How do we make... shipping crates?

Posted on August 01, 2014 by Marcel Rothmund, Images by Robert Hack

Building shipping crates involves more than just pinning together wooden planks, as an inside look at mtu's joinery shop reveals.
Friedrichshafen, Germany

The joinery shop at mtu is where they make shipping crates for engines and gensets ranging in proportion from the size of a suitcase to the dimensions of a prefabricated garage. But the job involves much more than nailing together top, bottom and sides. The crates have to be designed for weights of up to 35 tonnes and enormously diverse transportation requirements.

The joinery shop very much stands out among the numerous assembly and production shops at mtu. Instead of the smell of oil in the air, there is a scent of fresh pine, accompanied by the sound of circular saws rather than of CNC machine tools. Siegfried Keller and his colleagues are in the process of making a wooden base for an engine shipping crate. He is holding a metal corner plate in his hand to point out how important it is in the construction of the crate: "We designed these corner plates ourselves for reinforcement. Without them, the crane lifting cables would cut straight through the wooden battens like a knife through butter," he explains. Siegfried Keller is team leader in the mtu joinery shop. Over many years, he and his team have learned from practical experience how to build crates for shipping mtu products so that they are received safe and sound by customers all over the world. For standard products such as genset engines, the bottom section of the crate is provided by a supplier. For all other engines with variable dimensions, the mtu joinery shop constructs the base to order.

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A shipping crate consists of a crate base to which the engine is fixed, with side walls and a cover. All parts of the crate are made from spruce and plywood. That is because wood has the ability to flex when the heavy crates are lifted. However, since the wooden battens could still be cut in half by the steel lifting cables as the crate is hoisted up, metal corner plates are needed for reinforcement.

The construction of a shipping crate starts with the measurement of the engine's external dimensions. Every day, Siegfried Keller pays a visit to the paintshop next door. Here, in front of the spray booths, staff prepare the engines for receiving their final paint-finish. In the middle of the room is a Series 4000 marine engine. Siegfried Keller measures its external dimensions and marks them off on a wooden slat. Besides the length, height and width of the engine, he also marks the positions of the holes to be drilled for the engine mountings. With the help of this slat, his staff make up the finished crate for the marine engine. The base is formed by two solid wooden beams. The joinery workers nail planks to their underside to form the bottom of the finished crate. Onto the base, they then nail wooden battens called cross-runners to which the metal corner plates are then fixed. Across the top of the cross-runners they attach three more battens – the length runners. These are what the finished crate will stand on. The crate-builders then turn the base over with the help of a crane and fix wooden blocks in place for attaching the engine mountings. They then screw threaded rods into the blocks so that the engine can be bolted onto the crate base. "We use about one and a half million nails a year," says Siegfried Keller. In one month, the joinery shop gets through as many as two or three articulated truck-loads of solid timber and one truck-load of plywood. But the wood has to meet an important requirement if it is to be used for making mtu crates - it has to have been heat-treated. This is what the International Plant Protection Convention (IPPC) specifies and what most countries outside Europe demand. Otherwise, undesirable insects lodged inside the wood of the crates could be carried into other countries and continents. Siegfried Keller points to the official black stamp on the wood. "That has to be visible on every piece of wood used, or else we have problems with customs," he reveals.

When the finished marine engine is delivered to the dispatch area from the paint shop, the base and sides of the crate are ready for assembly. A crane lifts the engine onto the base, which has been lined with laminated aluminum foil, and the joinery shop workers bolt it down tightly onto the threaded rods. They then pad the engine with foam wrap. Over the foam wrap they hang little cloth bags on strings. "The bags contain a drying agent that absorbs the moisture in the packing," explains Siegfried Keller. The next step is to vacuum-pack the engine in laminated aluminium foil. The joinery staff screw a humidity indicator into the foil so that the air humidity inside the packing can be checked from the outside later on. "A marine engine can be in transit on container ships for up to six weeks, but packed like this it is perfectly protected," says Siegfried Keller.

After the joinery team have bolted the sides and top of the marine engine crate to the base, they fix a sign on the outside and spray the mtu logo onto each end. The engine is now ready to embark on a long journey to its new owner - safe inside its mtu-made crate, it will be sailing across the ocean all the way to India.

Point of contact

Albert-Wilhelm Franz
+49 7541 90 8513
+49(0)7541 908513
+49(0)7541 90908513

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