Most plastic pallets are made by injection moulding, in which molten plastic (usually HDPE or polypropylene) is injected into a steel mould in a large machine whose clamping force is measured in hundreds or thousands of tonnes. Alternatives are rotational moulding, which uses cheap molds for hollow pallets in smaller runs; compression moulding, used for pallets from mixed recycled plastic; and thermoforming of heated sheet. The machine choice is largely a trade-off between tooling cost, cycle time and the strength and weight of the finished pallet.
Overview of the main processes
The materials and pallet types are described in plastic pallets: types, materials and applications. This page looks at how they are manufactured and what equipment each route requires.
| Process | How it works | Typical features | Tooling |
|---|---|---|---|
| Injection moulding | Plastic is melted in a screw and injected under pressure into a closed steel mold | Ribbed, thin-walled, accurate; fast cycles; high volume | Expensive molds, large presses |
| Rotational moulding (rotomoulding) | Powder or resin is heated in a mold rotating on two axes to coat the inside | Hollow, seamless, thick walls; slower cycles | Low-cost molds |
| Compression moulding | A measured charge of molten plastic is pressed in a mold | Suited to recycled mixed plastics; simpler materials handling | Moderate mold cost |
| Thermoforming (twin-sheet) | Heated plastic sheets are formed in molds and fused together | Lightweight hollow structure | Moderate mold cost |
| Structural foam | Gas in the melt creates a cellular core | Stiff, thick parts; limited surface finish | Similar to injection |
Injection moulding machines
Injection moulding dominates the production of rackable, nestable and hygienic pallets in large series. The machine has two main units: the injection unit (a screw that melts and meters the plastic) and the clamping unit (a press that holds the mold shut against injection pressure). Pallets are large parts, so the clamping unit is the driver of machine size and price.
Published machine data shows the range:
- A pallet-molding machine described by its maker, Wilmington Machinery, as a low-pressure injection press has a clamping force of 350 tons, processes up to 1,200 lb (about 545 kg) of HDPE per hour, and produces pallets up to 40 lb (about 18 kg) and about 4 × 4.3 ft in size at about 30 pallets per hour. It can process recycled plastic as pellets or flakes.
- A large-scale system for pallets from post-consumer recycled material has been built around an injection molding machine with 27,000 kilonewtons of clamping force, equivalent to roughly 2,750 tonnes-force.
These figures are manufacturer claims for specific configurations, but they illustrate that a pallet line can range from a few hundred to a few thousand tonnes of clamping force. Low-pressure and "recycled-capable" machines use long screws, two-stage injection and hot-runner molds to handle variable feedstock.
Auxiliary equipment
A complete injection line also includes:
- Material handling and drying (for virgin pellets, recycled flakes or regrind).
- Shredder or granulator for sprue, rejects and old pallets that are fed back into production.
- Mold temperature control units with chilled-water circuits, because cooling time is the longest part of the cycle.
- Robots or take-out devices to remove and stack the pallets.
- Trimming, branding and RFID insertion stations, if required.
- Quality testing equipment for weight, dimensions, deflection and load.
Rotational moulding
Rotomoulding places a measured charge of polyethylene powder in a hollow metal mold, which is heated in an oven while rotating around two axes. The powder melts and coats the walls, then the mold is cooled and opened. The result is a seamless, hollow part with thick, continuous walls.
Compared with injection moulding, molds are significantly cheaper and designs can be changed more easily, which suits lower volumes and specialized pallets, such as heavy-duty, insulated or foam-filled units. Cycle times are much longer, so cost per pallet is higher at large volume. Rotomolded designs avoid joints, which are possible failure points under abuse, whereas injection designs use ribs to cut weight while keeping stiffness.
Compression and other processes
Compression moulding presses a measured charge of molten plastic (often from an extruder) in a mold between two halves. It is used for pallets made from mixed or contaminated recycled plastics that would be difficult to inject, and it can include fillers or reinforcement. Pallet makers using this route emphasize low-cost feedstock over precise dimensions.
Thermoforming heats plastic sheet and forms it in molds, and twin-sheet versions fuse a top and bottom to create a hollow pallet. Some designs also assemble pallets from several parts by welding or by screws, which combine different processes and materials. Choice of process affects whether a pallet can be nested, racked or used in automated systems; see nestable, rackable and stackable pallets.
Moulds: what drives their cost
A pallet mould is a precision steel tool, often the largest single investment after the press. Factors that raise cost and lead time include:
- Size and weight of the tool, which scale with pallet footprint.
- Complexity of ribs, feet, runners, drainage and fork-entry features.
- Steel grade and hardening needed for abrasive materials such as filled recycled plastics.
- Hot-runner system with many gates for even filling.
- Cooling channels and temperature control that determine cycle time.
- Inserts and interchangeable features for different pallet variants or logos.
- Surface finish and texture.
A rotational mold is simpler and cheaper, but still has to be designed for even wall thickness and heat flow. Because a mold is specific to a pallet design, a plant planning a range of sizes must budget for several molds and mold-change equipment. Prices vary widely between suppliers and countries, so quote requests should specify pallet drawings, material, annual volume and expected mold life.
Planning a plastic pallet plant
Key questions before investing:
- Feedstock: virgin or recycled? Supply, price volatility and contamination control determine the machine type. Recycled content strategies are tied to circular economy for pallets.
- Volume and product range: high volume of one design favors injection; varied low-volume products favor rotomolding.
- Pallet performance: required load rating, fire behavior, hygiene and racking performance, tested to standards such as those in pallet testing standards.
- Utilities: electricity, cooling water, compressed air and floor space for large presses and molds.
- Market and costs: the comparison with wood is explained in wood vs plastic pallets.
Frequently asked questions
What is the main machine used to make plastic pallets?
Large injection moulding machines, with clamping forces from a few hundred tonnes upwards. Published examples range from 350 tons for a low-pressure machine to a 27,000 kN system for recycled material.
Why is rotational moulding used if it is slower?
Molds are much cheaper and the process produces hollow, seamless parts with thick walls. It suits smaller series and special designs.
Can plastic pallets be made from recycled plastic?
Yes. Some machines are designed to process recycled pellets or flakes, and compression moulding is often used for mixed recycled plastics. Quality control of the feedstock is essential.
What decides the cost of a pallet mould?
Size, complexity, steel quality, the number of cooling channels and the hot-runner system. Larger and more complex pallets need heavier, more expensive tools.
Sources
- Economical press joins family of pallet-molding machines — Plastics Machinery & Manufacturing
- Flexible large-scale system for injection molding: safely process post-consumer recycled material — PolyForm NEXT
- Rotomolded pallets vs injection molded pallets — Racklify Encyclopedia
- The process of key role for warehousing: plastic pallet injection molding — Huarong