DFM & DFA: The differences, benefits and how to do them?

Two buzzwords that we often hear in our industry are “DFM” and “DFA”. These should be given consideration right at the beginning of a project and continue to be used until after a product has been manufactured. So, what do they mean? What are the differences? What’s the importance of DFM & DFA, and how do we do each one well?

DFM stands for “Design for Manufacture”. DFM is the process of designing parts with a chosen manufacturing process in mind. Knowing the chosen manufacturing process during the part design phase will ensure the design of that part is optimised to suit the process, resulting in a better, lower cost product. The DFM process can be broken down into 4 areas; chosen manufacturing process, part design, material selection and finally the environment the parts are to be used in. Consideration must be given to each of these areas. If just one area is neglected, this could lead to expensive and embarrassing product failures further down the road.

The chosen manufacturing process and part design areas of DFM go hand in hand. As a design engineers, when designing a component, we will consider both the desired function / design intent of the component as well as the chosen manufacturing process. We will design the component to conform to the good manufacturing principles for the manufacturing process we have chosen. This will include considering things like physical size and shape of a component right down to intricate geometry of particular features. For example, when designing for injection moulding, we will design the part in a specific way. This involves following the common design rules for injection moulding, like adding a split-line to the part, adding different draft angles to areas of the part and ensuring there are no undercuts in the design (just to name a few!). However, if it was decided that the part was to be CNC machined instead, then the design features of a CNC machined part wouldn’t need to incorporate a large majority of these injection moulding design features.

DFM is an important part of any product development cycle. It should be applied early on in the process for the most cost and time savings. Appreciating and giving consideration to these 4 areas of the DFM process will enable you to engineer and manufacture a product that performs to a high standard with robust, lasting performance. Addressing potential issues at those early stages of product development will help you get it right first time or at least require less prototyping and fewer product iterations.

DFA stands for “Design for Assembly”. Design for assembly is a process by which products are designed with ease of assembly in mind. For example, if a product contains fewer parts, it will take less time to assemble, thereby reducing assembly time and costs.

Although Design for Assembly (DFA) and Design for Manufacturing (DFM) principles are often looked at as one combined subject, they are actually quite separate methodologies. Design for Assembly is the optimisation of the product and the assembly process, while Design for Manufacture focuses on the manufacturing process and material selection.

The aim of DFA is to make the assembly process easier, faster, and more consistent therefore increasing productivity. Some of the main principles of DFA to keep in mind as you start your project are; minimising part count, built-in fasteners, use of standard parts, part symmetry and poka-yoke assembly specific design features. Giving consideration to these principles throughout the design process of your project will set you on the right path to achieving an efficient and successful design for assembly.

Designing symmetric components is another way to ensure an efficient DFA methodology. This makes the assembly process easier for workers as it reduces the time trying to identify which way round similar looking components should be mounted etc.

Finally, incorporating assembly specific design features into your parts, such as physical obstructions to prevent components from being fitted wrongly, or adding identifying physical features to parts making them easier to identify and assemble is one of the easiest ways to reduce assembly time. One of the simplest but most effective poka-yoke design features is the UK electrical plug & socket. The 3-prong design for the plug and socket, ensures the plug can only be connected to the socket in the correct, single orientation. Incorporating these poka-yoke design features into your part design will make sure your product can’t be assembled incorrectly and will avoid many potential issues down the line.

Hopefully this has given you a brief overview of the value that Design for Manufacture and Design for Assembly principles have in new product and medical device design. Giving consideration to these two methodologies can not only help you reduce the time to market and costs of your product, but also guide you to design a more robust, effective product that can last the test of time, and be easily used out in the real world! If you need help with your new product DFM & DFA optimisation then please get in touch.