The Design for Six Sigma (DFSS) process also uses a phasing approach - Identify, Design, Optimize, and Validate (IDOV).
It can be viewed as the design process itself, or it can occur directly within each of your company's Engineering subsystem processes, i.e. Concept, Preliminary, and Product definition.
Or, it can occur as an offshoot of DMAIC, where technology entitlement has been achieved in the process and it’s time to look for a design solution to further improve the process Sigma.
IDENTIFY represents market needs, customer requirements (CTS), regulatory requirements, process optimization requirements, sub-system design requirements, etc. It can occur in a variety situations and phases. The data should be in a ranking format (Ordinal scale) to permit some cost and performance trade-off decisions to be made.
DESIGN, of course, represents both the initial concept generation or any re-designs required accommodating technology limitations.
OPTIMIZE encompasses a variety of activities and utilizes the majority of the DFSS tools. This is where the design concept is repeatedly adjusted and modified to produce a simple robust design of a known and verifiable cost and quality level.
VALIDATE represents all the detail, product, and prototype testing as well as verification of the product/process interaction.
As you can see in the picture below, design typically represents the smallest actual cost element in products, yet it leverages the largest cost influence. Therefore, if one were to identify the very top item in the list of the vital few this would surely be it!"!
Any incremental improvement in the design, through the use of the Design for Six Sigma process has a large direct impact on actual cost. For example: If we achieve a 30% savings through simplification (DFMA), this would translate into over 21% overall cost savings – a phenomenal achievement indeed! Yet the same 30% applied to Labor or overhead results in 1.5% savings overall."
The main reason is that elemental improvement tries to optimize a part or process, whereas DFSS may eliminate the part or process, or simplify it. This will often result in a direct reduction in material and labor cost, and an indirect reduction in the cost of overhead.
Yet, any improvement in one of the other three elements remains within that element. For example, a more efficient way of nesting sheet metal details on a 2-axis router machine will reduce the raw material requirement, and if carried out well will not increase the machine utilization time. The net savings, however, remains within that area and does not usually extend to the other elements of product cost.
If we use the Design for Six Sigma process to design a transactional process up-front with a minimum level of process steps, all the while meeting customer requirements, we will reduce the opportunities for defects". The goal is to decrease the probability of defects occurring on each unit, item, or service provided.
In order to reduce the likelihood of the event that a unit will not meet the specification, we must reduce the opportunities for defects – the events we measure that provide a chance of not meeting a customer requirement."
Consider the various processes that exist functionally and across your company. The existence of many processes and process steps increases opportunities for defects in information accuracy. Therefore, the quality level of correct information is not as high as it should be and we need to design a simple, standard process.
After understanding the process through process maps and requirements, we can standardize and optimize the selected process to meet the established targets for its accuracy. If we have data for each process step, we could use various statistical tools to establish process capability targets for each step.
Statistical analysis techniques would enable us to determine which steps are not adding value to the process. We may also want to look at cycle-time. Here, process simulation tools can be a very effective way to optimize cycle-time in the process.
We could also determine how to make this design more robust by determining the important interactions in the process. We can identify the variables that cause uncontrollable variation and then design the process to be robust to these variables. The possibilities are endless."
In summary, the Design for Six Sigma process is applicable to product, transaction and service design.
May 10, 16 09:24 PM
A Quality Control Plan is a documented description of the activities needed to control a process or product. The objective of a QCP is to minimize variation.
May 10, 16 08:49 PM
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May 10, 16 07:28 PM
The Weibull distribution is applicable to make population predictions around a wide variety of patterns of variation.