Design for Six Sigma
Encyclopedia
Design for Six Sigma is a separate and emerging business-process management methodology related to traditional Six Sigma
. While the tools and order used in Six Sigma require a process to be in place and functioning, DFSS has the objective of determining the needs of customers and the business, and driving those needs into the product solution so created. DFSS is relevant to the complex system/product synthesis phase, especially in the context of unprecedented system development. It is process generation in contrast with process improvement.
DMADV, Define – Measure – Analyze – Design – Verify, is sometimes synonymously referred to as DFSS. The traditional DMAIC (Define – Measure – Analyze – Improve – Control) Six Sigma process, as it is usually practiced, which is focused on evolutionary and continuous improvement manufacturing or service process development, usually occurs after initial system or product design and development have been largely completed. DMAIC Six Sigma as practiced is usually consumed with solving existing manufacturing or service process problems and removal of the defects and variation associated with defects. On the other hand, DFSS (or DMADV) strives to generate a new process where none existed, or where an existing process is deemed to be inadequate and in need of replacement. DFSS aims to create a process with the end in mind of optimally building the efficiencies of Six Sigma methodology into the process before implementation; traditional Six Sigma seeks for continuous improvement after a process already exists.
, operations research
(solving the Knapsack problem
), systems architecture
and concurrent engineering
. DFSS is largely a design activity requiring specialized tools including: quality function deployment
(QFD), axiomatic design
, TRIZ
, Design for X
, design of experiments
(DOE), Taguchi methods
, tolerance design, Robustification
and response surface methodology
. While these tools are sometimes used in the classic DMAIC Six Sigma process, they are uniquely used by DFSS to analyze new and unprecedented systems/products. A graphical flowchart of common DFSS tools can be seen at DFSS Roadmap.
and design for quality. In general Six Sigma with its DMAIC roadmap focuses on improvement of an existing process or processes. DFSS focuses on the creation of new value with inputs from customers, suppliers and business needs. While traditional Six Sigma may also use those inputs, the focus is again on improvement and not design of some new product or system. It also shows the engineering background of DFSS. However, like other methods developed in engineering, there is no theoretical reason why DFSS can't be used in areas outside of engineering.
DFSS in Software Engineering acts as a glue to blend the classical modelling techniques of software engineering such as OOD
or ERD with statistical, predictive models and simulation techniques. The methodology provides Software Engineers with practical tools for measuring and predicting the quality attributes of the software product and also enables them to include software in system reliability models.
There are no official standards from international bodies that describe the way of working for DFSS. This can however change in the future.
See also:
Six Sigma
Six Sigma is a business management strategy originally developed by Motorola, USA in 1986. , it is widely used in many sectors of industry.Six Sigma seeks to improve the quality of process outputs by identifying and removing the causes of defects and minimizing variability in manufacturing and...
. While the tools and order used in Six Sigma require a process to be in place and functioning, DFSS has the objective of determining the needs of customers and the business, and driving those needs into the product solution so created. DFSS is relevant to the complex system/product synthesis phase, especially in the context of unprecedented system development. It is process generation in contrast with process improvement.
DMADV, Define – Measure – Analyze – Design – Verify, is sometimes synonymously referred to as DFSS. The traditional DMAIC (Define – Measure – Analyze – Improve – Control) Six Sigma process, as it is usually practiced, which is focused on evolutionary and continuous improvement manufacturing or service process development, usually occurs after initial system or product design and development have been largely completed. DMAIC Six Sigma as practiced is usually consumed with solving existing manufacturing or service process problems and removal of the defects and variation associated with defects. On the other hand, DFSS (or DMADV) strives to generate a new process where none existed, or where an existing process is deemed to be inadequate and in need of replacement. DFSS aims to create a process with the end in mind of optimally building the efficiencies of Six Sigma methodology into the process before implementation; traditional Six Sigma seeks for continuous improvement after a process already exists.
DFSS as an approach to design
DFSS seeks to avoid manufacturing/service process problems by using advanced Voice of the Customer techniques and proper systems engineering techniques to avoid process problems at the outset (i.e., fire prevention). When combined, these methods obtain the proper needs of the customer, and derive engineering system parameter requirements that increase product and service effectiveness in the eyes of the customer. This yields products and services that provide greater customer satisfaction and increased market share.These techniques also include tools and processes to predict, model and simulate the product delivery system (the processes/tools, personnel and organization, training, facilities, and logistics to produce the product/service) as well as the analysis of the developing system life cycle itself to ensure customer satisfaction with the proposed system design solution. In this way, DFSS is closely related to systems engineeringSystems engineering
Systems engineering is an interdisciplinary field of engineering that focuses on how complex engineering projects should be designed and managed over the life cycle of the project. Issues such as logistics, the coordination of different teams, and automatic control of machinery become more...
, operations research
Operations research
Operations research is an interdisciplinary mathematical science that focuses on the effective use of technology by organizations...
(solving the Knapsack problem
Knapsack problem
The knapsack problem or rucksack problem is a problem in combinatorial optimization: Given a set of items, each with a weight and a value, determine the count of each item to include in a collection so that the total weight is less than or equal to a given limit and the total value is as large as...
), systems architecture
Systems architecture
A system architecture or systems architecture is the conceptual model that defines the structure, behavior, and more views of a system.An architecture description is a formal description and representation of a system, organized in a way that supports reasoning about the structure of the system...
and concurrent engineering
Concurrent engineering
Concurrent engineering is a work methodology based on the parallelization of tasks . It refers to an approach used in product development in which functions of design engineering, manufacturing engineering and other functions are integrated to reduce the elapsed time required to bring a new product...
. DFSS is largely a design activity requiring specialized tools including: quality function deployment
Quality function deployment
Quality function deployment is a “method to transform user demands into design quality, to deploy the functions forming quality, and to deploy methods for achieving the design quality into subsystems and component parts, and ultimately to specific elements of the manufacturing process.”, as...
(QFD), axiomatic design
Axiomatic design
Axiomatic design is a systems design methodology using matrix methods to systematically analyze the transformation of customer needs into functional requirements, design parameters, and process variables....
, TRIZ
TRIZ
TRIZ is "a problem-solving, analysis and forecasting tool derived from the study of patterns of invention in the global patent literature". It was developed by the Soviet inventor and science fiction author Genrich Altshuller and his colleagues, beginning in 1946...
, Design for X
Design for X
Under the label Design for X, a wide collection of specific design guidelines are summarized. Each design guideline addresses a particular issue that is caused by, or affects the characteristics of a product...
, design of experiments
Design of experiments
In general usage, design of experiments or experimental design is the design of any information-gathering exercises where variation is present, whether under the full control of the experimenter or not. However, in statistics, these terms are usually used for controlled experiments...
(DOE), Taguchi methods
Taguchi methods
Taguchi methods are statistical methods developed by Genichi Taguchi to improve the quality of manufactured goods, and more recently also applied to, engineering, biotechnology, marketing and advertising...
, tolerance design, Robustification
Robustification
Robustification is a form of optimisation whereby a system is made less sensitive to the effects of random variability, or noise, that is present in that system’s input variables and parameters...
and response surface methodology
Response surface methodology
In statistics, response surface methodology explores the relationships between several explanatory variables and one or more response variables. The method was introduced by G. E. P. Box and K. B. Wilson in 1951. The main idea of RSM is to use a sequence of designed experiments to obtain an...
. While these tools are sometimes used in the classic DMAIC Six Sigma process, they are uniquely used by DFSS to analyze new and unprecedented systems/products. A graphical flowchart of common DFSS tools can be seen at DFSS Roadmap.
Arguments over the separation of DFSS from Six Sigma
Proponents of DMAIC techniques might claim that DFSS falls under the general rubric of Six Sigma. It is often seen that the tools used for DFSS techniques vary widely from those used for DMAIC Six Sigma. In particular, DMAIC practitioners often use new or existing mechanical drawings and manufacturing process instructions as the originating information to perform their analysis, while DFSS practitioners often use system simulations and parametric system design/analysis tools to predict both cost and performance of candidate system architectures. While it can be claimed that two processes are similar, in practice the working medium differs enough so that DFSS requires different tool sets in order to perform its system design tasks. DMAIC Six Sigma may still be used during depth-first plunges into the system architecture analysis and for "back end" Six Sigma processes; DFSS provides system design processes used in front-end complex system designs.Similarities with other methods
Arguments about what makes DFSS different from Six Sigma demonstrate the similarities between DFSS and other established engineering practices such as Probabilistic designProbabilistic design
Probabilistic design is a discipline within engineering design. It deals primarily with the consideration of the effects of random variability upon the performance of an engineering system during the design phase. Typically, these effects are related to quality and reliability...
and design for quality. In general Six Sigma with its DMAIC roadmap focuses on improvement of an existing process or processes. DFSS focuses on the creation of new value with inputs from customers, suppliers and business needs. While traditional Six Sigma may also use those inputs, the focus is again on improvement and not design of some new product or system. It also shows the engineering background of DFSS. However, like other methods developed in engineering, there is no theoretical reason why DFSS can't be used in areas outside of engineering.
DFSS, applied to Software Engineering
Historically, Design for Six Sigma (DFSS) was created in part because Six Sigma organisations found that they could not optimise products past three or four Sigma without fundamentally redesigning the product. This means that ‘Six Sigma’ levels of performance have to be ‘built-in’ or ‘by design’. The DFSS for Software Engineering is essentially a non superficial modification of "classical DFSS" since the character and nature of software is different from other fields of engineering. The methodology describes the detailed process for successfully applying DFSS methods and tools throughout the Software Product Design, covering the overall Software Development life cycle: Requirements, Architecture, Design, Implementation, Integration, Verification and Validation. The methodology explains how to build predictive statistical models for software reliability and robustness and shows how simulation and analysis techniques can be combined with structural design and architecture methods to effectively produce software and information systems at Six Sigma levels.DFSS in Software Engineering acts as a glue to blend the classical modelling techniques of software engineering such as OOD
Ood
The Ood are a fictional alien species with telepathic abilities from the long running science fiction series Doctor Who. In the series' narrative, they live in the distant future ....
or ERD with statistical, predictive models and simulation techniques. The methodology provides Software Engineers with practical tools for measuring and predicting the quality attributes of the software product and also enables them to include software in system reliability models.
Critics
Many critics have been written on the internet (search for "Six Sigma Comments, DFSS comments" / "Six Sigma sucks") about the exact process that DFSS (and Six Sigma) tries to describe. The general way of working might currently not be so clear.There are no official standards from international bodies that describe the way of working for DFSS. This can however change in the future.
See also:
- Reference Harvard Business review; http://blogs.hbr.org/davenport/2008/01/why_six_sigma_is_on_the_downsl.html.
- Six SigmaSix SigmaSix Sigma is a business management strategy originally developed by Motorola, USA in 1986. , it is widely used in many sectors of industry.Six Sigma seeks to improve the quality of process outputs by identifying and removing the causes of defects and minimizing variability in manufacturing and...