When to Use Lean Six Sigma Tools? - PART I

In many scenarios, new lean six sigma practitioners, uncertain about the methodology, tend to get confused on when to use the different lean six sigma tools. This article, the first of a two-part series, gives an overview on when to use different Lean Six Sigma/Change Management tools and in which phases of DMAIC (Define, Measure, Analyze, Improve and Control). 

#1: Fish Bone Diagram (Ishikawa diagram) or Cause and Effect Diagram

To brainstorm the causes of variation (represented by bones of the fish) that lead to the effect (represented by the head of the fish! (6Ms – Man (and Woman!), Machine, Method, Mother Nature (Environment), Measurement System and Materials. Ensure that Man (or Woman) ONLY doesn’t get blamed as the cause of variation; don’t debate endlessly whether a particular cause is Method or Man etc - note down the causes first and then classify later

Which phase of DMAIC to use? Measure/Analyze

#2: Hypothesis tests

To test and prove or disprove a hypothesis (for example, to test whether the average production time of a shift 1 is greater than shift 2). Ensure you use the right hypothesis test. Also ensure the pre-requisites for each hypothesis test are met. Refer Minitab Statguide for detailed information.

Which phase of DMAIC to use? Measure/Analyze

#3: 5-Why Analysis

To get down to the root cause of a particular problem/issue. Ensure that God doesn’t get blamed for everything.

Which phase of DMAIC to use? Analyze 

#4: Cause and Effect matrix (C&E matrix)

To rank each X against Primary Y, Secondary Y and the Counterbalance and prioritize Xs. Operational definition of rating (9-3-1-0) an X against a Y should be clear and agreed upfront.

Which phase of DMAIC to use? Measure/Analyze

#5: Kaizen event

When the problem/issue needs to be solved immediately and requires a focused effort (and time) from the team. Ensure the pre-work is planned thoroughly and completed prior to actual kaizen event; scope should be defined such that the problem/issue can be solved and solution implemented within 3 - 5 days (or atleast a pilot).

Which phase of DMAIC to use? Improve

#6: 5S

To sort, organize and perform housekeeping of files, products, service items, maintenance tools, clothes, etc. Helps with increasing productivty and employee morale

Which phase of DMAIC to use? Any Phase

#7: Poka Yoke

To mistake proof a solution/process/sub process. Physical prevention of an error is the best form of poka-yoke - strive for this.

#8: Value Stream map

To not only map out the flow of a process, but also get in-depth information about the process such as Customers, Suppliers, Downtime, Errors, Production time, Inventory, Value added time, Information flow, Material flow, People flow, Throughput rates, Incoming raw material rates, 8 wastes etc; to determine the bottlenecks in a process.

Don’t rely on existing process maps/SOPs to construct a VSM; observe and walk through the process (Gemba) 3 - 4 times to get a good understanding of the process before constructing a VSM.

Which phase of DMAIC to use? Measure

#9: Process Map

To visualize the flow of a process. Swim lane process map can be used to capture the steps of the process as well as the who executes those steps.

Which phase of DMAIC to use? Define/Measure

#10: Measurement Systems Analysis

To rule out the possibility that Measurement System is one of the causes of variation (one of the 6Ms)

Ensure that the MSA is conducted with full cooperation from the participants; Ensure all the rules of the MSA are followed (for example, minimum number of operators, parts etc). Refer Minitab Statguide for detailed information.

Which phase of DMAIC to use? Measure

#11: Design of Experiments

To experiment actively and determine the optimum levels of critical Xs to achieve the desired Y. There are many types of DOEs. Refer Minitab Statguide for detailed information.

Which phase of DMAIC to use? Analyze/Improve

#12: Regression

To establish an equation between critical Xs and Y and predict future values of Y. Always test whether the assumptions of the model are valid or not (for example, for least squares method, all residuals must be normally distributed, should show no pattern or in other words remain a mystery!). Refer Minitab Statguide for detailed information.

Which phase of DMAIC to use? Analyze/Improve

SOURCE: processexcellencenetwork