Pallet manufacturing process explained

16 Sep 2013

Pallets may appear to be simple structures that support loads but their design and manufacture is a sophisticated process. They provide a structural base for a load and protect it when it is in storage and during handling and transportation. Wood is the most common pallet material. Plastics – mostly high-density polyethylene (HDPE) and polyethylene teraphthalate (PET) — are thermoplastics that are resistant to weather and corrosion and used to make very durable pallets.

Wood

Customers buying wooden pallets can choose from standard sizes in 100 per cent natural timber or engineered wood, or give precise specifications on materials and design that the manufacturer will follow. Once the vendor is clear about the specifications and delivery date, the process begins.

• The appropriate wood is selected and the pallet deck boards and stringers – the three or more parallel pieces of timber that cross them at right angles – are cut to size. The wood is usually softwood (coniferous), though engineered timber can be as hard and durable as some hardwoods. Notches may be cut in the stringers if four-way access to the pallet sides is required.

• Pure timber has to be treated under the ISPM15 international regulations to prevent the spread of pests and fungi. The wood must be heated to a minimum of 56 degrees Celsius over 30 minutes. The treatment kills pests and minimises the moisture content of the wood, making for lightweight pallets. Engineered wood is exempt from ISPM15 as pests would have been destroyed by heating and gluing during the manufacturing process.
• The wooden pallets are assembled according to specifications in an automatic process that can make up to 250 pallets each hour. Once the order is complete, it is shipped to the customer

Plastic

Customers order plastic pallets according to specifications as in the case of wood. However, in contrast to wood, there are a number of manufacturing processes for these pallets.

• The high-pressure injection-moulding process starts by melting the plastic – usually HDPE resin — material and colorant together in a container. The melt is injected into a mould that is clamped together under pressure. This is a costly but very fast process.

• Structural foam moulding is a low-pressure version of injection moulding. Polyethylene or polypropylene and nitrogen gas are injected into a mould cavity. Heat is applied to activate blowing agents and create foam with a solid skin. This process requires less material than the high-pressure injection moulding.
• Thermoforming is the most common plastic pallet manufacturing process. Polyethylene pellets are heated to create a nearly liquid plastic sheet. This is pulled into a mould and vacuum-formed.
• In the compression-moulding process, a two-piece mould is loaded with plastic using extruders, or even manually. Once filled, a press closes the two moulds. Pressure forces the plastic material into the mould cavities.
• Rotational moulding is a process that dates from the 1970s. Powdered plastic is loaded into a mould. This is then heated as it rotates in two planes perpendicular to each other. The rotation ensures distribution and fusion of the plastic.
• Profile extruded pallets look like wood pallets and are constructed in a similar way. Plastic is melted, forced through an extruder, then cooled and cut to size. The separate pieces are joined using screws, nails, glue or heat welding.

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Let’s take a look at what goes into the manufacturing of pallets. Because pallets are such a common sight at every imaginable shipping destination, they may seem as if they are knocked together with spare bits of lumber. But the pallet production process is sophisticated and precise.

Typically when an order is received, the customer information is already in a databank and so when a standard kind of pallet is ordered, the specifications are already known. However, a new customer may need pallets designed, or they may have unique specifications and that need to be addressed. Once a vendor knows the time line for delivery, the production process begins. 

First the wood needs to be cut. The appropriate material is selected and the deck boards and stringers are all cut to fill the order. At this point, some secondary processes may be applied such as cutting 4-way notches in stringers to allow access from all 4 sides of the pallet. This is also when the wood may be treated if it will be shipped out of the country. 

Once the wood is cut, it is assembled.  High volume nailing machines that are fully automated are used to mass produce the pallets often at a rate of 225 pallets per hour.  Smaller orders of less than 200 are usually assembled by hand. Setting up the machine for lower numbers is not worth most producers’ costs. When the order is complete, it is delivered to the customer.

Shipping for Savings

60% of the cost of a pallet comes from the cost of the lumber. Since every manufacturer is buying the same wood and has similar labor costs, the main source of savings is shipping. A manufacturer who is geographically closer to your operation will cost less. However, you can save on pallets by placing efficient orders that fill up a truck. Most trucks can carry 600 pallets, so if you are not buying full truckloads, you are spending more per pallet on transportation costs. If two manufacturers have very different costs than you in the same geographic area, they are probably lowering their cost by using lower quality wood.

The production of wood pallets, like any other shipping container, must result not only in quality products but also guarantee a secure supply chain and reasonable shipping costs. From the expedient processing of orders, through to assembly and shipping, a major vendor can provide a seamless service for businesses requiring wood pallets for a variety of materials.