Design for Manufacture and AssemblyIntroduction

Note: this is an adaptation of a presentation from

Dr. Denis Cormier, intended for use as an Intro to DfMA

for students enrolled in Multidisciplinary Senior Design

John Kaemmerlen 10/31/13

Stages of Product Development Process Concept Development System Level Design Detailed Design Prototype Build Prototype Evaluation and Refinement Production Ramp-Up

“D” = Design …..

Overview – where does DFMA fit?

Concurrent Engineering “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 to the market.” Source: Wikipedia

Longer initial design phase, but design it right the first time around.

DFMA is one element of concurrent, or simultaneous, engineering.

What Does This Have To Do With DFMA?

As we design components and subassemblies, one mindset is “we are just making one, as long as we can machine the parts and assemble the device, no big deal”

A better mindset is “what if my client wants to use our design to make 1,000 of these devices, or a million? Are there aspects of the design I should manage differently than what I might typically do?”

Relevance to MSD

Design for Manufacture (DFM) Design individual components so that they can

be manufactured as easily and inexpensively as possible while maintaining the required functionality

Design for Assembly (DFA) Design assemblies of parts so that they can be

assembled as inexpensively as possible Minimize assembly time Minimize the number of assembly errors

DFMA Objectives

Standardization – use or re-use of standard components across products, or across subsystems, saves design time and reduces the chances of error (e.g. buying a catalog circuit board that has the required functionality, vs. designing, building, and testing a custom board that is a “perfect match” to the needs Could be a “make item” (i.e. an item made in your factory) Could be a “buy item” (i.e. an item you purchase from a supplier

such as screws, washers, grease, etc)

Material choices – metal vs. plastic vs. ceramic vs. ….. Ease of design, cost to machine, and material cost should all be considered

Examples of DfMA approaches

Solidworks is capable of generating a great deal of highly useful DFM&A analysis data Design of plastic molded part features Measurement of feature sizes, volumes, surface

areas, etc. Assembly animations Clearance and interference checking

These issues will be relevant on some MSD projects

Solidworks

Review of fundamental machining processes Milling, drilling, turning, etc

Guidelines to ensure that a part can be machined Minimize the number of machine setups Ensure that standard cutting tools are sufficient Ensure that cutting tools can reach the surfaces to

be machined without collisions Ensure that cutting tools can remove the material

that needs to be removed Check achievable tolerances and surface finishes

Design for Machining

Many kinds of assembly Manual assembly Automated assembly Welding, Brazing, Soldering Gluing

Examples of DfA principles Minimize the number of parts in the assembly Make parts easy to grasp, move, orient, insert Design to enable automated insertion into a tool or

machine, and automated ejection Minimize use of parts that make the sequence of the

process less efficient (e.g. parts on an SMT circuit board that cannot withstand a reflow oven environment)

Design for Assembly

Design for Manufacturability Handbook James G. Bralla McGraw-Hill

Reference