This document describes the development of a high capacity aerodynamic air bearing (HCAB) for laser scanning applications. The HCAB was developed to support larger mirrors of up to 6 inches in diameter compared to prior aerodynamic bearings that were limited to 3.5 inches. It uses a cylindrical bearing design with a patented speed bump stabilization system to provide stability at speeds up to 25,000 rpm. The HCAB eliminates the need for lubricants and their associated issues, while providing performance comparable to aerostatic bearings at a lower cost by not requiring additional air supply equipment. A second version of the HCAB was also developed that incorporated an internal optical encoder.
Electronics for Imaging (EFI) contracted with Axis New England to design a reference system to test print heads from different manufacturers and understand variations between them. Axis New England designed a system using New Way Air Bearings' 65mm flat round air bearings to provide precise, zero-friction motion. The air bearings enabled the system to meet EFI's stringent specifications of 5 microns of straightness and flatness over the 30" print zone. Testing with the system helped EFI better characterize print heads and further development of inkjet printers.
This document summarizes a seminar presentation on air bearings in high precision systems. It discusses the history of air bearings, how they work by generating an air film for near frictionless motion, their applications in areas like CMMs, medical devices, and production machinery where precision and cleanliness are important. The advantages of air bearings are noted as greater precision, higher speeds, increased tool life and surface finish compared to traditional bearings. The main disadvantages are higher manufacturing accuracy needs and requirement of a clean, dry air supply. In conclusion, air bearings provide a clean solution for high speed, precision applications.
Air bearings use a thin film of pressurized gas to provide a low friction interface between surfaces. There are two main types: aerostatic bearings, which can lift loads vertically up to 3 inches; and aerodynamic bearings, which can lift loads just enough to float them horizontally and can move loads over 100 tons. Air bearings have applications in cutting and medical equipment due to their advantages of low friction, no lubrication needs, and long life. However, they require precise manufacturing and a clean supply of compressed air, and tend to be more expensive than other bearing types.
An air bearing is a type of bearing that uses a pressurized gas, typically air, to generate a film that separates two surfaces in relative motion without physical contact. There are two main types: aerostatic bearings, which use an externally pressurized gas supply, and aerodynamic bearings, which generate the gas film through relative motion. Air bearings offer benefits like greater precision, higher speeds, improved surface finish, and lack of maintenance compared to traditional bearings. However, they also require high manufacturing accuracy, a clean air supply, and have higher costs. Applications of air bearings include hovercraft, lifting heavy weights, and future vehicles.
This document provides an introduction to air bearings, including their advantages over rolling element bearings such as near-zero friction, wear, and ability to operate without lubrication. It describes the basic operating principles of aerostatic air bearings, which use a pressurized air supply to create an air film between surfaces. Key benefits discussed include zero friction, zero wear, higher speeds and stiffness, suitability for clean environments, and longevity. Commercial applications of air bearings mentioned include coordinate measuring machines, semiconductor manufacturing equipment, and high-precision machine tools.
Ceramic bearings are typically constructed with a ferrous inner and outer ring or race with ceramic balls in the place of steel. Ceramic bearings offer many advantages over all steel bearings, such as higher speed and acceleration capability, increased stiffness, lower friction and more. Ceramic balls are also nonconductive. Ceramic bearings are available in all standard industry configurations such as, angular bearings, thrust bearing, pillow block bearing, needle bearings, and roller bearings.
summer training report on NBC for B.TECH studentsAbhishek Gora
The document discusses taper roller bearings, which can take both axial and radial loads. Taper roller bearings are composed of an inner race, outer race, rolling elements, and a cage. They are available in single, double, and four row configurations. Taper roller bearings are used in heavy duty applications like construction equipment, axles, gearboxes, and engine motors due to their ability to handle large loads and their durability.
Electronics for Imaging (EFI) contracted with Axis New England to design a reference system to test print heads from different manufacturers and understand variations between them. Axis New England designed a system using New Way Air Bearings' 65mm flat round air bearings to provide precise, zero-friction motion. The air bearings enabled the system to meet EFI's stringent specifications of 5 microns of straightness and flatness over the 30" print zone. Testing with the system helped EFI better characterize print heads and further development of inkjet printers.
This document summarizes a seminar presentation on air bearings in high precision systems. It discusses the history of air bearings, how they work by generating an air film for near frictionless motion, their applications in areas like CMMs, medical devices, and production machinery where precision and cleanliness are important. The advantages of air bearings are noted as greater precision, higher speeds, increased tool life and surface finish compared to traditional bearings. The main disadvantages are higher manufacturing accuracy needs and requirement of a clean, dry air supply. In conclusion, air bearings provide a clean solution for high speed, precision applications.
Air bearings use a thin film of pressurized gas to provide a low friction interface between surfaces. There are two main types: aerostatic bearings, which can lift loads vertically up to 3 inches; and aerodynamic bearings, which can lift loads just enough to float them horizontally and can move loads over 100 tons. Air bearings have applications in cutting and medical equipment due to their advantages of low friction, no lubrication needs, and long life. However, they require precise manufacturing and a clean supply of compressed air, and tend to be more expensive than other bearing types.
An air bearing is a type of bearing that uses a pressurized gas, typically air, to generate a film that separates two surfaces in relative motion without physical contact. There are two main types: aerostatic bearings, which use an externally pressurized gas supply, and aerodynamic bearings, which generate the gas film through relative motion. Air bearings offer benefits like greater precision, higher speeds, improved surface finish, and lack of maintenance compared to traditional bearings. However, they also require high manufacturing accuracy, a clean air supply, and have higher costs. Applications of air bearings include hovercraft, lifting heavy weights, and future vehicles.
This document provides an introduction to air bearings, including their advantages over rolling element bearings such as near-zero friction, wear, and ability to operate without lubrication. It describes the basic operating principles of aerostatic air bearings, which use a pressurized air supply to create an air film between surfaces. Key benefits discussed include zero friction, zero wear, higher speeds and stiffness, suitability for clean environments, and longevity. Commercial applications of air bearings mentioned include coordinate measuring machines, semiconductor manufacturing equipment, and high-precision machine tools.
Ceramic bearings are typically constructed with a ferrous inner and outer ring or race with ceramic balls in the place of steel. Ceramic bearings offer many advantages over all steel bearings, such as higher speed and acceleration capability, increased stiffness, lower friction and more. Ceramic balls are also nonconductive. Ceramic bearings are available in all standard industry configurations such as, angular bearings, thrust bearing, pillow block bearing, needle bearings, and roller bearings.
summer training report on NBC for B.TECH studentsAbhishek Gora
The document discusses taper roller bearings, which can take both axial and radial loads. Taper roller bearings are composed of an inner race, outer race, rolling elements, and a cage. They are available in single, double, and four row configurations. Taper roller bearings are used in heavy duty applications like construction equipment, axles, gearboxes, and engine motors due to their ability to handle large loads and their durability.
A bearing is a device that supports load and reduces friction between moving parts. There are two main types: plain/slider bearings and rolling/anti-friction bearings. Rolling bearings use balls or rollers to create separation between surfaces and are more commonly used. Common bearing materials include metals, alloys, and some non-metals. Bearings must be properly selected, mounted, lubricated, and maintained to maximize their lifespan and prevent premature failure.
The document discusses different types of bearings used in machines and their functions. It describes sliding contact bearings like hydrodynamic and hydrostatic bearings, and rolling contact bearings like ball and roller bearings. The key types of rolling contact bearings are explained as journal/sleeve bearings, thrust bearings, and guide bearings based on the direction of load and motion. Common applications of rolling contact bearings and their advantages are also summarized.
Air springs come in two types: bellows and piston. Bellows springs consist of rubber bellows that replace coil springs, while piston springs have a metal air container with a sliding piston attached to the lower wishbone.
Air or pneumatic suspension systems are becoming more popular than conventional metal springs for vehicles. They allow for variable wheel deflection control, maintain constant vehicle height to avoid headlight alignment changes, have less variable spring rates between loaded and unloaded states, and provide improved ride comfort and noise reduction to reduce driver fatigue.
An air suspension system works by using an air compressor to fill air springs mounted in the same positions as coil springs to around 240 MPa pressure, stored in an accumulator tank regulated
IRJET- Design and Fabrication of Manual Roller Bending MachineIRJET Journal
This document describes the design and fabrication of a manual roller bending machine. The machine uses a roller mechanism powered by a manually operated spindle wheel to bend metal strips. It has a supporting frame to hold the roller assembly. One roller is connected to the spindle wheel via a chain drive mechanism to power it. A movable center roller can be adjusted using a screw mechanism to control the bending angle. The machine is designed to be portable and affordable while reducing human effort during operation. Design calculations are provided for components like the chain drive, power screw, and required bending forces and torques for different metal thicknesses. Dimensions and a 3D model of the machine are also presented. Testing showed the machine can successfully bend metal strips but takes more
The document discusses vibration monitoring techniques for detecting rolling element bearing failures. It describes the different frequency regions of vibrations produced by bearings, including the rotor vibration region, prime spike region, and high frequency region. It then explains different transducer systems that can be used, including REBAM probes that directly measure bearing vibrations and casing vibration measurements. The key conclusions are that rotor vibration and prime spike measurements from permanent probes or casing sensors are the primary techniques for monitoring bearings and determining when replacement is needed, while high frequency measurements can provide early failure indications but require closer monitoring due to changing readings.
Analysis of hydrodynamic fixed pad bearing to reduce vibration by replacing f...ijsrd.com
Rotating machineries are always subject to vibrations due to critical speeds, unbalance, and instability. Usually the least expensive modification of a machine to make is the bearing. A wide variety of bearings have been developed to combat some of the different types of vibration problems. This report consist the analysis of 360deg hydrodynamic bearing of Boiler Feed water Pump. The boiler feed water pump is very critical rotatory equipment of Thermal power plant the bearing of this pump must be able to withstand in vibration and other hydraulic forces while still maintaining a high degree of reliability. This report consist analysis and design of 360 hydrodynamic bearing also replacing fixed pad by flexural pad and analysis bearing vibration and compare vibration for the same condition with the help of FEM Method in ANSYS.
Optimised designs can be supplied in taper roller bearings with high strength cages and, for arduous applications, in a range of advanced special materials.
The document is a presentation on bearings created by Akash Panchal. It discusses the definition of a bearing, provides a brief history, and examines various types of bearings like ball bearings, roller bearings, plain bearings, and their functions. It also looks at bearing selection, arrangement, lubrication, and life calculation. The presentation contains several diagrams and is intended to provide an overview of bearings.
Sliding Contact Bearing Theory Prof. Sagar DhotareSagar Dhotare
In present ppt covers following points:
Introduction of Sliding Contact Bearings
Classification
Applications
Different lubrications systems
Hydrodynamic bearing concept and working
Comparison between sliding and rolling contact bearings
PETROFF’S EQUATION For Hydrodynamic Journal Bearing
Dimensionless Parameters used in SCB
Design procedure for Hydrodynamic Journal Bearing
Nylon bearings offer excellent load bearing capacity, corrosion resistance, and are lightweight compared to steel. Proper bearing design requires considering the operating environment including temperature and moisture, as well as calculating the necessary press fit, running clearance by accounting for shaft allowance, temperature and moisture factors, and ensuring the bearing size can withstand the load and surface speed. Questions about the bearing design process are welcome.
Bearing Life Optimization of Taper Roller Bearingijsrd.com
The life of the Taper Roller Bearing is most important factor with the optimum dimension, life and the geometry both of these are important to stay in the market. These parameters are determined the cost and quality of the bearing. To increase the life of bearings, the dimension of the bearing should be optimum to get the reliability and function of the bearing. In this project the geometry of the bearing component is trying to optimize with the desired life. By optimize the dimension of the Pocket corner radious of bearing component, the total mass of the bearing component. By reducing the weight of the bearing component ultimately total efficiency as well as total cost of the bearing is also reduced. The mass of bearing is reduced by changing the geometry of the dimension of the bearing component. The optimization has been carried out by keeping the results of the existing bearing constant.
The document discusses CG-1 hydrodynamic bearings produced by HTB corporation. The bearings can operate continuously at temperatures up to 400°F without external cooling, unlike traditional bearings that require cooling below 200°F. The CG-1 bearings use modern materials like high temperature polymers instead of babbitt metals, can improve strength and efficiency over traditional designs, and reduce costs by eliminating external cooling needs.
This document summarizes the mounting of machine elements for a concrete mixer. It discusses the main components of a concrete mixer including bearings, worm gears, drums, yokes, sprockets, and frames. It then focuses on the mounting of bearings and gears. For bearings, it describes the types of bearings and different mounting methods, including both bearings fixed or one floating. For gears, it outlines different attachment methods like using fixing screws, keys and circlips, cotter pins, and locking assemblies. Finally, it provides an example of selecting bearings from a manufacturer's catalog.
Design and analysis of bodyworks of a formula style racecareSAT Journals
Abstract: The aim was to develop a body of the racecar with the proper studies and analyses, taking into account several factors, to present an optimum structure as a final result. These factors include, but are not limited to, weight, cost, drag resistance, functionality and aesthetics. The expected product is to not just be appealing to the eye but also increase the performance of the vehicle. Additional objectives include being able to accommodate the budget while maintaining a highly competitive level to perform well in on the race track. The new design will reduce the weight of the prototype and as well as the air drag, taking into consideration the ground effects desired to be implemented in the vehicle as a crucial factor. Moreover, the new body will be easier to dismantle reducing the service time. Keywords: drag resistance, aesthetics, performance, weight, cost.
The document describes the parts and assembly of a hydraulic punch press machine. It lists the various metal parts that make up the machine, including the square solid pipe, punch, die, oil tank, motor housing, gear pump, pressure control valve, and hydraulic cylinder. It explains that the gear pump and hydraulic cylinder work together to provide reciprocating motion to the ram via hydraulic pressure from the oil tank. The aim of the project is to develop students' skills in teamwork, problem-solving, report writing, and applying interdisciplinary knowledge to manufacturing problems.
This document discusses thrust bearings, which are machine components that support axial loads and constrain rotational motion. It describes how thrust bearings reduce friction in automobiles, aircrafts, manufacturing equipment, and more. The document categorizes different types of thrust bearings, including ball thrust bearings, tapered roller thrust bearings, cylindrical roller thrust bearings, spherical roller thrust bearings, and needle roller thrust bearings. It provides a high-level overview of thrust bearings and their applications before diving into specific types.
Static analysis of alloy wheel using ansys15.0eSAT Journals
1. A static analysis of an alloy wheel was performed using ANSYS 15.0.
2. The alloy wheel was designed using reverse engineering and modeled in CATIA. It was then imported into ANSYS for analysis.
3. Under a pressure load of 200kPa applied to the rim surface, the maximum equivalent stress was found to be 11.283MPa, below the yield strength of the alloy. The maximum deformation was 0.033mm. The minimum safety factor was 21.
An air bearing is a non-contact system that uses a film of pressurized gas, usually air, to separate two surfaces moving relative to each other. It has less friction than other bearing types like rolling or plain bearings since there is no contact between surfaces. Air bearings also don't require lubrication and have long lifespans. There are two main types: aerostatic bearings which provide high lift and aerodynamic bearings which provide enough lift to float loads of up to 100 tons. Air bearings work by inflating to form a seal and allowing compressed air to escape and float the load above the surface. They have applications in lifting heavy weights and hovercraft transportation.
A bearing is a device that supports load and reduces friction between moving parts. There are two main types: plain/slider bearings and rolling/anti-friction bearings. Rolling bearings use balls or rollers to create separation between surfaces and are more commonly used. Common bearing materials include metals, alloys, and some non-metals. Bearings must be properly selected, mounted, lubricated, and maintained to maximize their lifespan and prevent premature failure.
The document discusses different types of bearings used in machines and their functions. It describes sliding contact bearings like hydrodynamic and hydrostatic bearings, and rolling contact bearings like ball and roller bearings. The key types of rolling contact bearings are explained as journal/sleeve bearings, thrust bearings, and guide bearings based on the direction of load and motion. Common applications of rolling contact bearings and their advantages are also summarized.
Air springs come in two types: bellows and piston. Bellows springs consist of rubber bellows that replace coil springs, while piston springs have a metal air container with a sliding piston attached to the lower wishbone.
Air or pneumatic suspension systems are becoming more popular than conventional metal springs for vehicles. They allow for variable wheel deflection control, maintain constant vehicle height to avoid headlight alignment changes, have less variable spring rates between loaded and unloaded states, and provide improved ride comfort and noise reduction to reduce driver fatigue.
An air suspension system works by using an air compressor to fill air springs mounted in the same positions as coil springs to around 240 MPa pressure, stored in an accumulator tank regulated
IRJET- Design and Fabrication of Manual Roller Bending MachineIRJET Journal
This document describes the design and fabrication of a manual roller bending machine. The machine uses a roller mechanism powered by a manually operated spindle wheel to bend metal strips. It has a supporting frame to hold the roller assembly. One roller is connected to the spindle wheel via a chain drive mechanism to power it. A movable center roller can be adjusted using a screw mechanism to control the bending angle. The machine is designed to be portable and affordable while reducing human effort during operation. Design calculations are provided for components like the chain drive, power screw, and required bending forces and torques for different metal thicknesses. Dimensions and a 3D model of the machine are also presented. Testing showed the machine can successfully bend metal strips but takes more
The document discusses vibration monitoring techniques for detecting rolling element bearing failures. It describes the different frequency regions of vibrations produced by bearings, including the rotor vibration region, prime spike region, and high frequency region. It then explains different transducer systems that can be used, including REBAM probes that directly measure bearing vibrations and casing vibration measurements. The key conclusions are that rotor vibration and prime spike measurements from permanent probes or casing sensors are the primary techniques for monitoring bearings and determining when replacement is needed, while high frequency measurements can provide early failure indications but require closer monitoring due to changing readings.
Analysis of hydrodynamic fixed pad bearing to reduce vibration by replacing f...ijsrd.com
Rotating machineries are always subject to vibrations due to critical speeds, unbalance, and instability. Usually the least expensive modification of a machine to make is the bearing. A wide variety of bearings have been developed to combat some of the different types of vibration problems. This report consist the analysis of 360deg hydrodynamic bearing of Boiler Feed water Pump. The boiler feed water pump is very critical rotatory equipment of Thermal power plant the bearing of this pump must be able to withstand in vibration and other hydraulic forces while still maintaining a high degree of reliability. This report consist analysis and design of 360 hydrodynamic bearing also replacing fixed pad by flexural pad and analysis bearing vibration and compare vibration for the same condition with the help of FEM Method in ANSYS.
Optimised designs can be supplied in taper roller bearings with high strength cages and, for arduous applications, in a range of advanced special materials.
The document is a presentation on bearings created by Akash Panchal. It discusses the definition of a bearing, provides a brief history, and examines various types of bearings like ball bearings, roller bearings, plain bearings, and their functions. It also looks at bearing selection, arrangement, lubrication, and life calculation. The presentation contains several diagrams and is intended to provide an overview of bearings.
Sliding Contact Bearing Theory Prof. Sagar DhotareSagar Dhotare
In present ppt covers following points:
Introduction of Sliding Contact Bearings
Classification
Applications
Different lubrications systems
Hydrodynamic bearing concept and working
Comparison between sliding and rolling contact bearings
PETROFF’S EQUATION For Hydrodynamic Journal Bearing
Dimensionless Parameters used in SCB
Design procedure for Hydrodynamic Journal Bearing
Nylon bearings offer excellent load bearing capacity, corrosion resistance, and are lightweight compared to steel. Proper bearing design requires considering the operating environment including temperature and moisture, as well as calculating the necessary press fit, running clearance by accounting for shaft allowance, temperature and moisture factors, and ensuring the bearing size can withstand the load and surface speed. Questions about the bearing design process are welcome.
Bearing Life Optimization of Taper Roller Bearingijsrd.com
The life of the Taper Roller Bearing is most important factor with the optimum dimension, life and the geometry both of these are important to stay in the market. These parameters are determined the cost and quality of the bearing. To increase the life of bearings, the dimension of the bearing should be optimum to get the reliability and function of the bearing. In this project the geometry of the bearing component is trying to optimize with the desired life. By optimize the dimension of the Pocket corner radious of bearing component, the total mass of the bearing component. By reducing the weight of the bearing component ultimately total efficiency as well as total cost of the bearing is also reduced. The mass of bearing is reduced by changing the geometry of the dimension of the bearing component. The optimization has been carried out by keeping the results of the existing bearing constant.
The document discusses CG-1 hydrodynamic bearings produced by HTB corporation. The bearings can operate continuously at temperatures up to 400°F without external cooling, unlike traditional bearings that require cooling below 200°F. The CG-1 bearings use modern materials like high temperature polymers instead of babbitt metals, can improve strength and efficiency over traditional designs, and reduce costs by eliminating external cooling needs.
This document summarizes the mounting of machine elements for a concrete mixer. It discusses the main components of a concrete mixer including bearings, worm gears, drums, yokes, sprockets, and frames. It then focuses on the mounting of bearings and gears. For bearings, it describes the types of bearings and different mounting methods, including both bearings fixed or one floating. For gears, it outlines different attachment methods like using fixing screws, keys and circlips, cotter pins, and locking assemblies. Finally, it provides an example of selecting bearings from a manufacturer's catalog.
Design and analysis of bodyworks of a formula style racecareSAT Journals
Abstract: The aim was to develop a body of the racecar with the proper studies and analyses, taking into account several factors, to present an optimum structure as a final result. These factors include, but are not limited to, weight, cost, drag resistance, functionality and aesthetics. The expected product is to not just be appealing to the eye but also increase the performance of the vehicle. Additional objectives include being able to accommodate the budget while maintaining a highly competitive level to perform well in on the race track. The new design will reduce the weight of the prototype and as well as the air drag, taking into consideration the ground effects desired to be implemented in the vehicle as a crucial factor. Moreover, the new body will be easier to dismantle reducing the service time. Keywords: drag resistance, aesthetics, performance, weight, cost.
The document describes the parts and assembly of a hydraulic punch press machine. It lists the various metal parts that make up the machine, including the square solid pipe, punch, die, oil tank, motor housing, gear pump, pressure control valve, and hydraulic cylinder. It explains that the gear pump and hydraulic cylinder work together to provide reciprocating motion to the ram via hydraulic pressure from the oil tank. The aim of the project is to develop students' skills in teamwork, problem-solving, report writing, and applying interdisciplinary knowledge to manufacturing problems.
This document discusses thrust bearings, which are machine components that support axial loads and constrain rotational motion. It describes how thrust bearings reduce friction in automobiles, aircrafts, manufacturing equipment, and more. The document categorizes different types of thrust bearings, including ball thrust bearings, tapered roller thrust bearings, cylindrical roller thrust bearings, spherical roller thrust bearings, and needle roller thrust bearings. It provides a high-level overview of thrust bearings and their applications before diving into specific types.
Static analysis of alloy wheel using ansys15.0eSAT Journals
1. A static analysis of an alloy wheel was performed using ANSYS 15.0.
2. The alloy wheel was designed using reverse engineering and modeled in CATIA. It was then imported into ANSYS for analysis.
3. Under a pressure load of 200kPa applied to the rim surface, the maximum equivalent stress was found to be 11.283MPa, below the yield strength of the alloy. The maximum deformation was 0.033mm. The minimum safety factor was 21.
An air bearing is a non-contact system that uses a film of pressurized gas, usually air, to separate two surfaces moving relative to each other. It has less friction than other bearing types like rolling or plain bearings since there is no contact between surfaces. Air bearings also don't require lubrication and have long lifespans. There are two main types: aerostatic bearings which provide high lift and aerodynamic bearings which provide enough lift to float loads of up to 100 tons. Air bearings work by inflating to form a seal and allowing compressed air to escape and float the load above the surface. They have applications in lifting heavy weights and hovercraft transportation.
1. Bearings are components that allow parts in a machine to move smoothly against each other. There are two main types: sliding bearings which use lubrication between sliding surfaces, and rolling element bearings which use balls or rollers to minimize friction.
2. Thrust bearings are a type of rolling element bearing designed to support high axial loads on a shaft. Common varieties include ball, roller, and tapered roller thrust bearings.
3. Bushings are plain bearings that can be inserted into a housing to provide a bearing surface, and come in solid, split, or clenched designs to accommodate rotation.
A bearing is a machine element that supports another moving element, known as a journal, and allows relative motion between their surfaces while carrying loads. There are two main types of bearings: sliding contact bearings and rolling contact bearings. Sliding contact bearings include journal or sleeve bearings, which support radial loads and come in full or partial designs. Rolling contact bearings use balls or rollers between surfaces to reduce friction. Key considerations in bearing design include load capacity, friction, lubrication, and heat dissipation.
This document discusses the calculation of bearing life and dynamic load ratings. It provides formulas and factors for calculating the radial and axial forces on bearings based on machine design and operating conditions. It also summarizes the Lundberg-Palmgren and SKF equations for calculating an equivalent dynamic bearing load and adjusted rating life of a bearing based on operating load and speed.
Bearings are used to support rotating shafts and allow frictionless rotation. Plain or sliding contact bearings include journal, footstep, and thrust bearings which have direct sliding contact between the shaft and bearing material. Journal bearings support radial loads on a shaft running through the bearing. Footstep bearings support vertical shafts with axial loads. Thrust bearings support axial loads on a shaft passing through the bearing. Common bearing materials include brass, bronze, and babbitt metal which can be replaced if worn.
This document discusses materials, heat treatments, and dimensional stability of rolling bearings used in SKF bearings. The key points are:
1) Bearing rings and rolling elements are made of through-hardening carbon chromium steel or case-hardening chromium-nickel steel and manganese-chromium steel.
2) Heat treatments include bainitic hardening, case hardening, and martensite hardening, each with advantages like dimensional stability or hardness, and disadvantages like cost or risk of cracks.
3) Dimensional stability is highest in bainite-hardened materials and martensite-hardened bearings can experience the most diameter change with heat.
This is a presentation about ball bearing manufacturing manufacturing process. There are mainly 6 parts of knowledge included in this presentation. Please visit
Bearing designations provide information about the bearing type, size, and any supplementary details. The basic designation indicates the product type, standard design, and size. Supplementary designations specify alternative designs, bearing components, and special types. Designations are broken into categories including internal design, external design, cage design, and performance enhancements. Together, the basic and supplementary designations precisely identify bearing characteristics.
This document discusses different types of bearings used in mechanical engineering. It describes bearings as machine components that support another element and allow relative motion while carrying a load. There are two main types - sliding contact bearings and rolling contact bearings. Rolling contact bearings, also called anti-friction bearings, use balls or rollers between elements and have lower coefficients of friction than sliding contact bearings. The document further details types of rolling contact bearings like ball bearings, roller bearings, and their construction and applications.
Rolling element bearings transmit loads through rolling contact and provide lower coefficients of friction than sliding contact bearings. They are composed of an inner race, outer race, rolling elements (balls or rollers), and a cage. Ball bearings are further classified as deep groove, angular contact, or filled notch types. Roller bearings use cylindrical or tapered rollers and have higher load capacity than ball bearings. Bearing life is rated based on the number of revolutions or hours it can operate before spalling or pitting failure occurs, with an L10 life rating meaning 10% of tested bearings will fail by that point.
Bearings are machine elements designed to reduce friction, carry loads, and guide moving parts. They come in many types including ball bearings, roller bearings, and thrust bearings which use either rolling or sliding friction. Over time, bearings have evolved from early wheels to modern designs with inner and outer rings and cages to separate rolling elements. Proper bearing selection, installation, and maintenance are important to maximize bearing life.
Bearings are used to support rotating shafts and come in different types depending on whether they are designed to withstand axial thrusts, radial loads, or both. The main bearing types are ball bearings, which use spheres, and cylindrical roller bearings, which use cylinders, with each type having different capacities for loads and misalignment. Deep groove ball bearings can withstand both radial and axial loads, while angular contact ball bearings have increased axial load capacity and self-aligning ball bearings are very tolerant of misalignment.
National Engineering Industries Ltd. (NEI) was founded in 1946 in Jaipur, India as a bearing manufacturer. It has since expanded to multiple manufacturing plants across India. NEI produces a wide range of bearings including ball bearings, tapered roller bearings, and specialized bearings. Key milestones included establishing technical collaborations with international bearing companies and expanding production capacity. NEI's bearings are used across various industries including automotive, rail, electric motors, and agriculture. The company aims to be a self-reliant indigenous bearing manufacturer for India.
This document provides an analytical report on an employee satisfaction survey conducted at National Engineering Industries Limited in Jaipur, India. It begins with an introduction to the company, which manufactures bearings. It then discusses the objectives, methodology and data collection process for the employee satisfaction survey. The majority of the document consists of a data analysis chapter that analyzes the results of the employee satisfaction survey. It concludes with suggestions for improving employee satisfaction based on the findings.
This paper introduces air bearings. High-speed air bearings offer very specific advantages over other, more conventional bearing technologies. The reason use of air bearing air bearings as it avoid the traditional bearing-related problems of friction, wear, and lubricant handling, and offer distinct advantages in precision positioning and high speed applications. The use of air bearings means tool life can be greatly extended. Air bearings provide extreme radial and axial rotational precision. The factors affecting the performance of the air bearing like friction, wear, stiffness, load capacity. This paper also introduces with the types of air bearing. New air bearing products like flat bearing, air bushing, vacuum preloaded bearings, air bearing slides, radial bearing and its applications in various fields. It also discuss about the advantages and disadvantages of air bearings.
This document discusses different types of bearings and their failure modes. It describes rolling contact bearings and their parts. Common failures for rolling contact bearings include wear damage, smearing, false brinelling, and corrosion. Cage failures include wear from contamination, tilting, and fractures. Sliding contact bearings are also discussed. Journal bearing failures like seizure, wear, oil whirl, and oil whip instabilities are explained. The document concludes by discussing research on air foil bearings which don't require external lubrication systems and their potential advantages and challenges.
Bearing are machine element that allow components
to move with respect to each other. A little consideration will
shows that some part of power wasted in overcoming the
frictional resistance and due to the contact of surfaces large
amount of wear and tear takes place between the contacted
surfaces. Hence to avoid wear and tear in sliding contact
bearing and to reduce frictional resistance the thin layer of fluid
is introduced which is called as lubricant. Air bearing are
introduced to reduce such frictional resistance and wear of
sliding contact bearings. Air bearings are bearings that use a
thin film of pressurized air to provide low frictional load
bearing interfaces between surfaces. There is a small gap
between two surfaces i.e. two surfaces do not touch. As these
bearings are contact free various problems in traditional
bearing like friction, wear, particulates, and lubricant handling
are avoided. There are advantages like precision positioning,
such as lacking backlash and static friction as well as in high
speed application. Other than this characteristics, stability is
also important factor in air bearing.
IRJET- Analysis of Static Load Bearing Capacity of the Ball Bearing – A ReviewIRJET Journal
The document summarizes research analyzing the static load bearing capacity of ball bearings. It discusses using finite element analysis to determine capacity without destructive testing. The research found a linear relationship between the deviation of capacity results from finite element vs practical testing and the bearing size. A linear interpolation equation was developed relating deviation to bearing size. Laboratory testing on bearings of different sizes validated the relationship and showed deformation increasing with load. The research concludes the equation can be used to determine static capacity from bearing size.
This document discusses bearings and lubrication. It defines bearings as any support in direct contact with a moving machine part that is designed to minimize friction. The main types of bearings are described as anti-friction bearings, which provide rolling contact, and plain bearings, which have sliding contact. Anti-friction bearings like ball and roller bearings are advantageous because they have lower starting friction than plain bearings. Plain bearings can use materials like bronze and are simpler but have higher wear. Proper lubrication is also discussed, including different lubrication systems like oil misting which has advantages like lower temperatures and positive pressure prevention of contamination.
THERMAL STRESS ANALYSIS OF A BALL BEARING BY FINITE ELEMENT METHODIAEME Publication
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High capacity aerodynamic air bearing (hcab)
1. High capacity aerodynamic air bearing (HCAB) for
laser scanning applications
Sean M. Coleman
Lincoln Laser Co., 234 E. Mohave, Phoenix, AZ 85004
ABSTRACT
A high capacity aerodynamic air bearing (HCAB) has been developed for the laser scanning market. The
need for increasing accuracies in the prepress and print plate-making market is causing a shift from ball
bearing to air bearing scanners. Aerostatic air bearings are a good option to meet this demand for better
performance however, these bearings tend to be expensive and require an additional air supply, filtering and
drying system. Commercially available aerodynamic bearings have been typically limited to small mirrors, on
the order of 3.5” diameter and less than 0.5” thick. A large optical facet, hence a larger mirror, is required to
generate the high number of pixels needed for this type of application. The larger optic necessitated the
development of a high capacity ‘self-generating’ or aerodynamic air bearing that would meet the needs of the
optical scanning market. Its capacity is rated up to 6.0” diameter and 1.0” thick optics. The performance of
an aerodynamic air bearing is better than a ball bearing and similar to an aerostatic air bearing. It retains the
low costs while eliminating the need for ancillary equipment required by an aerostatic bearing.
Keywords: Scanner, spindle, polygon, airbearing, air bearing, aerodynamic, scanning, prepress, laser.
1. INTRODUCTION
Lincoln Laser Company has been producing air bearings for the scanning market since 1990. Until recently,
the largest mirror used on these scanners was limited to 3” diameter by 0.4” thick. But now, with the inception
of HCAB, it is possible to aerodynamically spin mirrors up to 6” diameter by 1” thick and up to 25,000rpm
(limited by the windage or air drag of the optical configuration chosen).
2. BALL BEARING VS. AERODYNAMIC AIR BEARING
There are many problems associated with the use of precision ball bearings at high speeds and large
payloads. These are related to issues such as lubrication, vibration, particle generation and shipment
methods.
Lubricants are the life blood of ball bearings. Much consideration is given to make sure that the right type and
amount of lubricant is used in the ball bearing for a particular application. Lubricant sling, migration, and
outgassing are critical problems associated with ball bearings. At high speeds, the lubricants have a
tendency to ‘sling’ out of the bearing. Lubricants also tend to seep or ‘migrate’ along surfaces as well as
evaporate, commonly referred to as outgassing. All three phenomena cause smudging of the polygon and
optics close to the MPA.
It is not possible to use seals to reduce the slinging for scanning applications because varying torque loads
increase the stability error of the motor polygon assembly (MPA). Non-contacting shields are used to retain
as much lubricant as possible without changing performance of the unit. A small gap is maintained between
the shield and inner ring, which allows small amounts of lubricant to escape. However, as the high speed
system continues to sling and migrate, the bearing eventually runs out of lubricant and fails. While
outgassing rates are not considerably high, they produce hazing on the optics that is detrimental to
performance of the optical scanning system.
2. Lubricant sling, migration, and outgassing are problematic for clean room environments because they
increase the particle count. While outgassing can be controlled by using vacuum lubricants, there is no way
of preventing sling and migration.
Another particular problem of ball bearing scanners is related to the aerodynamic effect of a spinning flat plate
optic or polygon. The air wants to adhere to the spinning surface and is thrown out of the unit by its own
momentum. This creates a low pressure area in the housing, which can exacerbate the sling problem by
trying to flow air though the ball bearing and dispersing lubricant into the environment like a fan.
The bearing lubricant fill amount needs to be controlled in order to lessen the problems mentioned earlier.
There must be enough lubricant to keep the ball retainer wetted as well as free lube in the races to prevent
metal-to-metal contact. However, care should be taken to ensure that there is no excess lubricant, which
would accelerate sling and migration problems. The correct fill is usually obtained empirically.
The major advantage of HCAB is that it does not need lubricants other than air. All materials used in the
HCAB are either non-outgassing or low outgassing, therefore no materials get expelled that can harm optics
or other surfaces in the system.
Ball bearings support a rotor by rolling element contact with the bearing races. Errors in the geometry of balls
and raceways are transmitted to the unit housing and rotor as vibration, noise, and displacement. These
errors result in ‘ball pass frequencies’. When a ball runs over a disparity, it creates a displacement. This is
usually cyclical because the same disparity is encountered again and again; hence, the term ‘ball pass
frequency’. There are four resulting frequencies - fundamental train, outer race, inner race, and ball defect.
These frequencies are approximately calculable and proportional to the rotational speed of the rotor. These
frequencies can excite optical mounts if the resonant frequencies are similar.
The HCAB aerodynamic bearing ‘floats’ on air and transmits only an unbalance vibration, once per revolution
frequency. This unbalance frequency is common among both the ball bearing and aerodynamic bearing.
Precision ball bearings are delicate and require additional protection during shipping and handling. These
bearings use a different raceway curvature than their standard grade counterparts. Standard grade bearings
are meant to carry more load. The raceway curvature matches the ball curvature closely. The larger contact
area results in higher load capability, but increased start and running torques. The increased torques are not
acceptable for precision applications that require ultra smooth rotation. Precision ball bearings have less
contact area, to reduce torque, leading to high susceptibility to impact damage. Heavy optics coupled with
shipping shock loads can easily brinell precision bearings. Therefore, softer and thicker than normal shipping
foam is required to reduce possible shock amplitudes to an acceptable level.
The aerodynamic bearing is impervious to impact damage within the range associated with shipping. The
large conforming surfaces transmit shock without causing stress risers such as a ball on its raceway.
Balance disturbance, although rare, is the most common failure due to mishandling of aerodynamic units
during shipping.
3. DESIGN PARAMETERS
There were two designs investigated for the HCAB – the first one did not include an encoder, while the
second included an encoder. The design parameters for the first version of HCAB were: aerodynamic,
capable of spinning a 6” diameter by 1” thick mirror, bearing stability up to 25krpm, bi-directional, retrofitable
for pre-existing ball bearing units, impervious to airborne contamination, capable of horizontal and vertical
operation, and have a life of at least 20k start-stop cycles. The second version was designed with same
parameters, but in addition, it included encoder capabilities.
3. Figure 1: Motor polygon assembly (MPA) cut-away view.
4. DESIGN
There are several commonly used aerodynamic bearing configurations: cylindrical, biconic, cylindrical with
thrust, and spherical with thrust. For cost concerns and ease of manufacturing, a cylindrical bearing (fig 1)
was chosen.
The cylindrical air bearing design does not inherently provide axial support due to lack of a thrust bearing, so
a magnetic axial support system is employed. The polygon rotor is levitated by the interaction of a
stationary, high energy, permanent magnet situated in the housing and a ferrous coupling band on the rotor.
The geometries are chosen to maximize the axial stiffness and minimize any radial pull. Radial pull will side-
load the bearing and cause premature failure due to sleeve contact. The cylindrical bearing design is ideal for
polygon mirror applications since axial mirror position is not critical.
For stabilization of the bearing we chose the patented Lincoln Laser Speed Bump design. The speed bump
consists of an eccentric grind on the center surface of the bearing support shaft (fig 2). This creates a ‘wedge
effect’ that is used to preload, or slightly offset, the spin axis from the center of the support shaft. Without the
speed bump, the bearing will become unstable as the rotational speed increases.
Figure 2: Stationary shaft showing speed bump.
4. If we look at the air gap of the bearing as a flat surface, it can be modeled as parallel plates (fig 3).
Figure 3: Sheared fluid between parallel plates.
If the clearance between the plates remains constant, there is no pressure generation to support the bearing.
The shearing of the fluid is generated solely by the velocity gradient and no other forces are at work to
change the profile from one end to the other1
. Hence, no internal pressures are created. The clearance
needs to be varied to create a pressure wedge action.
Figure 4: Sheared fluid between wedged plates.
By ‘squeezing’ the air through a wedged area, a film pressure is produced (fig 4). It is this pressure that is
used to create bearing stability.
In a plain cylindrical bearing with no stabilization attribute, a wedge is inherently created as the rotor becomes
eccentric to the support shaft (fig 5). The pressure profile that is created forces the rotor back to the center.
However, because of the momentum built up in the rotor, it over travels center. This will lead to dynamic
instabilities as rotational speeds increase. This situation is much akin to a ball bearing system that has no
preload. A stabilization system is needed for high stiffness and stability.
5. Figure 5: Cylindrical journal bearing offset to create a wedge.
As the bearing becomes unstable, it tends to result in a ‘coning’ action of the rotor. Coning is described as
the deviation of the rotor’s principal axis rotating about the true rotational axis, as defined by the support shaft
(fig 6). A coning rotor will look similar to a dynamically unbalanced rotor, but with a much more severe and
lower frequency compared to the rotational speed. The instability usually increases toward a whirl speed of
half the rotational speed of the rotor or ‘half speed whirl’. Coning is detectable by optical systems even at low
ratios of whirl to rotational frequencies. By the time the rotor encounters half speed whirl, the bearing is
already in the process of experiencing contact failure. A contact failure of the bearing will occur at the bottom
and top edge of the rotor due to the tilt. The failure occurs very quickly after the onset of coning because of
the forces and surface velocities involved.
Figure 6: Coning or whirl.
The speed bump stabilization system works by creating a physical wedge geometry, which in turn creates
inherent wedges on opposing side of the shaft due to the offset. The geometry of the speed bump area
creates a wedge as air is sheared over the land (fig 7). The speed bump land creates a high pressure area
causing the axis of rotation to shift in the radial direction (fig 8). The upper and lower sections of the
cylindrical bearing surfaces react like another wedge is occurring. In essence, the top and bottom surfaces
are preloaded against the land creating a very stable bearing.
6. Figure 7: Pressure profile caused by
speed bump land.
Figure 8: Rotor displacement caused by speed bump
and resulting pressure profiles
To be a possible replacement for ball bearing scanners, the HCAB must be capable of horizontal and vertical
spin axis orientations. The Lincoln Laser Company speed bump design lends itself very well to both
orientations and tilt attitudes between. The speed bump works well in the vertical position by preloading the
bearing in the radial direction. The same preloading is used to “float” the rotor in the horizontal position. The
wedge effect created by the speed bump is so effective that in some payload configurations, lower lift-off
numbers are seen in the horizontal position. This was unexpected because the weight of the rotor was
directly on the bearing surfaces instead of the magnetic axial support system.
One caveat of the horizontal (or off vertical) orientation is that the speed bump land must be facing up to
avoid high lift off numbers and eventual premature failure. The speed bump must work against gravity, not
with it, to float the bearing during starts and stops. Any off-vertical angular orientation can be chosen so long
as the speed bump land is on the upper side of the shaft (fig 9).
Figure 9: Support shaft showing correct orientation of speed bump.
The orientation of the speed bump cannot be seen in an assembled unit because it is inside the bearing. This
requires an attribute on the assembly, such as a window or cable exit, to be chosen to insert the support shaft
in a particular angular orientation. For example, if a unit is to be used horizontally in a cable up orientation,
the speed bump land will be aligned to the cable exit upon assembly. The relation is kept so that the final
orientation of the unit (assembly) is compatible for horizontal use.
Before physical prototypes where built, different speed bump designs were simulated and optimized to a few
choices using Lincoln Laser proprietary software. The simulations were conducted to ensure smooth
operation through the entire speed range of 4 – 25 krpm. The software is capable of running dynamic
simulations outputting rotor displacement, attitude, and pressure profiles. The displacement is displayed in
x,y,z coordinates and the attitude or tilt is displayed in radians. Bearing stiffness can be calculated from the
7. program’s output by varying the inputs of side load or unbalance. The change in rotor displacement can then
be plotted against the side load, or unbalance force, to obtain bearing stiffness.
Airborne contamination is a problem for aerodynamic bearings, especially since they do not have a
pressurized supply of clean air like aerostatic bearings. The Lincoln Laser speed bump stabilization system
does not cause flow of outside air through the bearing. It uses air that already exists in the gap making it less
susceptible to contamination. On prior aerodynamic bearings of similar configuration, experiments were
conducted with powdered substances to simulate contamination conditions. No bearing failures resulted from
these experiments. It appeared that the small air gap coupled with the shearing forces repels common
contaminants such as printer toner, baby powder and chalk. Pumping-style stabilization systems such as
grooved herring bone, double chevron and some thrust bearings are susceptible to contamination. Care must
be taken with these systems by providing a clean environment or adding a filtering media to the intake side of
the bearing.
Tribology is of major concern to aerodynamic bearings. The only lubricant that is used is air molecules.
Common wearing materials are: ceramic on ceramic, stainless steel on ceramic, nickel plate on hard anodize
and tool steel on tool steel. Lincoln Laser has had the best results with a stainless steel sleeve rotor on a
stationary ceramic post. However, initial simulations showed that increasing the bearing surface area was not
able to overcome the increase in rotor weight thereby leading to instability or severely decreased load
capacity. This demonstrated the need for a different material dynamic to create a lighter weight rotor.
Initially, ceramic was considered a good choice since it was less than half the density of steel. It was decided
to reverse the materials of the two wearing surfaces. However, cost concerns arose at the aspect of
machining complex rotor shapes from ceramic. At the same time, a very robust ceramic coating was
developed and applied to the inside wearing surface of the rotor. This allowed the rotor to be changed to
aluminum for ease of machinability and weight reduction. The support shaft was changed to stainless steel
from solid ceramic further reducing cost and increasing manufacturability. The ceramic coating on the inside
of the aluminum rotor and the stainless steel shaft retained the same tried and true tribology and allowed a
much larger payload than expected.
It was decided to use an external motor supplier to produce a brushless direct current motor capable of the
speed and torque required to overcome the windage of the optic.
The first iteration motor tested was supposed to perform the function of drive motor and magnetic axial
support of the rotor. It was discovered that the high strength magnet required for axial support compromised
the upper speed due to magnetic viscous losses and high back emf. More notably, the increased axial
support resulted in proportionately higher unwanted radial pull. This resulted in high liftoff speeds and short
bearing life. The usual methods of centering the motor stator did not help. Small differences in the strength
of the individual magnet segments could not be easily corrected.
The second iteration motor was designed only for rotational power. Axial support was provided by the axial
support magnet and ring mentioned before. With the axial support taken care of, the magnetic coupling of the
motor magnet and stator were decreased significantly. Thus allowing higher speeds and longer bearing life
due to reduced side pull.
5. DESIGN VARIATION WITH ENCODER
A second variation of the HCAB was designed with an internal optical encoder. Cylindrical air bearings are
difficult to pair up with an optical encoder because of the axial movement of the rotor. Most optical encoders
consist of a light source and read head that straddles a transparent disk with printed or etched lines. The
internal clearances are usually very small, on the order of thousandths of an inch. This is too small for the
axial displacements seen with shipping impacts or even axial flutter while the unit is in operation.
8. The encoder chosen was a newly developed large gap reflective optical encoder. This allowed a stop to be
used in only one axial direction of the rotor and facilitated easy assembly. The one sided nature of the
reflective encoder allowed the rotor to be inserted or removed without disassembly of the encoder. The
straddling style encoder needed rotor stops in both directions and needed to be removed if the rotor was to be
pulled out of the housing. Also, the encoder position would have to be reset upon re-assembly. The large
gap of the reflective encoder tolerated considerable amounts of axial flutter with little error in position
reporting. Rotor position to encoder signal error was typically under 3 arc seconds.
The modular nature of the encoder required that the grating disk be manually centered at Lincoln Laser
Company. A special fixture incorporating a static air bearing spindle was used to support the HCAB rotor for
rotation while the disk was centered with an optical scope. After centering, the disk was affixed with a special
adhesive. Radial run out of the grating track can be controlled to .0002 inches in this manner for high
accuracy.
6. TESTING
An air bearing does not experience any wear when operating above its lift-off speed. The shearing action of
air in the gap is not enough to cause erosion of bearing materials. Theoretically, an air bearing can run
forever. However, an aerodynamic bearing has a weakness much like an airplane wing; it needs a certain
velocity to lift-off. When the bearing is at rest there is physical contact between the wearing materials. After
powering up a unit, a sliding contact continues until the lift-off speed is reached. At this point the rotor should
remain airborne through its entire speed range until it is powered off and slows back down to the lift off speed
and begins a sliding contact again to a stop. Therefore, starting and stopping is the only time that the bearing
experiences wear.
Why not continually run the MPA? Typically, in optical systems, there are power requirements necessitating
certain duty cycles and foremost, dusty environments cause impingement (sand blasting) on the optical facet.
A sealed, glass windowed MPA housing can alleviate the sand blasting, but it creates heating induced
balance and wobble problems at higher speeds.
The life span of aerodynamic air bearings is measured in hours of run time and number of start-stop cycles.
As stated before, the run time affects the optic more than the bearing and is dependent on the environment it
is used in. The key performance attribute is designing a bearing that survives thousands of start-stop cycles.
The prototype HCAB bearings were placed on an automatic cycling machine that brought the units up to an
appropriate speed, powered off and allowed to coast to a stop, then restarted and so on. This was done in
blocks of 10,000 cycles. All prototype bearings passed a 30k cycle limit for testing but not all bearings were
brought to failure due to time constraints. However, early prototypes allowed to run typically failed in the
100k+ cycle range; well beyond the 20k start stop cycle life requirement.
The stiffness of the bearing was theoretically calculated using Lincoln Laser Company bearing design
software. Unbalance was added statically and dynamically to the rotor (fig 10). The static unbalance was
used to calculate the radial stiffness and the dynamic unbalance was used to calculate tilt stiffness. Axial
stiffness was provided by the magnetic axial support and was not as important for polygon scanning. Hence,
axial stiffness was not controlled by the bearing and was not a consideration in the air bearing software.
When the rotor assembly dynamics were simulated, a displacement or eccentricity was seen with the
unbalance. The unbalance contributes a force to the rotor and can be calculated from the mass and angular
speed of the rotor. The force of the static simulation is divided by the distance (eccentricity) to obtain the
radial stiffness. The torque of the dynamic simulation is divided by the angular displacement of the rotor to
obtain tilt stiffness. The stiffness was found to be 0.26 lb/µin in the radial direction and 0.51 lb·in/µrad in the
tilt direction.
9. Figure 10: Static and dynamic unbalance.
Axial stiffness is provided by the magnetic axial support system. This is much ‘softer’ than the bearing
stiffness. Axial position sensitive systems, such as drum scanning, can not be accomplished with this
arrangement. Because of the soft system, ‘sag’ of the optical unit can be seen with gravity. ‘Sag’ refers to
the change in waterline height of the optic due to gravity and must be accounted for when designing a unit.
The axial stiffness was empirically found to be 66 lbs/in with a break away force of 5 lbs.
Windage refers to the amount of torque that is required to spin the polygon rotor assembly against
aerodynamic forces wherein motor is the limiting speed factor. The bearing is stable with all payload
configurations, but the motor/controller combination does not have enough power to make 25krpm with all
configurations. Since windage is the major cause of power consumption, it is also the largest contributor of
heating. More torque could be supplied by a different controller, but heating becomes a concern. For
example: an eight faceted 5.5” diameter, 0.60” thick mirror at 18 krpm requires 16.9 oz·in of torque. This
equates to 225 watts. If the unit requires a glass window, the heat is contained and a substantial temperature
rise of the unit will occur, again, leading to balance and track problems.
7. CONCLUSION
The HCAB development process has resulted in a precision rotary solution that eliminated many of the
problems associated with traditional ball bearing scanners. In addition, HCAB provides many advantages of
an aerostatic air bearing without requiring any additional equipment.
8. REFERENCES
1. Bernard J. Hamrock, Fundamentals of Fluid Film Lubrication, McGraw Hill, 1994