If your organization’s Lean Initiative is getting bogged down or you are not seeing the benefits you hoped for, it is likely you have poor flow. Rapid flow quickly identifies bottlenecks and weak processes which in turn become targets for quick improvements. At each improvement, throughput rises while lead times, inventories, and costs drop – a very powerful cocktail. The goal is to keep products moving at all times, with no delays in awaiting transportation or a machine to be freed up. For most, this is a drastic re-thinking.
While Workplace Organization (5S) is a necessary foundation for all lean operations, it seldom produces improved flow by itself. Sorting all non-necessary items is the first step, then setting processes in order and. Standardize work is absolute necessity for both controlling processes and as a basis for process improvement. Shine maintains the workplace in top condition, and Sustain keeps the whole effort going. Where most organizations stumble is in Set in Order. Processes are seldom really thought through during initial lean efforts, and 5S becomes window dressing of current efforts rather than a thoughtful reengineering of processes to minimize waste. If flow has not improved through 5S efforts, it is likely weak processes enable repeated interruptions and poor flow due to quality issues (Standard Work and Visual Factory) or poor flow design (Set in Order). Once basic workplace organization is established, concentrating on the flow of products through your facility will show the true promise of Lean.
Assessing flow with Value Stream Mapping
Value Stream Mapping, or VSM, is a method of creating a “one page picture” of all the processes that occur in a company, for order receipt until the customer receives the product. The goal of VSM is to depict all information and material flows across all value adding processes required to produce and ship the product to the customer. It should show all processes, those adding value and those not adding value (waste). Making a simple map such as the one below will show the major delays in processing and give clues to a path to improving flows.
The simple value stream map shows a Total Lead time of 68 days for value added processes totaling 15 minutes. Sadly, metrics such as these are not uncommon in companies as they start their Lean Journey. Most initial efforts at Workplace Organization work around the major flow issues – focusing on “house cleaning” and visual factory – important foundations, to be sure, but the result is a little like a sandwich without the meat. The beef is flow. Just like a burger without the beef, lean efforts without flow are not satisfying.
In addition to Value Stream Map, a spaghetti diagram, a diagram showing part path through your plant showing the current flow vs. potential future helps identify excessive parts paths. In the next figure each product line is shown using a different colored line, with the weight of the line indicating overall production volume.
Once the process is understood and the possibilities for manufacturing cells are identified, the flow challenge is manageable. Reorganize the plant flow as quickly as possible, focusing on one or two easily identifiable, regular products to cut your teeth on.
Cellular manufacturing organizes the plant around similar product flows, rather than processes, as in the classic machine shop. Cellular Manufacturing strives to develop small “factories within factories” to focus efforts and wastes associated with moving and processing, including transportation, setup, and long queue times. Imagine the setup in the figure at right:
How does each department know what to work on at any given time? The management challenge for traditional department layouts is traffic flow and queue management. Quality problems are not often identified until the entire batch is completed. Due to conflicting demands, priorities, setups, run sizes, and material requirements (and delays), the complexity becomes astronomical is short order. Now add department production goals. Supervisors measured on productivity will tend extend work on products using the same setups or “easy work” even if it is contrary to the needs of the company.
Cellular Manufacturing, or a Factory within a Factory, is achieved by breaking up traditional departmental layouts, dividing like-machinery concentrations and reconfiguring the plant into single piece flow layout.
The resulting manufacturing landscape offers a simplified management challenge. Products move from machine to machine rather than machine center to machine center, and products flow easily from one station to the next. Benefits include:
- Single piece flow means quality issues are identified immediately and adjustments made accordingly.
- Specialization in both machine and manpower largely eliminates setups and adjustments.
- Batching and queue for transportation and then processing are eliminated.
- Simplified flows can be balanced with ease.
- Cross training opportunities abound due to the proximity of processing centers.
- The entire process flow can be increased or decreased by adjusting cell resources.
Once cells are brought on line, revisit scheduling and kanban systems – they should benefit immensely from simplified flows. Use visual systems wherever possible to pass decision making to the lowest level possible and watch your plant hum!