NSK : World's First 100% Bioplastic Bearing Cage-Supporting Carbon Neutrality with Environmentally Friendly Products

NSK is committed to realizing a carbon-neutral society. As part of these efforts, in November 2021, NSK developed the world's first bearing equipped with a cage made of 100% plant-derived bioplastic for use in air conditioner fan motors. In this issue, we talk to the engineers behind this development about the background of the project and what drove them.

◆100% bioplastic bearing cage developed

AiharaNSK has always been committed to protecting the global environment, as indicated in its Mission Statement. Over the decades, this commitment has driven the development of many environmentally friendly technologies, products and materials. NSK's bearings-our mainstay product-are intrinsically eco-friendly because they help save energy by reducing friction and smoothing mechanical movement.

Our team carries out research into the plastic and rubber materials used in NSK products. In order to reduce CO2 emissions related to bearing materials, we developed a cage comprised only of bioplastic, which is produced entirely from renewable plant resources. Bearings are composed of balls or rollers (rolling elements) between the inner and outer rings. A cage is used to space the rolling elements at regular intervals and enable the bearing to rotate smoothly. The cage is therefore a critical component of the bearing.

HondaPlastic derived from fossil fuels is typically used to make these cages. This plastic is made from petroleum pumped from the ground, a process which releases CO2 into the atmosphere. CO2 is also emitted when the plastic is incinerated at the end of the product's lifespan. In contrast, the bioplastic cage we developed uses sesame plants as the raw material for the plastic. Since plants absorb CO2 from the atmosphere during photosynthesis, even if CO2 is emitted during incineration of bioplastic, it will be no more than the amount initially absorbed by the plants. Therefore, bioplastic CO2 emissions are basically net zero. Bioplastic raw materials are produced by cultivating, harvesting and processing plants, and these processes emit less CO2 than the processes used to make plastics from fossil fuels. Our bioplastic cage can reduce CO2 emissions by 91% over the product lifecycle compared to conventional cages (polyamide 66).

NSK has been developing and manufacturing bearings for over 100 years. We made the most of our expertise to develop a cage made of environmentally friendly materials without any compromise to quality. A bearing cage needs to be strong enough to withstand heat and load when in use. At the same time, the material needs to be easy to mold and also flexible enough to bend during bearing assembly. We leveraged materials technology, one of NSK's Four Core Technologies, to evaluate the potential of new materials to meet the requirements for bearing cages. The result is environmentally friendly cage that also delivers heat resistance and strength comparable to a conventional one.

AiharaWe also employed NSK's digital twin technology in the development of the new cage. NSK uses the digital twin approach to achieve high quality and efficiency in product development. Digital twin technology helps create innovative, unexpected solutions, and utilizes both the ability to gain insight into phenomena occurring in the real world, and the ability to apply reasoning by using technology to create a digital model and understand the essence of the underlying issue. We began by using digital technology to analyze how the material might behave, and predicted its molding potential and likely performance. By then creating a real prototype based on the digital results, we eliminated the need to make multiple prototypes, shortening the trial and error process. This made the development so efficient that it only took one-third of the usual time. As environmental awareness grows, I am delighted that we were able to rapidly develop this world-first product to help promote carbon neutrality.

◆Demonstrating product value to customers

HondaI hope that this new product will help draw more attention to bioplastic as an environmentally friendly material. Since it was my first product development project, I'm excited to tell everyone about it in this way, and I guess I also feel a responsibility to keep pushing forward (laughs). Although eco-friendly materials can also mean higher costs, going forward I want to help develop products that can reduce both environmental impact and costs. I will continue working with the needs of our customers in mind.

AiharaI had previously been involved in developing biodegradable plastics that can be used in bearings. When left in the ground, biodegradable plastic decomposes and returns to nature. Unfortunately however, our prior product developments did not translate into sales. I want to promote widespread adoption of this product by communicating to our customers that the benefits of this new product are worth the cost. There are always reasons for the way things turn out, so I would like to carefully review our past and present projects and find ways that NSK can expand its initiatives in this area.

◆Next steps in the development of bearings with bioplastic cages

IshiwadaBearings with the new bioplastic cage have now been adopted for use in air conditioner fan motors. Air conditioners have a built-in fan to generate air flow, and bearings are used in the fan motor to help it rotate smoothly, which in turn reduces the motor's electrical use and saves energy. Since air conditioners are used in living spaces, the equipment needs to be as quiet as possible. This is why the bearings must rotate smoothly and silently. Reliability is also important because longer bearing life means allows the air conditioner to operate quietly over a span of several years.

YoshimaIn the air conditioner market, the COVID-19 pandemic has fueled greater interest in indoor air quality. Demand for replacement air conditioners with advanced features such as ventilation and purification is expected to increase in developed countries. Air conditioner ownership in China, India, and other emerging countries is also expected to increase as incomes rise. Air conditioners often have a high market penetration rate and use a lot of electricity, which makes them a good target for eco-friendly initiatives. By offering bearings with bioplastic cages for air conditioners, we can not only provide the same quietness, high reliability, and energy saving as bearings with conventional plastic cages, but also deliver added value in the form of environmentally friendly materials.

Changing to a bioplastic material can have a huge impact on productivity and the accuracy of molding dimensions, so the shift represented a major product modification. By utilizing NSK's digital twin technology, we were able to simulate conditions at the time of molding and any potential problems that could arise when using conventional production equipment. We then verified and confirmed the product quality through test production and evaluation. As a result, we were able to develop a bioplastic cage with the same performance as a conventional one in just six months. Moreover, we maintained the same performance as the conventional plastic, including the lightweight, low-friction properties and the dynamic molding capability.

◆NSK will continue developing bearings to meet the needs of the future

IshiwadaBearings fitted with a bioplastic cage enable us to market our products by appealing to the new added benefit of environmental design. Going forward, I am keen to look into using environmentally friendly materials for other bearing components such as rings, grease, and seals. Along with parts for industrial machinery, such as air conditioners, our team also designs bearings for vehicle electrification. Based on market trends such as vehicle electrification and broader use of IT, bearings will need to incorporate even more advanced technology. I would like to help create bearings that support the environment while also offering even greater product performance.

YoshimaCustomers have expressed interest in our new bearing as an environmentally friendly product, and some have already requested samples. I would like to continue working to develop this product range with support from across NSK. At the same time, we will closely follow societal trends so that we can anticipate customer needs and move quickly to offer them the right products.