Engineers are trained to design for functionality and their CAD tools pre- dominantly design for functionality. However, really good product devel- opment comes from designing for everything, which is sometimes called DFX. This section details design considerations for DFX. The key is to consider all goals and constraints early.
3.5.1 Function
While the product has to work properly, it must be kept in mind that, although function is the most obvious consideration, it is far from being the only one. A redesign to correct a purely functional problem will result in another product development cycle, and another introduction. And those can introduce new, unknown manufacturability problems which can become an unexpected drain on manufacturing resources.
3.5.2 Cost
Cost has been the battleground of competition for decades. But the low- est product cost does not result from “cost reduction” measures per se. As
pointed out in Chapter 1, design determines more than three- fourths of a product’s cost.
For example, one high- tech company appointed a “cost reduction man- ager” for a critical new product line, who managed to reduce the projected cost to within the goal by buying the cheapest parts. However, the parts came from 16 different countries and it took 9 months to deliver first arti- cles. And this was on a leading- edge product! Furthermore, when produc- tion began, the part quality was so poor that plant production actually ground to a halt, thus delaying delivery even further.
The subject of cost will be treated in more detail in Chapter 6.
3.5.3 Delivery
Delivery is greatly affected by the design because the design determines how difficult the product is to build and assemble. The choice of the parts determines how hard the parts will be to procure and how vulnerable production will be to supply glitches. Standardization (Chapter 5) will affect the effectiveness of Lean Production, which is the key to fast factory throughput (see Chapter 4).
3.5.4 Quality and Reliability
Like cost, quality and reliability are determined more by the design than is commonly realized. Designers specify the parts and, thus, the quality of the parts. Designers determine the number of parts and so determine the cumu- lative effect of part quality on product quality, which is especially impor- tant for complex products (see Section 10.3). Designers are responsible for the tolerance sensitivity. The processes specified by the designer determine the inherent quality of the parts. Designers are responsible for ensuring that parts are designed so that they cannot be assembled incorrectly, which in Japan is called poka- yoke, or what we would call mistake- proofing (see Section 10.7). These are very much manufacturability issues because quality problems must be consistently corrected in the plant before a product can be shipped. Quality and reliability are discussed further in Chapter 10.
3.5.5 Ease of Assembly
Ease of assembly is what comes to mind when most people think of DFM because much attention has been focused on design for assembly (DFA),
later renamed DFMA, and software to analyze designs to look for oppor- tunities to improve the assembly of high- volume products. The DFM techniques presented herein optimize the ease of assembly by design, independent of production volumes. Chapters 8 and 9 present general guidelines for designing products that can be easily assembled.
3.5.6 Ability to Test
Test strategy is very much affected by the company quality culture. At companies with a good quality culture, quality is everyone’s responsibil- ity, including designers! The TQM (total quality management) philosophy is that, instead of being tested in, quality should be designed in and then built in using process controls. Theoretically, products need not be tested if all processes are 100% in control. However, few factories are that confident in their processes, so they may elect to conduct at least a “go/ no- go” func- tional test. Unsophisticated factories with higher fallout (failures) produc- ing complex products may need tests to aid in diagnostics. Designers of these products are responsible for devising a way to not only test the prod- uct but also diagnose any problems, to show the Rework Department how to repair it. In complex products, test development costs can exceed prod- uct development costs and can even take more calendar time. Test guide- lines are included in Chapter 8.
3.5.7 Ease of Service and Repair
Being able to repair a defective product is a manufacturability issue because any product failing any test will have to be repaired, thus consuming valu- able manufacturing resources. Service and repair in the field can be more troublesome because field service centers usually have less sophisticated equipment than factories. In extreme cases, field failures may be sent back to the factory for repair, thus diluting manufacturing resources. Designers should design in ease of service and repair (see Section 8.9).
3.5.8 Supply Chain Management
Supply chain management can be greatly simplified by the standardization of parts and raw materials (Chapter 5), part selection based on adequate availability over time, and product line rationalization (see Appendix A) to eliminate or outsource the old, low- volume, unusual products that have
the most unusual parts. In many cases, this simplification, performed in product portfolio planning and product development, will be essential to the success of supply chain management initiatives as well as programs to implement Lean Production, build- to- order, and mass customization.
3.5.9 Shipping and Distribution
The distribution of products will be revolutionized by build- to- order,26 which is the ability to build products on demand and shipping them directly to customers, stores, or other factories instead of the mass produc- tion tradition of building large batches and then shipping them through warehouses and distribution centers. Selling products from inventory presents many problems: The whole system depends on forecasts, which rarely come even close to predicting customer demands, especially when markets are fast moving. Inventory costs money to carry, usually 25% of its value per year!27 If forecasts were too high, then inventory will have to be marked down to “move the merchandise.” If forecasts were too low, then sales opportunities will be lost. Sometimes manufacturers try to compensate for inadequate forecasts by expediting production, but this can be expensive and can disrupt scheduled production.
3.5.10 Packaging
Packaging considerations should not be left until the first manufactured product reaches the shipping dock. Packaging variety and its logistics can be reduced with standard packaging that can be used for many prod- ucts. Unique information can be added by printing on- demand labels or directly onto the boxes. Environmentally friendly packaging materials and recycled packages are becoming more important.
Designing inherent shock resistance into the product can reduce the size and cost of protective packaging. Another packaging implication is that returns due to shipping damage may come back to the factory, thus adding cost, upsetting customers, and depleting manufacturing resources.
3.5.11 Human Factors
Human factors and ergonomics are social considerations that should be considered at the very beginning, because ergonomic changes would be difficult to implement after the design is complete. Good human factors
design (Chapter 10) of the product and process will reduce errors and accidents in use and during manufacture. In some industries (e.g., elec- tronics), many service calls deal with usability issues. Philips Electronics found that “at least half of returned products had nothing wrong with them. Consumers just couldn’t figure out how to use them.”28
3.5.12 Appearance and Style
Appearance and style should be considered an integral part of the design, not something that is added later. Sometimes, the style is dictated by an early industrial design study. This can really hamper incorporating DFM principles if they were not considered in the styling design. All factors of a design, including styling, need to be considered simultaneously through- out the design.
3.5.13 Safety
Safety should not be considered only after a recall or lawsuit. Careful design and simulations should be utilized to prevent safety problems before they manifest. If a safety issue surfaces, the root of the problem must be deter- mined and remedied immediately. Safety issues can create a major disrup- tion to engineering, manufacturing, and sales, in addition to jeopardizing the product’s and the company’s reputation. Designers should make every effort to design safe products the first time as a moral and legal obligation.
3.5.14 Customers’ Needs
The ultimate goal in designing a product is to satisfy customer needs. In order to do that, designers must thoroughly identify and understand cus- tomer needs (Section 2.11), and then systematically develop the product to satisfy those needs.
3.5.15 Breadth of Product Line
Using the principles of Lean Production and build- to- order, discussed in Chapter 4, products can be designed with standard parts and be produced on flexible manufacturing lines or cells. Common parts, standard design
features, modular subassemblies, and flexible manufacturing can be com- bined to satisfy more customers.
3.5.16 Product Customization
Customized products can be built as quickly and efficiently as mass pro- duction if products and processes are designed for mass customization.29 For more on mass customization, see Section 4.3.
3.5.17 Time- to- Market
Time- to- market is a major source of competitive advantage.30 In fast- moving markets, being first to market can have major market share implica- tions. Figure 3.2 shows the effect of an early product release on the revenue profile. The shaded area represents the extra sales due to the early introduction.
However, because the product development and tooling costs were paid for by the baseline sales profile, the shaded area is really extra profit.
3.5.18 Expansion and Upgrading
Designers should design products so that they are easy to expand or upgrade by the plant or by the customer. This capability may allow the company
Extra Sales with Early Introduction
Revenue Second
Upgrade First
Upgrade
Time
End of Life for Single Product Early
Release Date
Baseline Introduction
Date
Baseline Sales Profile
End of Life for First Upgrade
End of Life for Second Upgrade
Original Product Life Cycle
Extended Product Life Cycle FIGURE 3.2
Increasing revenue with early introductions and upgrades.
to increase profits by extending the life of each product. Marketing and finance representatives should be involved early to help formulate the prod- uct upgrading strategy and calculate its value. Crunching the numbers will point out the high profit potential in the latter stages of the products’ life- times after development costs are paid off, as shown in the upgrade exten- sions in Figure 3.2. Again, the product development and tooling costs were paid for by the baseline sales profile, so the shaded area is really extra profit.
Planning to extend a product’s lifetime with easy upgrades may be a very worthwhile goal to consider in the initial phases of the product design.
3.5.19 Future Designs
Similarly, current products should be designed so subsequent products can be based largely on current designs. This will save considerable time and cost in the next design if maximum use can be made of current engi- neering, parts, modules, and software.
3.5.20 Environmental Considerations 3.5.20.1 Product Pollution
Environmental design considerations should not be left to the first time the product or its process is fired up. Problems discovered at this stage may require major changes or a redesign to correct. Designers should antici- pate environmental trends and design products clean enough for future environmental standards.
3.5.20.2 Processing Pollution
Product designers specify the process whether they realize it or not. Even specifying the usual process may continue a process that is causing pollu- tion from solvents, combustion products, chemical waste, and so forth.
Designers of new products have the opportunity to optimize the environ- mental cleanliness of the processes. This is much easier to do in the early stages of the design than later. Do not wait until environmental activists or a regulatory agency force your company to change your processes, which would result in disruptive changes in the factory, costly penalties, engi- neering change orders, and maybe a product redesign.
3M Corporation formulated an environmental strategy called the 3P program: “Pollution Prevention Pays.” The theme is prevention of pol- lution at its source. The three elements of the program are recycling, re designing products and equipment for less pollution, and creating prod- ucts that do not pollute in the first place. Note that two out of the three methods depend on the design to reduce pollution.
3.5.20.3 Ease of Recycling Products
Similarly, companies should be concerned about what happens to a prod- uct after its useful life is over. Can it be recycled into new products? Can it be upgraded for extended life? The company may even be able to profit in some manner from the recycling or extension of its products. If the product must be disposable, it should degrade quickly and safely with- out aggravating solid waste disposal problems. These factors, like all the others, must be considered throughout the design phase.
3.5.21 Summary
All these factors should be emphasized early by product development teams because redesigns or major product design changes consume a great deal of design and manufacturing resources to implement.
Remember that changes and redesigns consume engineering time and money that should be invested in new product development. This leads to one of the most important design principles for design in general, not just for DFM: The further into a design, the harder it is to start satisfying additional needs.
It is important to design with a balanced set of design considerations. Do not let any considerations dominate the design or others will suffer. Many people do not have a clear understanding of whose job is it to incorporate these considerations into the design. Some may think that ease of assem- bly comes from the manufacturing department. Some may think ease of service comes from the service department. Many think that quality is the responsibility of the quality department. The correct view of responsibility is a paraphrase of the motto of TQM programs:
It is everyone’s responsibility to incorporate all considerations early into the design.
The consequences of not considering everything early:
1. It is very difficult to integrate considerations later and results in delays, extra cost, and depleted resources.
2. The considerations are never incorporated into the design, resulting in a product that is (1) less competitive, (2) must be withdrawn from the market, or (3) needs to be redesigned.