. In addition, Greenslade recommends computer modeling of tooling design, which can increase tool life and improve quality.
�Trial and error is not the best way to achieve zero-defect production.�
Process controls are essential for consistent production, he continued. This involves using �process monitors� on all equipment, tracking what the equipment � not the part – indicates about conformity. Process controls should monitor both �mission critical� and �free flow� features, he advised. A computerized collection system is preferable because handwritten control charts don�t analyze data.
Vendors are also important to the process, Greenslade stated, necessitating thorough requirement agreements that eliminate assumptions.
Sorting is necessary as well. Greenslade advised roller sorting all parts prior to shipping, which should remove most types of foreign material. This method can handle large volumes and is the least expensive sorting option. To ensure part compliance, more sophisticated sorting equipment, using laser, vision or sonic technology, is needed. Greenslade said companies should be prepared to invest in new equipment and employee training to get results.
�There�s nothing cheap about this,� he exclaimed.
Shipping zero defect parts requires a thorough plan based on logic, extensive use of statistics and strict execution. Given this, Greenslade acknowledged it�s unlikely that any manufacturer is currently operating at zero defects.
�It�s impossible to run a factory, day by day, 24/7, flawlessly.� \ �2003 FastenerNews.com