Six Sigma provides a number of methodologies for driving product defects down to less than 3.4 per million opportunities. Two of the best known processes have similar acronyms: DMAIC and DMADV. Both are used to eliminate defects, but they are used in different situations.
DMAIC is used to incrementally improve an existing process or product. It stands for:
DMADV is used to design a new product, or to radically redesign an existing process or product. It stands for:
- Validate (Verify)
That may not seem like much difference; the first three steps are identical, and only the last two steps are different. But the differences between DMAIC and DMADV are significant.
DMAIC is an approach to incrementally improving an existing process or product. It focuses on making adjustments and controlling something that already exists, with the objective of improving quality.
DMADV, on the other hand, is a Design For Six Sigma (DFSS) method that puts the focus on customers, and creating the right product or process correctly the first time. The customer needs must be quantified to create an objective specification, which in turn leads to an outcome that meets those needs. By creating an objective specification, with measurable parameters, there is a specific way to keep track of progress.
The DMADV (Define-Measure-Analyze-Design-Validate) method aims to redesign a problematic process or product. The approach initially follows the first three steps of DMAIC and then deviates in the last two-steps by introducing Design/Redesign and Validate steps to gain the improvements needed. This approach prevents problems from happening through quality and robust design concepts.
There is a variation of DMADV that adds an additional step. It is called DMADOV:
The basic difference between DMADV and DMADOV is that “O” for “optimize” has been added. This sounds like a trivial observation, but many organizations' design process do not include this refinement action. Oftentimes they produce only a minimally workable product or process. DMADOV forces attention on the need to optimize the design. Additional tools useful in this phase include “design of experiments (DOE), response surface methodology (RSM), and evolutionary operations (EVOP). These methods help the design team establish and refine design parameters.
Step One of DMADV – Define
DMADV starts by defining customer needs. The customer in most cases is an external entity, but customers can also be internal. For example, when designing a process that feeds components to another in-house process, the customer is internal.
The best sources for this information are the customers themselves. Make note of what they say they want, as well as what their own objectives are. For example, a customer may say a left-handed widget is needed, but after listening to what they need the widget to do, you might determine that a Teflon-coated left-handed widget might be a better solution. Discuss your ideas with the customer to define the best possible solution for the customer’s actual needs.
Information that can be used to define what the customer needs might also come from industry research, historical data, your sales department, and research your company has done. Whatever the source of information, the objective is to have the product design be primarily driven by what the customer needs and is willing to pay for.
Step Two of DMADV - Measure
The second step is to use the definition of what the customer wants to create a specification. The specification defines the product or service in a way that is measurable, allowing data to be collected and compared with the specified requirements. This is essential for ensuring the final product meets the customer needs, defined in the first step.
In this step, there are four categories of characteristics to be measured. These are:
- Critical to Quality (CTQ) - quality parameters that directly relate to the customer's needs.
- Manufacturing Process Capability [link requested to our “Process Capability” article, but none found.] – the capability of the process to meet its purpose. Can the product be made so as to meet the customer's needs?
- Risk Assessments – what are the risks and how can they be measured? For example, what are the regulatory requirements the product must meet? Are there measurable standards? What is the schedule that must be met, and what are appropriate milestones?
- Product Capabilities – establish the ways to measure how well the product meets customer needs.
If DMADV is being used to improve an existing process or product, then these characteristics would be measured in the existing process or product. As improvements are made, the progress from the existing condition toward the desired characters can then be measured.
Step Three of DMADV - Analyze
At this stage, the proposed process or product is analyzed and studied to determine whether there are better ways to achieve the desired results. Areas that need adjustment or improvement, both in the product and the process of making the product, are identified. A prototype may be built at this stage and analyzed. The purpose of this step is to come up with alternatives, analyze those alternatives, and incorporate those alternatives that improve the process or product.
Step Four of DMADV - Design
Based on what was learned in the analysis step, design the new process or product. As revisions are made, the analysis step is repeated to compare the new design with the specified characteristics. Customer test groups may be used to test new designs to determine how well they are meeting customer expectations.
Step Five of DMADV – Validate (Verify)
The fifth step involves verifying that the end result meets or exceeds the customer's requirements. This includes verifying the product is being made as it is supposed to be made, as well as whether it is meeting the requirements of the specification. This is on ongoing process. Even after the product is released, customer feedback should be encouraged and incorporated into future designs. The desired result is to have a product that perfectly meets the customer’s requirements and desires.
The book Six Sigma 100 Success Secrets, by Gerard Blokdijk, has a good summary of these five steps:
D means definition of goals to provide consistency between processes.
M is for measuring CTOs (critical to qualities), which consists of product risk assessments and capabilities among others.
A stands for analyzing various project designed and choosing the best one that fits business goals and objectives.
D is for designing of product details.
V means verifying the design that may also require project leaders to hand it over to process owners for confirmation.
DMADV and the Need for DuraLabel
Whether making a new product, designing a new process, or upgrading an existing product or process, DMADV involves significant change. Employees need to be warned about safety impacts of the changes, and be reminded about new procedures and standards. That's why having a DuraLabel custom label printer handy is crucial. With DuraLabel you can make whatever labels, signs, and tags are needed – from OSHA required safety signs, to labels providing equipment operating instructions.
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