Bushing Size Calculator
Estimate sleeve bushing ID, OD, press fit, installed running clearance, projected pressure, and fit status from shop dimensions and operating conditions.
Bushing size snapshot
| Material | Typical use | Base pressure | Temp limit | Clearance note |
|---|---|---|---|---|
| Oil-impregnated bronze | Small motors, fans, light shafts | 28 MPa | 120 C | Moderate clearance, good with oil |
| SAE 660 bronze | General pivots and machinery | 35 MPa | 230 C | Works well with grease grooves |
| PTFE-lined composite | Dry low-maintenance pivots | 25 MPa | 180 C | Use smoother shafts and light press |
| Acetal polymer | Light conveyor and clean equipment | 12 MPa | 90 C | Allow more thermal clearance |
| Nylon polymer | Low-cost idlers and guides | 9 MPa | 85 C | Moisture and heat can close clearance |
| PEEK polymer | Hot, chemical, precision applications | 22 MPa | 250 C | Stable for polymer, still needs clearance |
| Graphite plugged bronze | Hot or intermittent dry pivots | 32 MPa | 300 C | Often uses wider running clearance |
| Steel-backed bronze | Compact heavy-duty housings | 45 MPa | 180 C | Stiffer shell, less closure than solid bronze |
| Shaft size | Light oil clearance | Greased pivot clearance | Dry or hot clearance | Typical press fit |
|---|---|---|---|---|
| 6 to 12 mm | 0.015 to 0.035 mm | 0.025 to 0.050 mm | 0.040 to 0.075 mm | 0.02 to 0.05 mm |
| 12 to 25 mm | 0.025 to 0.055 mm | 0.040 to 0.085 mm | 0.070 to 0.130 mm | 0.04 to 0.08 mm |
| 25 to 50 mm | 0.045 to 0.090 mm | 0.070 to 0.140 mm | 0.120 to 0.220 mm | 0.06 to 0.12 mm |
| 50 to 100 mm | 0.080 to 0.160 mm | 0.120 to 0.250 mm | 0.200 to 0.380 mm | 0.10 to 0.20 mm |
| L/D ratio | Use case | Benefit | Watch item |
|---|---|---|---|
| 0.5 to 0.8 | Compact supports | Short package | Higher pressure and edge loading |
| 0.8 to 1.2 | General sleeve bearing | Balanced load and alignment | Good shaft support needed |
| 1.2 to 1.8 | Slow pivots and pins | Lower projected pressure | Can bind if bores are not aligned |
| 1.8 to 2.5 | Long guides | More bearing area | Sensitive to shaft straightness |
| Lubrication | Pressure factor | Clearance effect | Practical note |
|---|---|---|---|
| Oil film or oil feed | 1.00 | Can run tighter | Best for continuous rotation |
| Grease packed | 0.85 | Needs room for grease film | Common for pivots and pins |
| Dry or marginal | 0.55 | Needs extra clearance | Prefer PTFE, graphite, or dry-rated material |
| Water wash or wet | 0.65 | Check swelling and corrosion | Polymers and bronze need special review |
A sleeve bushing is a component that feature within a housing and features a shaft within it. The sleeve bushing allow for the shaft to move within the bushing. In order to understand the relationship between the shaft and the housings, it is necessary to understand the dimensions of the sleeve bushing.
The dimensions of the sleeve bushing will determine the amount of movement that the shaft has within the sleeve bushing, the grip that the sleeve bushing has on the bore of the shaft, and the strength of the sleeve bushing to allow for a certain load to be placed upon it by the shaft. The bushing size calculator will assist engineer in understanding these dimensions by taking the measurement of the system and presenting the potential trade-offs of the system design to the engineers. The first measurement of the system component that must be taken is the diameter of the shaft.
How to Choose the Right Sleeve Bushing Size
The diameter of the shaft will determine the other dimension of the sleeve bushing. To calculate the outer diameter of the sleeve bushing, the engineer will increase the calculated shaft diameter by the desired clearance for the system to run, and the outer diameter will be increased by twice the thickness of the walls of the sleeve bushing. A bushing size calculator will perform these calculation for the engineers, preventing the possibility of introducing mistake regarding the press fit of the shaft within the sleeve bushing.
A press fit will cause the inner diameter of the sleeve bushing to shrink; this is the result of the compression of the material of the sleeve bushing. A critical factor in determining the appropriate design of the system is the choice of material for the sleeve bushing. Bronze material can handle high level of pressure and temperature.
Bronze materials will expand less within the system than other materials, such polymer. Polymers will expand more rapid than bronze materials. This rapid expansion of the polymer will close the running clearance between the sleeve bushing and the shaft.
The bushing size calculator will allow engineers to alter the material used in the sleeve bushing. This alteration to the material will change the pressure limit and the thermal growth of the system. Another critical factor in the performance of the system is the running clearance between the sleeve bushing and the shaft.
The clearance between these components is a factor that will cause the machine to fail if the clearance is not set to the appropriate value. If the clearance between the shaft and sleeve bushing is too small, the sleeve bushing will seize within the housing as the temperature of the components increase. However, if the clearance is too large, the shaft will rock within the sleeve bushing.
The load on the sleeve bushing will become concentrated on the edge of the component. The bushing size calculator will allow engineers to input the desired starting clearance between the sleeve bushing and the shaft. The bushing size calculator will also calculate the operating clearance of the system after the press fit and the change in temperature is taken into consideration.
This operating clearance is the most important measurement of the system. Another factor that will have an impact on the performance of the system is the length to diameter ratio of the sleeve bushing. Short sleeve bushing will place the majority of the load on a small portion of the surface area of the bushing.
This can lead to edge loading of the sleeve bushing. On the other hand, long sleeve bushings will reduce the load placed on the bearing surface of the sleeve bushing. However, long sleeve bushings will become more sensitive to any misalignment between the shaft and the housing.
The bushing size calculator will utilize the length to diameter ratio that the engineer chooses for the sleeve bushing to calculate the length of the sleeve bushing and the projected area of the component. Using this projected area of the sleeve bushing, the bushing size calculator will calculate the projected pressure that the sleeve bushing will experience. This calculated pressure can be compared to the pressure limit of the sleeve bushing material to ensure that the pressure is within an acceptable range.
One more factor that will impact the performance of the system is the lubrication of the sleeve bushing. The lubrication of the sleeve bushing will alter the pressure limit of the sleeve bushing. For instance, oil will allow engineers to choose a smaller clearance between the sleeve bushing and the shaft and will allow for higher pressure within the system.
This is because oil will carry heat away from the components and will keep the two components apart. Grease will require engineers to choose a larger clearance within the sleeve bushing because grease require more room to properly form a film between the rotating components. Under dry or water-washed condition, engineers will have to choose a larger clearance within the sleeve bushing and will have to choose a sleeve bushing material that will allow the component to function with minimal lubrication.
The bushing size calculator includes a factor that can be used to alter the pressure limits of the sleeve bushing based on the lubrication that the engineer chooses for the system. The third final factor that will impact the performance of the system is the effect that the temperature will have on the clearance within the sleeve bushing. Both the shaft and the sleeve bushing will expand when the system reaches operating temperature.
The bushing size calculator can estimate the change in clearance that will result from the change in temperature of the components. This will allow the engineers to ensure that there is enough clearance for the shaft to allow for normal operation within the housing at operating temperature. If the operating temperature of the system is too high for the starting clearance that was chosen for the system, the engineers will have to change the starting clearance of the system or the material of the sleeve bushing to one that expands at the same rate as the steel shaft.
Many engineer will make mistakes when determining the dimensions of the sleeve bushing due to the assumption that the measurements of the machine as depicted on the engineering drawing are the actual measurement of the components. It is common for the diameter of the shaft to differ from the drawing due to plating or ground shafts. Additionally, the bore of the housing may be out of round or tapered.
While the bushing size calculator will not compensate for these difference, it will allow engineers to understand how sensitive the operating clearance is to changes in measurement. Engineers should measure the actual components before ordering the sleeve bushing; the actual measurements will be more accurate than the drawings. Tables are provided for engineers to input different shaft size and different lubrication condition to the system.
These tables are not stricture that engineers must follow. However, these tables will help engineers to avoid choosing a clearance between the sleeve bushing and the shaft that would be obviously incorrect. Based on the table and the parameter of the system, engineers can order a bushing of a certain size.
The bushing size calculator can help engineers test different variation of the system. The thickness of the walls of the sleeve bushing can be changed, the material used in the sleeve bushing can be changed, and the length of the sleeve bushing can be altered. These alteration to the system will change the operating clearance and the projected pressure within the sleeve bushing.
By rapidly altering these parameters, engineers can find the best sleeve bushing size for the system that they are engineering.
