Modern-day products are often made from a wide range of materials, each specifically designed for a specific set of properties. In most cases, these materials are formulated to meet a standard or design code. However, it becomes very difficult to prove to customers and regulators that your product has been manufactured according to industry norms and relevant codes if the materials and components cannot be traced and identified. This article will explain what material traceability is, why it is critical in a modern manufacturing environment and how to properly implement material traceability processes.
What is Material Traceability?
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.
Obtaining a valid material certificate is just the first step of material traceability. The material or heat number must be transferred over each time a portion is cut off from the original piece. This may need to be done in the presence of a certified inspector or by internal QC personnel depending on local regulations and the type of equipment. This transfer must be documented and a report needs to be generated to create a paper trail.
These material numbers must remain visible until the entire component is complete. If a number is to be covered during fabrication or removed due to machining it must be transferred to a more visible area. This does not necessarily need to be hard stamped — indeed there are situations where hard stamping is not recommended. Once a product is complete and all the components installed, a final inspection is performed to verify that the product’s materials are all traceable, all necessary material certificates are filed, and in some cases, a material map is completed that links the materials used to a specific part on a drawing.
When is Material Traceability Necessary?
Material traceability may be required for several reasons, the most common of which are listed below.
Material traceability is sometimes required to conform to specific standards. This can include items that come into contact with food, pressurized equipment, equipment exposed to corrosive environments, or aerospace and automotive components.
If a product is not governed by a specific standard or regulation, a supplier may still request that material traceability be maintained. This is to ensure the product conforms to its internal quality assurance procedures.
One small but important part of the ISO 9001 quality management system is effective material traceability. If a company is ISO-certified, it needs to ensure that materials are tracked, managed, and documented to maintain the certification.
Lastly, material traceability may be required to conform to the manufacturing companies’ internal quality management procedures. In general, it is beneficial to implement a traceability process even if no such requirement is enforced by the client or regulatory bodies. Simply put, this helps improve overall quality, ensures that suppliers deliver the quoted material, and if a client should request traceability in the future, the system is already in place.
Implementing material traceability is not a complicated process but robust procedures need to be developed to ensure compliance. Some of the key items to consider are listed below.
Suppliers must be aware of the fact that all materials must be supplied with a valid and readable material certificate. Some suppliers do not offer these by default so it is pertinent to state this requirement in the order.
Once the materials are delivered, they need to be checked by the receiver’s controller to ensure that the heat/batch number marked on the material matches the one printed on the material certificate. If this is not the case, the material must not be accepted and must be sent back to the supplier unless a valid certificate is presented.
Workshop personnel needs to be trained on the importance of material traceability. Parts can be marked out but no cutting can occur until the material numbers have been transferred and verified and the inspection reports generated.
Maintaining material traceability is simple but very paperwork-intensive. It may be necessary to hire additional QC personnel to streamline the process. Adding this responsibility to an employee’s existing duties is a sure-fire way to create a flawed traceability process.
Material traceability is often a critical part of manufacturing, and in some cases, untraceable parts or products may be rejected and scrapped by either clients or independent inspectors. This is a costly and unnecessary outcome. Implementing a material traceability process may take some time upfront but it will pay off in the long term.