A key benefit for the Lean manufacturer is the ability to assess conditions on the manufacturing shop floor or administrative office through simple observation. A popular name for this capability is “management by walking around – MBWA”. By simply walking through the manufacturing facility, activity in the Lean factory is easy to observe. Supervision requirements of a Lean line are diminished simply because of the simply flow layout of processes. All operators & technicians are trained and certified to perform the standard work at their workstations. Operators and technicians utilize production in-production signals to know what to do and when to do it.
Operators and technicians are trained to be flexible by moving to other workstations to complete standard work at each workstation. The one-piece-at-a-time flow of products on the line always indicates the status of the production. Because of these attributes of a Lean line, problems are easily spotted by the manager when performing a “MBWA” activity.
Organization and discipline are important elements of a Lean working environment. A Lean business transformation project also supports the simultaneous implementation of the 5S principles. All material locations are clearly marked and maintained. Only the necessary tools, fixtures, gauges, and other resources are located at workstations. Clutter and poor housekeeping habits are not tolerated on a Lean line. Time is provided to operators and technicians each day to clean and manage their workstation. Operators are responsibility for maintaining their workstations to be certain they are organized and operational for the next shift or next day.
Because a Lean line is designed to follow the process flow of a product, reliance on output from a shop floor control system to determine the location or the progress of an order is greatly reduced or completely unnecessary. Each day sequencing boards at the beginning of the line and at feeder processes clearly communicate the product mix to be built that day. At the end of the line, a linearity measurement is kept and the flow rate is posted indicating how the line is doing so far that day. The material kanban system indicates how fast material is turning and highlights any potential shortages. At the end of the day, operator flexibility and the IPK’s at each workstation will reveal if the line was under- or overstaffed.
In a Lean factory, products are manufactured sequentially and accumulate standard work from each workstation as the unit moves progressively from workstation to workstation until it is completed. A quantity of “one” is the batch size of products being transferred between workstations. Accumulation of semi-finished products between workstations is limited to the total number of in-process production signals (IPK) on the line. Because of production signal discipline on the Lean factory, large piles of WIP inventory cannot build up because there is no space allocated for its accumulation. On a mixed model Lean manufacturing line, a variety of different product configurations are being built at any point in time.
Because the standard work at each workstation has been balanced, operators on a Lean line are not required to walk along the unit being produced on a moving line or rush through their work just to keep up. Instead, they are instructed to take the appropriate time necessary to ensure that units transferred to the next downstream workstation contains the standard time amount of work assigned to their workstation and meets the quality standards defined by the standard work definition. Workmanship quality is greatly enhanced because the time necessary to perform quality inspection work is allowed at each workstation for every product.
An intrinsic value for operators working on a Lean line is job satisfaction. Operators are required to receive extensive training to perform the standard work assigned to a variety of workstations. A Lean operating system requires operators to flex up and down to different workstations in response to in-process production signals. Line operators and technician input and expertise about product production are actively sought during process improvement projects. Feedback from operators to production management is encouraged daily resulting in improvements being made to the manufacturing process. Operators are also encouraged to participate in kaizen activities that focus on a specific reduction in a non-value adding activity. Operators on a Lean line are highly motivated to complete their work in the assigned time and at the rate designed for the line. Operator’s knowledge of the line’s daily goals and production rate helps to promote self-management of the line reducing the need for constant supervision.