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Bushing Pressure
Bushing Pressure
What is Pressure?
Pressure, the force exerted from top to bottom, is the English letter code with a capital letter P, the full name is Pressure, so it can be interpreted as the force on the surface of an object in a unit area or a unit area or contact area, and the direction of the force is perpendicular to the surface.
Basic formula
Pressure = force/area. Pressure = Force / Area。 P=F/A
The force F in the formula does not only come from an external force exerted on the object, it can be the weight of the object itself, or both exist at the same time, so they are called loads.
- For the same area, the larger the load, the greater the pressure;
Conversely, the smaller the load, the less stress.
- For the same load, the smaller the area, the greater the pressure; Conversely, the larger the area, the less pressure there is.
Calculation example
A book weighs 5 kg and is 10 cm long and wide, put it on a table, and apply 20 kg of force to the book with one hand, what is the pressure on the table?
Answer:
F = 5 kg + 20 kg
= 25 kg
A = 10*10
= 100 cm2
P = F/A
= 25/100
= 0.25 kg/cm2
Examples of everyday life
- Small area, high pressure: knocking nails on wooden boards, needles for hospital injections, utility knives to cut paper, and feet to Lego.
- Large area and low pressure: People lie flat on the sea surface, cars drive in the snow to deflate tires, and traditional pencils become lighter and weaker.
- High load and pressure: The shoes of obese people are easy to break, and the truck is too heavy and the tires sink.
unit
Only commonly used pressure units are listed
| MPa | N/cm2 | N/m2 | kg/mm2 | kg/cm2 | kg/m2 | psi | |
|---|---|---|---|---|---|---|---|
| 1 MPa | 1 N/mm2 | 1×102 N/cm2 | 1×106 N/m2 | 1.02 ×10-1 kg/mm2 | 1.02 ×101 kg/cm2 | 1.02 ×105 kg/m2 | 1.45×102 psi |
| 1 N/cm2 | 1×10-2 Mpa | 1 N/cm2 | 1×104 N/m2 | 1.02 ×10-3 kg/mm2 | 1.02 ×10-1 kg/cm2 | 1.02 ×103 kg/m2 | 1.45 psi |
| 1 N/m2 | 1×10-6 Mpa | 1×10-4 N/m2 | 1 N/m2 | 1.02 ×10-7 kg/mm2 | 1.02 ×10-5 kg/cm2 | 1.02 ×10-1 kg/m2 | 1.45×10-4 psi |
| 1 kg/mm2 | 9.8 Mpa | 9.8×102 N/cm2 | 9.8×106 N/m2 | 1 kg/mm2 | 1×102 kg/cm2 | 1×106 kg/m2 | 1.422×103 psi |
| 1 kg/cm2 | 9.8×10-2 Mpa | 9.8 N/cm2 | 9.8×104 N/m2 | 1×10-2 kg/mm2 | 1 kg/cm2 | 1×104 kg/m2 | 1.422×101 psi |
| 1 kg/m2 | 9.8×10-6 Mpa | 9.8×10-4 N/cm2 | 9.8 N/m2 | 1×10-6 kg/mm2 | 1×10-4 kg/cm2 | 1 kg/m2 | 1.422×10-3 psi |
| 1 psi | 0.00689 Mpa | 0.689 N/cm2 | 6890 N/m2 | 7.03 ×10-4 kg/mm2 | 7.03 ×10-2 kg/cm2 | 703 kg/m2 | 1 lb/in2 |
Bushing pressure calculation
Although its appearance is circular, the projection area is calculated by diameter d multiplied by high h, similar to the concept of long L multiplied by wide W.
- Rotational motion, rocking motion, reciprocating motion, lining pressure formula P = F / dh
- Thrust washer, lining pressure formula P = 4F / [π(D)2-(d)2]
P is the pressure, in kg/mm2.
F is the load, in kg.
d is the inner diameter, in mm.
D is the outer diameter, in mm.
h is the height, in mm.
π is 3.14159.
Category – lining pressure calculation
Bushings
Radial pressure
Axial pressure
Flange Bushing
Radial pressure
Axial pressure
Washer
Axial pressure
What are the effects of pressure?
The pressure of the bushing will directly affect the life, whether it is reciprocating motion or rotational motion, it will generate heat due to friction, the larger the load, the greater the pressure, and the higher the operating temperature. Pressure and velocity will also cause temperature to rise, but the effect of pressure is smaller. In addition, when the pressure exceeds the pressure that the material can withstand, it will collapse immediately.
Applications
If the bushing is applied to the position of the rotating node, because there is little or little reciprocating and rotational action, so there is no consideration of temperature rise, then we only need to consider whether the bushing is sufficient to withstand the load, and the design elasticity is large in terms of evaluation.
How to improve when the pressure on the bushing is too high?
When the bushing pressure is too high, what can we do to improve it?
- Increase height (length).
- Increase the inner diameter.
- Change to a more high-temperature resistant material.
- Changed to a material with high pressure resistance.
- Change the mode of operation.
- Increase the support of the bushing.
Pressure or speed, the two affect the temperature rise, the improvement method is basically the same, but the speed accounts for more than the pressure, so the improvement of high pressure will be biased towards the load aspect, and the improvement of high speed will be biased towards the surface contact and environment.
Related online tools
We provide online calculation of theoretical values, only need to fill in a few dimensions, please click the link below
