An Introduction to “Model of Change Margins”:
As the saying goes “Change is Inevitable”, so is the design modifications of an engineering product or any parts associated with it. Engineering products undergo constant changes, during the entire product lifecycle. The amount of changes depends on what stage the product is currently in. For example, the amount of changes that a specific component undergo may be lesser when its in service state, that when it was during the design phase.
However, in most of the cases changes become problematic when it exceeds certain level of threshold. Hence products are usually designed with flexibility in place. Product flexibility can be defined as “the degree of responsiveness (or adaptability) for any future change in a product design” (Ross and Hastings, 2005). The boundary of this design flexibility is defined as “Change Margins” in a product. Even a product that is designed systematically anticipating and rating the potential changes to “future proof” the design, cannot be bent beyond certain bounds. “Change Margins” define the boundaries or a specific parameter of a part characteristic, beyond which a part or a product cannot be altered, regardless of any other factors that motivates the change.
“Change Margins” needs to be considered even before a specific design process starts. The designer should have an in-depth understanding of the relationship between various components and systems associated with the product, to estimate when knock out changes are likely to force redesign of the product and define “Change Margins” based on it. It is important to define “Change Margins” keeping in mind it does not affect the core purpose of the product for which it was designed for.
For example, a damaged display panel of a mobile phone can be replaced with a component from a different manufacturer than it was originally designed with. However, the design specifications of the display panel should be compatible with the original display panel, and it should also be compatible with the other components that are used in the mobile phone. A mobile phone that is designed to handle AMOLED (Active Matrix Organic Light Emitting Diode), cannot be replaced with a TFT (Thin Film Transistor). However, a 1500 mAh battery manufactured by Samsung which was used in the mobile phone, can be replaced with another 1550 mAh battery manufactured by LG. The “Change Margins” of the mobile phone define the boundaries or the extent of change that the product can undergo without affecting its core functionality.
Hence “Change Margins” play a vital role in a product design, therefore should be efficiently managed across product lifecycle by evaluating the flexibility regarding the manufacture and use of the product