What Drives Your Product Quality? Control or Assurance?
A key element to ensure the quality of products is to build quality by design as well as defect prevention at every step of the manufacturing process. This results in fewer defectives, lower cost of production through less scrap as well as increased customer satisfaction. This, however, does not mean that quality control or Acceptable Quality Level (AQL) checks are redundant.
For many manufacturing and quality personnel, the road to enjoying the fruits of assured quality products will be through a tough role of first becoming effective quality inspectors
For example, our plant was facing issues of flat packs in the marketplace. A controlled audit throughout the supply chain revealed higher levels of flat packs generated in the factory. The sealing design of the pack was changed and an hourly check introduced to test for seal integrity. This helped bring down ex-factory defects to <0.5%. Coupled with supply chain SOPs, overall defects were brought under control. Therefore, QC helped ensure packs were produced within design parameters, while QA brought in a new design and introduced controls to ensure the process was followed rigorously.
Another example - We were facing high levels of quality rejects on the process lines - almost twice that of our sister plants. The production and the quality team would argue on whose fault it would be. It was a tough decision on whether we should examine every part of the process to identify and eliminate root causes. We could not afford the time required for this process since we were supposed to keep the production lines running during peak season. It was finally decided to double the number of inspectors at the end of the line and the number of samples picked up every hour. This would help quarantine defective output while the line kept on producing. It was a high-cost option, but we had decided to go ahead with it to satisfy demand. This is a clear example of quality through control.
As managers, we may believe that our company has a robust quality assurance function but if the manufacturing process is out of sync, sometimes, we have no choice except stricter inspections.
Saurabh Lal, Director Supply Chain, India & South Asia, Kellogg Company
There are a few basic principle, many of which will be familiar to practitioners of Toyota Production Systems (TPS) and Total Productive Maintenance (TPM).
1. It is difficult to bring under control a process producing very high level of defects due to chance causes. End of line inspection is required to manage the quality of products. This may be the first line of defence. AQL inspection or line quality control can help here.
2. Use of SOPs and checklists by the operating personnel is important. It is equally important to check the data collected through such checklists that will help in root cause and trend analysis.
3. A separate team of inspectors helps in catching defectives but this removes accountability from the operator. Keep the line operators responsible for defect control at their workstations. Provide necessary tools at the immediate workplace. For example, if weight is regularly out of tolerance, provide a weighing scale at the work-spot. The operator can check the weight regularly and make an on-the-spot adjustment.
4. Use Add-ons (devices to signal a problem) and control devices. For example, if air pressure falls below a set value, an alarm should ring. Even better, empower the operators to stop the lines when they detect defectives.
5. Use poke-yokes (mistake-proofing techniques). An example would be to stop the line automatically when crushed packs are being produced. This prevents a defect from occurring in the first place.
6. Use the 7 QC tools (fishbone diagram, why-why, etc.) to identify root causes. This should be done through the operating personnel and small groups. Encourage Kaizens - small improvements done on the shop floor to eliminate causes of defects.
7. Most importantly, when faced with a problem - Go to Gemba (workplace) and look at the Gembetsu (the relevant objects/people/machines/methods).
There is a balance between quality control and quality assurance to achieve the level of quality you desire. For many manufacturing and quality personnel, the road to enjoying the fruits of assured quality products will be through a tough role of first becoming effective quality inspectors.