A Guide to Bearings
Bearings are essential components that help machines to continue running as efficiently and smoothly as possible. Without them, many machines would struggle to function at optimal levels and cease operating entirely due to the wear and tear exerted by friction and movement that would not be constrained by a bearing. Bearings come in a variety of shapes and sizes, including but not confined to:
- Plain bearing: Also known as a slide bearing, is a simple solution to numerous mechanical engineering problems. Having no roller elements makes it the least expensive type among bearings, while its compact size and lightweight qualities make it easy to install into applications requiring motion.
- Rolling bearing: Rolling-element bearings are important in creating machines that can move with a high degree of precision and efficiency. Placing the rolling elements between inner and outer races, it allows both parts to rotate relatively freely, thus enabling lightweight yet strong loads to take their place in the machine.
- Spherical, cylindrical, tapered, and needle roller bearings are examples of common types.
- Deep groove, thrust, and angular contact bearings are all different types of ball bearings.
- Jewel bearing: This is one particular type of plain bearing that uses a metal spindle that is held in a pivot hole lined with jewels. This pivot hole is usually shaped like a torus to provide superior surface-contact characteristics compared to other plain bearings – providing lower friction and longer-lasting operation.
- Fluid bearing: Given that there is no surface contact between the bearing elements, the load on the bearing can be supported by a thin layer of quickly moving liquid or gas, which lowers overall friction, wear, and vibration. This ensures smoother operation and higher efficiency compared to conventional bearings that require sliding friction for their work.
- Magnetic bearing: Magnetic bearings are revolutionizing the world of mechanical engineering as they open up a whole new realm of possibilities. By eliminating physical contact between two parts, they reduce friction, which reduces mechanical wear and decreases vibration significantly.
What are the reasons for producing them via printing?
- Geometry: 3D printing is revolutionizing the field of geometry, allowing complex shapes to be created in a way that was previously unimaginable.
- Materials: The ability to utilize different materials makes it possible to deliver on a wide range of projects with varying performance needs. Carbon-, fibre-, and ceramic-based materials, as well as metals and low-friction plastics, are examples.
- Accessibility: Accessibility has become a defining asset for many individuals in today’s world. With the ability to create bearings from the comfort of home, gone are the days of having to visit a store or local specialist for these necessities.
- Customization: With full customization available for bearings, you no longer have to design around them – instead, you can now fit the bearing components perfectly into your own designs.
- Accuracy: Accurately manufacturing standard-sized bearings and their movable components down to the exact specifications can be a very difficult task, especially considering the capabilities of 3D printing technology.
- Quality: Produced parts with 3D printing don’t always have the same exacting dimensions as their traditionally manufactured counterparts due to difficulty in controlling the diameter while using fused deposition modelling.
How does plastic factor into this situation?
Plastic bearings offer many advantages over metal for many applications. Not only are they much lighter, but they also require no external lubrication, as well as being corrosion resistant when used with glass or plastic balls. Additionally, plastic has the added advantage of operating quietly and not being magnetic at all. These advantages make them a popular choice for many manufacturers who are looking for an inexpensive and more efficient product.
Originally used primarily by subcultural individuals looking for innovative solutions in niche markets, 3D printed bearings have now been introduced to industrial applications with the help of materials like Acetal (POM), produced by manufacturer Igus. Providing users with cost-efficient prints, Acetal (POM) 3D printed bearings offer a low-friction and practical design which can potentially be used in engineering processes from robotics manufacture to product assembly.
Glossary of words and their meanings.
The following are some key terms in bearing design and operation:
- Bearing life: This means how long a bearing will work in a given operation before failing. The L-10 life, which estimates the time in which 90% of tested bearings will experience failure due to fatigue, is generally consulted by engineers to determine the expected bearing lifespan. A variety of environmental factors have been identified as influencing the longevity and performance of a bearing; from temperature levels and lubrication methods to issues such as contamination or misalignment caused by mounting difficulties or deformation.
- Internal bearing clearance: Bearing clearance is the amount that the inner race moves compared to the outer race as load and radial force is applied. Thus, it is important for ball bearings to have minimal clearance for optimal performance under radial loads – this is because both races of a ball bearing come with their own groove specifically designed to provide enough space between each part. Of course, too much space creates excessive heat and friction, obstructing the roller’s movement, while too little space damages internal parts by creating overly tight tolerance levels.
- Cage clearance: Without the proper clearance between a tapered roller bearing’s cage and its housing, it can lead to all kinds of issues. When the cage rubs against the housing, it causes the rollers to drag which in turn can lead to cage distortion and wear, resulting in roller misalignment and slanting. This can then increase the bearing failure rate dramatically due to the added strain it puts on the cage and rollers.
- Alignment: When it comes to bearing performance and durability, proper alignment of the shaft and housing is of utmost importance. Unfortunately, when the bearing is misaligned that can have disastrous effects such as a decrease in capacity and a reduction in the life expectancy, due to how the rollers will only carry the load on a small portion located near or at the end. This creates an increased concentration of force on just a handful of points on both inner and outer races, which will eventually lead to chipping, premature failure, and higher maintenance costs.
- Operating temperature: Temperature is one of the most important factors when it comes to determining the success of a bearing. Type of load, shaft speed and friction all play into temperature levels within a bearing assembly. In order to meet the needs of demanding requirements, each element must be made from materials that can withstand not only the load but also extreme variations in temperature as well.
It is also important to keep in mind that some heat generation is not due solely to external sources; internal processes can cause temperatures to rise as well.
- A load that is too heavy causes the races and rollers to become misaligned.
- rubbing between the races, retainer, and rolling elements
- a huge amount of lubricant causing a lot of churning
- surface friction caused by inadequate lubrication
- Lubrication: Choosing the right type and amount of lubricant for a given job ensures that heat levels are kept low, diminishing the risk of damaging the bearing and its components. What’s more, regular lubrication forces heat away from the bearing, decreasing wear and tear. On top of that, if temperatures run too high, it will keep friction under control with minimal cost and fuss.
Tip 1: Think about how you will use it in practice.
The application you have in mind is important when looking for the best bearing type to 3D print with. By following some key steps, you can identify which bearing type will work best for the job.
- Confirm operating conditions and environment. This requires knowledge of both component construction and function as well as their rotational speed, vibration, shock load and ambient temperature. The temperature rise in-system should also be taken into consideration when determining if the bearing is compatible with the intended operation.
2. Select bearing type and configuration. it is important to consider the workload requirements for an application. Knowing the mounting location, load direction, and load magnitude can help you select the optimal bearing for your design as well as determine if prototyping is necessary. By researching online CAD libraries and leveraging existing designs whenever possible, you can potentially reduce development time and costs.
3. Select bearing dimensions. it is important to keep in mind the design of your shaft as well as any potential limitations that your 3D printer’s capabilities may impose. Assembling a ball bearing in a 3D environment is tricky and requires accuracy; paying attention to exact measurements and channel facets is therefore essential for achieving a well-running bearing.
4. Select bearing tolerances. it is important to remain cognizant of the fact that these printers tend to print internal holes slightly smaller than the planned size. This may lead to a part that does not fit its intended application. To counter this issue, it is important to increase the diameter of the internal hole according to tolerance values provided by your 3D printer manufacturer.
- Tapered roller bearing: Uses for lathe spindles, bevel-gear transmissions, gearboxes, and axial and radial loads.
- Thrust ball bearing: These are only used for thrust loads, heavy axial loads, and slow speeds.
- Needle roller bearing: For radial load at slow speeds and oscillating motion use small-diameter rollers. Lightweight and small in size, they are used in the aircraft industry, bench drill spindles, and other applications.
- Slewing ring bearing: High axial loads supporting heavy but slow oscillating loads, such as a crane’s horizontal platform, a swing yarder’s wind-facing platform, or a horizontal-axis windmill’s wind-facing platform.
Tip 2: Planning, designing, and printing a 3D object.
- Consider print-in-place bearings: The design of these bearings incorporates a shaft connected to the print bed which allows for an entire bearing to be constructed in a single step. This eliminates the need for post-print assembly, saving even more time and resources. To aid in removing the bearing from the build plate, small slots can be included in the design which allows for easy disassembly with a standard screwdriver.
- Revolve is your friend: The revolving feature in CAD tools is an invaluable tool for modelling bearings. It allows users to effortlessly model revolutionary symmetric components like the rings and races of a bearing, as well as accurately rotate other elements. Additionally, having all components of the bearing included in the same “part” can make 3D assembly jobs much easier compared to importing multiple pieces and aligning them for each bearing.
- Test your circles: Before committing to a lengthy 3D print that requires printing complex circular objects, you should test your printer out first. Whether you are using FDM or another method of printing – if possible, the bearings should be printed upright so they can get as accurate of a shape as possible and not become an approximation.
- Bigger is better (for part accuracy): This accuracy translates into a sturdy and long-lasting product, capable of achieving its purpose successfully. Additionally, larger parts require more time and effort to complete; it may take hours or even days depending on the size of the print.
- Start small (with clearances): To ensure the best outcome, it’s important to start with a slightly tighter design and then slowly increase from there. This allows for more control over what’s being created and some adjustability if something doesn’t quite fit correctly.
- Consider soluble materials: With soluble support material, users can successfully 3D print intricate designs like bearings in place without having to manually remove support structures or maintain an internal surface.
Tip 3: Choosing the appropriate material for the task at hand.
3D printing technology has ushered in new possibilities for bearings, including the ability to customize and test a wide range of materials. By understanding their various properties and functions, makers can easily find the right material for any application.
- Nylon: It is a versatile material that can be used for all types of bearings thanks to its key properties of strength, flexibility, and low friction.
- Acetal: Due to its high stiffness, low friction, dimensional stability, and excellent wear resistance, this material, also known as polyoxymethylene (POM), is frequently used in machined plastic bearings.
- Igus Iglidur: As previously mentioned, Igus offers a number of filaments for 3D printers with a variety of characteristics (low coefficient of friction, abrasion-resistant, chemical-resistant, temperature-resistant) to suit various applications.
- PVA or HIPS (soluble support): A fully enclosed 3D print of bearings is an alternative option made possible by PVA and HIPS soluble support. To ascertain whether your design and material selection will work with soluble support in this situation, testing will be required.
It is important to note that traditional steel bearings will be stronger than plastic bearings. While there are many advantages to using a plastic-based material, they aren’t appropriate in situations where loadbearing and strength requirements are more significant. If this is the case, it’s important to consult your material supplier for technical datasheets, as these will clearly indicate if the desired bearing material is suitable and can withstand the loads required from it during operation.
Also, Check out some fantastic methods for post-processing your 3D prints to get rid of the support material and sand, finish, and protect your bearings. When adding a thin layer of metal to a printed bearing, durability increases without compromising the accuracy of your prints. The metal shell gives you peace of mind and prolongs the life span of your 3D print.
Helpful Instruments and Designs
if you take a look at some current bearing designs, you will see a clear benefit from making use of both caged print-in-place and metal ball bearings.
Bearings are one of the fundamental components of most manufacturing processes, and this comprehensive guide could be instrumental in making those projects more efficient than ever before.
With exciting advancements being made in 3D printing and bearing material & processes, the possibilities seem endless, and manufacturers have never been better equipped to tackle ambitious projects.
I am Ganesh Divte. I work as a Quality Assurance Engineer at Dhruvtara WireTech PVT LTD. I have experience in SLS, DMSL, FDM, and SLA additive manufacturing processes. I am very enthusiastic about additive manufacturing and its potential to change the way we manufacture products. I believe that Additive Manufacturing has the potential to revolutionize the manufacturing industry and make it more efficient and sustainable.