Light but strong – unbeatable aluminium

Alucar uses more than 300 tonnes of aluminium every year to fit out logging trucks. The most common metal in the world, it is light and strong and virtually corrosion-free. In frosty weather the material just gets stronger. The surface withstands all seasons and all weather conditions, and the superstructure also endures demanding terrain. In other words, it is the ideal metal for logging transport.  

Alumiininen apurunko
Aluminum subframe

Alucar is known for its aluminium, which is used in every single logging truck that leaves the company’s assembly hall to carry logs. All Alucar’s superstructures for logging trucks are made out of this silvery metal that presents the toughest competition for steel in the field of transport. Because the demand for durability in superstructures is great, Alucar uses almost the same aluminium alloy in its products as is used in aeroplanes.

“The alloy must have high tensile strength and yield strength, which translate as excellent load-bearing capacity,” says the company’s Product Manager Leif Finne.

More aluminium, less iron, more payload

Aluminium is generally favoured in transportation due to its light weight, because it means that the payload can be maximised while the transport equipment’s weight is low. Aluminium only weighs a third as much as steel, so when a logging truck’s steel bunks are switched to aluminium ones, the trailer combination becomes up to 300 kilograms lighter.

Recent arrivals on the market are some high-strength steel alloys that allow manufacture with thinner material. According to Finne, steel structures can also be made as light as aluminium, but what they gain in light weight they lose in strength to aluminium. “Repeated loading and movement cause fatigue in steel, but not in aluminium. Although an aluminium stake sometimes bends severely, for example when unloading, it can very well be made to return to its original shape and size. Because aluminium is both light and strong, it will increase a truck’s profit-earning capacity for the transport company,” he explains.

Superstructure affects handling characteristics

Aluminium profiles are made by extruding the metal into the desired shape. When the profile is well designed, the whole superstructure functions flexibly on top of the truck. The truck chassis itself has certain handling characteristics, but if the superstructure doesn’t carry the load right and yield with the chassis, manoeuvrability will suffer. This is why Alucar’s aluminium sub-frame is bent to follow the shape of the chassis and its mountings are designed according to the chassis manufacturer’s instructions.

“When driving along winding, hilly roads, the superstructure has to be flexible. The frame has to yield in the right way so that the drive wheels will stay on the ground,” Finne explains.

Longer operating life through surface treatment and bolted joints


Aluminium is mainly delivered to Alucar as ready-made profiles that are machined at their factory. The profiles have already been treated at the production stage with ageing and anodising processes to make their surface as hard and maintenance-free as possible. Ageing involves heating and cooling the metal to increase its hardness, whereas anodising means creating a protective layer on the surface of the profile. The result is a hard, erosion and corrosion resistant surface.

Finne explains that the aluminium superstructure is also stylish and easy to keep clean, thanks to its surface treatment. “There’s no need to paint it, just wash off the anti-icing salt when necessary. Due to anodising, dirt also comes off easily and keeping the equipment clean is effortless.”

Usually, aluminium products are manufactured by welding, but Alucar uses only bolted joints in its superstructures, because they have proven stronger in use. Metal always loses a little strength at the welded seam, and certain aluminium alloys may also fracture easily during welding. According to Finne, the pressure positions and point stress of the attached parts are so strong that, when you combine them with the continuous vibration and movement of a logging truck, only bolted joints are strong enough. “Bolted joints also make it easier to change spare parts. The profiles can also be designed to be joined so that they lock into each other without welding or bolts. This is how the cab is assembled from aluminium panels,” he says.

The right material for the right use

Although the positive properties of aluminium seem overwhelming in superstructures for logging trucks, a great deal of steel is still used in the industry. Finne believes that the reasons for this are price and old traditions. An aluminium timber bunk is a slightly larger investment, although in the long run it is more cost-effective.

“Alucar’s sub-frames are always made out of aluminium, because it has proven its superior durability in demanding conditions all over the world. The development of high-strength steel alloys is excellent for the industry, and Alucar too uses steel in some of its products. For example, some of our bunks are made out of steel according to our customer’s needs. Each sub-frame also has steel fixings and crane consoles.”

For over 30 years, Alucar has been honing its concept and expertise in the manufacture of aluminium superstructures for logging trucks. Not all superstructure manufacturers have this kind of experience, which is why they often opt for structures welded from iron and steel stock.

“It takes a huge amount of experience and know-how to develop your own aluminium profiles. Because we have designed the bolted joint concept and taken our 3D design very far, we also have an excellent maintenance service. If anything happens to your truck, we can quickly supply you with ready-made spares for the superstructure or even make a similar sub-frame package here and send it to you. Just put the bolts in the holes and that’s it, installation done,” says Finne.


The benefits of aluminium superstructures

  • Lightweight: more payload and profit-earning capacity for your transport equipment
  • Surface treatment: no corrosion
  • Durable structure: endures loading, vibration and dents
  • Appearance: stylish and durable surface without further maintenance
  • Bolted mountings: no welded seams to weaken the metal, easy to maintain and to change spare parts
  • Handling characteristics: correctly designed aluminium profiles yield with the movement of the truck chassis

Aluminium is environmentally friendly

  • As the earth’s bedrock disintegrates, more and more aluminium is created. It is extracted from bauxite which is found in a belt around the equator.
  • Aluminium is a valuable recyclable metal that can easily be sorted from other metals over and over again for practical reuse.
  • It takes a lot of energy to produce aluminium from bauxite, but smelting recycled aluminium only takes 5% of that energy.
  • Of all aluminium waste, three quarters returns to materials recovery, which is significant also for the economy.
  • Alucar’s aluminium supplier Purso Oy uses roughly half recycled and half primary aluminium in its production.

(Source: Purso Oy)