Thin section and stainless steel bearings for weight and cost-savings in vehicles
According to McKinsey & Company’s Lightweight, heavy impact report, the use of lighter materials in the latest aircraft and automobile designs will be essential to reducing the CO2 emissions these vehicles produce. But lightweighting presents design and cost challenges, as well as sustainability advantages, for manufacturers. To overcome these, here, Chris Johnson, managing director at specialist bearing supplier SMB Bearings, explains why design engineers should give serious consideration to thin section and stainless steel bearings.
More lightweight designs, relating specifically to the use of lighter materials, have long been a consideration for design engineers. This has particularly applied to aerospace where for instance, as written in DHM and Posturography edited by Sofia Scataglini and Gunther Paul, lightweight designs and materials are preferred for aircraft interiors, not only “ to reduce weight without compromising passenger comfort, or perhaps even while increasing comfort,” but to also save fuel costs.
The concept of lightweighting isn’t new. But the concept’s wider ramifications for fuel-, cost- and efficiency-savings are pushing it higher up engineers’ priority lists – especially as governments sharply increase their sustainability efforts, including the use of more advanced manufacturing concepts for reducing CO2 emissions.
Indeed, McKinsey & Company’s Lightweight, heavy impact report represents in-depth data on how lighter vehicles both in aerospace and automotive – emit fewer CO2 emissions: “Lightweight measures can help reduce CO2 emissions to a certain extent (approximately 0.08 g CO2 reduction per kilogram saved),” says the report. “If an original equipment manufacturer (OEM) manages to reduce the vehicle weight by 100 kg, it saves approximately 8.5 g CO2 per 100 km.”
While the sustainability advantages are clear, what exactly is “lightweighting”? The industrial software company, nTopology, described lightweighting as follows: “Doing more, with less’ is the primary purpose of lightweighting, but the benefits of lightweighting extend beyond material reduction. A lighter design can reap numerous benefits during the design phase and when the final product is in use.”
While lighter metals like aluminium are hugely beneficial, lightweighting is about more than simply choosing whichever material weighs less especially as heavier metals like nodular cast irons (NCIs) are still greatly relied upon in aerospace and automotive manufacturing. Instead, whatever material is used, manufacturers must design engineer parts into being more weight-efficient.
“Lightweight design of vehicles can be achieved in many different ways,” writes P.K. Mallick in Materials, Design and Manufacturing for Lightweight Vehicles, “that include material substitution, gage thickness reduction, redesign of the part shape and size, elimination of redundant parts, and consolidation of several parts into one or two without sacrificing the overall structural integrity or functionality.”
There are several examples of the use of carbon fibre for lightweighting. One is the use of carbon-fiber-reinforced plastics in Boeing’s 787 Dreamliner, and another is the carbon-fiber support structure of BMW’s Project I electric vehicle (EV).
The latter example is especially relevant as major vehicle manufacturers transition away from traditional internal combustion engines (ICE) to battery-powered electric vehicles, and the race is on to build lighter, more efficient cars to maximise vehicle range per charge. This demand hasn’t only created a need for new material and design engineering concepts but also for lighter, smaller bearings.
SMB Bearings is seeing increasing demand for lighter, smaller bearings in aerospace and automotive applications. Even though bearing components are small, they have a significant effect on a vehicle’s efficiency. For example, Lightweight, heavy impact cites the use of carbon fiber bearings for an Airbus A340 horizontal tail, reducing its weight by 50 per cent and cost by 30 per cent.
The latter advantage is vital because, as mentioned in McKinsey and Company’s report, “OEMs will be directly confronted with a threat to their margins and may have to deal with the additional cost of challenges that cannot be fully anticipated at the moment, such as repair and maintenance.”
Meanwhile, in EVs, a better choice of bearings can help improve the efficiency of an EV’s drive train, allowing cars to travel further on the same charge.
Automotive bearings must also undergo a great deal of stress, wear and tear, depending on the application. A specific application is the EV’s throttle, where bearings are essential for the valve to let in the correct amount of air. It’s necessary to find a bearing that can cope with extremely hot temperatures, rapid throttle movements and high levels of vibration.
For this reason, it is essential to choose automotive bearings carefully. SMB Bearings recommends the use of a specialist, high-quality stainless steel bearing. Its own 440 grade stainless steel bearings offer excellent load and speed ratings and enable smooth, fluid motion. They are suitable for temperatures as high as 300 degrees Celsius, while 316 stainless steel can cope with even higher temperatures.
As an authorised UK distributor of EZO brand miniature bearings, thin section bearings and stainless steel bearings, SMB Bearings offers automotive bearings to the TS16949 standard. ISO/TS16949 is an internationally recognised quality management standard written for the automotive industry. Aside from the bearings themselves, you must also consider the best lubricant for their application, which can have a dramatic effect on bearing performance.
Lightweighting trends provide real opportunities for manufacturers, in terms of creating new designs and concepts based on the new material. To this end, designers should give serious consideration to thin section and stainless steel bearings.
Lightweighting will be key in future cost competitiveness for manufacturers – as well as reducing the CO2 emissions emitted by tomorrow’s aircraft and automobiles
2023-04-13