Press Fit Engineering and Design Calculator

Torque Engineering and Design
Strength of Materials

Press Fit Engineering and Design Equations (See Below)

Use this engineering calculator to determine engineering and design parameters for cylindrical press fit applications.

 

  Enter numbers at BOLD Text Locations, Results in RED  
  Loads Interference Parameters Equations Ref  
  Torque to be transmitted (N-mm) torque Minimum required interface pressure (N/mm2) rPI    
  Axial force to be transmitted (N) force Differential Poisson radial interference due to axial force (mm) ddp 1  
  Coefficient of friction mu Differential thermal radial expansion (mm) ted 2  
  Operating temperature (oC)  ot Outer body rotating inner diameter radial displacement (mm) robd 3  
  Stress concentration factor at interface edge scf Inner body rotating outer diameter radial displacement (mm) ribd 4  
  Rotation speed (rpm) rpm Total additional diametrical interference amount to be added (to ibod) (mm) addi    
  Outer body input parameters Interference Fit Calculations (Assumes addi has been added to ibod)    
  Outside diameter (mm) obod Maximum diametrical interference (mm) maxdelta  (See diagrams)  
  Interface diameter (mm) obid Maximum resulting interface pressure (N/mm2) maxip 5  
  Plus tolerance (mm) obptol Minimum diametrical interference (mm) mindelta  (See diagrams)  
  Minus tolerance (mm) obmtol Minimum resulting interface pressure (N/mm2) minip 5  
  Modulus of elasticity (N/mm2) obe Minimum safety margin (min obtained pressure/required pressure)      
  Yield strength (N/mm2) obsy Maximum sustainable torque (N-mm) maxt    
  Poisson's ratio obn Minimum sustainable Torque (N-mm) mint    
  Coefficient of thermal expansion (1/oC) obcte Minimum safety margin (min obtained torque/required torque)      
  Density (g/cm3) obrho Outer body material stresses at maximum interface pressure    
  Inner body input parameters Radial displacement of inner surface (mm)   6  
  Engagement length (mm) L Radial press-fit stress at ID (N/mm2) obsr 7  
  Intended outside diameter (mm) ibod Circumferential press-fit stress at ID (N/mm2) obsc 8  
  Dimensioned outside diameter (mm)   Axial stress from applied axial Force (N/mm2) obsz 9  
  Plus tolerance (mm) ibptol Shear stress from applied Torque (N/mm2) obtau 10  
  Minus tolerance (mm) ibmtol Max radial centrifugal stress (N/mm2) obrc    
  Inside diameter (mm) ibid Max circumferential centrifugal stress (N/mm2) obcc 11  
  Modulus of elasticity (N/mm2) ibe Max Von Mises stress (N/mm2) obvm 12  
  Yield strength, obsy (N/mm2) ibsy Resulting safety factor (Yield stress)/(scf*Von Mises stress)      
  Poisson's ratio ibn Inner body material stresses at maximum interface pressure    
  Coefficient of thermal expansion (1/oC) ibcte Radial displacement of outer surface (mm)   13  
  Density (g/cm3) ibrho Radial press-fit stress (N/mm2) ibsr 14  
  Shrink-fit design Circumferential press-fit stress (N/mm2) ibsc 15  
  Desired assembly clearance at deltaT (mm) ddt Axial stress from applied axial Force (N/mm2) ibsz 16  
  Required differential temperature if heating outer body (oC) robdt Shear stress from applied Torque (N/mm2) ibtau 17  
  Required differential temperature if cooling inner body (oC) ribdt Max radial centrifugal stress (N/mm2) ibrc    
  Press-fit design Max circumferential centrifugal stress at ID (N/mm2) ibcc 18  
  Maximum assembly force to press fit (N) Fpfmax Von Mises stress at ID (N/mm2) ibvm 19  
  Minimum assembly force to press fit (N) Fpfmin Resulting safety factor (Yield stress)/(scf*Von Mises stress)      
 
     
  Evaluate the stresses at inside, outside and sqrt(DiDo) diameters  
  For the Outer Feature  
  case 1: stresses at inner radius Case 2: stresses at outer radius Case 3: stresses sqrt(DiDo)/2  
  Radial press-fit stress (N/mm2)  
  Circumferential press-fit stress (N/mm2)  
  Axial stress from applied axial Force (N/mm2)  
  Shear stress from applied Torque (N/mm2)  
  Radial centrifugal stress (N/mm2)  
  Circumferential centrifugal stress at ID (N/mm2)  
  Von Mises stress at ID (N/mm2)  
  For the Inner Feature  
  case 1: stresses at inner radius Case 2: stresses at outer radius Case 3: stresses sqrt(DiDo)/2  
  Radial press-fit stress (N/mm2)  
  Circumferential press-fit stress (N/mm2)  
  Axial stress from applied axial Force (N/mm2)  
  Shear stress from applied Torque (N/mm2)  
  Radial centrifugal stress (N/mm2)  
  Circumferential centrifugal stress at ID (N/mm2)  
  Von Mises stress at ID (N/mm2)