Where Do Product Defects Come From?

An Analogy: Defects in a Coffee Shop

One of the most transparent businesses you can study and experience is a coffee shop. In a coffee shop, the customer experience is a result of the cafe's environment, order accuracy, wait time, and coffee attributes including taste, aroma, temperature and consistency. Of course the wait time and cafe's environment - seating, lighting, and noise-levels - can make or break the experience, but we'll focus for now on just order accuracy and taste. Well run coffee shops deliver a delightful customer experience.

Unfortunately, we've all had days when our coffee orders were messed up. This happens more often than we like, and even happens to us at our favorite coffee shops! Your coffee order can go wrong in two ways:

  1. An Error or Mistake: You got the wrong drink.
    • Your order was written incorrectly by the cashier
    • The barista made the wrong drink
    • The barista missed an important ingredient
  2. Variation: Your coffee tastes different.
    • Your coffee was over-brewed and tastes burnt
    • Milk temperature was not set correctly
    • Your espresso doesn't have enough foam

Sources of Defects in a Coffee Shop

Let's track your coffee order from order-entry to delivery to see where things could go wrong. As you can see, your order can be messed up at any step from order-to-delivery.

Order to delivery process in a coffee shop and defects at each step

Coffee: Order-to-Delivery Process

So how does a coffee shop get to zero defects? Focusing on the make process (i.e. focusing on the work of the barista) will eliminate some of the defects. But as you can see, defects can also occur during the order-entry process, and can be be introduced by weaknesses in other supporting business processes. For example, coffee machines must be maintained and cleaned. A steam wand that's not cleaned results in poor quality foam. Similarly, inadequate inventory management process could result in milk being used past its expiry date.

This is an important point. Very often companies assume that all their defects originate in the "make” or manufacturing process, and they focus all their efforts on the worker (in this case - the barista). This flawed assumption prevents companies from ever getting to zero defects. Defects can originate at any point from order-to-delivery, and therefore the path to zero-defects requires robust business processes at every step along the way.

Sources of Defects in Manufacturing

In the modern manufacturing environment, hundreds of business processes - from order entry through product inspection and test - need to function flawlessly in order to ship a defect-free product.

As an example, let's follow a piece of semiconductor capital equipment (machinery for chip manufacturing) from design through installation at customer site. In this business, teams must design the machines, configure the machines for each customer, buy the parts to make the machines, assemble and test the machines, then ship them out customers around the world. When the machines reach the customers' sites, they need to be installed, and subsequently serviced to keep them up and running.

There are over a hundred business processes from order-through-delivery and through machine operation. And as a result there are hundreds of possible sources of quality problems. Here is a rough breakdown of defect source based on my experience in this industry.

sources of defects in manufacturing

Semiconductor Equipment: Order-to-Delivery Process

A defect can be introduced at any step along the way, from the design and engineering processes, to the installation and startup process. As you can see, if these companies focused on only the manufacturing process, they would never get to zero defects.

Instead, the path to zero defects requires an organization-wide attention to detail, and a mindset of continuous improvement towards ALL the business processes from product design to product-usage.