What is design for manufacturing (DFM)?

Design for manufacturing (DFM) is the product development practice of designing a product for optimally efficient and cost-effective part fabrication, assembly, and mass production.

Notably, DFM requires evaluation of all aspects of the manufacturing process for a proposed product—from material selection, manufacturing methods, prototyping, and assembly to testing, regulatory compliance, service, and repair—during the initial design phase.

The main benefit of DFM is that it enables product design and manufacturing engineers to identify potential problems and resolve them before they become time-consuming and costly to address. In this way, DFM helps speed time to market, improve product quality, minimize costs, and maximize profitability.

Design for manufacturing is sometimes used interchangeably with design for manufacturing and assembly, or DFMA. This can be a little misleading because design for manufacturing places plenty of emphasis on assembly— and because DFM and DFMA coexist with several other ‘design for’ disciplines (and corresponding ‘DF’ acronyms). See the sidebar for more information.

The principles of DFM

Ask ten different manufacturers to name design for manufacturing principles, and you’ll likely get ten different lists. But most will settle on some combination of the following key principles.

Simplification

In many ways, simplification is the core of DFM: reducing the complexity of a product design offers tremendous potential shorten assembly times, speed time-to-market, reduce overall costs, and improve product quality and serviceability.

A key simplification strategy is functional integration—reducing the number of parts and fasteners by consolidating multiple parts or components into a single part. Other simplifications—smooth versus textured part surfaces, simple versus highly detailed structures—can avoid errors or added costs such as part weakness, breakage during demolding, or wasted material.

Standardization

Using widely available standardized parts, components, and materials can help shorten lead times, reduce inventory cost,s and prevent supply chain issues.

A frequently-cited example of standardization is the widespread use of USB-A or USB-C interfaces in electrically powered products or computer peripherals. Standardizing on these interfaces makes components easier for manufacturers to source, and the resulting products easier for customers to own.

Modularity

Modularity—breaking a product down into individual, independent, and interchangeable sub-assemblies—lets designers test, troubleshoot, and upgrade portions of a product without impacting (and without the risk of negatively impacting) the entire product.

Modules can be assembled in parallel, perhaps even by multiple manufacturing partners, to streamline production. And in some cases, the same module can be part of multiple products in a product line.

Material selection and manufacturing process compatibility

Designs should specify materials that meet product performance and functional requirements, such as the ability to withstand certain temperatures or chemicals, or the strength to support a certain amount of weight. For example, a medical device for use in a patient room or operating room should be made from materials that can withstand chemical or UV disinfection.

The design and materials should also be compatible with the intended manufacturing and assembly processes. Plastics for injection molding should have the proper consistency; plastics for snap-fit parts should have the proper elasticity or flexibility; metals should be suitable for CNC machining or press-brake forming.

Tolerances—the allowable variations in a part or component’s dimensions or material performance—should match the capabilities of the selected materials and available manufacturing methods. Many design engineers practice tolerance optimization—imposing rigid tolerances only where necessary for proper product functionality, and more relaxed tolerances wherever possible. At the other end of the spectrum, there may be no available manufacturing methods that match design tolerances, which may force a redesign.

Ease of assembly

The easier a product is to assemble, the greater the potential to reduce factory and labor costs, assembly times, production cycles, and time to market. Several of the DFM principles discussed above—simplicity, standardization, modularity—contribute to ease of assembly. Other factors include:

• Part designs that are easy for workers to grasp and hold in the proper position for assembly
• Parts that can be assembled using automation (e.g., robots) with minimal human handling
• Product designs that require fewer assembly steps, which minimize the potential for error.
• Error-proofing incorporated into the design—grooves, guides, pins, asymmetrical design elements, or other features that make parts easy to align, or impossible (or virtually impossible to assemble incorrectly). This is often referred to as Poke-Yoke (‘mistake proofing’), after a practice that originated at Toyota in the 1960s for preventing human assembly errors (or making them instantly obvious to assemblers or inspectors).

These and other assembly-specific principles are often referred to separately as design for assembly or DFA (see the sidebar).

Compliance and risk management

When designing products for any industry, factoring compliance and risk management into the earliest design phases can avoid significant downstream costs.

This is especially for products in highly regulated industries. For example, medical device manufacturers need to comply with quality management and safety regulations and standards such as

• The United States Food and Drug Administration Quality Management System Regulation (FDA QMSR), which aligns previous US regulations with the international standards outlined in ISO 13485
• IEC 60602-1, the international safety standard for medical electrical equipment.

Changing a product design to address a compliance issue is time-consuming and expensive even during the later prototyping stages, and can be prohibitively expensive once a product is launched.

DFM methodology and tools

Starting early

The earlier in the product development cycle that DFM principles and considerations are raised, the greater the impact—and the shorter the time and the lower the cost to implement product design changes. Making a design change during the concept phase is quick, easy, and inexpensive—just a few clicks in a CAD file. Making a change after tooling has been built, after the production process has begun or after the product is in the market can be disastrous, resulting in extensive redesigns, new molds, wasted time and materials, buybacks, production stoppage,s and, in the worst cases, discontinued products.

The most successful manufacturers implement DFM at the very start of the cycle, when the initial product concept is born, so that product function, appearance, and manufacturability are part of the design from the start.

Cross-functional collaboration

To have any impact at all, DFM requires involvement and collaboration across every constituency with a stake in the product—not only design, engineering, and manufacturing but research and development, regulatory compliance, procurement, sales, marketing, and customer service. An integrated, cross-functional team is much more likely to identify and address potential manufacturing issues before they become expensive downstream problems.

But a cross-functional DFM process isn’t just about cost avoidance. Open, robust communication across functions often leads to innovative problem-solving and new features that product design teams might not find on their own.

Constant, frequent iteration

DFM is an iterative process: the initial design concept undergoes a cross-functional DFM analysis, is revised based on inputs from the analysis, analyzed again, revised again, and so on. Each iteration brings the design closer to a ‘golden sample’—a final prototype that represents the optimally manufacturable version of the product.

Rapid prototyping

Rapid prototyping technology enables design teams to quickly produce a three-dimensional model of a product or part from a CAD file. Rapid prototyping technologies include

• 3d printing (or additive manufacturing), which ‘prints’ a three-dimensional model layer by layer using plastic, composite or metal material
• CNC machining, which carves a model or part from metal or solid material
• Sheet metal fabrication, which essentially uses the same tools used in sheet metal manufacturing to create a prototype.

Rapid prototyping can improve and accelerate DFM analysis, testing, and validation at every phase of the process, from evaluating initial design concepts to testing fit, assembly, function, tooling, and even limited production runs.

Learn more about rapid prototyping

DFM software

Today, most CAD/CAM software, such as AutoDesk Fusion 360, Solidworks, or Inventor, includes DFM capabilities such as

• Automated design analysis that checks models for potential manufacturing issues such as complex geometries, wall thicknesses, or tight tolerances.
• Digital simulation capabilities that allow teams to create virtual prototypes—and use them to analyze the physical properties of a part or component before building a physical model. Digital simulations let design and engineering teams examine and evaluate everything from potential stress points in the part structure to material flow through injection molds to the efficiency of different assembly sequences.
• Cost optimization for estimating manufacturing costs based on different design parameters, materials, and tools, enabling design teams to choose the most cost-effective production methods early in the design cycle.
• Artificial intelligence (AI) and machine learning capabilities that can quickly predict manufacturing issues based on historical data, and automate routine tasks to shorten design, prototypin,g and review cycles.
• Detailed reporting for sharing information across functions.

The best DFM software not only automates DFM tasks—it democratizes DFM analysis. Without the software, many DFM functions would depend on inspection and analysis by seasoned design and manufacturing engineers. DFM software extends these analytical capabilities to more stakeholders, which can dramatically accelerate the transition from design concept to viable prototypes.

The benefits of DFM

As noted in the introduction, DFM has tremendous potential to reduce manufacturing costs, shorten time to market, and improve product quality.

Most of the available data on DFM results comes from case studies written by companies that sell DFM software or service, and many of those case studies are decades old. We’ve cited some of the most recent data we could find.

Cost reduction

It’s a generally accepted principle that 70-80% of manufacturing costs are determined by design decisions made in the earliest phases of the product development process. Properly implemented, DFM can lock in savings during these critical initial stages and set the cost of manufacturing on a lower, optimized trajectory for the life of the product.

Boothroyd Dewhirst Inc.—pioneers in DFM research and makers of DFMA® Software—report labor savings averaging 47%, material and tooling savings as high as 40%, and overall cost reductions as high as 78% from using DFM or DFMA software or systematic DMF or DMFA analysis.

Faster time to market

By streamlining and accelerating virtually every design, preproduction, and production workflow, DFM shortens the entire product development and manufacturing cycle.

Recently, advanced technologies like AI and digital simulation are yielding attention-getting gains. Eaton, Inc., manufacturer of intelligent power management systems, used AI-driven DFM software to reduce new product design time up to 87%. In another example, a medical device manufacturer used a ‘digital twin’ simulation to cut time-to-market in half.

Improved product quality and reliability

DFM contributes to greater product quality and reliability in two ways: by simplifying product designs, because fewer parts and fewer complexities mean fewer potential points of failure; and by error-proofing, to make parts easier to fabricate and assemble correctly.

In an analysis conducted by the American Society for Quality, companies that adopted DFM practices reported up to an 18% overall increase in product quality KPIs such as defect rate (defects per million opportunities or DPMO), first pass yield (FPY), and rework rate.

It’s worth noting that the potential production cost or time savings resulting from designing for fewer parts or opting for standard components or materials must always be weighed against the risks of warranty claims, recalls, and other reliability-related issues over the length of the product lifecycle.

 

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