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1、FIVE STEPS FOR PACKAGE CUSHION DESIGN缓冲包装设计5步法Introduction Better Package and Product Design Saves Money and Improves Customer Satisfaction. Packaging can be unnecessarily expensive in a couple of ways: 1. Inadequate design results in shipment damage 2. Over-design or poor design (more protection th
2、an is required or materials being incorrectly used ) results in excessive material cost. High cost of damage in shipment should be unacceptable to those who are aware of the claims costs and the lost customers. Conversely, the cost of waste resulting from over-packaging (poor and unneeded material u
3、tilization) is less visible and more difficult to aggressively pursue. This total waste, estimated at billions of dollars, could be significantly reduced if packages were properly designed for shock and vibration protection. This text describes a basic procedure for logically designing and testing c
4、ushioned packages. The techniques outlined here are not new. Nevertheless, the logical, step-by-step procedures are not yet universally used by all package designers . Increasingly the theories and techniques presented here are also being used by product designers to evaluate and improve the ruggedn
5、ess of products. Indeed, often it is more economical to permanently improve products than to provide temporary cushioning which will later be discarded. The procedure can be broken down into five basic steps. This 5 Step Method was developed in conjunction with the Michigan State University School o
6、f Packaging.1. Define The Environment Shock: choose the most severe drop height you wish to protect against. Vibration: Determine a representative acceleration vs. frequency profile.2. Define Product Fragility Shock: Determine the products shock damage boundaries. Vibration: Determine the products c
7、ritical resonant frequencies.3. Choose The Proper Cushioning Select the most economical cushioning to provide adequate protection for both shock and vibration.4. Design and Fabricate The Prototype Package5. Test The Prototype Package Shock: Use the “Step Velocity” test method. Vibration: Verify adeq
8、uate protection at the critical frequencies. This chapter discusses only shock and vibration. Other environmental factors such as compression, humidity, temperature, and other potentially destructive forces should also be considered in designing and testing a package. A similar, logical treatment of
9、 the products needs for protection from these hazards should also be incorporated. In some cases, only minor modifications may be required to account for these other factors after a sound, basic design for shock and vibration has been completed and tested. Step 1 Define the EnvironmentShock It is ge
10、nerally agreed that, regardless of the transportation mode, the most severe shocks likely to be encountered in shipping result from handling operations. These result from dropping the package onto a floor, dock or platform. Of course, many kinds of drops are possible (flat, corner, edge, etc.), but
11、we know that the most severe transmitted shock occurs when a cushioned package lands flat on a nonresilient horizontal surface. It is reasonable, then, to design cushioned packages for this flat drop. In designing for shock protection, the first consideration is selecting the design drop height. Cha
12、rts similar to the one shown in Figure 1 will be helpful. The chart takes into consideration both the package weight and the probability of drops occurring from specified heights. When selecting the probability level, factors such as the relative costs of products and package, shipping costs, and th
13、e percentage of loss which can be tolerated must be considered.Vibration The transportation vibration environment is complex and random in nature. The basic method of testing for package design is not to simulate the vibration environment, but rather to simulate its damage-producing capabilities. Th
14、us, a procedure which identifies the product and component resonant frequencies, and which leads to protection at those frequencies, can be expected to produce effective result .Figure 1 Probability Curves for Handling Shocks You may select acceleration levels and frequency ranges from environmental
15、 data and acceleration-frequency profiles such as shown in Figure 2, from a vibration acceleration envelope like that in Figure 3, or, from a power spectral density summary plot as shown in Figure 4. Acceleration levels and frequency ranges you select must be consistent with the available additional
16、 data, experience, judgement, and knowledge about the product.Figure 2 Frequency Spectra for Various Probabilities-Railroad (vertical direction, composite of various conditions)Figure 3 Vibration Acceleration Envelope-Railcar The actual shape of the acceleration-frequency profile is not as important as being able to sufficiently excite the critical components over the r
