Statistical Process Control And Quality Improvements

Improving Quality and Reducing Variation (Six Sigma) in Factories in China

We Provide Manufacturing Support in the Following Locations

cmc-locations-map

Many Chinese factories that sell on the domestic market or to other developing nations think that a 5% defect rate is generally acceptable. Yet this is unthinkable to most of their customers from North America, Europe, and Japan. The challenge here is to change mentalities as well as putting proper systems in place.

Manufacturing Industries We Serve

Statistical-Process-Control

Statistical Process Control

Before thinking of inspection and testing methods at the end of the line, the focus should be to operate processes in a way that minimizes quality issues. Process control is the first step to focus on when equipment is involved (e.g. temperature, pressure, and time for molding) or when changes in components can impact quality (e.g. humidity, color, and viscosity for glueing).

We help factories identify the process control parameters that are critical in their operations, we collect data and consult suppliers in order to decide on these parameters’ acceptable levels, and we teach the production staff to make good use of an SPC (Statistical Process Control) system.

Mistake-proofing

Mistake proofing manual operations (“poka yoke”)

We also need to reduce human mistakes. This is not easy but in many cases, there is a way to error-proof operations with a mix of creativity (e.g. a pin in the right place on a fixture) and technology (e.g. sensors) - known as poka-yoke. It makes sense to focus on the sources of mistakes that have the highest impact on the finished product’s quality.

This is typically the industrial engineers’ and the process engineers’ job. Unfortunately, most people in Chinese factories consider human mistakes unavoidable. This is the wrong attitude!

Quality-system

Quality system

This is primarily an information management system. Operators should know as early as possible if they are not producing quality parts. This feedback loop is crucial not only for immediate containment of the bad parts, but also for proper corrective actions to be put in place. The goal is to solve issues once and for all.

A good quality system also ensures feedback from customers is well correlated with the issues detected by internal inspections and internal audits. If you are regularly surprised by customer complaints, your system is not set up properly.

Supplier-quality

Supplier quality

Your suppliers have a direct impact on your own products’ quality. As our consultants often say: "Your suppliers’ quality is your quality." Yet this is often neglected by manufacturers. We often see failure rates to the tune of 20% on some incoming QC reports, and yet most of these batches are released to production.

Helping suppliers with process control, mistake proofing, and quality systems might be the priority. A good complement is putting in place a strong supplier management system that pushes your purchasing department to improve your supplier pool over time.

product-design

Product design

One source of quality problems might be the product design. It might not be conducive to good manufacturability, and in turn that might affect quality. In some cases we can work with the production and the design departments to make changes without losing the original design and engineering intents of the design.

With these five elements in place, there is no reason the factory can’t make high quality products. In China, most factories can be coached into reaching a Cpk of 1.33. Reaching a Six Sigma quality level (Cpk above 1.5, and if possible of 2.0) is much more challenging and usually requires very deep changes.

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