Cycle Time Definitions and Line Balancing (Yamazumi) Charting · Cycle Time Definitions and Line...

EDMM 4870

Cycle Time Definitions and

Line Balancing (Yamazumi)

Charting

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EDMM 4870

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Ideal Cycle Time:

The maximum time (generally in seconds) to perform a process; in terms of

Standardized Work, it is the Total Time to perform the entire cycle.

Cycle time definitions:

1. Where there are a series of processes that are linked, there will be a

“Maximum Cycle” and a “Minimum Cycle” time.

2. The Ideal Process is where the Maximum and Minimum are equal.

3. Cycle time should not include delays and outside interference. It should

include everything on the Standardized Work / Job Break down Sheet.

Actual Cycle Time:

The maximum time (generally in seconds) to perform a process; in terms of

Standardized Work, it is the Total Time to perform the entire cycle, plus the Periodic

Work is added in.

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Each of these operations is required to make one finished good. There

are 8 operations and the critical cycle or “bottle neck” is 20 seconds.

Operation01

Operation02

Operation03

Operation04

Operation05

Operation06

Operation07

Operation08

Series1 16 19 14.5 17.5 20 11.25 12.5 17

0

5

10

15

20

25

Sec

on

ds

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Identifying Waste in Cycle Imbalance:

1. Find the “Critical Cycle” or “Bottleneck”

2. The time not being utilized by the other processes is waste.

Operation01

Operation02

Operation03

Operation04

Operation05

Operation06

Operation07

Operation08

Series1 16 19 14.5 17.5 20 11.25 12.5 17

0

5

10

15

20

25

Sec

on

ds

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Operation01

Operation02

Operation03

Operation04

Operation05

Operation06

Operation07

Operation08

Waste 4 1 5.5 2.5 0 8.75 7.5 3

Seconds 16 19 14.5 17.5 20 11.25 12.5 17

4 1 5.5 2.5 0 8.75 7.5 3

0

5

10

15

20

25

Sec

on

ds

4 + 1 + 5.5 + 2.5 + 8.75 + 7.5 + 3 = 32.25 seconds waste

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EDMM 4870

How much labor is being wasted in this process?

“Critical Cycle is 17.8

seconds

All the processes are limited by the “bottleneck”, which is 17.8 seconds.

17.8 x 6 operations = 106.8 seconds will be worked to produce one Unit.

The “Actual” Labor is 12.35s + 14.22s +17.8s + 13.5s + 11.91s + 8.44s = 78.22 seconds.

EXERCISE 01 – Processes 1 through 6 are in series and will result in one (1) Unit

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106.8s - 78.22s = 28.58 seconds are being wasted per unit.

In this example, let’s say this is a supplier to you and you believe their price is too high. They

disclose to you that their fully loaded cost is $68.00/hour, and you think they are about $0.25

too high for the part that you are buying from them, is there hope to reduce the price?

EXERCISE 01 – Processes 1 through 6 are in series and will result in one (1) Unit

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EDMM 4870

At 28.58 seconds of wasted labor per part (which is 0.0079 hours/part) and a loaded cost of

$68.00/hour, the supplier has approximately ($68.00 x 0.0079 = ) $0.54 of added costs to the

part.

You thought we were paying about $0.25 too much, does there seem to be some data to

support that?

Remember:

to convert

seconds to hours;

divide by 3,600.

So, 25.58 / 3,600

= 0.0079 hours.

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Working with the supplier and showing them some basic Lean principles and tools, the process has been

better balanced (see chart on right). “Critical” or “Bottleneck” cycle is Process 2, and it is 15.34.

The new waste is now 13.74 seconds; or 0.0038 hours; at $68.00/hr. = $0.2595.

This new line balance has reduced the wasted labor by (previous was) $0.54 - $0.26 = $0.28.

Now you can negotiate the $0.25 price reduction, they keep the $0.03, and all the learning from the

improvement event.

12.35

15.34 15.11 15.15

11.91

8.44

0

2

4

6

8

10

12

14

16

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Process 1 Process 2 Process 3 Process 4 Process 5 Process 6

Tasks move to Operations 2 and 4.

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Line balancing (Yamazumi)

• Line Balancing is leveling the workload across all processes in a cell or value stream to remove bottlenecks and excess capacity.

• A constraint slows the process down and results if waiting for downstream operations and excess capacity results in waiting and no absorption of fixed costs.

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Yamazumi Chart (Stack or Pillar charting):

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Line Balance ChartTakt Time (27sec)

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Line Balance

• Show visually what each Team Member is doing

• How close each operation is loaded to Takt time

• Identify waste:

– Waste is incurred whenever there is unnecessary movement or

excessive wait time or rework (Correction)

– Error of most companies is to “balance the load among Team

Members “. This does not make the waste obvious

– Minimize walking time

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Cycle Time

• Amount of time to process 1 unit

• Includes human & machine work, walking & waiting time

• Determine by taking the average time to process one part

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Theoretical # of Associates = = = 3.6 = 4 AssociatesTotal Work Time

Takt Time

13+28+16+19+22

27

Takt Time (27sec)

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Methods for Loading Team Member

Waste Waste Waste Waste

Takt

Takt

Waste is not obvious! i.e. not

likely to be addressed

When allocating work, try NOT to

balance work between Team

Members. Load individual Team

Members as close to Takt time

as possible!

Make waste more obvious & more

likely to be addressed!

Waste

Waste

Waste

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Value Added, generally are defined as any processing that is converting raw

materials / components to what the Customer wants.

Here are some examples:

1. It must transform the product or service.

2. The customer must be willing to “pay” for it.

3. It must be done correctly the first time.

Therefore, anything that does not fit these definitions, will fall in the category of

“waste”.

• Corrections – Reworking

• Over Producing

• Motion that adds no value

• Material Movement / Transportation and Handling

• Waiting (machine and/or Team Member)

• Inventory

• Process Inefficiencies18

EDMM 4870

The Team Member is

working in a process

where the equipment

cycles every 25 seconds.

How much Idle (Waste)

did the Engineer who

launched this process

design for this Team

Member?

Cycle Time = 25s;

25.0 – (All Value Added

Time;

1.89s + 2.45s + 2.10s +

0.89s.) =

17.67 seconds.19

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If this Team Member is being paid $16.50 / hour and Fringes and Benefits increase this

cost to $23.60 / hour and the team member will work at this job all year, how much are they

being paid to add no value to the product? (Reminder; the process makes a part every 25

seconds and for this exercise, the process runs 7.2 hours a shift and there are 245 working days

in a year.

Because most hourly Team Members are paid by the ‘hour’, we need to convert the

wasted time of 17.67 seconds into hour’s:

0.0049 hour per part of wasted time x ((7.2 hours x 3600)/ 25 seconds per part) x 245

working days a year) x $23.50/hour (including fringes) =

$29,249.94 of the $48,880 (2,080 hours x $23.50) is paid to this team member to do nothing

that adds value to the product; almost 60%.

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Process 01Process 02


Raw

Material

Finished

Material

Example 01:

In this process, there is only one team member performing all the processes. Please note that the time to

get the raw material from the tote is included in the total cycle time of Process 01. Also, Process 04 includes

the time to perform Process 04 and place the item in the Finished goods container and step back to the

Raw Material container.

Question 01; How much total Labor is there for making one complete unit?

Question 02: How much Line Imbalance it their in this layout?

Question 03; If this process runs 3 shifts a day, 245 days a year and there is 320 minutes per shift (with

OEE and PFD removed), how many parts will this process manufacture in a year?

25

28

25

17

0

5

10

15

20

25

30

Process 01 Process 02 Process 03 Process 0421



Raw

Material

Finished

Material

Example 01: In this process, there is only one team member performing all the processes. Please note that the time to get the raw

material from the tote is included in the total cycle time of Process 01. Also, Process 04 includes the time to perform

Process 04 and place the item in the Finished goods container and step back to the Raw Material container.

Question 01; How much total Labor is there for making one complete unit?

25s + 28s+ 25s + 17s = 95 seconds


None. With only one team member operating each station, there is no

imbalance.

Question 03; If this process runs 3 shifts a day, 245 days a year and there is 320 minutes per shift (with OEE and

PFD removed), how many parts will this process manufacture in a year?

(245 days x 3 shifts x 320 minutes/shift x 60 seconds/minute ) / 95 seconds =

148,547 per year.

25

28

25

17

0

5

10

15

20

25

30




Raw

Material

Finished

Material

Example 02

The process is not different for cycle time and activity per process, however, your customer has called and

their annual demand is increasing from 140,000 units a year, to 250,000 units a year.

Question 01; What do you propose be done to meet the new demand?


25

28

25

17

0

5

10

15

20

25

30




Raw

Material

Finished

Material

Example 02

The process is not different for cycle time and activity per process, however, your customer has called and

their annual demand is increasing from 140,000 units a year, to 250,000 units a year.

Question 01; What do you propose be done to meet the new demand?

Add a team member and combine processes. Because Process 01 and 03 are the

same value, there is no advantage if process 01 and 02 are combined, versus 02 and

03; they will always add up to 53 seconds, while the other process is (25 + 17) 42

seconds. Using the total of 14,112,000 seconds in a year and divide this by 53

seconds (the critical cycle time) = the annual yield is 266,264; which exceeds the

Customer requirement of 250, 000 units per year.


Refer to the answer in Question 01; where we see 42 seconds and 53 seconds; so

the line balance is (42 / 53 ) = 79%.

25

28

25

17

0

5

10

15

20

25

30


Example 03

The process is not different for cycle time and activity per process, however, the process is now staffed with

four (4) Team members; one at each station. Still 320 minutes per shift x 3 shifts x 245 working days/year.

Question 01; What is the potential yield per year?

Question 02: How much Line in the same layout, but staffed with four team members?

Question 03; How much waste is there in this line balance ( in seconds )?

25

28

25

17

0

5

10

15

20

25

30




Raw

Material

Finished

Material25

Example 03



Question 01; What is the potential yield per year?

14,112,000 seconds/year divide by maximum cycle time (28 seconds) = 504,000/yr.

Question 02: What is the new line balance?

Minimum Cycle / Maximum Cycle 17 / 28 = 60.7%


Maximum Cycle time x number of Team Members – Aggregated Time;

28 seconds x 4 = 112 seconds – 95 seconds (25s + 28s+ 25s + 17s) =

17 seconds

25

28

25

17

0

5

10

15

20

25

30




Raw

Material

Finished

Material26

Example 04






17 seconds

Question 01: Referring to the answer from Example 03, if our fully burdened cost is $75.00 per hour, how

much is this imbalance costing us?

25

28

25

17

0

5

10

15

20

25

30




Raw

Material

Finished

Material27

Example 04






17 seconds

Question 01: Referring to the answer from Example 03, if our fully burdened cost is $75.00 per hour, how

much is this imbalance costing us?

Convert the 17 seconds of wasted labor into hours (17 / 3,600 ) and multiply by the

Fully Burdened Cost (17 / 3,600 ) = 0.0047 hours x $75.00/hour = $0.3542/part.

25

28

25

17

0

5

10

15

20

25

30




Raw

Material

Finished

Material28

Example 05

The customer has communicated that they will be needing 450,000 units per year. The challenge is that the

overall costs are still too high by $0.40 per part. All material costs are reduced as low as possible and there

is no other place to look, except in labor. The good news is that some “C.I.” type team members have

evaluated the processes and have determine the following about process 04.

Question: Seeing this new data, what do you propose the team try out?



Raw

Material

Finished

Material

25

28

25

17

0

5

10

15

20

25

30


Example 05






A first step is in determining what the Customer Takt time is. All along we have assumed

that they only thing made on this process is for this one customer, and for this example,

that is correct. So, we know our ‘allocated time’ from earlier examples and it is 14,112,000

seconds per year, so with the new demand of 450,000 units, the equation is as follows:

Allocated Time 14,112,000

Customer Demand 450,000



Raw

Material

Finished

Material

25

28

25

17

0

5

10

15

20

25

30


= 31.36 seconds Takt Time

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Example 05 - Continued






Answer: See if a three (3) TM process will work by combining the

loading process (3.38 to Process 03) and adding the pack-

ing of the part to Process 01; which will increase it to

(25.0 + 1.41 + 3.76 = ) 30.17.

Using the 14,112,000 seconds/year divide by 30.17, the

annual capacity is 467,749; in excess of the Customer

Demand and 31.36 Takt Time.



Raw

Material

Finished

Material

Get part and place in tester and activate tester, 3.38

Tester Cycle time and auto ejects from tester, 8.45

Get part and step to Finished Goods container and pack, 3.76

Return to testing machine., 1.41

0

2

4

6

8

10

12

14

16

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Process 04

30.1728 28.38

0

5

10

15

20

25

30

Process 01 Process 02 Process 03

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Example 05 - Continued





Question: Did the proposal reduce the labor cost by $0.40/part?

Answer: Original Cost is 28s x 4 TM’s = 112s; 112/3600 x $75 =

$2.3333 per unit.

New layout is 31.17 seconds x 3 team members = 91.51s;

91.51 / 3600 x $75.00 = $1.8856 per unit

$2.3333 - $1.8856 = $0.4477 cost reduction; Target Achieved!

Also; line balance improved to 92.8%.



Raw

Material

Finished

Material

30.1728 28.38

0

5

10

15

20

25

30

35

Process 01 Process 02 Process 03

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