Six Sigma Fundamentals: A Complete Introduction to the System, Methods, and Tools

As we have already said, the approach of DFSS is quite different from the DMAIC model. Therefore, the training is also different. Fundamental issues for this training are:

• Understand and employ the DCOV process.

• Define and select a six sigma project for design, or redesign, of goods or services.

• Correlate customer needs with the specific features of a product or service.

• Analyze the potential effect of failures on the selected design.

• Achieve robust design levels that will function over the environmental areas of use.

Generally, the training for DFSS is of five-day duration, and it provides an overview of the six sigma approach to planning and design. The DCOV strategy emphasizes design for manufacturability of goods and/or the repeatability of services. Each phase is discussed together with the methods and tools typically used. A typical roll out follows the following steps:

• Explain the roles and responsibilities of the black belt, DFSS engineer and green belts in the DFSS process.

• Identify the DFSS training sequence for those involved in DFSS process sequence.

• Explain the DFSS, DCOV model/process.

• Demonstrate how the assessment measures the DCOV process.

• Identify the selection criteria for design projects.

Typical overall objectives of DFSS training are to:

• Apply coaching tools to support the engineering processes for DFSS.

• Select the appropriate customer satisfaction variables.

• Explain a transfer function and the relationship to improving customer satisfaction.

• Select the appropriate tools for applying the DCOV process.

• Explain robustness improvement strategies that will improve customer satisfaction.

• Identify resources available for assistance.

Specific training objectives for each phase of the DCOV model are as follows:

• Define. To capture the voice of the customer, trainees must learn to:

  • Establish the scope and goals of the project.

  • Develop the six sigma project plan.

  • Flow the macro process.

  • Describe the DCOV process and its associated steps.

  • Describe the relationship between DFSS activities and organizational timing.

  • Describe the relationship between DFSS and six sigma processes.

  • Establish balanced metrics.

  • Establish critical to customer metrics.

• Characterize. Trainees learn about system design, including how to:

  • Validate the measurement systems.

  • Identify process options that will satisfy customer requirements.

  • Identify weaknesses of the process actions.

  • Develop and understand the cause and effect matrix.

  • Employ statistics, experiments and observations to verify cause and effect.

  • Apply functional structure methods for flowing CTS big Ys down to lower level technical metrics, the small ys.

  • Determine critical little ys from list of technical metrics.

  • Select the appropriate tools for evaluating and generating new design concepts.

  • Explain evaluation criteria and assessment for this step.

• Characterize. Trainees learn about the functional mapping aspect of the DCOV model, including how to:

  • Determine method for relating little ys to critical to quality (CTQ) design parameters.

  • Describe how to flow little ys down to design parameters (xs) and noise factors (ns) using the transfer function.

  • Determine critical xs and ns.

  • Characterize robustness opportunities.

  • Explain evaluation criteria and assessment for this step.

• Optimize. Design for robustness is the topic of training for this aspect of the DCOV model. Trainees learn how to:

  • Characterize the present long time in service robustness for the product.

  • Select methods for improving product and process robustness by further minimizing product sensitivity to manufacturing and usage conditions—as required.

  • Explain the relationship of robustness and producibility.

  • Identify the appropriate tools to use when designing to be insensitive to variation.

  • Explain the process of robust assessment.

  • Explain the function, criteria for selection as a tool and interpretation of outputs of parameter design, tolerance design, statistical tolerancing and analytical reliability and robustness.

  • Explain the evaluation criteria and assessment for this step.

• Optimize. For the design for productivity function of the DCOV model, trainees must learn to:

  • Select process and product characteristics that will meet customer requirements.

  • Characterize capability and stability of present process.

  • Minimize process sensitivity to product and manufacturing variations—as required.

  • Explain the relationship of this step and the organization's milestone timing for product development as well as robustness.

  • Explain the purpose and selection criteria for determining the appropriate tools to make the product insensitive to noise.

  • Explain the purpose and selection criteria for each of the countermeasure tools as appropriate, including dynamic control plan, poka-yoke, sequence modeling and selective assembly.

  • Explain the evaluation criteria and assessment for this step.

• Verify. The verify step in the DCOV model involves assessment and testing, and training therefore focuses on how to:

  • Estimate sigma for process capability and product function at job one and over time.

  • Explain the evaluation criteria incorporated in the assessment.

  • Explain the use of the assessment in processing through the DFSS process.

  • Identify tools for assessing actual performance, reliability and manufacturing capability.

  • Explain what is meant by demonstrating customer correlated performance over time.

  • Explain the relationship between establishment of a transfer function, ys, xs and ns, and the development and execution of a quality design and verification plan.

  • Explain the evaluation criteria and assessment of this step.

  • Verify that the design can satisfy customer requirements.

Selected topics are covered in greater detail as needed. The typical content is:

• Why the DFSS approach is different.

• What does six sigma mean to a designer.

• Capability indices and their use.

• The DCOV strategy and when to apply it.

• How to define a six sigma project.

• Principles to apply in establishing metrics for a project.

• Correlating the voice of the customer with product features (QFD).

• The analysis phase and conceptual design.

• Concurrent design.

• Principles of experimentation.

• Statistical tolerancing.

• Concept of reliability.

• Decision matrices.

• Failure modes and effects analysis (FMEA).

• Fault trees.

• What constitutes an adequate pilot program.

• Planning for control.