November 3

How are Lean Production and Quality Related?


When being introduced to the concept, most people ask how are lean production and quality related? As this is a common question, I thought I’d share it with everyone in this post.

So, how are lean production and quality related? Lean Production focuses on improving process performance. Process performance can be measured in terms of quality of the output, cost creating the output, and delivery on time. As these three variables are interlinked, lean places an equal importance on quality, cost and delivery, and ensures that what gets processed is right-first-time, exactly at the right time and in the most efficient way.

When implementing lean production techniques, you can focus too much on increasing productivity, without equal thought to improving quality and getting things right first time. In this case, you can quite literally be making errors faster.

In order to get lean production right, you must focus on speed AND Quality.

Process Perspective

Lean focuses on process improvement. This means that the spotlight is always on a business’ processes.

In conjunction to this, a process has a number of variables:

Process Model

Every process has:

  • A number of inputs
  • The process steps themselves
  • The outputs to that process

Process Inputs

The process inputs are all those things that feed the process. They can be a multitude of factors, from the raw material, to the equipment you use, to the information needed and the resource working in the process.

The Process

This is the actual process – all the steps that go into transforming a product or service. The process takes the inputs and converts them to an outcome or output.

The Outputs

These are the outputs to the process. They’re what the process has converted.

Take a quoting process, for example.

  • The inputs would be the information taken from the customer.
  • The process is the actual steps, taking the information and converting it into a quote for the customer.
  • The output is the quote itself, sent to the customer.

This output can be measured in terms of the quality of quote and the speed it was turned around. We can then measure against what we expect. For instance:

  • All quotes turned around within 5 hours
  • 75% conversion rate on quotes

Quality is Critical

Notice above, that quality is one of the key outputs from a process?

You can measure a process’ output in 3 main ways:

  • Quality – How good is the process output?
  • Cost – How much did it cost us to get the output?
  • Delivery – How long did it take?

These outputs, including quality, are always governed by how good the inputs and the process itself are.

The Relationship Between Inputs and Process Steps

It’s clear to see that both inputs and the process steps will dictate how good the output is.

This in turn will have an impact in speed, cost and quality to plan.

Getting the information wrong up front, or not getting all the information can lead to delays, extra time and resource creating the quote, and also a poor quality quote.

If the process is not slick enough, you can get similar results.

Your process’ output, therefore, is only as good as the quality of the inputs and the process itself.

So as, we provide a strict focus to processes in lean production, we’ll naturally look at these three variables in everything we do:

  • How quick are we turning the process around in accordance to our targets?
  • How much time and effort is this costing us against our targets?
  • Is the quality to the levels that we expect?

If all or even one of these questions are below target, then through our lean production framework, we’ll attack it, so we can improve it for the better.

This would involve improving some the quality of some of the input steps and also the process steps too.

Quality – Cost – Delivery are Linked

The reality is that these three process outcomes are linked. For instance, if we’re not asking the right questions from the prospect, then it in itself is a poor quality input.

This will then have a knock on effect to the cost and delivery of the process. It would mean that we’d have to go back and reprocess something we could have done right first time (quality). If we don’t capture this problem up front (quality), then we may have to re-do the whole quote again, when the customer rejects it (cost and delivery).

The customer may well go elsewhere because of the poor quote anyway (quality).

In lean, we pay equal attention to these three factors, because they affect each other, interchangeably.

The 4 Goals of Lean

In light of this, there are 4 lean goals to target:

  1. Pull – Rather than producing as much as possible, customer demand should pull goods or services through the production processes. This concept minimises over production, inventory and working capital.
  2. One-piece flow – Focusing on one single piece at a time (ideally), minimises work in progress, process interruptions, and also vastly reduces lead time. IT reduces waiting time and improves quality too. How does it improve quality? Is it easy to spot errors when you’re processing large mountains of work at any one time? Would it be easier to spot errors if the amount of work you process at any one time is reduce? The answer to this is a resounding yes. By reducing your working progress, it’s easier to see and fix errors. AS a result, small batches (or the ideal one piece flow) means your quality should be consistently high.
  3. Takt – This is the heart beat of a lean production system. It’s how fast you need to make your products, to meet customer demand. Takt allows us to balance workload, achieve continuous flow and respond flexibly to changing customer demand.
  4. Zero Defects – Mistakes happen, but a lean company doesn’t pass on defects to the next step in the process. Mistakes from previous steps must be fixed before carrying on. And at the source of this is the ability to be able to spot an error when it happens, and then fix the process so the problem doesn’t happen again.

These 4 elements all go into improving quality, cost and delivery of all processes, as one entity.

Related Questions

What Does Quality at Source Mean? Quality at source simply means to fix the problems where they started. This means to create a continuous improvement culture, where the people running their processes, identify errors, stop and fix them. This whole approach means that it’s not just enough to ract to problems and get over them.

It’s a case of stopping, and fixing the process so there’s a systematic improvement and the problem is unlikely to return again.

Quality at source directly empowers teams and uses them to make continuous improvements as a habit.

What’s the Easiest Way of Improving Quality at Source? The easiest and probably the quickest way is to ask 5 whys, when your team highlight a problem. The 5 why technique is simply a questioning framework, whereby you ask why over and over again until you get to the root cause to fix the process problem. This doesn’t mean you have to stop on the fifth why. Keep going until you find a root cause.

Here’s an example:

The machine keeps stopping


Because the machine keeps over heating


Because there’s not enough coolant going to the machine


Because the thermostat is not working and doesn’t trigger the switch to release more coolant

Fix: Fix the broken thermostat and create a preventative maintenance programme to maintain the machine

This 5 why technique is simple but effective and requires you to go to the problem, observe and ask why until you get a process fix.

Keep implementing this framework, and you’ll start to put longer term fixes in place and across your processes.


You may also like

How to Begin Your Lean Journey: 5 Steps to Making an Impact

5 Reasons Why Continuous Improvement in Manufacturing Is Important

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