Machine Spare Parts Boxes.

Everything follows from one fact: a spare may sit unopened for years. Ordinary industrial packaging is specified for weeks or months in transit, and three things degrade over a longer horizon.

The part corrodes. Humidity cycling in an unheated store will rust bare steel over several years regardless of its condition when packed. VCI liners release a protective vapour onto metal surfaces — and for multi-year storage the protective life of that liner is worth confirming rather than assuming.

The board weakens. Paperboard absorbs and releases moisture with the surrounding air. Over repeated cycles it softens, so a box that was adequate when packed can be structurally poor by the time it is needed. Moisture-resistant board addresses this.

The identification disappears. This causes the most frustration in practice. Adhesive labels lift and fade; a box marked on only one face becomes anonymous on a rack. A part nobody can identify gets replaced and the original written off.

Print part numbers directly onto the board, large, on multiple faces — and include the machine reference, because whoever needs it in five years may not have the original documentation.