Quality at the Source

The quality management function has evolved from mere inspection to quality planning to quality management to Design for Six Sigma. However, many organizations still strongly believe in inspecting quality into product. They perform incoming inspection in the receiving of materials from suppliers, in-process inspection, final inspection, out-of- the-box audit, audit on the field, and many other non-value-added activities. While these inspections are sometimes necessary to protect the customer from receiving bad product, the idea is to eliminate the wasteful inspections across quality management processes by building in quality at the source.

The most effective way to maximize the resources of your organization is to ensure that quality (as defined by your customers) is built in to whatever product or service is produced by the people doing the work. The traditional method of having inspectors at the end of the process only results in sorting the good products from the bad. The inspector cannot change or affect the quality of the product; it cannot be inspected in. Having a separate in-process inspector catches the defect earlier in the process, but again he or she is only sorting the good from the bad. It has also been proved many times that even 100%

inspection is only 80%–90% effective.

Quality at the source involves a cultural change. It requires an organization to move away from the notion that the defects will be caught by the end-of-the-line inspector.

Implementing this change requires clear definition of employee expectations. One aspect of the change is employee ownership of the process and its output. This ownership typically involves the authority to optimize the process (empowerment) and the accountability that comes with the authority. However, it requires management to properly train the employee on the identification of the critical to quality attributes as well as how to use any associated test tools or equipment.

Six Elements of Quality at the Source

Standard Work

Throughout the value stream, there are points where critical tasks are performed that affect the end quality of the product or service. It is important for operators to know what those critical points are throughout the entire value stream. However, they cannot be expected to remember every critical task, especially in value streams where there are many control points and tasks at each process. Therefore, management must aid the worker in remembering what to inspect, how to inspect, and what to do when an error or defect is detected. This should also include how to perform a critical task to prevent an error or defect from occurring.

Management should provide documentation to the worker to reinforce the various potential quality issues associated with a given process. This documentation should be simple, not full-blown manuals or standard operating procedures (SOPs). In lean organizations, this documentation is called standard work. Manuals and SOPs can be used as a starting point from which standard work can be developed. Standard work is described in more detail in Section 2.2.6. For quality at the source to work effectively, standard work should provide information to quickly guide the worker through the quality aspects of the task and into the value-added activities. The documentation should provide the purpose;

scope; applicable references; step-by-step procedure with pictorial demonstrations;

flowchart in SIPOC (Supplier-Input-Process-Output-Customer) or a swim lane flowchart (cross-functional flowcharts); process controls; environmental, health, and safety conditions; metrics; and applicable records.

Documentation also provides an opportunity to standardize training of employees. This not only provides a means of training employees on how to do the job and perform key tasks, but also provides a reminder to the trainer to inform and make sure the employee understands the key potential quality issues associated with the task he or she is performing. Documentation also allows training employees on inspection methods and how to quickly perform them at each step. Training has to meet the needs of the trainee depending on his or her past education, skills, and experience. Effectiveness of the training has to be measured to address any gaps. Periodic in-process audits should be performed to review the effectiveness of processes.

Successive Checks

Often, inspections are performed at different points in the value stream. Shingo was concerned that inspections were not being performed at a time that optimizes the value stream. Shingo believed that inspections, in their current state, may not occur early enough in the process to provide the best information necessary to identify the root cause of the quality issue. Without this information, it is difficult to resolve the issue and drive improvements to prevent the issue from happening in the future.

Successive checks are checks by employees of the tasks performed by other employees upstream in the value stream. Successive checks prevent the addition of value (performing value-added work) to faulty material or information. Shingo believed that the rate of continuous improvement can be more rapid as quality feedback becomes faster. By having each employee inspect the work of the upstream employee, quality feedback can be given on a more timely basis. With successive checks, each process step performs both production and quality inspection.

Self-Checks

Self-checks are checks (or micro inspections) done by the employee performing a task according to his or her standard work. Self-checks prevent sending defective material, parts, or information forward in the process to the next process step. The inspection should be visual and fast, with the employee looking for each potential quality issue quickly and then moving on to the next process step. After all key inspections have been performed;

any corrective action necessary due to a quality issue can then be initiated immediately at the point of occurrence.

While successive checks provide quick quality feedback, having the employee who performs the task check his or her own work provides even faster quality feedback. Self-checks tend to utilize poka-yoke (mistake-proofing) devices, which allows employees to assess the quality of their own work. Because they check every unit produced or service performed, employees may be able to identify the process conditions that changed, resulting in the quality issue. This insight can be used to perform a root cause analysis, immediately correct the issue, and prevent defects from occurring in the future. Because self-checks provide quality feedback faster, they are preferred to successive checks whenever possible.

While successive checks and self-checks are process-results oriented, Shingo believed that inspection prior to work (or source inspection) is the ideal method of quality control since feedback about process conditions is obtained before a process step is performed. Source inspection is intended to keep defects from occurring during the work. The addition of poka-yoke (mistake-proofing) devices into the inspection method help to evolve successive checks and self-checks into source inspections.

Visual Management

Another element of quality at the source is the development of visual aids. Visual management aids are simple tools utilized as communication aids to show work standards (examples of good and defective product) and inspection methods. One form of visual management aids is the single point lesson.

Single point lessons are commonly used to show how a task should be performed, how a product or service should be inspected, and what to look for during the inspection. Single point lessons can be created on single sheets of paper all the way up to large displays that are easily accessible to the employee performing the task (i.e., viewable while the work is being performed). The single point lesson relies heavily on photos and contains very little, if any, writing. The concept of the single point lesson is to utilize a visual picture to guide the employee through the process and make it easier to identify defects before more value is added to the product or service.

Poka-yokes (mistake-proofing devices) can be combined with visual aids to speed up the inspection process. More information on visual management (visual aids) can be found in Section 2.2.1.

Poka-Yoke

Poka-yoke is also known as mistake-proofing. In Japanese, poka means “inadvertent error”

and yoke means “prevention” Poka-yoke means the implementation of simple, low-cost devices that either detect abnormal situations before they occur or stop the process once they occur to prevent defects (Dennis 2007, 98).

Poka-yoke devices can be used to ensure that correct process conditions are met prior to an employee performing a task. When used effectively, poka-yoke devices can make inspection systems at every step possible by reducing the time and cost of inspection to near zero. More information on poka-yoke can be found in Section 2.3.7.1.

Continuous Improvement

While Shingo supported self-check and successive check inspections, he was insistent that the true intent of the inspection is to identify quality and process issues immediately and communicate them to drive root cause analysis, prevent defects, and improve the process.

His intent was not to use inspection to sort out defects.

Inspections, visual management, and poka-yoke devices are only as good as the current state of workforce knowledge. Fortunately, humans have the capacity to continuously learn. Shingo believed that these jidoka elements should evolve as we learn more about how processes can go wrong and how we can correct them and prevent defects from occurring in the future.

Traditional quality systems have relied mainly on expert knowledge to ensure that quality is inspected into a product or service before and after it is made. While using quality at the source effectively can make every employee responsible for adhering to standards of quality and productivity, it can also make those same employees responsible for creating those standards in the first place. A lean enterprise builds quality into products and services at every step in the process. However, while improved quality is an outcome of lean transformations, lean concepts and tools seem to get all the attention. Just as tools such as 5S are credited with significant productivity improvements, quality at the source can produce significant quality improvements immediately.

Quality at the source has many other advantages, including better-informed employees, creation of a culture of customer focus, reduction in defect rework, elimination of other forms of waste (e.g., inventory due to poor quality), and most importantly the empowerment of employees.