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DFMA Design for Manufacturing and Assembly

Updated on September 7, 2010

What is DFMA?

DFMA is an abbreviation for "Design for Manufacturing and Assembly" or "Design for Manufacturability and Assembly. It a system comprised of various principles that, when used properly, will improve the ability for a design to be easily manufactured and assembled. It is most benificial to consider these principles during the design phase of new product development. This system can be divided into three major sections. The first is the raw material. Choosing the right material is the foundation of a good design. Second is the machines and processes used to work the raw material. The right process is essential for creating finished parts that will meet your design requirements. Third is the assembly of the product. It is during the assembly of the finished product that provides the greatest opportunity to apply DFMA principles. The proper use of DFMA principles will allow one to design a high quality product.

This picture is of an investment casting which demonstrates the DFMA principle Near Net Parts
This picture is of an investment casting which demonstrates the DFMA principle Near Net Parts

DFMA Raw materials

Choosing the best raw material for the design is the first step in using DFMA to design a world class product. There are many factors that need to be considered when choosing the best material for a design. First the material must have the correct mechanical and chemical properties to meet the design criteria. Second when possible one should choose a standard material that is readily available. Using special materials may increase purchase price and lengthen deliveries. Third use near net parts whenever possible. The raw material's profile should be as close to finished parts as possible to reduce processing.

DFMA Machines and processes

Choosing the appropriate machine and processes can drastically reduce the time and further increase the quality of the parts. When determining the best machine for the job, there are many things to consider. First and foremost is the material being processed. Some materials may require coolant and others may require special fixturing or tooling. Second is to apply as liberal tolerances as the design will allow. It typically takes longer and is more costly to hold tighter tolerances. Third is the machines capabilities. Pick a machine and process that can provide desired finish, hold tolerances required, and be repeatable. Next is the tooling. You will need to pick tooling with the best combination of finish, performance, life and cost. Another consideration is fixturing. Proper fixturing is necessary for quality while fixturing that is user friendly can reduce the amount of labor time in the manufacturing process.

DFMA Assemblies

Assemblies is the area with the most potential in applying DFMA principles. First you can reduce the parts count in an assembly. You can reduce parts by eliminating or combining multiple parts. Second by making parts symmetrical when the design allows. Having asymmetrical parts require more attention in the positioning of the parts at assembly. Third is simplicity of design. Typically the simpler the design the less opportunity for mistakes. Also referred to as the kiss principle. Next is self fixturing. The usage of the part itself to help position or align itself with a mating part. Whenever possible try to avoid using parts in your design that are easily tangled. Tangled parts take time to untangle that may be spent doing productive work. You will also have to think about accessibility. If a part is hard to get to it may take more time to position and assemble it. Last but surely not least is poka yoke or mistake proofing. The goal of poka yoke is to make it impossible to make a mistake.

DFMA software basics

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Comments on DFMA

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    • daxramadani profile image

      daxramadani 6 years ago

      Great stuff! What is a typical road map of DFMA? Is it any different than GM's PPAP?

    • johnyater profile image

      johnyater 7 years ago from Hamilton, Ohio


      Thanks for read and comment!

    • profile image

      Mike Allin 7 years ago

      This is especially true for mass produced parts. I hear what LeanMan is saying and I remember learning about this in supply chain books. As a supplier to various auto companies, a big thing with them has been mass customization in which new models are DFMA but with certain elements that can be mixed and matched and combined together to create something "custom." Great hub.

    • johnyater profile image

      johnyater 7 years ago from Hamilton, Ohio

      I whole heartily agree with you. There are to many design engineers that do not seem to care about the problems that are encountered with their design during machining and assembly. I will be the first to admit that everything that I send to the shop is not perfect, but I spend my time at Gemba observing them so that my designs, like a good wine, will get better with time....

    • LeanMan profile image

      Tony 7 years ago from At the Gemba

      Too many engineers design for the sake of design and seem to think that they are creating a work of art without any thought of how it will be assembled...

      More design engineers out there should read this. (and should have it tattooed on the inside of their eyelids!)