Total Quality Management

In Japanese, TQM comprises four process steps, namely...

1. Kaizen – Focuses on Continuous Process Improvement, to make processes visible, repeatable and measurable.

2. Atarimae Hinshitsu – The idea that things will work as they are supposed to (e.g. a pen will write.).

3. Kansei – Examining the way the user applies the product leads to improvement in the product itself.

4. Miryokuteki Hinshitsu – The idea that things should have an aesthetic quality which is different from "atarimae hinshitsu" (e.g. a pen will write in a way that is pleasing to the writer.)

TQM requires that the company maintain this quality standard in all aspects of its business. This requires ensuring that things are done right the first time and that defects and waste are eliminated from operations.

TQM in manufacturing

Quality assurance through statistical methods is a key component in a manufacturing organization, where TQM generally starts by sampling a random selection of the product. The sample can then be tested for things that matter most to the end users. The causes of any failures are isolated, secondary measures of the production process are designed, and then the causes of the failure are corrected. The statistical distributions of important measurements are tracked. When parts' measures drift into a defined "error band", the process is fixed. The error band is usually a tighter distribution than the "failure band", so that the production process is fixed before failing parts can be produced.

It is important to record not just the measurement ranges, but what failures caused them to be chosen. In that way, cheaper fixes can be substituted later (say, when the product is redesigned) with no loss of quality. After TQM has been in use, it's very common for parts to be redesigned so that critical measurements either cease to exist, or become much wider.

It took people a while to develop tests to find emergent problems. One popular test is a "life test" in which the sample product is operated until a part fails. Another popular test is called "shake and bake", in which the product is mounted on a vibrator in an environmental oven, and operated at progressively more extreme vibration and temperatures until something fails. The failure is then isolated and engineers design an improvement.

A commonly-discovered failure is for the product to disintegrate. If fasteners fail, the improvements might be to use measured-tension nutdrivers to ensure that screws don't come off, or improved adhesives to ensure that parts remain glued.

If a gearbox wears out first, a typical engineering design improvement might be to substitute a brushless stepper motor for a DC motor with a gearbox. The improvement is that a stepper motor has no brushes or gears to wear out, so it lasts ten or more times as long. The stepper motor is more expensive than a DC motor, but cheaper than a DC motor combined with a gearbox. The electronics are radically different, but equally expensive. One disadvantage might be that a stepper motor can hum or whine, and usually needs noise-isolating mounts.

Often, a "TQMed" product is cheaper to produce because of efficiency/performance improvements and because there's no need to repair dead-on-arrival products, which represents an immensely more desirable product.

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