At its simplest, material traceability is the process of ensuring that the materials that make up all the parts on a finished product have records spanning back to their production. This is often achieved with a paper trail. Material traceability must not be confused with product traceability which allows more granular tracking of the product and can include details such as when it was manufactured, who manufactured it, and which machines were used.
The process of making a product materially traceable starts with the procurement of the required materials. These materials should be delivered with a batch certificate, material certificate, or mill test report (MTR). Despite the different names, these documents refer to essentially the same thing.
In the case of metals, the material certificate allows for the tracking of the material all the way to the specific ladle of molten metal used. The number used to identify a specific batch or “heat” of molten metal is called the heat number. In addition to this, the material certificate will indicate the date the material was cast, the elemental makeup, results of mechanical tests, and the standards with which it complies, amongst other details. Most materials that have verified mechanical properties will have a material certificate and associated heat number. In the case of plastics, the term, “batch certificate,” is often used instead.
A material certificate is important as it proves that the material meets its standardized properties. After all, engineers select the specific grade of stock based on its mechanical properties and need confirmation that the batch they receive is up to spec. The material certificate exists as proof that the material has been manufactured according to the relevant standards. It therefore must be linked to the material via a permanent label on the material itself. This can come in the form of hard-punching, tags, indelible paint, or (in the case of plastic) stickers.