Unloading Loose-Loaded Containers: The Efficiency Challenge

Such as Romanian lumberjacks, for example. One of Sweden’s leading DIY chains has found that these foresters from Eastern Europe offer a source of hunky, vigorous labour at an attractive price.

This company is not alone in resorting to “grey” solutions on the margins of the labour market. Unloading containers is a rough, tough environment, one of the few truly labour-intensive aspects of the modern economy. Owing to the wide range of items to be handled, and the variety of conditions in which these items can be found, the only two processes that nowadays remain manual in logistics are the loading and the unloading of containers.

Coping with the boom in e-commerce

Yet these big steel boxes are the oil that keep the wheels of the world economy turning. Containers have boosted globalisation more than all the trade agreements in the past 50 years put together. The number of containers in global trade has trebled since the mid-1990s, reaching 152 million in 2019. And “peak container” is nowhere near in sight.

Cargo ship approaching an industrial shipping harbour.

Across the world, companies are gearing up to cope with the boom in e-commerce fuelled by the Covid pandemic. Like never before, the supply chain is flooded by containers carrying everything from tires, gym equipment, white goods and electronics to clothing or wine.

So making the unloading process more efficient could unlock a big new source of value for delivery centres, third party logistics operators (3PL), or indeed any business that relies on getting large numbers of packaged goods to market. Surely machines must be the solution? Let’s look at some recent experience.

Man or machine for loose-loaded containers?

With its high use of manual labour, the logistics of loading and unloading containers has been an attractive subject for robotics research, because it was considered an area with high potential for automation. However, the results have not justified the optimism.

Containers are largely unloaded by hand since they are nearly always packed chaotically. To make best use of the available space, containers are often loose-loaded (floor-loaded) with individual cartons instead of pallets, which complicates the process of getting the cargo out at the delivery centre. The variety of transported goods is high and time requirements are strict. A robotic system suitable for any container unloading task must therefore be highly sophisticated.

Despite the large number of mechanical unloading systems for containers or trucks, none has yet to achieve widespread use. The high variability of packing patterns, combined with short processing times, poses a headache for fully autonomous systems. Especially in complex scenarios, this leads to system downtime and costly manual interventions.

View from inside an empty shipping container.

Are robots the future of container unloading?

In 2011, the EU launched “RobLog” (Robotic Logistics), a research project to develop an autonomous system to unload containers. The aim was to achieve a completely new level of automation in this part of the logistics chain. Four years and some €7 million later, the project leaders concluded that the flexibility of any mechanical unloading system has an upper limit. Even when a system is designed to handle a wide range of parcels, stacked in a variety of ways, a package may turn out to be ungraspable by a machine for unforeseeable reasons, such as deformation during transportation. This means that even when high levels of flexibility are built into the technology – which comes at a cost, of course – and this is combined with full standardisation of a container’s contents, there can be no guarantee that the autonomous unloading system is fool-proof.

The researchers’ strong conclusion was that the human being cannot be replaced in the unloading process. Instead, they wrote, what is needed is a fast and smart man-machine collaborative interface: “Hence, designing cheaper, simpler and less flexible autonomous systems able to collaborate with human operators is deemed to be the success key for robotic automation of logistic processes.”

Parameters of an efficient solution for loose-loaded containers

This is bad news for Romanian lumberjacks – machines have a place in the unloading process after all. And it is good news for operations managers who have had to rely on manual labour to get their containers destuffed.

“It is hard to find people who want to do this job. Who wants to stand for several hours a day in a small steel box that can be a furnace in the summer and a freezer in the winter?” says Anders Pettersson, head of R&D at TAWI in Sweden.

“One of our larger customers discovered that, as soon as a person found out that they were doing container unloading the next day, they would call in sick. Doing manual heavy labour like this is not attractive to a modern, educated workforce, and moreover it comes with a range of health and safety risks.”

Unloading loose-loaded containers is therefore a good example of an industrial process in which semi-autonomous systems – combining machines with human operators – are the right way to perform complex tasks using human-machine interaction. Machines have the potential to transform the unloading process, Anders says, as long as the man-machine interface is designed to take into account key efficiency challenges, including:

• The number of warehouse doors
• Frequency of deliveries
• Size of cartons / packages
• One-touch or two-touch handling
• How tightly they are packed
• Flexibility – the holy grail

By looking at these challenges one by one, we can begin to identify the parameters of an efficient solution:

Number of warehouse doors

Nine out of 10 companies that use a machine to unload containers will have a telescopic boom conveyor. This is not a new product, it has been around for 30 years. Boom conveyors rarely have any lifting aids, they cannot handle large products such as garden furniture, and the sheer size of the machine means you cannot get a forklift anywhere near the warehouse door. But they are inflexible in another important way. This is a massive structure that is fixed to the door itself. 3PL companies can typically have dozens of doors on their warehouses, meaning a substantial investment to mechanise them all. Ideally, a machine needs to move from door to door in response to changing needs.

A distribution warehouse with several ports and a large variety of packages.

Number of deliveries

Deliveries are often irregular. If you do business with Amazon, for example, their peak season starts with Black Friday in November, after which they triple or quadruple their business in the peak season. “On a recent customer visit to a 3PL in southern Sweden, I found that the company had just four containers this week and was expecting 87 the next,” Anders Pettersson says. “The only thing constant about the volume of work is that it varies all the time.” From a facility and personnel point of view, this highlights the need for flexibility. With boom conveyors attached to warehouse ports, this also means a lot of time when the machinery stands idle.

Size of cartons / packages

In e-commerce, it is common to move quickly between different assortments of goods. Companies riding the e-commerce wave can find their business dealing with toys one moment and then skis, canoes, or even pool tables the next, with huge volumes coming into the same warehouses to be handled by the same equipment. Loose-loaded containers are usually filled with the big items at the bottom and the smaller ones at the top – warehouse employees clamber over the boxes and make staircases out of them. With small boxes it is almost always quicker to unload manually, but then you come to the bottom layers with the heavy stuff, and even those Romanian lumberjacks might need some mechanical help.

One-touch or two-touch handling

In the majority of cases, you need to get the boxes onto a palette and into the warehouse. Then the question is whether the process is “one-touch” – directly from the container to the palette – or “two touch”, requiring an additional stage when the goods are sorted. If you get a container with large items such as furniture, you will probably want to palettize the goods directly in the container so the forklift can take them. Smaller boxes usually require additional work, because they need sorting to be placed on the right palettes. If you have a lot of different-sized boxes, you have a lot of sorting to avoid a mix of products on the same palette.

How tightly they are packed

Loose-loaded containers come mainly from Asia. They are filled right up to the ceiling to accommodate the maximum volume of product. These containers are not loaded with the customer in mind, so unloading them can be like playing Tetris. Sometimes they are packed to tightly that it requires force to pull a carton out of its place, or the packaging itself can be distorted by the process of transportation. Space inside the container is cramped, you move one box and others can tumble down on top of you.

Flexibility – the holy grail

“This environment is super stochastic – when you open the container doors, you never know what you are going to find,” Anders says. “If you have the same boxes loaded in the same patterns in every container, automating the unloading process is far more straightforward. But it’s rarely like this. E-commerce is fast moving and situations are highly fluid with regards to the challenges companies face.” This makes flexibility the number one requirement of any efficient unloading system that is going to pay back your investment with higher productivity.

Towards an efficient man-machine solution for loose-loaded containers

At present, there is no system on the market suitable for unloading the full spectrum of heterogeneous parcels outlined above. For operations managers seeking a faster turnaround of container cargo, the need for efficiency and a swift, clear return on their investment usually means that manual labour is the default solution. After all, why invest in expensive automation if a human can do a better job?

TAWI is a leading global provider of smart-lifting solutions, based in Sweden. Its telescopic mounted loader, fitted with a vacuum lifting arm, can be found in many workplaces, where it has become a go-to solution for unloading containers where health and safety concerns are high.

In response to extensive research on customer needs, TAWI is working on a new generation of mechanical aids to resolve the complex issues identified above. The new technology promises substantial efficiency gains and a rapid ROI. Rather than replacing workers, it seeks to empower them to tackle all the loose loaded container challenges in a safe, intuitive and highly flexible manner.

To get TAWI’s expert insights into logistics and lifting challenges, please contact us today.