Design for Manufacturability

Design for manufacturability (DFM) is the concept of creating a product that can be consistently manufactured without problems, at minimal cost. This article outlines the benefits of DFM; summarizes the features of available DFM technologies; notes how specific companies are incorporating DFM into their manufacturing processes; and provides a glossary of relevant DFM terms. Although products may be manufactured from raw materials by hand or by machine, this article focuses on manufacturing by machine.

Keywords Additive Manufacturing (AM) Technologies; Computer-aided Design (CAD); Computer-aided Engineering (CAE); Concurrent Engineering; Global Vehicle Architecture; Design for Manufacturability (DFM); Poka-yoke; Product Lifestyle Management (PLM)

Overview

Manufacturability

The manufacturability of a product refers to characteristics that make the product suitable for reproduction (manufacture), usually on a large-scale basis.

Manufacturability is dependent upon two conditions:

1. The ability to consistently manufacture a reliable product without problems
2. The ability to manufacture the product at minimal cost

Design for Manufacturability (DFM)

When the two conditions for manufacturability — the ability to manufacture a reliable product without problems, and at minimal cost — are given foremost consideration during the design cycle of a product, the concept is known as design for manufacturability (DFM), also known as design for manufacture.

The principle behind DFM is to create the ability to economically manufacture a reliable product into its initial design rather than to fix problems later in the manufacturing process. This principle expands the idea of "do it right the first time" into "do it right the first time, but as inexpensively as possible."

DFM generally relies upon standardization practices; it incorporates manufacturing processes that use standard parts, reduce the number of parts, and minimize handling during production. However, the most sophisticated DFM strategies allow for a range of product customization. (Examples of customization of DFM practices are cited in "AM Technologies — Applications" in the "Applications/Further Insights" section of this article and in "Case Study — General Motors (GM) — Reaching for the Market and Cost Saving Benefits of DFM by Adopting Global Vehicle Architecture Practices" in the "Further Insights" section.)

DFM practices may result in both direct cost savings and indirect cost benefits for the manufacturer.

Direct cost savings for the manufacturer using DFM practices may result from:

• Eliminating the extra materials and labor needed to correct mistakes
• Reducing the overhead associated with extra materials and labor
• Minimizing wear and tear on machinery
• Shortening the development and manufacturing cycles, thus hastening time-to-market of the product
• Lowering the number of product returns

Indirect cost benefits for the manufacturer using DFM practices may result from:

• Lowering employee turnover due to higher satisfaction with output
• Improving customer satisfaction due to offering a more reliable and economical product
• Gaining industry status as a manufacturer of reliable, economically-priced products

Since manufacturers' success and profits usually rely upon producing reliable products at the lowest possible cost and in the shortest possible timeframe, the concept of DFM is an attractive one.

Depending upon the product or manufacturing process, DFM may incorporate one or more of the following solutions:

• Additive Manufacturing (AM) Technologies (also known as "rapid prototyping")
• Computer-aided Design (CAD)
• Computer-aided Engineering (CAE)
• Computer-aided Manufacturing (CAM)
• Concurrent Engineering
• Poka-yoke
• Product Lifecycle Management (PLM)

Applications

This section outlines the important features of specific DFM solutions and notes how certain companies are applying some of these technologies to their manufacturing processes. DFM solutions generally involve computer technology. In addition, many of the computer technology solutions are used in combination, leading to such common practices and acronyms as CAD/CAE and CAD/CAM.)

The following DFM solutions, along with specific company applications, are summarized:

• Additive Manufacturing (AM) Technologies
• Computer-aided Design (CAD) and Computer-aided Engineering (CAE)
• Computer-aided Manufacturing (CAM)
• Concurrent Engineering
• Poka-yoke
• Product Lifecycle Management (PLM)

Additive Manufacturing (AM) Technologies

Additive Manufacturing (AM) Technologies, also known as "rapid prototyping," allow a manufacturer to fabricate customizable parts of any shape from complex materials. (Rapid prototyping refers to quicker-than-average production of models for the purpose of working out problems.) Because of its intent to tackle the manufacturing issues involving the complexities of shape and materials, AM technologies have the potential to move beyond providing cost-cutting benefits to actually achieving new, higher manufacturing capabilities (Rosen, 2007).

Rosen (2007) explains that hearing aid manufacturers Siemens, Phonak, and Widex, are making hearing aid shells with AM machines that enable custom manufacturing of thousands of parts, and Align Technology is using AM to produce clear braces. In contrast, Rosen mentions how Boeing uses AM technology to produce rapid prototypes for fighter jet parts that are intended for low volume manufacturing.

Computer-Aided Design (CAD) & Computer-Aided Engineering (CAE)

Computer-aided design (CAD) is routinely used by designers to produce digital drawings and designs. In manufacturing, digitally-stored CAD designs are often the basis for computer-aided engineering (CAE), which is the analysis of a product's structural integrity and performance.

Proctor & Gamble employs CAD/CAE to develop virtual prototypes of products; evaluate their suitability and effectiveness; and determine their ability to be manufactured economically. For example, through CAE, Proctor & Gamble is able to ensure two important features of their products:

1. Reliability of the products' containers: The containers won't break or crack if dropped, the lids won't leak, and the products will flow properly from their containers.
2. Performance of the products: The products function as intended during consumer use for persons with a range of human physical characteristics (Dodgson, 2006).

Computer-Aided Manufacturing (CAM)

Computer-aided Manufacturing (CAM) uses computer technology to control the manufacturing process.

Longhorn Machine Inc. is a Houston-based company that manufactures small quantities of large, complex parts for offshore drilling and oil servicing customers. The parts are very expensive to build and specifications are so precise, that deviations of more than a few ten-thousandths of an inch are unacceptable to customers. In addition, the parts must be delivered according to a rigid schedule so that customers don't lose money waiting for the parts. To meet these strict requirements and maintain a profit, Longhorn needs to make the parts correctly on the first try. In 2005, Longhorn replaced their older CAD system with a software package called EdgeCAM, which allows two programmers to run all their machines. As a result, programming time dropped from 250 hours per job to 10 hours ("Using CAM," 2007).

Concurrent Engineering

Concurrent Engineering is a method of product or process design that includes simultaneous input from everybody with a stake or role, including engineers, salespersons, support personnel, vendors, and customers, throughout the entire design process (Sapuan, 2006).

Because it removes communication and design barriers by engaging all the stakeholders throughout the design process, concurrent engineering results in the following benefits (Dubensky as cited by Sapuan, 2006):

• Involvement of all functions and personnel
• Better processing considerations
• Improved manufacturing launch considerations
• Fewer product revisions after the manufacturing process begins
• A better product
• Improved worker involvement and satisfaction
• Management involvement and acceptance

Success in concurrent engineering initiatives relies upon constant communication and management of the language, facts, and product and process requirements by everyone involved in the initiative. For example, each group involved may use different jargon. Or, each may have a different perspective about what constitutes product requirements. Old Manse, a Minnesota company, employed concurrent engineering to solve the issue differences among its groups. Old Manse manufactures the HexopaterTM, a medical device that increases the mobility of patients who have undergone extensive limb surgery. Old Manse found that it was a long, difficult process for the engineering group to detect design problems of the HexopaterTM once the design was completed. In response, Old Manse instituted concurrent engineering practices by including manufacturing engineers as members of the design and development teams. As a result, the number of engineering design changes dropped dramatically (Kumar & Addie, 2006).

Poka-yoke

The catchy-sounding term, Poka-yoke is the concept of mistake-proofing the entire manufacturing process by preventing mistakes in the product design, the process, and from human actions. Poka-yoke refers to the mechanisms used throughout a manufacturing process to ensure that proper conditions exist before a process step is begun. Or, if it is not possible to invoke poka-yoke before the process actually begins, then it is used to detect defects at the earliest point in the process (Manivannan, 2007).

Johnston Sweepers, which is owned by the Bucher Group from Switzerland, has this philosophy: Get it right the first time. To do this, Johnston applies poka-yoke practices to error-proof its manufacturing operations by fine-tuning each step of the operation so precisely and accurately that the products don't need to be inspected afterwards. In fact, a wet paint plant that Johnston built four years ago has never produced a single warranty defect (Dwyer, 2007).

Product Lifecycle Management (PLM)

Product Lifecycle Management (PLM) integrates all the people, processes, and information related to a product in order to communicate information across the enterprise, from initial product concept to the end of its life. PLM takes the concept of concurrent engineering — people and process integration throughout the design cycle — further, by applying the principles throughout the product's life, from inception to disposal.

Hendrick Motorsports, a racing organization that fields six NASCAR racing teams, is challenged with tracking and remanufacturing 700 race car engines a year. Hendrick's goal is to fix auto parts in 2-3 days and reduce variability in vehicle performance to 0.5%. To achieve its ambitious goals, Hendrick utilizes Teamcenter, a PLM system from UGS Corp. Teamcenter allows Hendrick to record, track, and communicate all engine part histories, failures, and repairs to those who need it, including engineers and on-the-spot repair staff (Bartholomew, 2006).

Further Insights

This section summarizes the features of four additional DFM solutions: spreadsheets, model-based design tools, dimensional measurement tools, and manufacturing intelligence tools, and presents a brief case study of how General Motors is reaching for the market and cost saving benefits of DFM by adopting global vehicle architecture practices.

Additional DFM Solutions

Manufacturers and the vendors who cater to them, continue to develop DFM tools and technologies in their quest to solve the issue of manufacturing more reliable products, more quickly, at a lower cost.

Here is a sampling of four additional DFM solutions that can be found in the manufacturing environment:

1. Spreadsheets
2. Model-based Design Tools
3. Dimensional Measurement Tools
4. Manufacturing Intelligence Tools

Spreadsheets

The first additional DFM solution is the spreadsheet model. Spreadsheet models are the most basic of DFM tools. These are produced in-house by companies who are working through DFM issues, but have not yet moved to more sophisticated technologies. While the use of spreadsheets as a DFM solution may seem primitive, it is often the impetus for a company's exploration of and desire for more advanced DFM solutions (Miller & Benes, 2005).

Model-Based Design Solutions

The second additional DFM solution is the model-based design tool. In November 2006, Clear Shape Technologies debuted with two DFM tools that manage all the aspects of variability that affect design: OutPerform and InShape. OutPerform is used during the physical design of the product to identify timing and leakage problems and calculate changes needed. InShape checks each layer of a design to ensure that elements conform to the actual fabrication process model. It scans an entire design, then automatically generates a set of "fixing guidelines" that designers can use to implement changes in third-party tools. Chief Executive Officer, Atul Sharan, stresses that InShape doesn't create rigid guidelines, but rather produces a DFM hot spot list. Designers can also use InShape to perform what-if analyses (Santarini, 2007).

Dimensional Measurement Solutions

The third additional DFM solution is the dimensional measurement tool. CogniTens offers two dimensional measurement tools for manufacturers in the automotive industry: Optigo and OptiCell. Optigo is a portable tool for shop floor operators and engineers that comes in several flexible platforms and offers high accessibility in a variety of engineering and manufacturing environments. OptiCell is a fully automated platform that provides recurring measurements of parts and assemblies on the shop floor. Both Optigo and OptiCell automatically transform measurements into 3D information that provides comprehensive measurement analysis (CogniTens, 2007).

Manufacturing Intelligence Solutions

The last DFM solution is the manufacturing intelligence tool. Aprio is a software company that produces a line of DFM tools that enable manufacturers of integrated circuits to inject manufacturing intelligence into existing design tools. The tools include Halo-Quest, which predicts how a layout will look in silicon and identifies errors (D.V., 2007).

Case Study — General Motors (GM) & Global Vehicle Architecture Practices

Global vehicle architecture involves taking a modular approach to engineering the vehicle components so that a variety of vehicles can be built from the same components. A versatile feature of global vehicle architecture is that customization of the vehicle components may be performed in either a centralized geographical location, or in decentralized locations. The option of decentralized vehicle customization becomes a significant benefit if product preferences and legal modifications vary by customer location.

Global vehicle architecture produces cost and time savings in engineering, materials, plant tooling, and vendor tooling and General Motors (GM) is in the forefront of global vehicle architecture practices. Currently, GM engineers six of its vehicle models for global applications and has plans to introduce the global architecture platform on four more models. Gene Stefanyshyn, GM's vehicle line executive for global architecture, estimates that 36 vehicle combinations are possible using the building blocks of GM's global architecture. By implementing global vehicle architecture instead of regional architecture, GM is reaping the benefits both in geographical reach and in cost savings: Global vehicle models are either on sale now, or will be, in six continents, and GM estimates that savings in product development will be $500 to $1000 per vehicle (Kranz, 2007).

Conclusion

DFM practices offer many direct cost benefits for manufacturers, including cost savings in materials and labor, more reliable products, and faster time-to-market potential. They also offer indirect cost benefits, including lower employee turnover, higher customer satisfaction, and improved industry status. A variety of commercial DFM solutions are already available and manufacturers and the vendors who cater to them are developing new and more sophisticated solutions to meet the goals of consistently manufacturing reliable products, in the minimum amount of time, at minimal cost. Although DFM generally relies upon principles of standardization — it incorporates manufacturing processes that use standard parts, reduce the number of parts, and minimize handling during production — the most sophisticated DFM strategies allow for a range of product customization.

Terms & Concepts

Note: While some of these terms are in broad language usage (defect, error, and mistake), the definitions provided here are tailored to the manufacturing process.

Additive Manufacturing (AM) Technologies: Enable the fabrication of parts and devices that are geometrically complex, have graded material compositions, and can be customized. This technology is also known as "rapid prototyping" (Rosen, 2007). (See also "Rapid Prototyping.")

Computer-Aided Design (CAD): The use of computer technology to draw and design products; used chiefly by architects, engineers, and graphic artists.

Computer-Aided Engineering (CAE): The use of computer technology to perform various analyses of computer-stored designs for factors such as structural integrity and performance. CAE is used in combination with CAD.

Computer-Aided Manufacturing (CAM): The use of computer technology to control the manufacturing process.

Concurrent Engineering: A method of product or process design that includes simultaneous input from everybody with a stake or role (including engineers, salespersons, support personnel, vendors, and customers) throughout the entire design process.

Defect: The result of any deviation from product specifications that my lead to customer dissatisfaction. Two conditions may result in a product being considered defective: 1) the product has deviated from manufacturing or design specifications, or 2) the product does not meet internal or external customer expectations (Manivannan, 2007).

Design for Manufacturability (DFM): The tailoring of product designs to eliminate manufacturing difficulties and minimize costs (Rosen, 2007). Also known as design for manufacture.

Error: Any deviation from a specified manufacturing process (Manivannan, 2007).

Error-proofing: Designing the process to prevent mistakes; to stop errors from occurring; to warn that an error has occurred; and to prevent assembly errors through design strategies. There are three basic approaches to error-proofing: Physical (installing components like fixtures or sensors that eliminate the conditions for errors); operational (making modifications or installing devices that reinforce the correct procedure sequence); and philosophical (identifying situations that cause defects and fixing the situation). This term is often used interchangeably with "mistake-proofing" (Manivannan, 2007). (See also "mistake-proofing.")

Global Vehicle Architecture: A modular approach to engineering vehicle components so that a variety of vehicles can be built from the same components. In some cases, the customization of the vehicle modules is truly "global" in the geographical sense because it is performed in the country of sales.

Manufacturability: The features that make a product suitable for manufacture on a large scale basis.

Mistake: The execution of a prohibited action; the failure to correctly perform a required action; or the misinterpretation of information essential to the correct execution of an action (Manivannan, 2007).

Mistake-Proofing: Designing the process to prevent mistakes from occurring, to stop an error from occurring during further processing, or to warn that the error has occurred. This term is often used interchangeably with "error-proofing" (Manivannan, 2007). (See also "error-proofing.")

Poka-yoke: A concept introduced by an engineer at Toyota Motor Corporation in 1961 that uses process or design features to error-proof the entire manufacturing process by preventing the manufacture of a non-conforming or faulty product; promoting safer working conditions; and preventing machine damage. The original term was "baka-yoke" which translates as "fool-proofing," but in 1963, a worker at Arakawa Body Co. refused to incorporate the process into her work because she felt that the term was dishonorable and offensive, so it was changed to poka-yoke which means error-proofing or mistake-proofing (Manivannan, 2007).

Product Lifecycle Management (PLM): A strategic business approach that applies a consistent set of business solutions in support of the collaborative creation, management, dissemination, and use of product definition information across the extended enterprise from concept to end of life; integrating people, process and information (CIMdata, Inc. as cited by Gould, 2002).

Rapid Prototyping: Quicker-than-average production of models for the purpose of working out problems. (See also "Additive Manufacturing [AM] Technologies.")

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Suggested Reading

Albert, M. (2007). Always in the learning mode. Modern Machine Shop, 79, 100-105. Retrieved June 15, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=24510259&site=ehost-live

Azariadis, P., Moulianitis, V., Alemany, S., Gonzalez, J.C., De Jong, P., Van der Zande, M., et al. (2007). Virtual shoe test bed: a computer-aided engineering tool for supporting shoe design. Computer-Aided Design & Applications, 4, 741-750. Retrieved June 23, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=25292652&site=ehost-live

Blankenhorn, J. (2007). Achieving high density designs without compromising manufacturability. Printed Circuit Design & Manufacture, 24, 27-29. Retrieved June 19, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=23789419&site=ehost-live

Fantoni, G., Taviani, C., & Santoro, R. (2007). Design by functional synonyms and antonyms: A structured creative technique based on functional analysis. Proceedings of the Institution of Mechanical Engineers — part B — Engineering manufacture, 221, 673-683. Retrieved June 23, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=25209046&site=ehost-live

Van Vliet, H.W., & Van Luttervelt, K. (2004). Development and application of a mixed product/process-based DFM methodology. International Journal of Computer Integrated Manufacturing, 17, 224-234. Retrieved June 21, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=11622776&site=ehost-live