Tutorial $5$: Motion Study and work designs

$[36$ marks$]$

$5\mathrm{.}1.$ The worker reached for the small part a short distance away in the workplace, picked up the part, and placed it in a vise. The worker then rotated the screw handle of the vise three turns to hold the part between the vise jaws. In rotating the screw handle, he had to grasp and regrasp the handle six times due to the limited rotation ability of his own wrist. On the final turn, he applied additional torque to tighten the vise. Write a list of the Therbligs that comprise this motion sequence and label each basic motion with a brief description.

$5\mathrm{.}2.$ Suggest improvements to the method in $5\mathrm{.}1.,$ indicating the nature of the improvement that might result.

$5\mathrm{.}3.$ An assembly worker is performing a repetitive manual task consisting of inserting $8$ plastic pegs into $8$ holes in a flat wooden board. A slight interference fit is involved in each insertion. Each work cycle consists of her picking up a board from the stack of boards located on the left side of the worktable $($about $40$ cm away from center, where they are placed by a material handling worker$),$ performing the $8$ insertions, and then placing the assembled board into a rack that is next to the starting stack. Her first step in the work cycle is to reach for the top board in the stack with her right hand, pick it up$,$ and exchange it to the left hand. While holding the board in her left hand, she picks up the pegs from a tray about $10$ inches away in front of her with her right hand and inserts them into the holes in the board, one peg at a time. The rack holding the completed boards has a capacity of six assemblies. When the rack is full, the worker gets up from her worktable, picks up the loaded rack, carries it to a pallet located on the floor three feet away from the workplace, and places it onto the pallet. The pallet only holds four racks on one layer. A material handling worker riding in a forklift truck must periodically take the pallet away and replace it with an empty pallet. Because of delays by the material handling worker, the assembly worker is occasionally forced to stop working and wait for the pallet exchange to occur.

$5\mathrm{.}3\mathrm{.}1.$ Identify some of the principles of motion economy that are violated in this work cycle.

$5\mathrm{.}3\mathrm{.}2.$ What recommendations for improvement would you make?