Offering a high quality product is no longer a differentiator for today’s manufacturers. A high quality product is just a basic expectation of your customer and is a minimum requirement as your customer considers their purchasing decision. Today’s successful manufacturers know this and their products reflect this realization. While a high quality product is a given for today’s manufacturer, the remaining challenge is controlling the costs of achieving this high level of quality. The Lean technologies introduce quality at the task level for each process as a way to achieve the high level of quality today’s customer require.
Many manufacturers have chosen to achieve their quality initiatives using an aggressive inspection disciple in an effort to discover defects before they are shipped to the customer. While inspection for defects once a process is completed can be an effective strategy, it can also be expensive.
The primary cause of quality defects is variability in the manufacturing process. Variability is defined as having multiple procedures for completing the work elements of a process or an individual task, with only one way being the correct way. Almost all manufacturing processes contain some variability. How a manufacturer deals with this variability is the source of the cost of quality. Until a process can be made 100% fail-safe, with no chance of producing a defect, the best option is to require the operator to perform an inspection at the point where variability occurs, not after completion of the process. When performing a process work task that has variability in a traditional operating system, interpreting the one correct way to complete the work is often left to individual operators. If the interpretation is made by an operator with extensive experience or a strong skill set, the interpretation is likely to be correct, resulting in a high-quality product. Conversely, if another operator who may be very well intentioned, but with less experience and training or underdeveloped skills, makes another interpretation of the correct way, the result may be very different. The more the process variability, the more opportunities for individual interpretations and workmanship-related defects increase. If the correct way to complete work is left to individual interpretation, the impact on product quality can be disastrous. Customers rarely demand specific inspection work. They simply require the product to perform as advertised. It is the manufacturer’s responsibility to decide how quality gets built into its products.
Unfortunately, inspection work is always non-value-added because no change is made in form, fit, or function of the product and the time required to perform the inspections adds to the total product cycle time. Until a fail-safe process can be developed allowing only one correct way to produce a product, inspections are the only way to ensure that process variability is not subject to individual operator interpretation. The long term solution is continuous improvement and kaizen project initiatives. Once started, opportunities to reduce variability are discovered, quality is improved and manufacturing response time is reduced. These projects are never-ending and must become a way of life in any Lean operating system.
Lean methodology values ideas and suggestions for continuous improvement. Operators who build a product day in and day out often understand the nuances of a product better than the engineers who designed it. Ignoring the immense storehouse of operator product knowledge is often listed as the eighth waste of manufacturing. The essence of a Lean line is standardization of methodology, procedures, and operator/technician behavior. Standard work is an important component of Lean technology. Standardization reduces the opportunities for individual interpretation. Once a Lean operating system is in place, individual interpretation by operators is not permitted. The effort required to balance the line, install the kanban systems, and operate the line based on the staffing necessary to produce an established daily rate is the product of facility optimization and line design.
Operators and technicians are responsible for performing the quality work required to ensure that a task with variability has been completed according to the one correct way. At each workstation where variability occurs, operators are trained to perform two quality checks in addition to the required standard work assigned to the workstation for every unit produced. These quality checks, in combination with the required standard work, are the three types of work to be done during each workstation.
1. The first quality inspection is of the upstream operator’s work.
2. The required value-added standard work required to be completed at the workstation.
3. The second quality inspection is a visual verification of the operator’s own value-added standard work to ensure any possible variability at the workstation.
Lean technology standardizes work content and streamlines all process required to meet customer demand by balancing and linking processes to one another. Lean methods include improvement activities aimed at reducing customer response time and eliminating the non-value-added work embedded in the standard work times across the entire series of linked processes. Lean also requires that priorities for kaizen projects be directed at eliminating non-value added work and reducing response time, inventories, and working capital. A Lean operating system is designed to identify improvement opportunities that yield the greatest lead time reduction, quality improvement and working capital reduction.