Plastic trays are made by two main processes. Vacuum forming heats a plastic sheet and pulls it over a mould. Injection moulding forces molten plastic into a closed steel tool. Both make good trays, but they suit different orders. This guide sets out where each one fits so you can brief a supplier with the right process in mind.
Aravinth Polymers is a vacuum forming plant in Chennai. We do not run injection moulding, so when a part belongs in an injection tool, we will tell you that.
How Each Process Works
In vacuum forming, a sheet of ABS, HIPS, PVC, APET, GPET, HDPE or PP is clamped and heated until soft. The machine draws it down onto a single mould, and vacuum pulls it tight against the mould surface. The part cools, and then it is trimmed out of the sheet.
In injection moulding, plastic pellets are melted and pushed under high pressure into a cavity between two halves of a steel tool. The plastic fills the gap between the halves, cools, and the tool opens to release a finished part.
That difference in tooling drives most of the comparison below.
Tooling Cost and Time
A vacuum forming mould has one side only. We make ours in-house from MDF or aluminium. MDF suits prototypes and short runs. Aluminium suits volume production and repeat orders. Either way, the mould is simpler than a matched injection tool, so it costs less and is ready sooner.
An injection tool has two matched halves machined from steel, with cooling channels and an ejection system. It is a much larger investment and takes longer to build. Changing it after it is made is also slow and costly.
For a tray that may change after the first trials, vacuum forming gives you room to revise. Our tool room handles changes such as deeper pockets, revised ribs, extra cavities and trim changes.
Order Quantity
Vacuum forming suits low and medium quantities, and it scales to steady repeat orders once an aluminium mould exists. Our minimum order is 500 pieces, and smaller trial batches can be run off a prototype tool.
Injection moulding needs very large quantities before its tool cost spreads thin enough per piece. If you need a small tray in huge numbers for years with no design change, injection moulding may give the lower piece price. For most custom trays, kit trays and blisters, the tooling saving from vacuum forming wins.
Wall Thickness and Detail
A vacuum formed tray takes its wall from the sheet. You choose one gauge, from 0.15 mm up to 6.0 mm on our machines. The sheet stretches as it forms, so walls and deep corners end up thinner than the flat sheet. A good mould design and the right polymer keep that thinning under control.
Injection moulding controls the wall on both faces. It can make thick and thin sections in one part, solid bosses, screw holes, snap clips and fine ribs on either side. If your part needs those features, it belongs in an injection tool.
Thermoforming also holds looser tolerances than injection moulding. We agree achievable tolerances on your drawing before tooling and hold them against the approved first article.
Part Depth and Size
Vacuum forming handles deep pockets well when the polymer suits the draw. GPET, ABS and HIPS are our usual choices for tall pockets and deep boxes. Our forming area goes up to approximately 1000 x 1200 mm, depending on the machine and depth of draw. Large, shallow trays and covers are a natural fit, because a big injection tool for the same part would cost far more.
Injection moulding suits small, dense parts with complex shapes. It is less practical for large, thin-walled trays.
Which One Fits Your Tray
| Need | Vacuum forming | Injection moulding |
|---|---|---|
| Tooling cost | Lower, MDF or aluminium | Higher, machined steel |
| Tool ready | Sooner | Later |
| Design changes | Easy to revise | Slow and costly |
| Best quantity | Trials to steady repeat orders | Very high, stable volumes |
| Wall | One gauge, thins at corners | Controlled on both faces |
| Features | Pockets, ribs, flanges, snap lids | Bosses, clips, threads, fine detail |
| Large shallow parts | Good fit | Costly tool |
Pick vacuum forming for returnable trays, kit trays, ESD trays, blisters and clamshells. Pick injection moulding for small solid parts with features on both faces, ordered in very high volumes.
Talk to the Sales Desk
Send a drawing, sample or photo to the sales desk and we will check whether your tray suits vacuum forming. Call or WhatsApp +91 91767 57077, email sales@arvindpolymers.com, or use the details on our contact page. We will confirm formability, recommend a material and price the mould and the part together.