For equipment that requires shock protection select the approximate Fragility from the chart below.
Chart 1
|
Approximate Fragility of Typical Packaged Articles |
| |
|
Extremely fragile |
Missile guidance systems, precision aligned test instruments |
15 - 25 G's |
|
Very delicate |
Mechanically shock mounted instruments and electronic equipment, Disk Drives |
25 - 40 G's |
|
Delicate |
Aircraft accessories, Computers, Laptops, Flat Panel Monitors, Standard Monitors, Printers, Scanners |
40 - 60 G's |
|
Moderately Delicate |
Television receivers, aircraft accessories |
60 - 85 G's |
|
Moderately Rugged |
Major appliances |
85 - 115 G's |
|
Rugged |
Industrial machinery |
115 G's and up |
Divide the equipment weight, pounds, by the bearing area (surface that will rest on the foam), square inches. This will establish the foam loading, pounds per square inch (psi)
For Loading 0.1 to 0.3 psi use 2.0 lbs./cubic foot Polyurethane
For Loading 0.3 to 0.6 psi use 4.0 lbs./cubic foot Polyurethane
For Loading 0.5 to 1.0 psi use 4.0 lbs./cubic foot Polyethylene
Enter Chart 2 at the fragility level; proceed horizontally to intersect the curves at the required height of drop move vertically from this point of intersection down to the indicated foam thickness required. Repeat for each axis of drop.
Add to the size of the equipment, twice the thickness of foam. This will establish the optimum case size.
Chart 2
Foam Selector: for more information on different types of foams.