DESIGN FOR MANUFACTURABILITY
from the Book: "Design For
Manufacturability and Concurrent Engineering"
Design for manufacturability is the process of proactively designing products to (1) optimize all the manufacturing functions: fabrication, assembly, test, procurement, shipping, delivery, service, and repair, and (2) assure the best cost, quality, reliability, regulatory compliance, safety, time-to-market, and customer satisfaction.
Concurrent Engineering is the practice of concurrently
developing products and their manufacturing processes.
Design for Manufacturability and Concurrent Engineering are proven design methodologies that work for any size company. Early consideration of manufacturing issues shortens product development time, minimizes development cost, and ensures a smooth transition into production for quick time to market.
Quality can be designed in with optimal part selection and proper integration of parts, for minimum interaction problems. By considering the cumulative effect of part quality on product quality, designers are encouraged to carefully specify part quality.
Design for Manufacturability can reduce many costs, since products can be quickly assembled from fewer parts. Thus, products are easier to build and assemble, in less time, with better quality. Parts are designed for ease of fabrication and commonality with other designs. DFM encourages standardization of parts, maximum use of purchased parts, modular design, and standard design features. Designers will save time and money by not having to "re-invent the wheel." The result is a broader product line that is responsive to customer needs. Click here for article on standardization.
Companies that have applied DFM have realized substantial benefits. Costs and time-to-market are often cut in half with significant improvements in quality, reliability, serviceability, product line breadth, delivery, customer acceptance and, in general, competitive posture.
Designing Products for Manufacturability
In order to design for manufacturability, everyone in product development team needs to:
The Bad Old Days before DFM
Before DFM, the motto was "I designed it; you build it!" Design engineers worked alone or only in the company of other design engineers in "The Engineering Department." Designs were then thrown over the wall leaving manufacturing people with the dilemma of either objecting (but its to late to change the design!) or struggling to launch a product that was not designed for manufacturability. Often this delayed the both the product launch and the time to ramp up to full production, which is the only meaningful measure of time-to-market.
The Good New Days of Product Development Teams
One way that manufacturability can be assured is by developing products in multi-functional teams with early and active participation from Manufacturing, Marketing (and even customers), Finance, Industrial Designers, Quality, Service, Purchasing, Vendors, Regulation Compliance specialists, Lawyers, and factory works. The team works together to not only design for functionality, but also to optimize cost, delivery, quality, reliability, ease of assembly, testability, ease of service, shipping, human factors, styling, safety, customization, expandability, and various regulatory and environmental compliance.
By the time a product has been designed, only 8% of the total product budget has been spent (the incurred cost line). By that time, the design has determined 80% of the cost of the product! See the "committed cost" line on the graph from the book Design for Manufacturability & Concurrent Engineering.1 In Dr. Anderson's DFM Seminars, he shows a dozen similar graphs from various companies. Once this cost is locked in, it is difficult for manufacturing to remove it.
A key conclusion of this graph is that the concept/architecture phase alone determines 60% of the cost! This starts with
creative concept ideas that hold the biggest potential of all cost reduction
ideas. Product architecture determines crucial strategic decision
regarding product definition, technology, team composition, technology, part
combinations, and off-the-shelf parts (next topic). Further, this phase
determines strategies for manufacturing, supply chain, vendors, quality,
reliability, service, variety, configuration, customizations, and derivative
products. Theese decisions determine cost throughout the life of the
product. Concept/architecture activities have the highest impact of all
cost reduction strategies.
Paradoxically, one of the first decisions the team has to make is the optimal use of off-the-shelf parts. In many cases, the architecture may have to literally be designed around the off-the-shelf components, but this can provide substantial benefits to the product and the product development process:
Off-the-shelf parts are less expensive to design considering the cost of design, documentation, prototyping, testing, the overhead cost of purchasing all the constituent parts, and the cost of non-core-competency manufacturing. Off-the-shelf parts save time considering the time to design, document, administer, and build, test, and fix prototype parts.
Suppliers of off-the-shelf parts are more efficient at their specialty, because they are more experienced on their products, continuously improve quality, have proven track records on reliability, design parts better for DFM, dedicate production facilities, produce parts at lower cost, offer standardized parts, and sometimes pick up warrantee/service costs.
Finally, off-the-shelf part utilization helps internal resources focus on their real missions: designing products and building products
Some Key Design for Manufacturability Guidelines
A1) Understand manufacturing problems/issues of current/past products
A2) Design for easy fabrication, processing, and assembly
P1) Adhere to specific process design guidelines.
P2) Avoid right/left hand parts.
P3) Design parts with symmetry.
Understand the manufacturing process well enough to be able to design parts and dimension them for fixturing. Parts designed for automation or mechanization need registration features for fixturing. Machine tools, assembly stations, automatic transfers and automatic assembly equipment need to be able to grip or fixture the part in a known position for subsequent operations. This requires registration locations on which the part will be gripped or fixtured while part is being transferred, machined, processed or assembled.
Use concurrent engineering of parts and tooling to minimize tooling complexity, cost, delivery leadtime and maximize throughput, quality and flexibility.
Design of Experiments can be used to determine the effect of variations in all tolerances on part or system quality. The result is that all tolerances can be optimized to provide a robust design to provide high quality at low cost.
The "rule of ten" specifies that it costs 10 times more to find and repair a defect at the next stage of assembly. Thus, it costs 10 times more cost to find a part defect at a sub-assembly; 10 times more to find a sub-assembly defect at final assembly; 10 times more in the distribution channel; and so forth. All parts must have reliable sources that can deliver consistent quality over time in the volumes required.
The Rule of 10
Level of completion Cost to find & repair defect
the part itself X
at sub-assembly 10 X
at final assembly 100 X
at the dealer/distributor 1,000 X
at the customer 10,000 X
The Importance of Good Product Development
Dr. Anderson is a California-based consultant specializing in training and consulting on build-to-order, mass customization, lean/flow production, design for manufacturability, and cost reduction. He is the author of "Design for Manufacturability & Concurrent Engineering; How to Design for Low Cost, Design in High Quality, Design for Lean Manufacture, and Design Quickly for Fast Production" (2004, 432 pages; CIM Press, 1-805-924-0200; www.design4manufacturability.com/books.htm) and Build-to-Order & Mass Customization, The Ultimate Supply Chain Management and Lean Manufacturing Strategy for Low-Cost On-Demand Production without Forecasts or Inventory" (2004, 520 pages; CIM Press, 1-805-924-0200, www.build-to-order-consulting.com/books.htm). He is currently writing the book, "Half Cost Products: How to Develop, Build, and Deliver Products at Half the Total Cost." He can be reached at (805) 924-0100 or firstname.lastname@example.org; web-site: www.build-to-order-consulting.com.
1. David M. Anderson, Design for Manufacturability & Concurrent Engineering; How to Design for Low Cost, Design in High Quality, Design for Lean Manufacture, and Design Quickly for Fast Production (2004, 432 pages; CIM Press 805-924-0200; www.design4manufacturability.com/books.htm). Click here for the DFM book description and order form.
2. David M. Anderson, Build-to-Order & Mass Customization; The Ultimate
Supply Chain Management and Lean Manufacturing Strategy for Low-Cost On-Demand
Production without Forecasts or Inventory," (2004, 520 pages; CIM Press 805-
924-0200, www.build-to-order-consulting.com/books.htm; ISBN 1-878072-30-7).
Click here for the Build-to-Order book description and order
For more information call or e-mail:
Dr. David M. Anderson, P.E., CMC