3 Manufacturing Quality Control Best Practices

Published 28 Apr 2022

The 3 Quality Control Methods

Modern manufacturing SOPs (standard operating procedures) vary depending on the industry, nature of the business, business size, and branding. What highly successful corporations have in common, however, is their use of the following tried and tested quality control and assurance methods; six sigma, lean and kaizen.

1. Six Sigma

After Motorola pioneered the use of Six Sigma in the mid-80’s, several companies across a wide range of industries have since adapted it as a standard business practice. 

Six Sigma is a problem-solving method that aims to reduce defects and manage variations from set internal specifications. The term “Sigma” in statistics refers to the standard deviation from the mean or average of a process data set. 

As a concrete example, a process needs to have a maximum of only 3.4 defects per one million opportunities to be considered of “Six Sigma Quality.”

Six Sigma has three main goals:

  • Improve customer satisfaction
  • Reduce production/service costs
  • Increase profits

Methodologies

In order to obtain Six Sigma certification, management must first determine if they’re trying to improve an existing product or process or create a new one.

DMAIC (Define, Measure, Analyze, Improve, Control)

The DMAIC methodology is used to improve existing processes that fail to achieve set goals:
Define customer needs and expected results.
Measure relevant empirical data such as current performance.
Analyze available data and do a root-cause analysis to accurately identify the real problem instead of its symptoms.
Improve the current process by conceptualizing solutions from the expected output, current performance, and identified root cause.
Control the new process to avoid deviations beyond standard limits. This step may be done as many times as needed until the process has been optimized to meet project goals.

DMADV (Define, Measure, Analyze, Design, Verify)

By contrast, the DMADV methodology is used to come up with new processes or products of
Six Sigma Quality:
Define goals for product design and functionality based on customer needs and the organization’s identity.
Measure the viability of ideal production rate, product capabilities, and possible obstacles or causes of failure.
Analyze objectives to develop optimal design.
Design a product or service based on the available information.
Verify design through rigorous testing.

2. Lean

As Toyota rose to become one of the top automotive manufacturers in the world, it also popularized Lean (or Lean Manufacturing), a management philosophy later adapted by other companies. 

The primary focus of Lean is to identify and eliminate “waste” in the production process in order to improve overall efficiency. “Waste” is described as steps and/or arrangements deemed unnecessary by logical analysis and which must be discontinued.

More specifically, Lean aims to identify the presence of and eliminate the “Seven Deadly Wastes” detailed below:

  1. Overproduction – When your product supply exceeds customer demand
  2. Waiting – When too much time is spent waiting in between steps in production and nothing is being accomplished
  3. Transport – Inefficient transportation of materials and finished products
  4. Motion – Inefficient execution by workers, equipment, or machines
  5. Overprocessing – When there are unnecessary processing steps taken or the processing standards are inefficient
  6. Inventory – When inventory levels exceed necessity and the workload is too high that it negatively affects quality
  7. Defects – Amount of work dedicated to identifying and fixing production mistakes

Tools

Though numerous companies apply Lean principles to their operations, their techniques and tools of choice may vary. Below are some of the most widely used tools and techniques for practicing Lean:

  • 5S (Sort, Set in Order, Shine, Standardize, Sustain)
    The 5S system focuses on organizing the workplace, ensuring that items, equipment, documents, and other workplace staples are in their proper places so that work performance can improve organically through management and safety.
  • PDCA (Plan, Do, Check, Act)
    PDCA (or PDSA) is a problem-solving technique developed by W. Edwards Deming that aims to accomplish the following:
    Plan: Establish the desired result and propose a solution to achieve it
    Do: Test the proposed solution and gather data to gauge effectiveness
    Check (or Study for PDSA): Study/analyze the data gathered from the test and compare results to desired outcome
    Act or Adjust: Make adjustments to the solution based on the data from the “do” and “check” phases until the goal is achieved

     

    Another staple in Toyota’s business process is the A3 Report, referred to as such for it being a one-page report usually printed on A3-size papers. The A3 Report uses Deming’s PDCA/PDSA problem-solving technique to identify, eradicate, and prevent problems in operations.

  • 5 Whys
    Toyota pioneered multiple manufacturing and management models that have become business standards in several organizations, and 5 Whys is no exception. This Lean technique is used by team managers to identify the root cause of a problem by asking “why” five times until it is discovered.

Examples of 5 Whys in action

Problem The team failed to meet last month’s sales quota

Why did the team fail to meet the quota?

We ran out of products in the middle of the 3rd week.

Why did we run out of products?

We were only able to produce 70% of the projected demand

Why did we fail to produce 100% of the product demands?

Our materials for production had expired

Why did our materials expire?

We failed to check expiry dates

Why did we fail to check expiry dates?

No designated team or person was assigned to check them

Root-cause

There is no process for assigning who is in charge of monitoring materials

3. Kaizen

Kaizen is a Japanese term that means “change for good,” but is more loosely translated in the west as “continuous improvement.” What makes it different from other process improvement methods is that it aims to involve the entire organization, from top management to the assembly line workers, in its implementation. Having a Kaizen Culture in your organization means each individual, regardless of rank, is empowered to look for opportunities to improve every day, no matter how small.

Tools

Listed below are some of the most common Kaizen implementation tools used by companies:

  • SIPOC (Suppliers, Inputs, Process, Outputs, Customers)

    SIPOC is a mapping tool with the primary objective of ensuring clarity in process workflows. By doing so, unnecessary activities are discontinued, accountability becomes clear, and the overall process is optimized for maximum efficiency.

  • Gemba Walk

    Performing a gemba walk means that executives, on a regular basis, will walk around the actual space where the work is being done (be it the production floor of a call center or a manufacturing plant) in order to observe objectively, understand the process, ask questions, and identify opportunities for improvement. Its goal is to ensure that upper management learns how things are actually done, instead of simply commenting on and reviewing individual work performance.

  • 8D Report

    The 8D Report or the Eight Disciplines Model is a problem-solving technique used to contain, resolve, or prevent issues identified in a product or process by quality engineers and other responsible personnel. Initially only used by the automotive industry due to Ford’s influence, it is now widely used in a variety of industries, including manufacturing, healthcare, and retail, with great success. The 8D Report is a comprehensive method that aims to eliminate problems by identifying and attacking its root cause(s). It achieves this by utilizing a combination of expertise, data analysis, management tools, and data validation.