Six Sigma Process Mapping by Mohamad Hisham Hamdan MBB

Process mapping is an essential tool in helping us understand the activities and sequence of steps involved in any process. It also helps to identify areas where data collection should take place. It is commonly used at the early stages of project definition or project development to visualize the activities involved in a process.

By comparing the “as is” against the “ideal” process diagram we can identify opportunities for improvement , such as identifying the non-value added activities or condensed certain steps into one so that the lead time of a process can be shorten.

A process map may have various levels of detail. At the system level, the process map depicts linked processes (a product is a function of processes), whereas the subsystem level represents operations that are linked (a process is a function of operations).

There are various types of process maps. The Macro Flow Diagram is a general version that shows only major activities without any decision points. The deployment version identifies the sequence and persons responsible for completing each activity. The tabular version (process mapping format) allows us to compare “observed” against “target” values of a process map.

All process maps have some key elements, regardless of the nature of the product. Start and end points, activities, decision points and connectors are common to all process maps.

To ensure that a map is accurate and complete, it is recommended that the input of all team members be considered and validated.

Process Map can be used to improve CT tree as example below by Six Sigma Academy:

In order to improve the customer’s CTS (Critical To Satisfaction) characteristic “aircraft appearance,” a Champion and a Master Black Belt were studying the possibility of launching a Six Sigma project in the assembly area of the CRJ aircraft model. Following customer feedback, they decided to further refine this CTS characteristic as “skin appearance,” and they decided to concentrate on the mid-fuse section. The number of scratches per skin was defined as the CTQ (Critical To Quality) characteristic and a Six Sigma project was launched. The Six Sigma Black Belt knew that, in order to define the current defect-per-unit level, she needed to collect data. So she gathered the Six Sigma team to draw a Process Flow Diagram.

During a brainstorming session, the team identified the standard as a skin having zero scratches. They also agreed that the activities to study would be bound by those taking place in a particular assembly department. After having identified all the steps that take place in the department, they used the standard symbols to draw the Process Flow Diagram.

The team decided to organize data collection at the following steps:  a) load skins in racks; b) apply spray dots; c) drill and apply liquid shim; and d) scratch repair. Collecting data prior to the inspection points allowed the team to assess the “hidden factory.” In deciding which steps add value, the team considered a) Does the customer recognize it as important and would he/she pay for it if asked? b) Does the step change the product/service physically? and c) If done right first time, would this step be necessary? The following were identified as non-value operations:  a) inspection; b) application of liquid shims; and c) rework dots. Thus, possible improvements were identified at early stages of the project.

A Six Sigma Black Belt is assigned to a project with the objective of improving the quality of parts used in the assembly area. To narrow the scope of the project, the team decided to focus on reducing the amount of shimming used to close gaps and mismatches between ribs and spars.

To better understand the existing process, one of the steps the Black Belt did was to draw the “as is” process map. Upon further analysis and discussion, the team proposed a series of changes to reduce the number of operations required to fabricate the components. Some of the modifications include:

·         Changing the raw material to T6 condition, thus eliminating operations for heat treating and delays in freezer storage;

·         Producing the parts in the machine shop instead of stretch forming, thus combining almost all fabrication steps, eliminating the need for multiple deburr operations and combining inspection steps.

By utilizing this relatively easy but powerful tool, the team was able to obtain some quick improvements, reduce the complexity of the process and increase the capability of the CTQ.

This tool can be used by all levels in the organizations (i.e., Champions, Master Black Belts, Black Belts, etc.) and is applicable to all areas of the business (i.e., manufacturing, transactions, engineering, etc.).