Design for Six Sigma (DFSS)

In a typical Six Sigma project, the DMAIC approach is used to improve an existing process. It requires a process to be in place and functioning.

Design for Six Sigma (DFSS or DfSS) focuses on identifying customer needs and then designing products and services to meet them. Unlike Six Sigma, which typically uses the DMAIC (Define - Measure - Analyze - Improve - Control) approach, DFSS typically uses the DMADV (Define - Measure - Analyze - Design- Verify) approach.

1. DMADV Approach:

The DMADV approach has been described as follows:

D – DEFINE: Define the process, or design goals (Voice of the customer)

M – MEASURE:  Measure Critical to Quality aspects

A – ANALYZE: Analyze designs

D – DESIGN: Detail design of the product or process

V – VERIFY: Verification of the proposed solution through testing. 

Design verification involves checking whether the designed product meets all the functional and non-functional requirements specified by the customer. Design verification normally starts after the design phase of the project. It should be performed at regular intervals during the development cycle.

Design verification is performed by comparing the actual output with the expected output. If the two outcomes match, there is no discrepancy between the expected and actual outputs.

Verifying the functionality of the product requires performing tests on the product. For example, verifying the functionality of a software program may involve running the program under test, analyzing the result, and making sure that it matches the requirements.

The second part of design verification is checking whether the design satisfies the non-functional requirements defined by the customer. Non-functional requirements describe characteristics of the product which cannot be tested functionally. Examples of such characteristics are safety, environmental compatibility, aesthetics, ergonomics, ease of use, etc.

In addition to DMADV, there are some other alternative approaches as well, such as DMADOV and IDOV.

2. DMADOV Approach:

DMADOV approach is similar to the DMADV approach. However, it contains an additional step of optimizing the design.

O– OPTIMIZE:  Refine the design

Design optimization is the refinement of a design by improving its performance, reliability, manufacturability, maintainability, cost, etc. Optimizing a design is done using an iterative approach where the designer modifies the design based on the results obtained from the previous iteration. There are different types of optimization techniques that can be applied to any design problem. These include:

Flow analysis: This technique helps identify bottlenecks in manufacturing processes.

Functional analysis: This technique helps determine how much time will be required for each function.

Reliability analysis: This technique helps determine the probability of failure for various components.

Cost analysis: This technique helps estimate the cost of manufacturing and assembling a particular component.

Material requirements planning: This technique helps plan the production schedule for a given set of orders.

Manufacturing engineering: This technique helps design new machines, tools, etc., to make parts more efficiently.

 

3. IDOV Approach:

IDOV stands for “Identify, Design, Optimize, Verify.” The approach consists of four steps.

I– IDENTIFY: In this stage, you define the Voice of the Customer.

D– DESIGN: Here, you need to design the product or process to meet the identified requirements.

O– OPTIMIZE: After designing, you need to optimize the design.

V– VERIFY: Once the optimized design is available, you must verify if they meet the desired goals.

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