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.

Standard Work and the PDCA cycle.

I love teach Standard Work to young Engineers, their expectations are always what type of software I going to show, and they look very confused when I say “ dear Team to day I’ll teach all of you to walk, see, draw and ask why? 5 times, and then Standard Work “...."Genchi Genbutsu".

I recommend to perform the training on Genba rather than, meeting rooms or classroom.

The process to improve a production line using Standard Work is directly related with the PDCA cycle is not just “Before and After”.

The team should PLAN (Draw the current situation Standard Work, ask 5 times why? For all the None Value Add Activities –NVA- that they being capable to see at that moment and creates the Kaizen News Paper – Improvement Plan); and then go ahead with the DO (The first try, or as I call it Try-Storming, physical changes transform the line to U shape cell maybe etc.); following by the CHECK  (this is the second draw or review; for sure the Team will be able to see clear new or more NVA than before, new challenges are going to be added to Kaizen News Paper – Improvement Plan) the Team must now go for the ADJUST ( could be just one or more it is up to the goal achievement in terms of productivity , Takt Time , Operators Numbers, Quality etc.).

On these examples you can see how the changes on production floor are follows.

Obviously many specific improvements on process must being done; this is not easy; the implementation time is up to the Team member’s skills and if tool room that makes possible supports them the process changes. Plus the others formats and tools.

See some improvements that are needed to reach the goal, please take it as examples.

I hope this help you in your next project.

Understanding the Correct Sequence to Kaizen - Why some Full automated equipment end up being inefficient and ineffective?

I have visited many different industries, and is very usual to see full automated equipment (Robots) with high inefficiency, those equipment were considered as the answer of all the problems, but the reality shows different negatives results as expected.

Taiichi Ohno always teaches about the Correct Sequence to Kaizen:

“ Manual work kaizen means thinking of better ways of using the existing equipment. Rather than buying new equipment (Robots) it is important to thing of how the work should be done.”

If you install a robot and think only, “this is convenient, it does my work for me “ then this is not an example of using the robot effectively. It is important to do kaizen on the robot as soon as you install it or to change the method to work well with the robot (Material supply, Information, Product flow, etc.).

Video.

Pictures;

The team must consider on cell design ,how the material must be replaced ? Before release to production, the robot will do the cycle very well however it will stop due lack of material.

The team must understand the real problem here , because even with robots there are some products that goes out without being packaged. Is the conveyor sped synchronized to the Takt Time?

Instead if you say, “We can do this if we could just buy a robot ,” and buy a robot without even knowing if there is a better method than the current one , then eventually you will not do kaizen at your genba unless you can buy a robot. That would be bad. But if you first see how well you can use the machines you have, and how you can use the existing equipment event better, then when you install the latest machines you can add on yours improvements.

I always advise built machines or robot mock up’s before to proceed with next action this is part of 3P.

The right pad to follow is do kaizen after kaizen; there are 3 types of kaizen:

a) Manual work Kaizen.

b) Equipment Kaizen.

c) Process Kaizen.

Do the kaizen to the manual work first. Once you know how make more improvements, but the machine you have is preventing this, then you can look at the right machine that will further improve productivity and quality.

When the latest machine is installed before you have the skill to do kaizen, the machine will end up running you. JJJ There is a correct sequence to kaizen.

The first step in kaizen is manual work kaizen. Manual work kaizen is the must important because as a result of manual work kaizen you will learn many things about changes you need to make to your equipment, or changes you need to make to your process as a result of change you make to your equipment.

Cellular Manufacturing – Deployment Guide

Cellular Manufacturing , is a Lean Manufacturing approach for building a variety of products, delivering flexibility for Customers with minimum waste , variation and overburden.

Cellular Manufacturing consists of people, machines and work stations typically in U shape in processing sequence with flexible deployment of multi-skilled operators.

Elements of good Cellular Design.

•       Design allows for One Piece Flow.

•       Process steps are error proofed - Quality built into the process.

•       Equipment and work stations are close together.

•       Tools and material are presented at point of use based on frequency of use and ergonomics.

•       Materials and tools are controlled visually making them very easy to identify

•       All work areas are safe and ergonomic.

•       Metrics and other key performance indicators are tracked and clearly seen

•       Schedule is visual

Cellular Manufacturing - Where to deploy

Cellular Manufacturing eliminates waste by improving processes  as well as operations. A process is a continuous flow through which raw material is converted into finished products in a series of operation. In contrast, operation focuses on action in particular process step.

Deployment Guide.

Fig.

Phase 1:

Map the Current Value Stream

•       See 7 Flows

•       See 7 Waste

•       Identify customer demand

•       Identify Kaizen burst

Fig.

Use the 8 Standard work tool kit to baseline the sub processes and sub metrics.

(1)  Standard Work Sheet

(2)  Time Measurement sheet

(3)  Spaghetti Chart

(4)  Value Added Ratio

(5)  Standard Work Combination Sheet

(6)  Takt / Cycle Graph

(7)  Target Sheet

(8)  Capacity analysis chart

Fig.

Analyze the process Product and Process communality to gets maximum benefit

PQ Analysis ( Product/Quantity) displays product mix as pareto chart

PR Analysis ( process/ route) Highlights processing similarities between different products

Helps identify product families that could be made in the cell,  using same sequence of machines.

Phase 2:

Break down the manufacturing process in the sequence the product is built. Arrange the work stations, people and machines sequentially in the way the product is built without de coupling the line.

Discuss and agree on new process map.

Fig.

Ensure safety and good ergonomics

A process flow layout with the end point near the beginning point

Use dedicated hand tools and gravity to assist operator

Minimizes the waste of walking

Place machines very close for min WIP

Eliminate space where WIP accumulates

Fig.

Revise the std work sheet for new process and new layout

Make new Standard Operating Procedures for the new process

Fig.

Phase 3:

Create forcing functions for Continuous Improvement

Low Inventory manufacturing keep surfacing and amplifying problems for continuous improvement. Keep Single Piece Flow and Std WIP to amplify the impact of all other problems.

Some common problems

1. Multi skilling
2. Tools not available
3. Machine Break down
4. Change Over
5. Defects
6. Cycle Time

Fig.

One person can run several machines/processes in a process sequence

Cross training gives flexibility and helps team take full responsibility for their process

Fig.

Total productive maintenance (TPM)

A Company wide approach for reducing equipment related losses such as downtime, sped reduction and defects

Helps ensure equipment is  ready to run when needed.

Fig.

Visual Management

A bulletin board displaying team activities and results in the manufacturing floor

Typical sections :

Company Vision

Mandatory Metrics

            MultiSkill

            Yield

            WIP DOS

            Linearity

            MLT

Continuous Improvement Metrics

Projects summary

Kaizen Burst for Future

Fig.