InsightFab
Knowledge Base/Motion Study: Therblig Analysis to Reduce Ineffective Motions
Lean Production6 min read

Motion Study: Therblig Analysis to Reduce Ineffective Motions

This article highlights how seemingly minor "ineffective motions" by operators can significantly impact product yield and efficiency, as seen when a factory's CPK plummeted due to a few extra seconds per material change. It introduces "Therblig Analysis" as a powerful method to systematically identify and eliminate these hidden inefficiencies, ultimately smoothing production lines.

That Day the CPK Report Came Out, and the Room Was Silent for Three Seconds

I still remember years ago, when our machine's Cpk report came out, it was terrible, only 1.08. In the meeting room, everyone was silent for three seconds, the air thick. The boss's gaze scanned us like an X-ray. At that time, our production line had switched to a new product, and we thought it was just a temporary period of yield fluctuation. However, it turned out the problem wasn't process parameters at all. After careful observation, we discovered that operators were always clumsy when changing materials. Each material change took an extra 30 seconds, and accumulated over a day, this extra time caused the DPMO to soar directly to 6210.

Where's the Problem?

Simply put, it's because there are too many "ineffective motions"! Think about it, in the factory, do we often see colleagues taking a long detour just to get a tool? Or bending down, standing up, then bending down again, like doing aerobics? These seemingly insignificant actions, accumulated over time, are the culprits behind your Cpk dropping and production bottlenecks. In a semiconductor factory, time is money; every second cannot be wasted.

At this point, an old classic method comes in handy, called "Therblig Analysis." You might think this is a strange name, sounds very academic, but frankly, it breaks down human motions into 18 basic elements. Just like we disassemble a product's BOM (Bill of Materials), it labels each motion with codes like "transport," "grasp," and "release." The goal is simple: to identify those motions that can be "optimized" or "eliminated."

In other words, it's about looking with a magnifying glass to see what your operators are actually doing. Which motions are truly contributing? Which are just busywork?

How to Actually Do It?

It's actually not difficult; the simplest method is "video recording." Take your phone, point it at your operator, and record their entire operation process. Especially those points you feel are "stuck" or "clumsy."

  1. Deconstruct Motions: Watch the video frame by frame and list all the operator's motions from start to finish. For example: "walk to the material rack," "bend down," "pick up the box," "walk to the machine," "open the machine door"... The more detailed, the better.
  2. Categorize: According to Therblig's 18 elements, categorize the motions you've listed. For example:

* "Walk to the material rack": This is "Transport Empty" or "Search."

* "Pick up the box": This is "Grasp."

* "Open the machine door": This is "Use."

* "Looking around for a screwdriver": This is "Search" and "Select," a very typical ineffective motion.

  1. Measure Time: Use a stopwatch or software to accurately record how much time each motion took.

I once caught a case this way. In a material change process for a certain machine, we found that operators spent an average of 15 seconds "searching" for the correct material tray. After analysis, it was due to unclear material rack layout logic and no unified numbering, causing operators to have to look down for a long time each time. Later, we redesigned the material rack numbering and placed frequently used material trays in the prime access zone. We managed to cut 10 seconds off that 15 seconds. You see, these 10 seconds, multiplied by hundreds of material changes a day, equate to several hours of production capacity. The Cpk also slowly increased from 1.08 to above 1.35.

The Most Common Pitfalls

To be honest, the biggest pitfalls are "feeling troublesome" and "not seeing the problem." Many people think that operators are already used to it, so there's no issue. But in reality, many potential problems are hidden within these "habits."

I also encountered a situation where we spent a lot of effort optimizing the height of the workstation and tool placement. However, we found that operators would still casually place a frequently used tool in a position that "seemed convenient" but was actually far from their body. Why? Because they simply didn't understand the importance of "fixed-point positioning." Therefore, optimizing the environment alone is not enough; you also need training to let them know the purpose of these adjustments, so they will execute them more consciously.

Additionally, don't try to solve all problems at once. Start with the most obvious and frequent motions. For example, motions repeated more than 50 times a day, or motions that get stuck every time.

One Thing You Can Do Today

Pick up your phone and record the entire operation process that you feel is "stuck" or "clumsy."

Want to try it yourself?

Every tool mentioned in this article is available on InsightFab — just upload a CSV to analyze.

Go to Tools

More in this category

The Application of Lean Production in the Service Industry: More Than Just a Manufacturing Plant Tool

Drawing on fifteen years in semiconductor manufacturing, the author unexpectedly identifies significant waste in a service setting. This article illustrates how applying Lean Production principles, typically used in factories, to the service industry can reveal and eliminate inefficiencies, ultimately boosting productivity and stakeholder satisfaction.

Misconceptions of Lean Manufacturing: Why Many Implementations Fail

This article addresses common misconceptions about Lean Manufacturing, opening with a compelling example where Cpk values deteriorated post-implementation. It clarifies that effective Lean adoption involves precisely eliminating non-value-adding waste, rather than merely simplifying processes or indiscriminately cutting resources, providing a more practical perspective on its true objectives.

Man-Machine Chart Analysis: Synchronous Operations Design

This article introduces Man-Machine Chart analysis, a practical approach to addressing high machine idle rates caused by asynchronous interactions between operators and equipment, often leading to "man waiting for machine, and machine waiting for man." It explains how to identify and eliminate time gaps to transform waste into efficient production, optimizing workflows and reducing operational costs.