Design Management Group

Variety without complexity

Many companies design products one at a time, without considering the wider implications of component proliferation. Products which on the surface perform similar functions, underneath contain different assemblies, control systems, components, assembly methods and production techniques. The product range can be viewed as a series of icebergs, waiting to sink the corporate ship!

Typically, this proliferation is due to poor planning of the product range, little connectivity between different development teams working on different products and ineffective reuse of technology. A common result from this lack of planning, during product design is the development of highly efficient manufacturing processes to compensate.

A key to delivering cost effective products is to provide users and customers with the greatest possible variety of solutions, whilst minimising the production complexity within the business, through the reuse of technology, parts and processes.

Hierarchy of design decisions

The variety of product offerings and the relationship between these products is a strategic business issue, which must be considered prior to the start of any individual project. Product platform planning requires a systematic consideration of markets and available technologies in order to establish those technologies which can form the basis of different product offerings in different market segments.

Later in the design process, opportunities for reuse of technology reduce. During the concept design stage, the key trade off is between the level of modularity or integration in the product design. The decision to develop a modular product is linked to several key business issues:

Product change

How will the product be upgraded? Will add-ons be available, Will the product be adapted for different markets? Which parts will wear or need replacing? Are there any consumables? Is flexibility in use important?

Product variety

How many models are required in order to satisfy different market requirements and how are these models related?

Product performance

Does the product need to be optimised for cost, weight, aerodynamics, acceleration, size, speed, efficiency or other primary properties? Is an integral architecture important in order to optimise these physical characteristics.

Manufacturability & product (unit) cost

Can existing production capability be utilised more effectively through modularisation? Will unit cost be adversely affected by the addition of interfaces between modules? Can components be standardised across products? Can processes be standardised?

Service and maintenance

How will the product architecture impact on serviceability and maintenance?

Product development management

Is my development team distributed and are the modules and interfaces clearly defined? If my product architecture is highly integrated, does the project team communicate well and is there an appropriate mechanism for conflict resolution?

During the detailed design stage, it is important to consciously design for the reuse of components and processes. Wherever possible, production processes including tooling decisions and assembly methods should be consistent. A proliferation of tooling requirements can be as costly as a proliferation of parts. Likewise, components should be standardised wherever possible, including fasteners. Only when the opportunities for part or process reuse are exhausted should a component be designed to be consciously different.

Pros and cons of modularity

The choice between integral or modular products is in essence an economic one and should not be based on opinion or philosophy. Modularity has both positive and negative implications, as summarised below:

Further information

• Cutherell D, (1996), Product Architecture, The PDMA Handbook of New Product Development, pp. 217-235
• Galsworth, (1995), Smart Simple Design : Using Variety Effectiveness to Reduce Total Cost and Maximize Customer Selection, John Wiley & Sons
• Meyer & Lehnard, (1997), The power of product platforms, Free Press, USA
• Norman D A, (1998), The design of everyday things, MIT Press, UK
• Otto & Wood, (2000), Product design, Prentice Hall
• Reinertsen, (1997), Managing the design factory, Simon & Schuster
• Ulrich & Eppinger, (2000), Product design and development, McGraw Hill, USA