Ahelical compression spring is to be made of oil-tempered wire of 4-mm diameter with a spring index of c = 10. the spring is to operate inside a hole, so buckling is not a problem and the ends can be left plain. the free length of the spring should be 80 mm. a force of 50 n should deflect the spring 15 mm. determine the spring rate. determine the minimum hole diameter for the spring to operate in. determine the total number of coils needed. determine the solid length. determine a static factor of safety based on the yielding of the spring if it is compressed to its solid length.

Ashielded metal arc-welding operation is accomplished in a work cell by a fitter and a welder. the fitter takes 5.5 min to load components into the welding fixture at the beginning of the work cycle, and 1.5 min to unload the completed weldment at the end of the cycle. the total ength of the weld seams 1200 mm, and the travel speed used by the welder averages 300 mm/min. every 600 mm of seam length, the welding stick must be changed, which takes 0.8 min. while the fitter is working, the welder is idle (resting): and while the welder is working the fitter is idle. (a) determine the average arc-on time as a fraction of the work cycle time. (b) how much improvement in arc-on time would result if the welder used flux-cored arc welding (manually operated), given that the spool of weld wire must be changed every 10 weldments, and it takes the welder 5.0 min to accomplish the change? (c) what are the production rates for these two cases (weldments completed per hour)? attach your work and solutions.