Extrusion for food packaging
Plastic sheet extrusion is a manufacturing process used to make flat plastic sheets that are later formed into food packaging products. In simple terms, it works by melting plastic and pressing it into a wide, flat shape with a uniform thickness. These sheets are not usually final products on their own; instead, they are the starting material for many common food packaging items.
What is extrusion in food packaging?
Extruded plastic sheets are primarily used as the base material for thermoforming. The sheet is reheated until flexible and then formed into packaging using moulds, vacuum or pressure. This enables the production of common formats such as meat trays, ready meal trays and yoghurt pots.
Sheet extrusion is widely used because it provides a reliable and efficient way to produce consistent material. It allows control over thickness, clarity and strength, which are important for protecting food and maintaining shelf life.
How the process works
Plastic pellets are heated and melted before being pressed into a continuous, flat sheet. This sheet is then carefully cooled using rollers to achieve consistent thickness and surface quality.
To ensure the sheet keeps a consistent thickness and smooth surface, it passes through a set of polished cooling rollers, often called calender rolls. These rollers cool the plastic and control its final dimensions. Once cooled and solid, the plastic sheet is either cut into flat sheets or wound into large rolls, ready for the next processing step.
Why it matters for food packaging
Extruded sheets enable packaging that protects food, supports shelf life and can be produced efficiently at scale. The process allows control over clarity, strength and thickness, and supports multi‑layer structures for added protection.
Materials are selected based on application needs. PP is used for yoghurt pots and microwaveable trays, PET for clear containers and lids, while PS has traditionally been used for trays and cups but is being phased down. Recycled materials, including rPET, are increasingly used to support regulatory and sustainability requirements.
