Meaning
Quantitative calculation used to determine the cumulative effect of individual part variations on the final fit and function of a mechanical assembly. Accurate tolerance stackup analysis ensures that parts manufactured at different locations will fit together correctly during final assembly. The process identifies potential interferences or gaps that could compromise the mechanical integrity of the product.
Calculation Method
Summation of the maximum and minimum limits for every dimension provides a conservative view of the possible fit issues. While performing a tolerance stackup analysis, the designer looks for scenarios where all parts are at their size limit simultaneously.
Interference Prevention
Prediction of the actual variation often uses a root sum squared method rather than a simple addition of the limits. This part of the tolerance stackup analysis assumes that most parts will fall near the middle of their specified range rather than at the extremes. Using a statistical model allows for looser tolerances on individual parts, which reduces the cost of manufacturing.
Design Optimization
Identification of the most sensitive dimensions allows engineers to focus their quality control efforts where they matter most. Results from the tolerance stackup analysis guide the selection of manufacturing processes that can achieve the required precision. This focus ensures that the final enclosure closes properly and that all internal connectors align with their respective openings while maintaining the necessary thermal clearance for the internal batteries.
A failure to optimize these dimensions often results in mechanical interference during the final assembly of the product.
