Design for Six Sigma (DFSS) is a disciplined problem prevention approach, used to achieve the Six Sigma goal. In addition, DFSS is a systematic process to prevent defects affecting what is important to the customer. Industrial Design Engineering (IDE) providing a fundamental set of principles that determine good industrial design practice, can help a project team implement a DFSS process. This CRC News discusses a new paradigm based upon a case study, which provides a great opportunity for the engineering organization to accomplish customer satisfaction and profitability. Application of IDE design principles in DFSS presents a systematic design model. This is achieved by adding a feedback, to validate the process variables according to customer attributes.
In today’s industries, new technologies are being developed and improved at a very fast pace. In this dynamically changing world, product development cycles are expected to be much shorter than in previous years, while the expectation for quality has become much higher. To meet these demanding requirements, products have to be developed in the shortest amount of time that are safe, reliable, environmentally-sound and competitive.
Design for Six Sigma is a systematic methodology that utilizes process definition, tools, training, measurements and management controls to enable project teams to design products and processes that meet customer/consumer’s expectations. These products and processes can be produced and serviced at Six Sigma quality levels. IDE is one of the DFSS tools that can help ensure that our design specifications, manufacturing capabilities and systems integration are fully aligned with the voice of customers.
A typical DFSS process is comprised of the following phases:
- Define: clear definition of the project goals and customer deliverables (internal and external)
- Measure: accurate measurements that determine customer needs and specifications
- Analyze: ensure that the process options meet the customer needs through analysis
- Design: a detailed design of the process to meet the customer needs
- Verify: verification that the design performance and ability meet customer needs.
Based on benchmarking, business key strategies and features of engineering organization’s products, the inventive problem solving process Design for Six Sigma (DFSS) process is comprised of the following five phases:
- Situation Appraisal: clarifies the problem situation (‘what happened ´).
- Problem Analysis: the actual cause of the problem and the relationship between cause and result are searched for (why did it happen).
- Decision Analysis: based on the decision making criteria, choices are made to arrive at potential problem resolutions (how should we act).
- Risk Engineering Analysis: potential future problems and business opportunities are anticipated and actions are developed (what will the result be).
- Validation/Communication: Validate/communicate the project, product, and process lessons learned through Business Communication.
IDE is one of the Design for Six Sigma tools the team has applied, and described briefly above. This CRC News provides an example for systematically introducing IDE into Design for Six Sigma. The applied ground transportations case study is based on an actual benchmarked DFSS project; i.e. the development of an innovative engine crankshaft-sealing system, for a low-emission engine.
This case study, used in the Design for Six Sigma (DFSS) represents an inventive problem solving model as shown by the attached. In addition to the forwarding mapping process in a typical IDE, the project team added backward mapping between Risk Engineering Analysis and Situation Appraisal through design validation. This backward mapping ensures that the innovative engine crankshaft sealing system can be produced and serviced at Six Sigma quality levels. This is evident through validation of its performance, reliability, manufacturability and serviceability.
Using DFSS terminology, this feedback mapping represents “Flowing-Up Process Capability” after “Flowing-Down Requirements”. In the IDE case-study, the feedback mapping between Risk Engineering Analysis and Situation Appraisal consists of; the modeling and testing for sealing capability testing, mechanical integrity testing, reliability/useful life testing, and process capability to assure the following Critical-To-Quality characteristics (CTQs) are satisfied:
- Non-leakage
- Long sealing life
- No dirt entry
- High fatigue strength
- Resistance to torsional vibration
- Low defects/scraps during manufacturing
- Low manufacturing variable cost
- Ease to assemble
- Zero-defects at vehicle launch
- High reliability/product useful life
- Low preventive maintenance cost
- Low spare parts cost
- Low part replacement cost
- Zero-defects to engine overhaul
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