Point #3: Cease dependence on inspection to achieve quality

“Routine 100 per cent inspection to improve quality is equivalent to planing for defects, acknowledgement that the process has not the capability required for the specification” – W.E Deming – Out of the Crisis – Page. 28

Why is this important?

As Deming said, if you have to perform 100% inspection on your products then you are acknowledging that the process isn’t capable of achieving the required product specification.

This leads to the production of defects, some of which may be re-worked in to saleable product while others may just have to be scrapped.

There are huge costs to running your process in this way.

First, you buy and process raw materials in to things that the customer is willing to pay for. If you produce a defect then you will either have spent time and money on making something that will go in the bin and you may only get scrap value for (a tiny fraction of the resources spent on producing) or you’ll have to spend more resources in correcting the defect, thus increasing your production costs per unit. If your inspection is at the end of the process before the product is sent to the customer, you may have spend time processing a part that was defective from the start!

Second you have to employ & train people to perform the inspections. Do the inspectors add value in the eyes of the customer? Are inspections something that the customer would be willing to pay for? Spending time & resources on inspections is non value added and is a direct cost to the business.

Third, there is a morale cost to producing defects. No one comes to work and actively wants to do a bad job and people loathe spending time sorting or re-working defective parts because it feels like a huge waste of time (which it absolutely is). You may ask why they should care what they spend their time on as they are getting paid no matter what but money only fulfils a basic need… having pride in the work that you do contributes towards the need for self-esteem and thus to the overall engagement of the workforce.

Note: There may be certain industries where quality control is critical and must be done on 100% of the parts produced (like the blades in aircraft engines).

How do we end up here?

We can end up in this situation when our process has so much variation that we produce high levels of defects and then we don’t take the time to understand and reduce the variation back to acceptable levels. If your focus is on output rather than quality, you are likely to end up in this situation.

If you do decide to implement high levels of inspection, then do so consciously and only for a limited amount of time while you sort out the true causes of variation.

What can we do about it?

Getting to the root cause of variation can be difficult, time-consuming and has a cost associated with it, but that doesn’t mean you shouldn’t do it. The cost of not doing it is far greater than the cost of doing it so having a focus on producing quality is a must.

Collect some data

In an ideal world, your process would be so robust as to not need any inspection whatsoever, but seeing as many companies aren’t at that stage, most will need some sort of routine inspection in place whereby X number of parts per batch are inspected.

This routine inspection data can be used to plot control charts of your process to determine whether you are drifting out of control.

This data from routine inspections and any feedback you receive from customer complaints help build a picture of what your defects are, which occur most frequently and in which part of your process. It is important to keep track of this data and to use pareto charts to highlight which ones you should focus on tackling first.

Understand the nature of the defect

First, you need to understand what types of defects you are creating and where they are likely to be coming from. If you show the defect to those who do the work, they will likely be able to tell you how it is produced and at the very least they should be able to tell you which part of the process the defect is coming from.

Here are just a few ways defects can be produced:

• Poor machine maintenance
• Poor tooling maintenance
• Badly designed processes
• Poor training
• Inadequate raw material quality / standards

Don’t forget to use technology to your advantage! We implemented iPads in our factory in 2025 and gave the operators ways to feedback on quality issues & their causes whereby the relevant people were automatically notified of the defect

Fix the cause of the defect

This can be easier said than done as there can be a multitude of things that influence the process at the point that the defect is produced.

If the defect is caused by poor reliability of your machine, you may need to call in the equipment manufacturer to diagnose and fix the problem (at the very least you’ll get a list of things you can do yourself to get the machine back to a low-variation state).

The tooling is the next thing to consider; if your tools (jigs, dies, print plates etc) are not kept in good condition, these can cause quality defects in your process. You’ll need a robust system of inspection, upkeep and storage in order to maintain their quality.

Poorly designed processes can make it easier for mistakes to be produced. The Japanese practice of Poka Yoke (mistake proofing) is a concept whereby you design your process in such a way that making a mistake is not possible. What if the shape of car fuel tank openings were different shapes and corresponded only to one type of nozzle for petrol or diesel? If one was round and the other was square, you physically couldn’t put the incorrect fuel in your car.

Training is usually done on the job by someone who already works in that process, but just like driving, a person can pick up bad habits over time that make their results more variable and will then pass these on to the trainee. Over time this can erode performance and understanding of the employees and lead to higher variation and poorer quality. We will look at training in point #6 but take a look at TWI (Training Within Industry) in the meantime.

Defects can come from a poor process or training within your own system as described above but they can also come from the supplier of the raw material itself. This is why you need to have KQAs (Key Quality Attributes) on the materials you are receiving, have close partnerships with your suppliers and not award work solely on the basis of price (we’ll explore this last point more in Deming’s point #4). Make sure that your raw materials are fit for purpose and don’t cause unnecessary variation within your own processes.

Note that trying to fix a defect by telling your team to simply “Do better” is the least robust way to ensure that you don’t make the same mistake again. Take some time to really think about the problem, go & see where the defect is produced and ask the team what they think.

Make sure you always ask yourself: What changes need to be made in order to prevent this mistake from ever being produced again?

Some questions to ask yourself:

Here are a few questions to ask yourself to help you think about your quality and your inspection practices:

• What is the current level of defects picked up during routine inspections?
• What defects are picked up by customers?
• Where are most of my defects produced?
• What are the top 3 defects produced? (by number and also by cost – these may not be the same)
• What can be done to eliminate the causes of these defects so they never occur again?