ISE 311: Ergonomics & Work Measurement

Time Study / Learning Curve Experiment

(Due Friday, April 24, 2009)

Purpose:

  1. To gain practical experience in the design and development of a time study.
  2. To assess worker exposure to job risk factors of posture, force, muscle use, and repetitive movement.

Equipment: Ergonomic Workstation

8 Flashlights

Stopwatch

Overhead transparency markers

Procedure

Part A: Workstation Set-up

  1. Use the improved workstation layout you developed in the RULA portion of the Work Evaluation Labor develop an improved workstation design for the assembly of flashlights. Arrange the flashlight parts according to your design. Note: your design must assume that all parts arrive at the station as given (e.g., no one is pre-assembling any of the parts before they arrive at the station).
  1. Select one person to perform the task of assembling the flashlight, a second to time the task elements, and the third to time the entire task (as a check).
  1. Perform a methods analysis and record the prescribed work method for the task. Break the task into appropriate elements for the time study. Have the assembler practice the prescribed method once or twice and ensure that your elements are appropriate (i.e., that the elements timer is able to time each one). Record the elements on the time study sheet.
  1. The assembler should assemble the flashlights, one at a time, while being timed. The elements timer will record the element times on the time study sheet. The total task timer will record the total times on a separate sheet. The assemblerwill need to assemble the complete set of flashlights twice (for a total of 16 repetitions) in order for the observed times to generate a reasonable learning curve approximation.

Results

  1. Calculate the average and standard deviation of the time required to perform each element and the overall task. Show these in a table in the body of the report.Include your time study data in an appendix.
  1. Apply a rating to the pace of the assembler. Based on this rating, calculate a normal time for the assembly task.
  1. Calculate a learning curve for assembling the flashlights. Estimate how long it should take to assemble 100 flashlights using this layout. Include your calculations in the appendix.
  1. Calculate how many observations would be required in order to be 95% confident that the observed time it takes to perform the task is within +10% relative accuracy of the actual time.
  1. Be sure to include a sketch of your layout in the body of your report (including dimensions).

Conclusions

  1. Summarize the results of your time study and recommend a normal time for the assembly task based on the learning curve you calculated.
  1. Discuss any insights you have gained from this lab with respect to time study. Your discussion should include a brief discussion of your level of confidence in the task time you determined (i.e., would you recommend that a “real” flashlight assembly line use your normal time to set productivity levels?)
  1. Discuss the real usefulness of stopwatch time studies in industry. What benefits do they provide to engineers and management in determining capacity, productivity levels, compensation schemes, etc.? How can they be used in the evaluation of new tasks, task designs, etc.?
  1. Keep one copy of the report for each member of the group (they will need the data and layout sketch for the next homework assignment.)