Streamlining the Value Stream
By streamlining the value stream (and dispersing functional departments), we can significantly reduce and often completely eliminate waste.
Steps to streamlining the workflow:
- Value Stream Mapping: Understand the sources of waste in the value stream and map the future state.
- Work Analysis: Collect detailed data on the work process and analyze that data.
- Macro Workflow: Plan physical changes to the flow and layout of the facility.
- Micro Workflow: Fine tune the flow and layout at the work center level.
Why start with a value stream map?
- The initial value stream map serves as a jumping off point for improving the overall value stream.
- A value stream map documents the flow of a product from the dock of the raw material suppliers through the manufacturing facility to the customer’s dock. In addition to showing the steps that the product takes, it also shows the process performance of each step and the time of each step.
What is involved in work analysis?
- Work analysis involves detailed engineering studies that look at units of production and the elapsed time needed to produce those units. (Yes, stopwatches and tape measures are still used!)
- The engineering studies set the stage for designing work cells, determining how to level load operations, defining labor requirements, and setting lean manufacturing goals.
- Effective work analyses cannot be done using historical data or educated guesses. Work analyses can only be done by going out into the process and timing operations.
- Some of the opportunities for improvement will become obvious even at this early stage in the process. While collecting process performance data and observing the process, constantly look for ways to improve the operation. With the employees that work in the area, develop ideas to eliminate waste. Sometimes an entire task or process step can be eliminated or combined with another task taking a big bite out of waste.
Improve the workflow at a macro level.
- Identify natural work flows for products or product families.
- Disperse functional processing centers.
- In lean manufacturing, functional departments are broken up and dispersed into cells where possible.
- Allocate the equipment based on work analysis data and the anticipated sales volumes for the cells.
- If two cells need to share a piece of equipment, consider making that equipment portable. If this cannot be done, then locate the common process equipment between the cells and flow the two cells around it.
Use cellular concepts.
- The ultimate goal for manufacturing cells is to start and finish production right in the cell, generating a complete product ready to ship as it exits the cell.
- Disperse the functional processing centers into work cells with sequential operations.
- Move equipment so that sequential process steps are in close proximity.
- Simplify the workflow; eliminate or combine steps where possible.
- Material handling and intermediate inventory are good candidates to eliminate.
Design around monuments.
- Monuments are pieces of equipment or departments that cannot be cost-effectively moved.
- Anchor the layout around the monuments.
Use raw material entry and shipping exit points to select process flow locations.
- The process flows handling the greatest cubic volume should travel the least distance.
- The location of the entry (receiving) and exit (shipping) points is critical to a macro workflow.
- The greater the processing volume (in cubic feet), the shorter the overall distance the process flow should be.
Don’t forget to incorporate support functions into the cells.
- For example, maintenance activities specific to a cell and special testing specific to a cell should be moved to the cell rather than kept in a centralized area.
Design effective work stations at the micro level.
- Once the overall facility workflow has been analyzed and an overall or macro flow has been selected, it is time to focus the efforts at the specific cell and work station level.
- Remember to incorporate 5S concepts such as Sort and Set-in-Order techniques when laying out and organizing the cells and related work stations.
Characteristics of a lean value stream:
- No inventory piles (no WIP)
- Simulated continuous flow
- Operations in close physical proximity to each other
- Fast change-overs and set-ups
- Small lots
- Short cycle times
- Level loaded processes
- Reliable processes