Work element analysis explained

What a work element is

A work element is the smallest step of a job that can be timed and moved to another operator. “Install the bracket” is a work element. You can time it, and you could give it to the operator at the next station.

Each element is made of smaller motions. Installing the bracket means picking two bolts, lining up the bracket and torquing the bolts. Picking the bolts is not an element on its own. Nobody would give it to another operator, because it only happens as part of installing the bracket.

Each element also needs an end point you can see or hear, such as the click of a torque gun. Then everyone who times the job stops the watch at the same moment.

What the analysis is for

Work element analysis gives you a list of the elements in a job, in order, with an end point and a time for each one. It also sorts every second into value-added work, needed work or waste. Teams use the list to:

• Build a yamazumi chart. Each element is one block in an operator's bar on a yamazumi chart.
• Balance a line. In line balancing, you move whole elements between operators until each one fits under takt time.
• Find the waste. Once every second is sorted, you can see what to remove first.
• Write the standard. The elements, their order and their times become the operator's standardized work.

Value-added work, needed work and waste

Every second of a job is one of three kinds of time.

• Value-added work changes the product the customer pays for, such as torquing a bolt or seating a connector. Keep it.
• Needed work does not change the product, but the job can't be done without it today. Picking parts, lining them up and checking them are needed work. It is also called necessary non-value-added work. Reduce it.
• Waste adds nothing and is not needed, such as walking to a rack that is too far away or waiting for a machine. Remove it.

How to do a work element analysis

1. 1
   Watch the whole job first

   Watch several cycles before you write anything down. Ask the operator what they do and why.
2. 2
   List the elements in order

   Write down each step that could be given to another operator. Give each one an end point you can see or hear.
3. 3
   Time each element ten times

   Use a stopwatch at the job, not the planned times. Write down walks and waits too, with their times.
4. 4
   Use the lowest repeatable time

   For each element, use the lowest time that shows up more than once. Don’t use the average. Slow times come from problems like a missing part or a sticking tool. Fix those instead.
5. 5
   Sort every second

   Mark each part of each element as value-added work, needed work or waste.
6. 6
   Remove the waste first

   Take out the waste, then look for ways to reduce the needed work. Leave the value-added work alone.

The free time observation sheet records ten cycles for each element and finds the lowest repeatable time for you. You can then enter the times in the free yamazumi chart builder.

A worked example

An operator at a one-person bench fits a bracket and a connector to a metal housing. The bracket rack stands across the cell. The times are made up, in seconds, for one unit. As you scroll, the chart builds one step at a time.

The element sheet

The sheet lists each element in order, the point where it ends, and its time. The walk stays on the sheet, marked as waste, until it is removed.

Common mistakes

• Splitting the job too finely. “Pick two bolts” can't be moved to another operator. Time it as part of the element it belongs to.
• Making elements too big. “Assemble the unit” is one block that can't be split between operators. Break it into steps that someone else could do.
• Leaving out the end point. If an element ends “when the part is done,” two people will stop the watch at different times. Pick a sound or a movement.
• Moving waste to another operator. If the walk moves to the next station, someone still walks. Remove it before you balance the line.