What is Motion Study
Motion study is the systematic analysis of the movements an operator makes while performing a task, with the goal of eliminating unnecessary movements and improving the method. It is one of the two pillars of method study, alongside time study. Motion study was developed by Frank and Lillian Gilbreth and is the foundation of modern work design.
Why Motion Study Matters
Every unnecessary movement wastes time and creates fatigue. A sewing operator who reaches 20 times per piece for thread can save 3 seconds per piece just by moving the thread cone closer. Over 1000 pieces per day, that is 50 minutes saved. Motion study finds these opportunities without any capital investment.
The 18 Therbligs
Gilbreth identified 18 basic motions called therbligs, such as search, find, select, grasp, hold, transport, position, assemble, and inspect. Effective therbligs add value. Ineffective ones are waste. Motion study reduces ineffective therbligs.
Practical Example 1 — Sewing Station
Observation: operator reaches 30 cm for thread, 20 cm for scissors, and 15 cm for the next bundle. All three reach distances can be cut in half by rearranging the workstation. Saving: 4 seconds per cycle, 10 percent efficiency gain.
Practical Example 2 — Cutting Table
Observation: cutter walks around the table to change the marker. After motion study, the table is rotated so the marker is accessible from one side. Walking time drops by 15 minutes per day.
Practical Example 3 — Finishing Iron
Observation: operator lifts the garment twice before ironing. By changing the layout to a slide, one lift is removed. Saving: 2 seconds per piece, 8000 pieces per month, 4.5 hours saved.
Practical Example 4 — Office Clerk
Observation: clerk reaches for a stapler across the desk 40 times per day. Moving the stapler closer saves 20 minutes per day.
Principles of Motion Economy
Both hands should start and end together. Both hands should not be idle at the same time. Motion should be smooth and continuous, not zigzag. Use the lowest classification of motion. Use gravity instead of muscle. Keep tools and materials within easy reach.
How to Conduct a Motion Study
Observe the operation. Film it with a smartphone. Watch the film frame by frame. List all motions. Classify each as effective or ineffective. Propose a better method. Implement and measure the improvement. Update the SOP.
Common Mistakes
Watching from a distance without filming. Watching only the fastest operator. Skipping the operator's own ideas. Changing the method without training. Not updating the SOP after the change. Not measuring the improvement.
When to Use It
Motion study is used for high-volume, repetitive operations. It is especially useful for sewing, finishing, packing, cutting, and any workstation where small improvements multiply over thousands of pieces.