Trade-Off Curves

Describe the limits of performance that are possible with a given design approach in a simple visual form. They typically characterize the relationship between two or more key parameters that relate design decision(s) to factor(s) that customers care about over a range of values, for example, diameter and wall thickness of pipe (design decisions) to fluid pressure and velocity (customer requirements).

Trade-off curve sheets should include a picture of the part and/or process; a statement of the failure mode being considered; an analysis of the cause; possible countermeasures; a graph showing the conditions under which the failure mode occurs and the relationships between the key parameters (see illustration). Design groups then create engineering check sheets that summarize the key points from the trade-off curve studies into a compact and efficient form for use in design reviews.