【正文】 s, items with delicate mechanical alignments Very Delicate Medical diagnostic apparatus, Xray equipment Delicate Display terminals, printers, test instruments, hard disk drives Moderately Delicate Stereos and television receivers, floppy disk drives Moderately Rugged Major appliances, furniture Rugged Table saws, sewing machines, machine tools 1525 g39。s or lower. ? The highest static loading value within the cushioning range will result in the most economical design because it will use less cushioning material to provide adequate protection, thus lowering design costs. Step 3 Calculate Cushion Requirements ? The cushion bearing area is easily calculated as the product weight divided by our chosen static loading. a) 60 / = 200 square inches of foam b) 60 / = 43 square inches of foam (This is a % reduction in cushioning material) ? Designing to the minimum thickness is the general practice. ? By repeating this procedure with several materials, you can quickly generate parisons, which will allow you to strike an economical balance between material cost and package size. Step 4 Recognizing Design Constraints 1. Consider Compressive Creep ? Compressive creep is the gradual loss of thickness a material may experience if placed under a constant load for an extended period of time. ? Significant pressive creep will result in the packaged product loosening in the cushion and being vulnerable to excessive movement inside the package during shipment. Step 4 Recognizing Design Constraints ? As a general rule, creep of 10% is recognized as a practical upper limit. In some cases creep losses of over 10% in thickness have been shown to result in a significant loss of cushion performance. ? Should it be found that creep in excess of 10% is anticipated, designers should recalculate the functional foam requirement using a lower staticloading figure. Spreading the loading over a larger area will reduce pressive creep. Step 4 Recognizing Design Constraints ? Buckling is the nonuniform pression of a cushion. ? When buckling occurs, the energy of the impact is not transferred evenly throughout the cushion and more shock is transferred to the package contents. ? Buckling usually occurs when the cushions bee too tall and thin. ? Figure