4.2 A robot performs a loading and unloading operation for a machine tool. The work cycle consists of the following sequence of activities: Seq. Activity Time Robot reaches and picks part 5.0 sec from incoming conveyor and loads into fixture on machine tool. Machining cycle (automatic) 30.0 sec N 4.5 sec 3 Robot reaches in, retrieves part from machine tool, and deposits it onto outgoing conveyor. Move back to pickup position 1.5 sec The activities are performed sequentially as listed. Every 20 work parts, the cutting tools in the machine must be changed. This irregular cycle takes 20 min to accomplish. The uptime efficiency of the robot is 96%, and the uptime efficiency of the machine tool is 97%, not including interruptions for tool changes. These two efficiencies are assumed not to overlap (i.e., if the robot breaks down, the cell will cease to operate, so the machine tool will not have the opportunity to break down, and vice versa). Downtime results from electrical and mechanical malfunctions of the robot, machine tool, and fixture. Determine the hourly production rate, taking into account the lost time due to tool changes and the uptime efficiency. (6)