Merge: date=August 2008

Boxes and crates are often confused with one another; mostly when they are made of wood. Contrary to a crate, the strength of a wooden box is rated based on the weight it can carry before the cap (top, ends, and sides) is installed.

History

The first documented writings in the US about shipping crates is in a 1930 handbook (Technical Bulletin No. 171) written by C. A. Plaskett for the US Department of Agriculture although his writing imply that crates were defined before that time. C. A. Plaskett was known for his extensive testing and defining of various components of transport packaging.

Construction

Although the definition of a wooden crate as compared to a wooden box is clear, construction of the two often result in a container that is not clearly a crate or a box. Both wooden crates and wooden boxes are constructed to contain unique items, the design of either a crate or box may result in the use of principles from both. In this case, the container typically will be defined by how the edges and corners of the container is constructed. If the sheathing (either plywood or lumber) can be removed, and a framed structure will remain standing, the container would likely be termed a crate. If removal of the sheathing resulted no way of fastening the lumber around the edges of the container, the container would likely be termed a wooden box.

Crates can be made of wood, plastic, metal or other materials. The term 'crate' often implies a large and/or strong container. Most plastic crates are smaller and are more commonly called a case or container. Metal is rarely used because of its weight. When metal is used, a crate is often constructed as an 'open crate' and may be termed a 'cage'. Although a crate may be made of any material, for these reasons, the term 'crate' used alone often implies one constructed of wood.

Design

There are many variations of wooden crate designs. By far the most common are 'closed', 'open' and 'framed'. A Closed Crate is one that is completely or nearly completely enclosed with material such as plywood or lumber boards. When lumber is used, gaps are often left between the boards to allow for expansion. An Open Crate is one that (typically) uses lumber for sheathing. The sheathing is typically gapped by at various distances. There is no strict definition of an open crate as compared to a closed crate. Typically when the gap between boards is greater than the distance required for expansion, the crate would be considered an open crate. The gap between boards would typically not be greater than the width of the sheathing boards. When the gap is larger, the boards are often considered 'cleats' rather than sheathing thus rendering the crate unsheathed. An unsheathed crate is a frame crate. A Frame Crate is one that only contains a skeletal structure and no material is added for surface or pilferage protection. Typically an open crate will be constructed of 12 pieces of lumber, each along an outer edge of the content and more lumber placed diagonally to avoid distortion from torque.