Screwjack effects of wear on thread stripping load

Purpose of calculation:
Calculate thread stripping load on ACME leadscrew
Determine effects of wear on thread stripping load.
This calculation is featured as a case study.

Calculation Validation
Check against manufacturers recommendations

Select Acme Leadscrew thread Size (dia. - threads per inch)

1. Leadscrew Dimensions
   Outside diameter of thread
   Thread Pitch
   Inside diameter of thread
   Manufacterer's (Roton) Static Load Rating
   Manufacterer's (Roton) Operating Load Rating
   Thread angle
   Shear thickness per thread
   
   
2. Estimate wear allowance
   Maximum clearance and wear allowed
   Nut/collar thickness
   Shear Area
   
   
3. Nut material properties and nut shear strength calculation
   Calculated operating load
   Correlation between calculated and manufacturers value
   
   
4. Calculate normal loading with maximum allowable load nut wear
   Force on leadscrew
   Operating load
   
   
5. Calculate wear for nut thread stripping
   Critical Clearance/Wear Limit for nut stripping
   Amount of wear for nut stripping
   
   
6. Estimate Wear
   Bearing stress
   Rubbing Distance
   Surface Hardness (Brinell Hardness in kg/mm2 convered to psi)
   Wear Coefficients from ExcelCalcs Repository
   Unlubricated wear depth in 6 months - Ref. Juvinall Eqn. (9.1)
   Time to unlubricated load nut failure
   Lubricated wear depth in 6 months
   Time to lubricated load nut failure

   Calculation Reference
   Fundamentals Of Machine Component Design - Juvinall
   

Machinery's Handbook

Mechanical Engineers' Handbook

Schaum's Outline - Machine Design