High Precision Servo Motor Bearings Selection Guide-Precisely Match Your Application Scenarios
Selection should be based on motor parameters, operating conditions and performance requirements. Choosing the right one can keep the equipment running stably for several years, while choosing the wrong one may lead to frequent malfunctions and maintenance shutdowns. This article will provide a set of directly applicable selection methods to clarify the scenarios where mainstream bearing types are compatible, avoid common misconceptions, and help you precisely match the most suitable servo motor bearings.
1. Three-step selection method: Lock down the best solution layer by layer from parameters to requirements
The core logic of quality selection is "first define the constraints, then match the core requirements." The following three-step method can cover more than 90% of servo motor bearings selection scenarios, taking into account both science and practicality:
Step 1: Define the core parameters of the motor
The motor parameters directly determine the basic specifications of the bearings and are the starting point for selection. Two key indicators need to be confirmed with emphasis:
Motor power: Power is positively correlated with the load the bearing bears. For example, for small servo motors under 5.5kW, the load is smaller and regular-sized bearings can be selected; For medium to large servo motors above 11kW, choose bearings with a higher rated dynamic load (C value) to avoid shortened lifespan due to overload.
Rated speed: The speed is directly related to the critical speed design of the bearing. If the rated speed of the motor is ≥ 10,000 RPM, angular contact ball bearings or hybrid ceramic bearings should be preferred to ensure that the critical speed is 1.2 times higher than the actual speed; If the speed is less than or equal to 5000 revolutions per minute, deep groove ball bearings will meet the requirements and offer good value for money.
Supplementary note: It is necessary to confirm the motor shaft diameter, installation hole diameter and other size parameters
simultaneously to avoid the problem of "performance matching but installation not matching".
Step 2: Analyze the actual operating conditions
Operating conditions are the core factor affecting the stability and lifespan of bearings and need to be analyzed precisely in terms of load type and environmental conditions:
Load type: Determine whether the bearing is subjected to radial load, axial load, or combined load. Deep groove ball bearings are available for pure radial loads; For larger axial loads or combined loads, angular contact ball bearings (contact Angle 15/25/40。, larger contact Angle, stronger axial load-carrying capacity) should be selected; Tapered roller bearings are the best choice for heavy-load scenarios.
Ambient temperature and humidity: High-temperature environments require high-temperature bearing steel + high-temperature grease; In damp/dusty environments, priority should be given to IP65 grade or higher sealed bearings, or double-sealed structures to prevent water vapor and dust from entering.
Step 3: Match performance core requirements
Based on the parameters and conditions from the previous two steps, lock down the key performance indicators of the bearing to ensure a precise match with the equipment requirements:
Precision requirements: For general automated equipment, P5 grade precision is acceptable; Precision machining equipment requires P4 grade; For ultra-precision scenarios, P2 grade is required.
Sealing and lubrication requirements: For equipment that does not require frequent maintenance, pre-lubricated sealed bearings should be selected, with a maintenance-free period of over 2000 hours. For high-temperature and high-speed scenarios, open bearings that can be replenished with lubrication should be selected, along with regular maintenance with special grease.
Special requirements: Special attention should be paid to electrical corrosion resistance for servo motors in new energy vehicles; Aerospace equipment needs to emphasize low vibration noise; In harsh conditions, pollution and shock resistance should be enhanced.
2. Mainstream bearing type compatibility scenarios: Fit the right fit, quick selection
In combination with the above three-step method, the following three types of mainstream servo motor bearing fit scenarios can be directly referred to, helping you shorten the selection cycle:
1. Deep groove ball bearings: A cost-effective choice for general scenarios
Structural features: Simple structure, low coefficient of friction, capable of withstanding both radial and slight axial loads, easy
installation, and relatively low cost.
Core application scenarios: Suitable for general servo motors with motor power ≤7.5kW, speed ≤8000 RPM, medium load, such as automated conveyor lines, packaging machinery, small printers, ordinary machine tool feed motors, etc.
Recommended models: 60 series, 62 series, precision grade mostly P5, sealing type optional double-sided tape seal or open type.
2. Angular contact ball bearings: The core choice for high-speed, high-precision scenarios
Structural features: With contact angles (commonly 15。, 25。, 40。), capable of withstanding combined radial and axial loads, high precision grade (P4/P2 grade), excellent critical speed design, suitable for high-speed operation.
Core application scenarios: Suitable for high-precision equipment with motor power ranging from 5.5kW to 22kW and rotational speed ≥10000 RPM, such as CNC machine spindle motors, industrial robot joint motors, high-speed electric spindles, precision centrifuges, etc.
Recommended models: 70 series, 72 series, contact Angle 25 degree or 40 degree(25 for high speed and 40 degree for axial load), precision grade P4 and above.
3 Tapered roller bearings: A reliable choice for heavy-duty scenarios
Structural features: Tapered rolling elements and raceways design, extremely strong load-carrying capacity, capable of withstanding certain axial loads, suitable for low-speed, heavy-load conditions.
Core fit scenarios: Suitable for heavy equipment with motor power ≥ 15kW and load ≥30kN, such as large automated production line drive motors, mining machinery servo motors, printing machine main drive motors, automotive chassis servo systems, etc.
Recommended models: 302 series, 322 series, with precision grades mostly P5, require special grease to enhance wear resistance.
Iii. Guide to Avoiding Pitfalls in Selection: Avoid 4 Common Pitfalls to Reduce Decision-making Risks
In the actual selection process, many purchasers make mistakes due to ignoring key factors. The following four common mistakes need to be avoided:
Misconception 1: Only looking at the price, not the accuracy, and being greedy for cheapness and falling into traps
Harm: Choosing bearings with a precision grade lower than required to cut costs may lead to excessive positioning errors of the equipment. For example, replacing P4 grade with P5 grade in a CNC machine tool can reduce the qualification rate of processed parts by 10%-15% and increase the total cost instead.
The correct approach is to focus on the precision requirements of the equipment, prioritize matching precision grades, and then compare prices at the same precision, rather than simply pursuing low prices.
Misconception 2: Ignoring installation space limitations and choosing a larger model
Hazard: Without confirming the motor installation bore and shaft diameter size, blindly choosing a larger bearing with stronger
load-carrying capacity leads to inability to install or deformation of the bearing after forced installation, affecting operational stability.
Correct practice: Check the installation size parameters of the motor before selection, match the load and speed requirements within the
allowable space range, and choose thin-walled bearings if necessary.
Misconception 3: Blindly pursuing high speed while ignoring actual operating conditions
Harm: The use of angular contact ball bearings designed for high speed in ordinary scenarios not only increases procurement costs but also leads to higher maintenance costs due to higher lubrication requirements.
For general scenarios where the speed is ≤8000 revolutions per minute, deep groove ball bearings are preferred; Only consider angular contact ball bearings when the speed is ≥ 10,000 RPM to avoid excess performance.
Misconception 4: Ignoring the matching of lubrication and operating conditions leads to a significant reduction in lifespan
Harm: Using regular grease in high-temperature environments or open bearings in humid environments can lead to accelerated wear of the bearings, reducing their lifespan to less than 30% of the designed value.
Correct practice: Select the appropriate grease and seal type based on the ambient temperature and humidity, and ask the supplier for a
customized lubrication solution if necessary.
Conclusion: Select the right type and make the bearing the stable foundation of the equipment
The core of selecting bearings for servo motors is not to choose the most expensive ones, but to choose the most suitable ones. Through the three-step method of "defining motor parameters → analyzing operating conditions → matching performance requirements", combined with the
suitable scenarios of mainstream bearing types and avoiding common misunderstandings, efficient selection can be achieved, reducing
decision-making costs and operational risks.
