Vacuum Formed Trays

Vacuum formed trays are popular for material handling applications (i.e. moving parts or components around a factory or supply chain). The manufacture of trays involves heating plastic sheets and stretching them over a mould before being forced against it by a vacuum. Once cooled and removed from the mould, they are suitable for use as a container insert or as a standalone custom-made tray.

Vacuum forming and thermoforming are effectively the same processes, heating plastic to a malleable temperature before forming it to a specific shape. The difference in vac-forming, however, is the additional process of using a vacuum to force the plastic material to conform to the mould.

Manufacturers can use several different plastics for vacuum forming. Suitable materials include vacuum forming grades of ABS, PETG sheets and – most commonly – HIPs (High Impact Polystyrene sheets). The manufacture of vacuum formed trays is most widely from HIPs.

You can recycle HIPS and other polystyrene materials used in manufacturing vacuum formed packaging. Being recyclable minimises environmental impact. Besides this, High Impact Polystyrene is cost-effective to produce, meaning its use is widespread in the food industry.

Material webbing when vacuum forming is the unwanted wrinkles that can appear in the mould when the vacuum is applied, and the plastic stretches in an unplanned manner. It can happen if the flow of the heated sheet is not adequately controlled as the tool is raised into the material.

In engineering, the term “draft” refers to the amount of taper for moulded or cast parts perpendicular to the parting line. Engineers measure this in degrees or mm/mm (in/in). The draft or taper on the mould’s sides effectively allows the easy removal of the finished plastic from the mould.

A male tool is a positive tool that, when formed, produces a forming that is above the clamping of the clamped sheet. With a male tool, the visible surface of the formed part is usually the top surface; therefore, the plastic sheet’s thickness can hide some of the imperfections on the tool surface (producing a more attractive surface finish). A female tool is a tool that, when formed, creates a forming below the clamped sheet’s clamping. Projects that require sharp details or deep cavities use female tools.

For producing tote inserts and vacuum-formed trays, the tooling cost is significantly higher than for Correx® or plastic divisions (although the low unit costs make them competitive in high volume production). However, compared to similar tooling, such as injection moulding, vac-formed tools are relatively low cost.

If you use other types of tote inserts, such as cardboard or particularly foam inserts, shedding of material can occur over prolonged, repeated use. Shedding is where tiny particles of the foam material rub away, creating dust and fine debris, which can contaminate or damage parts (something known as FOD – foreign object debris).