What is in-mould labelling (IML)?
In-mould labelling (IML) is a production technique in which a printed plastic film is placed in the mould before injection moulding begins. During the injection process, the film and the base material fuse together. The label becomes an integral part of the product, rather than an element that is applied to it at a later stage.
How does IML differ from traditional labelling?
With traditional labelling, a label is applied after injection moulding using adhesive or direct printing. This introduces an extra step and a vulnerable interface: labels can peel off, dry out or become illegible following intensive cleaning or exposure to chemicals.
With IML, that interface does not exist. The film and the plastic fuse at a molecular level during moulding. The surface is smooth, fully resistant to moisture, cold and cleaning agents, and retains its legibility throughout the product’s entire life cycle. For crates that undergo dozens of cleaning cycles a year, that is no minor detail.
How does the IML process work?
A robot or automated system places the printed film, cut to size, into the open mould using electrostatic adhesion or vacuum systems. The mould closes and molten plastic is injected. The heat and pressure cause the film and plastic to fuse together at the interface.
Once cooled, the product with its integrated label leaves the machine. The cycle time differs only slightly from standard injection moulding. The robot’s insertion movement takes a few extra milliseconds, but it eliminates the need for a complete post-processing stage for labelling. From raw material to labelled end product, the lead time is shorter.
What does IML mean for logistics and traceability?
IML makes it possible to integrate barcodes, QR codes and RFID tags directly into the product. For crates circulating throughout the supply chain, this provides robust identification that does not fall off or become illegible after years of use. When linked to a warehouse management system, each crate provides continuous insight into its location, contents and condition.
Because the code is part of the material itself rather than an added label, data quality remains stable over the years. In food-processing environments, the smooth, seamless surface also prevents bacteria from breeding and meets HACCP and food-grade requirements.
For which products is IML most suitable?
IML is widely used on reusable crates for meat, fish, vegetables and bakery products. The colour-coding by sector, product line or customer withstands intensive cleaning cycles. In consumer packaging, IML is used for packaging and trays where high graphic quality is required. The print resolution of the film exceeds what direct printing on plastic can offer.
Products intended for multiple languages or markets can be produced using different films in the same mould, without the need for tooling changes.
When does the investment pay for itself?
IML requires a slightly higher investment in moulds and automation than standard injection moulding. With high volumes, these costs are quickly offset by the benefits, particularly when you factor in the costs of separate labelling, wastage due to poorly fitted labels and the management of a label stock. IML combines two production steps into one."
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