Mar 5 2023
Quality in a Manufacturing System
The literature on Quality does not dwell on its interactions with other components of a manufacturing system, like Production, Engineering, Production Control/Logistics, or Supply Chains. As a consequence, it is missing out on key relationships that affect the value of quality improvement.
Contents
Quantity versus Quality: A Conflict?
In particular, the literature presents quality and quantity as separate pursuits, missing out on their synergy. In the field, the relationship is often conflictual. This goes back to the time the first inspector rejected a unit that a producer wanted to be passed. As recounted by David Hounshell (1984), the concept of tolerances, now taken for granted, emerged in the 19th century specifically to mitigate this conflict.
In the 20th century, quality became a profession, a support department in manufacturing organizations, with a professional society, a specialized body of knowledge, and certifications, separate from the design of production lines or production control.
This separation is artificial if you consider manufacturing from a systems perspective. You don’t just need high quality because the market demands it but also because you cannot produce in volume without it. Ramping up production without a capable process is driving on a road full of potholes.
Deming’s View of Manufacturing as a System
When advocating the appreciation of manufacturing as a system, Deming drew a high-level map of materials and information flows:
Another View of Manufacturing as a System
Deming did not make quality a component of the system. The following diagram shows some of the system interactions between Quality and other functions within manufacturing. It’s about the work of maintaining and enhancing quality, not about who does it, and it’s admittedly not exhaustive. Highlighted in red are reinforcement loops.
How quality interacts with other components in a manufacturing system
The work of quality is shown as including four subjects:
- Capability. The ability of processes to meet expectations in terms of critical product characteristics is the foundation. Establishing, sustaining, and enhancing it has been the focus of SPC 100 years ago, Taguchi DOE 40 years ago, and applications of data science and AI today.
- Response. Even capable processes are subject to occasional, discrete breakdowns that cause the Quality department to receive or issue problem reports. The response ranges from filling out a form documenting the solution to recalling products.
- Compliance. Government agencies and customers issue mandates that the company must comply with to stay in business.
- Mistake-proofing. Capable processes with rapid problem response are still vulnerable to human error, which is prevented by mistake-proofing their operator interfaces.
It is not a complete list, as it does not include the calibration of equipment, training, the organization of recalls, or statements to the public when disasters strike. This incomplete diagram is intended to highlight a few relationships:
- The most vital in most manufacturing organizations is the way efforts on quality nurture the quality reputation of the company among its customers. In many markets, it is its crown jewel, but it is not the only interaction that matters.
- Once you have capable processes, you can organize production in flow lines and pull between lines, which allows you to detect and respond to quality problems an order of magnitude faster than when processing batches in a job shop.
- As the organization solves problems so that they do not recur, they become rare, and this lets human error percolate to the top among the remaining defect causes, which you address by mistake-proofing the processes.
Economics of Quality
Even recent American texts, like Pyzdek and Keller’s (2013), justify efforts in quality through “cost savings” that are aggregations of claims made over many projects about costs of failure, appraisal, and repair. They ignore the interactions highlighted above.
While not necessarily easy to quantify upfront, these interactions are the reasons to pursue quality improvement beyond what narrowly defined costs of quality would justify. They also explain the sequencing of the approaches:
- First, you establish process capability so that you can implement flow and pull.
- Then you leverage rapid problem detection to solve problems.
- Once problems are sufficiently rare, you switch your focus to mistake-proofing.
References
- Hounshell, D. (1984). From the American System to Mass Production, 1800-1932: The Development of Manufacturing Technology in the United States. United Kingdom: Johns Hopkins University Press.
- Baudin, Michel. (2001). When to Use Statistics, One-piece Flow, Or Mistake-Proofing to Improve Quality.
- Pyzdek, T., Keller, P. A. (2013). The Handbook for Quality Management, Second Edition: A Complete Guide to Operational Excellence. United Kingdom: McGraw-Hill Education.
#quality, #systemsthinking, #manufacturing, #costofquality
March 5, 2023 @ 8:41 am
Hi Michel,
HOW TRUE, HOW TRUE… given what appears (at least to me) to be such an obvious interaction and interdependence between quality and production (at any quantity level, but particularly in large volumes), the question arises as to why this critical relationship seems to have fallen into obscurity during the 21st century? I might contend, in this regard, that much of today’s seemingly lackadaisical attitude toward quality management is the direct result of a change in attitude (beginning at the highest levels within corporations) toward maximizing the delivery value to an organization’s targeted customers. It seems that many (if not most) of contemporary management teams are more keenly focused on maximizing returns to shareholders (and other financial stakeholders) than on meeting/exceeding the quality needs/expectations of its customers.
In the context of that perception, it’s also of interest to ask why customers are seemingly more tolerant of paying high prices for what amounts to lower quality products. Although that disparity gap has improved as of late, there are still many rather dramatic instances – across a wide range of industries – where the magnitude of the gap is being highlighted by the gravity of the consequences being experienced on both a personal and an environmental level. My own experiences – and those of family, friends, and acquaintances – in the healthcare arena point toward an increasing disregard for delivering high-quality medical services in favor of maximizing profits (often by increasing throughput). Here again, it seems to matter little what the customer/consumer/patient happens to experience as long as the provider gets paid for their services.
That said, I realize that it could be a bit of stretch for you to venture beyond the boundaries of a purely technical perspective on these matters, but I have strong sneaking suspicion that the root cause(s) of many of today’s (and likely tomorrow’s ) quality-related issues reside outside the technical realm and begin with the prevailing THINKING AND BEHAVING patterns that are tending to dominate within the business realm. And because of the systemic nature of organizations/institutions, it does not make much sense to look at and analyze persistent/pervasive problems/issues without taking into consideration the social/societal, economic and political/governance forces that are impacting (not for the better) the system(s)-of-interest.
March 5, 2023 @ 1:18 pm
We must create a new perspective on what we call quality, & see it with a wider perspective.
We must stop seeing Quality as a physical measure, but as a cycle to create & continuously improve & maintain our competitive advantage.
The cycle has 4 stages. Q 1-2-3-4. We should see this as a triangle with Q1 at the apex & Q2 & Q3 as the other corners. Q4 is also at the apex as the cycle repeats. Q1/Q4 – Q2 – Q3 – Q4
Q 1. The quality of the design to give the best Products, Services &. customer Experiences (PSE} available in your industry. They must satisfy your customers business, physical & emotional needs & wants more effectively than any competitor.
Q 2. The quality of manufacturing & activity conformance to produce the design (Q1) of your PSE.
Q 3. The quality of the performance of the PSE created at Q1 & Q2.
Q 4 The quality of the redesign to modify & improve the performance of your PSE. Then move through Q2 & Q3.
*Success is guaranteed if you repeat this cycle faster & more effectively than any competitor.
What Q cycles are you planning for your PSE’s? If you don’t have any, your future will be the same.
The 4 Q’s cycle, is the link between the quality of our internal activities & the external customer and market requirements.
The most important quality is called QX. This is the quality of the physical & emotional environment we create for our people to operate/work within.
Quality in a Manufacturing System | Lean Office .org
March 5, 2023 @ 4:37 pm
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March 5, 2023 @ 9:11 pm
Hi Sid,
Fully agree with the critical nature of QX… It’s a biggie!