The materials handling sector encompasses everything from elevators in skyscrapers, cranes, light conveyors (like baggage handling lines) and conveyors in mines. Each part of the industry is very different, but has similar underlying sustainability concerns – such as boosting energy efficiency, extending service life and lubricant disposal.
Grease disposal
At one time, lubrication grease was simply disposed of but now it must be recycled. This, however, is not so easy at achieve. For this reason, there is a concerted effort to cut the use of grease in applications such as lifts, conveyor pulleys and cranes. Less grease means less disposal, which ultimately means less pollution.
One solution is to use bearings that do not need re-lubrication. In bearings with solid oil the lubricating oil leaves the oil saturated polymer material onto the bearing raceways. The part is then lubricated for life – which has the added advantage of cutting the need for maintenance operations.
In the heavy conveyors application, another popular way to solve the problem is to use a ‘three barriers’ solution. The solution consists of: a housing with a seal, a sealed bearing, and grease filled in the space between the bearing and the housing seal. The solution has environmental benefits, since the use of grease is significantly lower, because you no longer need to purge the bearing clean with grease. The bearing itself needs small quantities of grease to function. Furthermore, the bearing life is significantly improved because it is working in a protected and clean environment. In a conveyor pulley this means that the life of the bearing system is longer or equal to the lagging on the pulley thus no longer a bottle neck.
Addedefficiency
A far more pressing concern is energy efficiency – as it is for many sectors. Elevator manufacturer KONE estimates that up to 10% of a building’s energy consumption comes from the elevators, which makes it a key target for efficiency gains. There are already ways of clawing back some of this energy, through regenerative drives for example, or through traffic analysis optimising the flow of people and number of elevators.
The move towards more sustainable and energy efficient products in lifts and elevators is partly accounted for by the strict LEED certification required for new building. This informs everything from building materials to construction methods. Regarding lifts, customers can specify the type of system they want and there is a definite trend in that they are increasingly demanding ones with higher standards of efficiency.
A third – and crucial – element of sustainability is to extend the working life of a product and its components. Every time you scrap a component, you are not just throwing away the material it is made from – but all its embedded energy and carbon all the way back up the value chain. For this reason, lengthening lifecycle is of huge benefit.
Within material handling, many lift manufacturers now insist that components last the life of the product. This can be achieved by specifying low-friction bearings – such as SKF Explorer bearings.
SKF recently introduced a new range of small, sealed SKF Explorer spherical roller bearings that can prolong – or even eliminate – service intervals. Fitted in a gearless traction motor in a heavy-duty elevator, it lowers energy consumption by around 145kWh per year – equating to a CO2 emission saving of two tonnes over the motor’s lifecycle. These cut friction by as much as 20%, with a subsequent up to 20 degrees Celsius reduction in working temperature, extending bearing life to match that of the lift system itself.
This helps deliver the ‘maintenance-free’ regime that is important to lift manufacturers. The sealed SKF Explorer spherical roller bearings form part of SKF’s Beyond Zero portfolio of products, which are designed to impart real sustainable benefits in their applications.
There are many examples of how sealed bearings extend the service life of elevators: one Asian elevator manufacturer switched its entire production to sealed SKF Explorer spherical roller bearings, as a low-maintenance solution that would last for at least 20 years. Similarly, a European elevator manufacturer used them with adapter sleeves when it needed a quickly mountable bearing on its first high-rise gearless traction machine.
Handling baggage
There is no particular sector within material handling that leads the way on embracing sustainability. Rather, there are individual companies that are taking the lead. A good example of this is Vanderlande, which has designed a baggage handling system using a ‘Cradle to Cradle’ (C2C) approach. It is an excellent illustration of a company developing a product with sustainability in mind.
Its ‘Blueveyor’ system – which has been running at Amsterdam’s Schiphol Airport since June 2014, consumes around half the energy of a conventional baggage system. C2C principles require the product to be fully recyclable at the end of its life, meaning that SKF had to adapt its Y-bearing unit slightly to accommodate this. It meant removing all polymer from inside the seal, and lubricating the bearing with biodegradable grease.
The bearings are used in belt conveyors on the handling line, with four used on each conveyor. Vanderlande specified the C2C guidelines to SKF, which was then responsible for developing the bearing solution based on this approach. The two companies have worked together extensively in the past, and SKF has a similarly progressive attitude to sustainability as Vanderlande.
Engineers love a challenge and there is none greater than helping to protect the planet and create a more sustainable future for all. Ultimately it is the role of engineers in projects like those demonstrated earlier, that will be crucial in helping to arrest the effects of climate change.
-2017 China(Guangzhou) Int’l Bearing and Equipment Exhibition
