The Box Compression Test measures the compressive strength of boxes made of corrugated fiberboard as well as wooden boxes and crates. It provides a plot of deformation vs compressive force.
Testing Methods/Procedures
A common method of conducting the test, as described in several published standard test methods, is to compress a box at a constant rate of 1/2 inch (12.5 mm) per minute between two rigid platens. The platens can be fixed so that they remain parallel or one can be pivoted or “floating”. The test can be conducted on empty or filled boxes, with or without a box closure. Conditioning to standard temperature and humidity is important.
The results of the constant rate of compression test can be:
- The peak load
- The deformation at peak load
- The load at a critical deformation (head space, etc)
- The ability of a box to protect the contents from compression damage
- etc
The dynamic loads have some relationship with expected field loads. Often factors of 4 or 5 are used to estimate the allowable working load on boxes.
A test can also be conducted with platens that are not mechanically driven but are free to move with a fixed mass (or fixed force) loaded upon them. The results of static load testing can be:
- The time to failure
- The time to a critical deformation
- The ability of a box to protect the contents from compression damage
As with any laboratory testing field validation is necessary to determine suitability.
Common factors which influence test results can be the following:
- Size and construction of the specific shipping container under test
- Grade and flute structure of corrugated fiberboard
- moisture content of the corrugated board (based on relative humidity)
- Orientation of the box during the test
- Inner supports, if used during testing (wood, corrugated board, cushioning)
- Contents (when box is tested with contents)
- Box closure
- Whether the compression machine has “fixed” or “floating” (swiveled) platens.
- Previous handling or testing of box
Relevant ASTM Standards
- ASTM Standard D642 Test Method for Determining Compressive Resistance of Shipping Containers, Components, and Unit Loads.
- ASTM Standard D4577 Test Method for Compression Resistance of a Container Under Constant Load
- ASTM Standard D7030 Test Method for Short Term Creep Performance of Corrrugated Fiberboard Containers Under Constant Load Using a Compression Test Machine
- German Standard DIN 55440-1 Packaging Test; compression test; test with a constant conveyance-speed