Six Sigma


The Problem

A company which supplies parts and services has certain requirements from its customers, which include low cost, reliable assemblies, and on-time delivery. While all three factors are important to both the supplier and the customer, the customer has identified delivery time as their primary concern since they do not have the resources to handle the variation. The supplier is late far too often, and if the supplier ships the assemblies too early, it causes problems for the customer. As such, the company wishes to use a Six Sigma approach to reduce variability in delievery times. Six Sigma is a term for various coroporate strategies used to lower variation and unpredictability in some aspect of a product.

The company held an internal meeting to improve their delivery process. They defined a measurement, Customer Delivery, which is the number of days between when a shipment is promised and when it is actually shipped. The measurement is positive number if the shipment is late and is negative if the shipment is early. At the meeting, the company discussed what they can measure at their facility as a predictor of Customer Delivery. Students will mathematically identify which factors contribute to variation in Customer Delivery and produce a set of recommendations for the company to reduce that variation.

Background Information

Since the supplier has decided that Customer Delivery has the highest priority in keeping their customers satisfied, the supplier would like to explore the various factors that cause the variability in Customer Delivery and determine mathematically which, if any, can be controlled. The delivery dates acceptable to the customer are in the time frame of 10 days early and 20 days late 95% of the time.

DMAIC – pronounced “Duh-May-Ick” – refers to a data-driven quality strategy for improving processes, and is an integral part of the company’s Six Sigma Quality Initiative. DMAIC is an acronym for five interconnected phases: Define, Measure, Analyze, Improve, and Control

Define who customers are, what their requirements are for products and services, and what their expectations are
Define project boundaries, the stop and start of the process
Define the process to be improved by mapping the process flow
Develop a data collection plan for the process
Collect data from many sources to determine types of defects and metrics
Compare to customer survey results to determine shortfall
Identify gaps between current production and goal performance
Prioritize opportunities to improve
Identify sources of variation
Create innovative solutions using technology and discipline
Develop and deploy implementation plan
Prevent reverting back to the “old way”
Require the development, documentation and implementation of an ongoing monitoring plan
Institutionalize the improvements through the modification of systems and structures (staffing, training, incentives)

From GE’s DMAIC Approach:

Materials Included

There are two versions of this project, the first for algebra students and the second for statistics. Both are available for download below, along with the appropriate Excel files.

  • DataFile.xls
  • GageRR.xls
  • MSAResults.xls
  • ICD.xls

Additionally, an optional extension to the project delves more deeply into some of the decision-making processes outlined in the main project. The extension is appropriate for both the Algebra and Statistics versions.