Lean Analysis Tools
Critical Path Analysis
Within every workflow or production path, there are core elements that are essential to its success. These elements are critical. When you look at the current state VSM, you need to identify those elements that are critical and highlight their interactions. These will be the fundamental components of the production or manufacturing system.
There are many methods of displaying Critical paths. Using Post-It™ notes allows you to physically create a flowchart and then sketch it onto paper if needed. You may also choose to use software like Microsoft Visio® to draw the flow. There are a number of software products available that will show these in PERT workflows or GANTT charts. PERT flowcharts are most commonly used within Lean as they are easier for most people to see the path of activity and develop value streams from.
There is also some discussion about how you show the timings for each activity in a PERT workflow. Current thinking is that the timings are displayed with the activity at an end point to each flow and the diagram below is what that would typically look like. You may find some people will place timings on the connectors for each activity, but that is becoming less popular.
This is not so much a method but a guide on all the potential areas for waste that need to be considered. The word is an acronym made up as follows.
- Transportation: Is there unnecessary or excessive movement between activities?
- Inventory: Do you have any excess raw materials: partly processed or completed products without value at any point in the process.
- Movement: How much do you move things about the production process? Are there repeats or extended movements without value?
- Waiting: Are things waiting for another action or held pending in the process?
- Overproduction: Are you creating too quickly or too many of the product for the customers’ demand?
- Over-processing: Are you creating something greater than that needed by performing beyond expectations without value?
- Defects: Are there items being produced that would be unacceptable to the customer from a quality viewpoint?
Kanban, JiT, Push & Pull
When you look at the process, determine whether it is pulling products from the previous part of the process or pushing items to instigate the next part of the process. Pushing items to the next part of the process relies on statistical forecasting and is prone to errors as demand changes and customer needs alter. Consider if you are using push processes and whether they can be changed to a pull process. This means that it is the next step that identifies the demand based on its needs. So only enough items are produced to meet that need, avoiding unnecessary inventory waste but always providing enough to meet the requirement of the process element that follows.
Kanban describes the way this information is transmitted, so that metrics are passed along the process flow to ensure needs are met. Similarly JiT or Just-in-Time examines the way delivery is scheduled at each stage of the process, so that only those items required arrive when they can be used.
Five S (5S)
The 5S tool allows examination of a process to identify non value-added elements. Although the original 5S words were Japanese, an Anglicized version has been created using the following words: Sort, Straighten, Shine, Standardize, and Sustain.
- Sort: Remove what is not needed
- Straighten: Organize what remains
- Shine: Clean the work area
- Standardize: Make sure a regular cleaning and maintenance schedule is in place
- Sustain: Embed 5S as part of the culture
It is worth using these 5 tenets and plotting the current effort or activity on each of these against a regular pentagram to see what needs to be moved to achieve the right levels. You can even award a score matrix and measure all locations within a business on these scales.