Section 2. The Pace for a Single Process Step Is Too Slow


2. The Pace for a Single Process Step Is Too Slow

Overview

Sometimes, even though the step is running, it isn't cycling fast enough to process entities to meet downstream demand. Pace is the speed of the process step when it is up and running doing VA work. This is not the average process rate that is traditionally captured. For a detailed explanation of Pace refer to "Overall Equipment Effectiveness (OEE)" in Chapter 7, "Tools."

Plan only to make improvements to the Pace after other categories of NVA work have been improved.

Measuring Performance

Measures of Pace of a process step are usually process-specific but are generally written in a form of number of entities per unit time, for example:

  • Kg product/hr

  • Patients/hr

  • Widgets/hr

  • Invoices (or orders)/hr

Similarly, they can be written as an average time to generate or process an entity, such as average processing time.

The data needs to be captured only when the process is running and should not take into account the average slowing of pace due to process stoppages, downtimes, and so on. Those elements should be accounted for in the %Uptime metric in OEE. If the primary concern is Uptime, then proceed to Section D in Chapter 3 instead.

Tool Approach

If a Baseline Capability hasn't already been done at a previous step, then:

Pace is challenging to determine; so a quick MSA is always worthwhile. The focus is on measuring validity, a sound operational definition, and a consistent measure of Pace while the process step is doing VA work, versus a detailed investigation of Gage R&R. See "Overall Equipment Effectiveness (OEE)" and "MSAValidity" in Chapter 7.

Pace capability is measured by taking the average Pace (over a period of time) as a percentage of the highest instantaneous Pace the process has achieved. See "Overall Equipment Effectiveness (OEE)" in Chapter 7. The data should be captured over a period of typically one week to one month (depending on process drumbeat) to get a reasonable estimate of average pace. There is usually less variation in the VA component of work, and, hence, 15 to 20 data points give a solid average. If there is known variability in the Pace, then capture 30 or more data points.


Even though we often consider a process step of this type to be the smallest, indivisible unit of a process, there are usually sub-steps within each step. To accelerate the Pace, it is useful to subdivide the single step into its sub-steps to see if there are any NVA sub-steps involved at a lower level.

This involves an excruciating level of detail for some, but in the majority of cases, it identifies opportunities where the process step waits for something (usually information, materials, testing, and so on).


From the VSM, identify actions to remove any NVA activity from the process step. Also, it is important to take advantage of any paralleling of sub-steps that might be available; if this step truly is the bottleneck in the process, then it is worth adding additional resource to it. A useful tool to help here is Critical Path Analysis:

Critical Path Analysis allows the Team to see the longest chain of activity in the process step that drives the Cycle Time. For more details see "TimeGlobal Process Cycle Time" in Chapter 7. Offloading tasks from the Critical Path reduces the Cycle Time accordingly.


At this stage it useful to take a step back and look at the big picture and ask the questions:

  • Why are we doing this?

  • Is there any other way to do this?

  • Does is make more sense to offload work from this step to other adjacent steps?

  • Is it better to add more resources to accelerate the step?

  • Is it better to split the step into two or more steps?

  • Is there a simple changing of technology or approach to the whole process that would help?

If, after answering these questions, there is still a desire to continue along this path to improve the Pace, then the roadmap to a solution from here on relies on the equation Y=f(X1, X2,..., Xn), where the Ys are the Cycle Time and the Primary Performance characteristic(s) of the process. For instance, if in a chemical production process we are interested in the assay of the product as a Primary Performance characteristic, then the Ys are assay and Cycle Time.

Go to Section C in Chapter 3 and focus on this single process step to determine which Xs can be manipulated to gain the best level of performance for the Ys (including Cycle Time).




Lean Sigma(c) A Practitionaer's Guide
Lean Sigma: A Practitioners Guide
ISBN: 0132390787
EAN: 2147483647
Year: 2006
Pages: 138

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net