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38 ISE Magazine | www.iise.org/ISEmagazine Do it right the first time • Deliver a robust design that is insensitive to noise. • Manage the variability in a design. Design for Six Sigma complements the product develop- ment process. The voice of the customer interpretation tools are key to design for Six Sigma, along with engineering and statistical methods used during product development. The main objective of design for Six Sigma is to "design it right the first time" by identifying product features and functions that the customer can recognize as being beneficial, ensur- ing the object of design can consistently deliver exceptional performance. Customers change constantly, and we need to be able to change to meet their needs through innovation and bench- marking. However, we want them to be satisfied right away – and design for Six Sigma practices can make sure your cus- tomer is happy the first time around. This will prevent the customer from going to your competitors, and it will gain commitment from them, along with future access to their buying power. Let's examine a couple of examples of how design for Six Sigma has been applied to design products. Example 1: Portable energy solutions Customers are always on the move with their electronic de- vices; however, finding charging stations is not always easy. Based on this need, a design for Six Sigma team focused on developing a portable charging solution that was versatile. By conducting an extensive survey to gather the voice of the customer, the design for Six Sigma team was able to gain a comprehensive perspective of customer needs, such as need- ing a minimum 5,000 mAh output charger that has a status indicator, is easy to use, small, universally compatible and able to withstand a 3-foot drop. The team then used quality function deployment to in- tegrate the customer expectations into the functional re- quirements. This step also involved conducting a thorough benchmarking analysis to identify areas for improvement and prioritize efforts for the product design. Design for X was then used to generate several concept de- signs, which were evaluated against the voice of the customer using Pugh's concept selection matrix to identify the supe- rior concept. Next, optimization methods were employed, including modeling the robustness and tunability of the mean critical functional responses and modeling vibrational sensitivities across the integrated product design in addition to creating a system additive model, system variance model and robustness additive model. The design for Six Sigma team applied these methods to the superior concept in order to minimize noise, improve reliability, reduce failures and improve functionality. Applying design for Six Sigma helped the product meet the needs of the customer by deploying the voice of the customer through the design of the product, which resulted in a univer- sally compatible charger with solar-charging capability. Example 2: Better beds for the hospital Design for Six Sigma also was used in a case to redesign a standard hospital bed. Hospital bed designs must comply with strict guidelines from the Food and Drug Administration to ensure safe op- eration to reduce potential life-threatening entrapment areas. In order to redesign a hospital bed effectively, all stakehold- ers, including patients and medical staff, must be considered to ensure a safe, comfortable and efficient final product. In addition, as medical costs continue to rise, expense is also a key factor. The first step in the project was to identify all of the stake- holders. This was done through social network analysis. Once the stakeholders were identified, an extensive survey was distributed to gather the voice of the customer from each stakeholder group to determine the critical characteristics. Using the voice of the customer, the design for Six Sigma team brainstormed ideas to improve the standard hospi- tal bed design, which were then organized using the Kano model. Exciting quality features included a built-in tablet for entertainment and ability to track medications. One-dimen- sional quality characteristics included adjustable height, suit- ably placed controls, ergonomic side rails and a bed that was easy to move around. Finally, expected quality characteristics included comfort and affordability. Since cost is an issue, the design for Six Sigma team focused on the expected and one-dimensional characteristics, which were ranked and prioritized. The design for Six Sigma team then employed quality function deployment to translate the customer expectations into functional requirements for all levels of the system ar- chitecture. This also involved a competitive analysis against three hospital beds that medical centers use widely. Using this information, the design for Six Sigma team de- veloped nine conceptual designs. Due to the complexity of the design, the team considered the system architecture to cascade the customer and product characteristics through all levels of the design. The conceptual designs were compared to the voice of the customer using the Pugh concept selection matrix. Through the comparative analysis, the best aspects of each conceptual design were combined to develop a hybrid design to better address the customer needs. The final design was optimized using the p-diagram to understand the input-output relationship of the performance parameters. Noise factors such as wear and tear, hydraulic malfunctions and electrical failures were considered in the p-diagram. This information was then used to identify po-