Definitions of Quality in Manufacturing

“Quality” is one of the most important concepts in manufacturing. But that doesn’t mean there’s agreement on what quality is. Ask 100 manufacturers and you’ll get 100 different definitions.

Quality standards like the ISO family, IATF 16949, and GxP are essential for producing quality products. There are few better tools for controlling costs, streamlining compliance, and guaranteeing safe, performant products.

They aren’t much help, however, where general definitions are concerned.

Even tried and true definitions (“Fitness for Use,” “Conformance to Requirements,” “When a thing does what it’s supposed to do”) can be maddeningly vague.

New technologies have spurred a resurgence of interest in quality in manufacturing–enough to earn the name Quality 4.0. Given this return to quality, now is a good time to revisit some of the canonical definitions of quality. They still have a lot to teach us about quality initiatives in the present, and where they might go in the future.

Why Definitions Are So Vague

In short, definitions of quality are vague because manufactured products are too varied to fit under a single, catchall definition.

In order to hold water as a concept, “quality” has to account for tremendous differences in manufactured products. Features of quality for, say, cutting-edge biologics, will differ from those for automobile parts. Quality standards for PCBs aren’t necessarily relevant for a food and beverage manufacturer.

Quality experts have long acknowledged this need for broad applicability in their definitions of quality. The experts at ASQ thus describe quality as “a subjective term for which each person or sector has its own definition.”

Still, there are commonalities that unite definitions across industry and product.

The ASQ argues that all quality products must meet two criteria:

1.) Quality products satisfy their stated or implied needs.

2.) Quality products are free of deficiencies.

Let’s unpack these points.

First, quality products “satisfy their stated or implied needs,” meaning they do what they say they’ll do. Second, quality products are free of deficiencies, meaning there’s no flaw in the design or production of the good that would prevent it from doing what it should do.

The beauty of this definition is that it applies to all manufactured products, from the most advanced pharmaceuticals to car parts. It applies equally well to industries where any new product requires months of regulatory approval and testing and industries where new products can roll off the lines at a moment’s notice.

In short, this definition establishes features of quality (goals, validation, and iterative improvement) that inform how manufacturers set and attain their standards.

Other definitions of quality tend to be similarly broad. Here are three of the most important.

1.) Fitness for Use

Joseph M. Juran, a foundational thinker in manufacturing and quality management, offered this definition in the mid-1950s. It has been relevant since. For Juran, quality is achieved when a finished product is suitable for use by its intended audience. Like quality, “fitness” itself can be vague. Nevertheless, Juran outlined five factors that, in balance, determine whether or not a product is fit for use:

1.) Who will use the product

2.) How they will use it

3.) The possibility and probability of danger caused by the product

4.) The economic resources of the user and producer

5.) How the user perceives quality in different products

5 factors influencing fitness for use
Factors Influencing Fitness for Use

This is an elegant definition of quality because it captures how much quality is a careful negotiation of objects, people, and perceptions. Here, quality is always relative to a consumer—their needs, resources, and safety. In Juran’s definition, the quality of something depends on how someone will use it.

2.) Conformance to Requirements

Philip Crosby, an influential contributor to management and quality theory, took a slightly different angle on quality. He defined “quality” not in terms of fitness, but in terms of requirements: those established for the product, and those of the consumer.

For Crosby, companies determine the requirements for a product based on their target consumer. When they design a product, manufacturers will establish its technical specs. These serve as a guideline for “requirements” on the product side.

At the same time, manufacturers do their best to scope the requirements of the consumer. A product that conforms to technical specifications but fails to fulfill the consumer’s need isn’t conforming to requirements. As a best practice, manufacturers will try to understand and eliminate the source of nonconformances whenever they arise.

3.) More than Making a Good Product

A much-cited essay in the Harvard Business Review argued that “Quality is more than making a good product.”

By this, the authors suggest that quality must be defined by customer needs in product design (what are the products and services they want?), as well as by how well the product satisfies those needs.

For these management scientists, quality isn’t something achieved on the shop floor. Rather, quality is the coordination of an entire company across a product’s lifecycle.

Starting to see a pattern? Across all accepted definitions, quality is relative to a consumer, a product, and an outcome.

Why Definitions of Quality Matter Now

The question remains: why now? Why dig up definitions of quality over half a century old?

The answer is: they’ve never been more relevant.

Quality 4.0 is often discussed in terms of technologies like AI, big data, IoT, computer vision. In reality, it’s much more than that.

Quality 4.0, at its core, names a shift in all aspects of quality–from culture to benchmarking to production to compliance–in the digital era. Still, quality returns to designing and producing goods that work for the end user.

But what does this look like in practice?

For one, new technologies have raised the ceiling in terms of repeatability, efficiency, and consistency in quality. Now, more than ever, manufacturers can leverage a dizzying range of tools throughout their QMS.

As new levels of quality become possible, understanding precisely what is meant by quality can help inform future efforts.

Second, the shift toward agile manufacturing has brought new attention to end-to-end product development. As all of these definitions of quality argue, quality starts with product design and continues through use by the consumer.

It should be no surprise that the ASQ suggests manufacturers add agile methodology to their lean programs. The overlaps between quality management and agile are many.

4 core principles of agile manufacturing
Principles of Agile

With the tools of Quality 4.0 at their disposal, manufacturers have an opportunity to serve their customers better than ever before.

And quality, at heart, means serving the consumer.

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