Design for Producibility

from the Perspective of Competitive Advantage

by
Edwin B. Dean

This topic area is better known by the terms design for manufacture or design for assembly. I consider each of these to be a subtopic within this more general realm of producibility which may include other topics as well.

Boothroyd and Dewhurst (1991) note that

Design for manufacture, DFM, means different things to different people. ... The key to successful product DFM is product simplification through design for assembly, DFA. DFA techniques primarily aim to simplify the product structure so that assembly costs are reduced.

Bralla (1996) notes that

In the Broadest sense, DFM includes any step, method, or system taht provides a product design that eases the task of manufacturing and lowers manufacturing cost.

Stoll (1986) provides and excellent overview of design for manufacture.

Whitney (1988) notes that at Nippondenso

When asked how much the factory cost, the project's chief engineer replied, "Strictly speaking, you have to include the cost of designing the product." A factory isn't just a factory, he implied. It is a carefully crafted fusion of a strategically designed product and the methods for making it.

Since software as a percentage of total system cost is significant and rising rapidly, one possible additional topic under design for producibility is design for software production. Production is typically associated only with hardware. But software is produced as well as hardware. What does it mean to produce software? How would we design software to be more producibile?

Generalizing these questions: What does it mean to produce a system which contains hardware, software, processes, people, and organization? What does it mean to make a system more producibile? What is producibility? Is producibility a well posed concept?

Bralla (1996) notes that

By manufacturability we mean the ease with which a product or component can be produced, it's simplicity, the straightforwardness of its configuration, the degree to which it minimizes labor, materials, and overhead costs, and the freedom that its design has from inherent quality and processing problems.

What is quality for the activity (produce,product)? Since quality is defined by the customer, the quality of production is defined by its downstream customers, as well as the goodness of the production process. These downstream customers are the activities which evaluate the product, test it, deploy it, operate it, support it, evolve it, retire it, and manage it. Thus the activity (produce,product) must, in some way, address the evaluability, testability, producibility, deployability, operability, supportability, evolvability, retireability, and manageability of the product. Doesn't the need to address downstream customers suggest that quality function deployment is a natural process for extending the definition of producibility?

I propose that there is a natural way to define the generalized producibility proposed here. Consider the function {produce,product}. Consider the functional measure {produce,product,attribute}, then {manufacture,this_bolt,duration} and {code,this_object,number_of_errors} are typical measurable instantiations (mathematical variables) of the class {produce,product,attribute}. These variables are quality characteristics within QFD of specific production processes. When target values or ranges are specified for these variables, they become the requirements for the design of the production process (Dean, 1992). They also measure the producibility of the production process. Hence they define the attributes of the function {test,{produce,product}}, i.e., the producibility of a specific production process is measured by a test of that production process.

Note that attributes can also be defined by downstream customers. From the perspective of retireing a food package, the customer desire might be that the package biodegrade. The associated quality characteristic might be {biodegrade,package,duration}. A target value of 3 years might be chosen. This downstream desire must be factored into the choice of material if the product is to be retireable. The question arises whether this retireability characteristic needs to be applied to the activity (design,product) or (produce,product). I suggest that it should be a design quality characteristic, but that the activity (produce,product) needs to ensure that is being met by the production process.

Maskell (1991) provides insights into specific measurable quality characteristics for producibility.

Ohno (1988) is must reading for any student or teacher of production.

References

Boothroyd G. and P Dewhurst (1988). "Product Design for Manufacture and Assembly," Manufacturing Engineering, April, pp. 42-46.
Bralla, J. G. (1996). Design for eXcellence, McGraw-Hill, Inc., New York, NY, USA.
Dean, E. B. (1992). "Quality Function Deployment for Large Systems", Proceedings of the 1992 International Engineering Management Conference, Eatontown NJ, 25-28 October.
Maskell, B. H. (1991). Performance Measurement for World Class Manufacturing: A Model for American Companies, Productivity Press, Cambridge MA.
Ohno. T. (1988). Toyota Production System: Beyond Large-Scale Production, Productivity Press, Portland, OR, USA.
Stoll. H. W. (1986). "Design for Manufacture: An Overview," Applied Mechanics Review, Vol. 39, No. 9, September, pp. 1356-1363.
Whitney, D. E. (1988). "Manufacturing by Design," Harvard Business Review, July-August, pp. 83-91.

Design for Producibility

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