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The length of key calculation determines the required length of a mechanical key based on the applied force, key width, and allowable shear stress. This ensures the key can safely transmit torque without shearing failure.
The calculator uses the formula:
Where:
Explanation: The formula calculates the minimum key length required to prevent shear failure under the applied load, considering the key's width and material shear strength.
Details: Proper key length calculation is essential for mechanical design safety, ensuring power transmission components can handle operational loads without failure while maintaining efficiency and reliability.
Tips: Enter force in newtons, width in meters, and shear stress in pascals. All values must be positive and non-zero for accurate calculation.
Q1: What is a mechanical key used for?
A: Mechanical keys are used to prevent relative rotation between shafts and mounted components like gears, pulleys, and couplings, ensuring torque transmission.
Q2: How is force on key determined?
A: Force is calculated from transmitted torque divided by shaft radius: F = T/r, where T is torque and r is shaft radius.
Q3: What are typical shear stress values for key materials?
A: Shear stress values vary by material: mild steel (40-60 MPa), alloy steel (60-100 MPa), bronze (20-40 MPa). Always consult material specifications.
Q4: Are there safety factors to consider?
A: Yes, engineering practice typically applies safety factors of 2-4 to calculated lengths to account for dynamic loads, material variations, and manufacturing tolerances.
Q5: Can this formula be used for different key types?
A: This formula applies to rectangular/square parallel keys. Other key types (Woodruff, tapered, round) require different calculations due to varying stress distributions.