Volume 37, Issue 4 (July 2009)
Prediction of Cushion Performance Less Than One Inch Thick
An important tool packaging engineers use when designing cushions to protect products from shock is the cushion curve. Cushion curves show deceleration values along the vertical axis versus the static loading (weight divided by bearing area) along the horizontal axis for a given thickness of cushion material and given drop height. Commercially available cushion curves display a thickness of one inch and greater. However, many times packaging engineers design packages with cushions less than one inch thick. This leaves the packaging engineer to either guess deceleration levels below one inch thick by trial and error, or to extrapolate from existing cushion curve data. The purpose of this study was to determine if using existing cushion curve information would accurately predict deceleration values below one inch thick. To do this, a procedure was developed comparing information collected from expanded polystyrene cushion samples greater than one inch thick (correlating to existing cushion curves) compared to information collected from samples less than one inch thick. The comparison looked for difference between the datasets. It was found that in fact there was a statistical difference, meaning existing cushion curves should not be used to predict deceleration values for cushion thicknesses below one inch.