DfM is an umbrella term under which several concepts – and significant cost-savings – reside.

A startling statistic shows the need for design for repair: Up to 50% of units returned for repair are not faulty. Several conditions can cause this waste of time and resources. But where many companies commonly err is by failing to select a manufacturing partner or bring an EMS company into the process until a new product is ready for volume production.

DfR is just one of six elements of design for manufacturing (DfM). All six support the argument that there are value and benefits to working with an EMS company early in the design cycle.

The product lifecycle consists of three stages: research and development, volume manufacturing and post-manufacturing. The R&D stage consists of creating the design, determining the bill of materials, developing the recipe to manufacture that design, and giving that input to a contract manufacturer for volume manufacturing. Little collaboration occurs between the R&D team and the contract manufacturer. Therefore, some elements of design for manufacturing (DfM) often are omitted from the product lifecycle.

A simple definition of DfM is "examining the long-term impact of decisions made during the design of a product." Companies can profit if early in the product lifecycle they examine the elements that comprise DfM and how they affect product cost. Let's look at the six elements of DfM in greater detail.

1. Design for sourcing. Most products used to be designed and manufactured within the same company. Communication between production personnel and design engineers was relatively easy. Indeed, it might be said that this interaction produced a rudimentary form of DfM in the product lifecycle. With the growth of outsourcing, design engineers have fewer opportunities to interact with the manufacturing team. Purchasing departments are separate and not coordinated. An engineer or buyer at the R&D stage might decide to purchase a component based solely on whether the component meets the desired specifications and how quickly it can be obtained. These are reasonable parameters for building small numbers of products, but volume manufacturing requires other considerations.

Sourcing involves answering questions about what to buy, where to buy, how much to buy and when to buy. An EMS company knows the suppliers. It knows which ones can produce the quantities needed and deliver them on time to the multiple locations in which the product might be built. Large EMS companies buy in great quantities and can take advantage of volume discounts. Because they use millions of components, they know the ones with the best quality and what works best in various designs with various conditions. Larger EMS companies maintain databases that track how certain components influence other DfM aspects.

DfM can impact the timing of the purchase. Two years may pass between initial R&D on a new design and the date that product is ready for volume production. At the beginning of the design cycle, the engineer or buyer chooses electrical components, materials, substrates, enclosures, connectors, and other building blocks of the new product. Important considerations include whether some of these are legacy products that might be obsolete by the end of the design stage, whether they are new and still possibly undergoing manufacturability and availability issues, and what products might be in the prototype stage and available for beta testing by the supplier or ready for use within the two years. EMS companies involved early in the design process can guide these decisions.

EMS engineers and buyers can anticipate procurement issues if engaged early in the design of a new product. Global manufacturers have price and availability leverage with suppliers, advantages not always available to R&D personnel. Their early awareness of the future need of a specific item can help them and their customer prepare a sourcing strategy and obtain firm commitments from preferred suppliers. When prepared for material and component purchases for volume manufacturing and armed with a sourcing strategy, EMS firms can achieve up to a 50% cost savings, depending on the commodity.

2. Design for logistics. Logistics, both inbound and outbound, can be a tremendous variable in the total cost of operation. Decisions made in the design phase can result in extra savings or costs in logistics. How big is the lead-time buffer? Is the production and delivery schedule flexible? How many parts or subsystems are sourced and from how many vendors and locations? What is the product size and modularity?

The design of the package can impact the type of logistics required and vice versa. This is also the time to discuss where manufacturing will take place. Where will the product be shipped? What will be the duties and tariffs? What type of paperwork will logistics require? Should product be shipped via truck, rail, sea or air? The global EMS provider is experienced with local transportation companies in target markets, customs and duties charged by local governments and regional authorities, and can help determine the most cost-effective place to purchase and manufacture product. EMS companies also typically can coordinate all pieces of the sourcing and logistics puzzle so that each piece fits smoothly.

3. Design for assembly. Streamlining the assembly process can result in tremendous cost and time savings and improve quality, reliability, throughput and yield. EMS companies have a vast database of knowledge about the capabilities of high-volume assembly equipment, all facets of the modern electronics production line, and systems in place for optimizing process flow.

Designers often produce prototypes on manual lab equipment, especially when manufacturing is outsourced and in-house manufacturing capabilities are limited or nonexistent. Building prototypes on manual equipment with the intent of transitioning production to automated equipment often creates problems, however. Designs are often developed around manual equipment without much consideration for future automation. But just because an assembly process is successful on manual equipment does not mean that the process is ready for fully automated production. Additional considerations must be designed into the process. For example, vision systems need adequate fiducials to ensure they can accurately locate and place components, and components need to be presented in a manner compatible with full-scale production. Failure to design for assembly can lead to a procedure that needs significant and costly refinements to process flow and materials before it is ready for volume manufacturing.

4. Design for test. DfT has both economic and technical advantages. The first and most obvious economic reason is to minimize investment in test equipment. As test equipment becomes more specialized, it also becomes more expensive. DfT focuses on the equipment needed to build a new product and eliminates duplicate test functions. A second and closely related financial justification for DfT is that it considers ways in which existing test equipment might be refitted and reused. Since testing high-tech products is expensive, it makes sense to optimize test procedures. Perhaps some tests are unnecessary or adequate reliability results can be achieved with less expensive methods. EMS companies typically have vast knowledge about actual test failures and their effect during manufacturing. By bringing this knowledge to the R&D phase, test times can be slashed without compromising product quality.

In addition to enabling selection of the best test equipment for a new product, DfT also looks at the setup cost of test. Test engineers examine fixture types and develop an effective, efficient test program. A final economic foundation for design for test is reduction of total test time.

The technical reasons for DfT are to:

• Speed up test execution.

• Improve fault detection.

• Provide accurate diagnostics to support fault analysis.

• Simplify repair.

• Evaluate needed test steps and alternative solutions for expensive testing.

5. Design for repair. As mentioned, up to 50% of units returned for repair are not faulty. The reasons are myriad. Sometimes the equipment used to determine whether a unit is faulty is nonstandard. Perfect test equipment for volume manufacturing might not fit the needs of repair functions. DfR supports the establishment of simple hardware and software modifications, as well as failure analysis and clear failure messages.

DdR encourages robust design so that alternate components can be used. One important aspect of robustness is modular design, which enables quick and simple disassembly during repair. DfR also ensures a new product permits easy access for repair tools, and that it has easy-to-locate labels with an identifiable model number, version and date of manufacture.

A significant, but perhaps overlooked, benefit of DfR is a plan to use repair data to refine material and product choices in future designs. Some EMS companies are particularly skilled at collecting and analyzing repair data and reporting back to customers.

6. Design for environment. DfE may be a new idea for some, but the concept is simple. DfE is a systematic application of environmental lifecycle considerations at the product design stage. DfE's aim is to avoid or minimize significant environmental impacts at all stages of the product lifecycle. This applies to everything from the sourcing of raw materials and components to the design and manufacture of the product, its distribution, use and end-of-life disposal.

On Aug. 13, 2007, DfE practices will become a requirement for all products bearing the CE mark. Key issues to consider are:

• Air emissions.

• Water discharges.

• Waste.

• Material use.

• Energy use.

• Water use.

• The natural environment, including flora, fauna, and ecosystems.

• Social factors such as noise and the nuisance effect of a product.

The equation for modern high-volume manufacturing can be stated as:

DfM = DfS + DfL + DfA + DfT + DfR + Design for x*

*to be determined as conditions require

DfM is most effective when employed as early as possible in design, where the design team involves the manufacturing team as a part of the design stage. It involves all stakeholders in the product from concept to development through manufacturing and end-of-life. This means an extra investment during the design stage, but it is an investment that in the end reduces total cost of ownership.

 

Ed.: This column was first published in the Dallas Basestation Conference e-newsletter in June 2006 and is reprinted here with permission from the author.

 

Petra Ebner is director of business development at Elcoteq SE (elcoteq.com).

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