The potential of polymer 3D printing
3D printing technologies have evolved significantly, with much of the research centred around the materials science field. This includes high-performance polymers with mechanical characteristics - so what does this mean for bearing design? Here Chris Johnson, Managing Director of SMB Bearings, explores the plastic bearing additive manufacturing (AM) landscape.
AM encompasses a range of technologies that create 3D objects by layering materials on top of each other. Specifically, in polymer 3D printing there are five processes: stereolithography (SLA), fused deposition modelling (FDM), selective laser sintering (SLS), multi-jet fusion (MJF), and material jetting.
Each of these processes impacts a material’s microstructure, such as the size, shape and orientation of the grains or crystals. This presents various challenges and opportunities.
For example, SLA offers a smooth surface finish, but components tend to be less durable than parts produced with other additive technologies. So, let’s explore the bearing design development and production opportunities facilitated by 3D polymer printing processes.
Design flexibility for small or medium batches
3D printing gives bearing manufacturers the design flexibility to produce bearings with bespoke elements and enhanced performance.The 3D printing process is relatively simple and doesn’t require expensive tooling. This allows manufacturers and design engineers to experiment with design features that wouldn’t have been economically viable using conventional bearing manufacturing methods.
Bearing manufacturers can use a diverse range of materials with 3D printing. For example, 3D printed reinforced polymers can match or be enhanced beyond conventional properties, which opens the door to exciting new design possibilities.
3D printing also allows manufacturers to provide a cost-effective low-volume production service — even for orders as low as ten bearing units. 3D printed moulds save time and money compared to expensive metal bearing moulds. They allow a more agile manufacturing approach, meaning that design engineers can test mould designs and modify them without incurring unfeasible production costs and high set up fees.
Light weight designs
For low load, low speed applications, plastic bearings offer fantastic performance characteristics and are five times lighter than their steel counterparts. This reduces the initial weight and energy needed to get them moving. In industries such as aerospace, automotive or medical technology, lightweight design can achieve better safety performance and cost savings.
Using 3D polymer printing processes, it is possible to design a component that is lighter, using honeycomb-like structures. This would be very difficult and time-consuming to achieve with traditional machining processes.
Opting for a 3D printed retainer in nylon (PA66) or another polymer material, can help to reduce the weight of the whole bearing. Carbon-fibre reinforced nylon is one of the most popular combinations for nylon printed materials. It offers many of the same benefits as standard nylon including high strength and stiffness, but it produces significantly lighter components. A 3D printed polymer cage may also reduce the wear on the rolling elements, compared to a conventional steel cage.
In the traditional manufacturing versus advanced manufacturing techniques debate, the good news is that you don’t need to pick a side. Polymer 3D printing can be used to supplement traditional bearing manufacturing techniques, offering rapid prototyping and enhanced performance characteristics that have the potential to rival metals. While 3D printed bearings aren’t commonplace just yet, the evidence is showing that they could be in the future.