Takt Time vs Manual Cycle Time: The method to calculate the Quantity of Operators.

This article was written based on my experience as consultant.

After many Kaizen event I have found there is 2 misunderstandings about how calculate the Number of Operators that are needed to run a production line or manufacturing cell.

When you implement standardized work a Takt Time base on customer demand must first be established for the area in question, for example 30 seconds TT, this is equal to set a rate of 120 UPH (Units per Hour).

Therefore; the next question is how many workers are needed in the manufacturing area, at this rate?

The answer depends on the total work content in the area and relation to demand ( TT).

It's also known as graph of “Takt Time vs Manual Cycle Time”, in many industries.

The more work content, the greater the number of workers that will be required; the less overall work content, the fewer workers that are needed.

Misunderstanding 1: 

I have found there is a misunderstanding of Overall Work Content, many people take the Cycle Time complete (Machine + Manual) and that is not ok, they must use the “Manual” Overall Work Content (Total Manual Cycle Time)

Please see this example.

The calculation shows that is possible to run this Manufacturing Cell with just 3 operators. 

Misunderstanding 2:  

There is other misunderstanding this is about the representation of TT, many people don’t understand this concept how interpret and calculate the Quantity of operators when they have operators working in parallel.

For example; when there are operations that are not possible to be separated, the activity must be done from the start to the end by one operator at time; and if the cycle time is greater than Takt Time; then you need use more than one operator to cover the rate needed, this means to have two or more operators working in parallel, for this case the Takt Time must be different.

You should never use the average of those operators as the Manual Work Content, you need represent as it is and make the calculations using other Takt Times equivalent.

Please see this example.

The calculation shows that is possible to run this Manufacturing Cell with just 5 operators; please note that here there is two Takt Times, but don't get confuse at the end the Cell will run at 30 Seconds of Takt Time; equivalent to 120 UPH. The operators 1 and 2 must works at 3 process in sequence  (Press, Trim and Spring).

I hope this be useful for you in your next Kaizen event.

Therbligs Motion Analysis, the next Step after Standard Work.

I teach the Therbligs Motion Analysis (TMA) to my customers, just after done the first improvement (Standard Work) on the process or manufacturing line or cell, the reason is very simple, after the first improvement you may think everything is ok, but is not true, due there is more waste, this type of waste are the human micro motions and usually are very difficult to identify since the beginning of Standard Work analysis.

The TMA , will help you to identify the next improvement steps , that may end on implementation of Hanedashi – Auto eject or a full Chaku- ChaKu Line (load–load).

Shigeo Shingo explains in one of his books; the real meaning of work is: “ a person exerts strength on a weighty task”

Thus, rather than assuming that a man in motion is working, we must be sure to ask whether he is really exerting his strength on some task that will produce value added.

Frank B. Gilbreth studied human motion and discovered basic elements of motion, which he called Therbligs. All human movement, he discovered, are composed of a mere 18 Therbligs.

Basic steps for TMA.

1.    Be sure to familiarize yourself with the 18 basic Therbligs Symbols before using this form.

2.    Fill in the basic product and process related information.

3.    Make small sketch of the area you are study for reminder or take pictures.

4.    Observe the motion overall several times to obtain familiarity, draw the Ohno’s circle and stay there.

5.    Write down the left-hand, right-hand, and eye-related motions one by one.

6.    Include a brief word or two of explanation if required in the provided column.

7.    Write down the work elements every few symbols for clarification.

8.    Write down your improvements ideas for each small motion.

Please see the next video, its about machine improvement and automation, please note that event with the Nut Feeder , the operator is doing other motions that not add value, he is using his left hand as bin – Hold “H” , the right hand is used to release load “RL”  and this operation has a Unavoidable delay “UD” is obvious that more work needs to be done.

Please see the next video ;  on this case the operator just needs to load the part and the machine has the Nut Feeder and Auto eject.

If you want to make a Chaku- Chaku line you need to think about this; how the NVA activities can be detected and eliminated? The first step is performing a TMA.

Hope this information helps you in your next project.

Kaizen Events and the Ideas Generator “TRIZ” - The way to generate creativity on the Kaizen Teams.

On kaizen Events the Teams must come up with solutions for the problems exposed on VSM, after set the targets and scope of the loop you want to fix; this must happen within a period of time of 5 days; obviously there are days where the Team will be confused & frustrated; because is very difficult to find the right solution is short time and with very low money or zero if is possible; it’s a real challenge for them.

This is the way that I was trained by my Japanese Senseis and works very well if you are working with companies that have high level of Maturity on this types of Kaizen events; they knows the process already; makes the effort from Monday to Thursday and by Friday the sense on success will compensate all the efforts done, hours of frustration and sleepless to find the solution to their problems, this is how the Kaizen events works.

"You are a fool if you do just as I say. You are a greater fool if you don't do as I say.

You should think for yourself and come up with better ideas than mine."

“Wits Don’t Work Until You Feel the Squeeze”

As consultant I teaches the Team; Tools and Techniques, to make the changes and improvements happen such as Cell Design, SMED, Standard Work, Hanedashi , Jidoka  etc. all the Lean Tools and Techniques that you already know.

And as consultant; if you want do your job well; you can’t give the solutions to the Team; just guide them to find the right solution by themself instead

However, I had to recognized that I could do more for the Team in order to find the right solution in a proper and ways, more structured and faster, and then I recall from my past experience; when I was Design Engineer the Training called TRIZ (Teoriya Resheniya Izobreatatelskikh Zadatch - Theory of inventive problem solving  - Started with Altshuller’s interest in invention and work in Soviet Navy patent office) , TRIZ was invented to creates improvement on new designs or improve the current ones , (the process are included as well) TRIZ has an structure very easy ; you have just to follow those principles and you will came up with new solutions. (As everything the experience is very important).

Therefore I started teaches TRIZ (summarized obviously) to the teams to identified the right pad of solution during the Kaizen Events.

The solution does not needs to win the Nobel Prize; just to solve the problem on the faster an less expensive but effective way.

In the 1960s and 1970s, Genrich S. Altshuller, the Father of TRIZ ; he categorized the solutions into five levels.

•    Level one. Routine design problems solved by methods well known within the specialty. No invention needed. About 32% of the solutions fell into this level.

•    Level two. Minor improvements to an existing system, by methods known within the industry. Usually with some compromise. About 45% of the solutions fell into this level.

•    Level three. Fundamental improvement to an existing system, by methods known outside the industry. Contradictions resolved. About 18% of the solutions fell into this category.

•    Level four. A new generation that uses a new principle to perform the primary functions of the system. Solution found more in science than in technology. About 4% of the solutions fell into this category.

•    Level five. A rare scientific discovery or pioneering invention of essentially a new system. About 1% of the solutions fell into this category.

There are also 40 Inventive Principles.

Here just one example; of how to reduce the cycle time, micro movements and increase the productivity, the rules where simple; don’t buy anything or call external supplier for this; use Try-Storming, the Moonshine tool room and follow the method TRIZ.

Before.

After.

As final comment; the Consultant must find the way to help the Teams, and maybe this means look out of the box of Lean Manufacturing tools as well.

I hope this help you in your next Project.