325-tut-6-bushings

325-tut-6-bushings - MECH 325 Machine Elements Tutorial 6...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: MECH 325 Machine Elements Tutorial 6 – Bushings 1. Adapted from Shigley, Problem 12‐22 (8 and 9th Eds.) th An Oiles SP 500 alloy brass bushing is 1 in long with a 1‐in bore and operates in a clean environment at 70°F. The allowable wear without loss of function is 0.005 in. The radial load is 500 lbf. The shaft speed is 200 rev/min. Part 1: To be demonstrated by the TA a. Estimate the number of revolutions for radial wear to be 0.005 in. Part 2: To be done by the class b. Estimate the wear expected for 1 million revolutions if the speed is reduced to 80 rev/min, the load is increased to 800 lbf, and the material is changed to Oiles SP 800. 2. Adapted from Shigley, Problem 12‐23 (8th and 9th Eds.) A cast bronze bushing is to give a maximum wear of 0.002 in for 1000h of use with a 125 rev/min journal and 100 lbf radial load. The maximum permissible lubricant temperature is Tmax = 300°F and ambient temperature is T∞ = 70°F. The overall coefficient of heat transfer is ћCR = 2.7 Btu/(h∙ft2∙°F). The coefficient of sliding friction is fs = 0.03. There is to be a design safety factor of nd = 2. Assume that available bushing sizes are given by the entries with “●” in the table below. The environment is clean. L ID ½” ⅝” ¾” ⅞” 1 ” 1¼” 1½” 1¾” 2 ” ½” ● ● ● ● ● ⅝” ● ● ● ● ¾” ● ● ● ● ⅞” ● ● ● 1” ● ● ● ● ● ● 1¼” ● ● ● ● ● 1½” ● ● ● ● ● 1¾” ● ● ● ● 2” ● ● Part 1: To be demonstrated by the TA a. Using starting values for f1 and f2 of unity, find the required bushing length. Part 2: To be done by the class b. Use the result from part a. to refine the computation and see if there is a better choice of bushing. (Hints: the approximations f1 = f2 = 1.0 are likely not valid; the value of D is not fixed at this point.) MECH 325 Additional Information Tutorial 6: Bushings ...
View Full Document

Ask a homework question - tutors are online