Cellular Manufacturing
Designing and Implementing One
Piece Flow in Manufacturing
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and is intended for the business use of students
of the Lean Implementer Training program
administered by ISI. Any reproduction for sale or
distribution to other organizations is prohibited.
Cellular Manufacturing
• …is a lean manufacturing approach that helps
companies build a variety of products for their
customers with as little waste as possible.
• In cellular manufacturing, equipment and
workstations are arranged in a sequence that
supports a smooth flow of materials and
components through the process,
with minimal transport or delay.
One Piece Flow
• …is a condition that exists when
products move through a manufacturing
process one unit at a time, at a rate
determined by the needs of the
customer.
• The opposite of one piece flow is mass
production with batches and queues
One Piece Flow Creates:
• Quicker delivery
• Reduction in storage and
transportation.
• Less damage, deterioration, or
obsolescence.
Typical Manufacturing Cell
Working In A Cell
• Operating in a U-Shaped Cell
• Becoming Multiskilled, Multimachine
Operators
• Using Small, Flexible Machines
• Using Autonomation (Jidoka) to
Eliminate Machine Watching
Working in a Cell
Operating in a U-Shaped
Cell
• Reduce travel distance
by arranging equipment
and workstations closer
together.
• Beginning of process is
closer to end of
process….minimizes the
travel distance for next
cycle.
Cell Lay-Out
input
output
Steps of Cell Design
1. Document the current process
2. Define the product family and
calculate TAKT Time for the cell
3. Balance the work to create flow
between work-stations that meets
demand
4. Design the cell for ergonomics
5. Test and de-bug the cell design
Document the Current
Process
The basic steps to understanding the
current conditions:
– Collect Product and Production Data
– Document Current Layout and Flow
– Time the Process
– Calculate Process Capacity and Takt Time
– Create Standard Work Combination Chart
Document the Current Process
Collect Product and Production Data:
– Product Mix:
• A high volume process tends to pull the maximum
benefit from the improvement, while low variety avoids
issues such as changeover.
• Use pareto analysis (20:80 rule on product
type/quantity) to determine high volume process.
– Production Resource Data:
• Shifts per day
• Hours per shift; break time
• Work days per month
• Monthly product volume requirements from customer
• Approach assigning work
• Finished goods inventory turns per month
Document the Current
Process
Document Current Layout and Flow:
Two activities are involved in understanding what operations make up
the process and how that process is currently performed
• Process Route Analysis:
– Helps to identify processing similarities between different products
and groups of products that could be made in a cell.
• Process Mapping:
– Use of Standard Work Sheet to process map the current layout and
path of the products going through process.
– Record distance the product must travel during processing.
– Record quantity of WIP in the process at a given time.
– Record number of people currently required to run the process.
Document the Current
Process
Time the Process:
– Use time observation sheet to collect the cycle
time for each machine operation and work
station in the process.
– Determine a sample process lead time for the
total process.
– Determine the value-added ratio. The valueadded ratio is the time spent actually machining
or working on the product divided by the total
process lead time.
Document the Current Process
Calculate Process Capacity and Takt Time:
• Develop a Process Capacity Table to reflect the manual
as well as the machine time for each operation in a
process.
• Calculate the Takt time. It is the pulse or the beat of the
factory.
Takt Time =
Daily Work Time
Daily Required Quantity
Document the Current Process
Create Standard Work Combination Chart:
• Graphical display for each operation in the process.
• Depict the relationship between manual work time,
machine work time, and walking time for each step
in an operation as well as the non-cyclical time.
• Draw a solid line to indicate the Takt time.
Standard Work Combination Chart
BEFORE IM PROVEMENT
Man
Mch
Wlk
Time in seconds
No
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Element Cy clic al Man Mch
take blank fr. Pallet,
lad to P1 and hit
5
buttons
P1 c yc le
7
take part fr. P1 and
2
plac e to T1
travel fr. T1 to pallet
take part fr. T1, load to
4
P2 and hit buttons
P2 c yc le
5
take part fr. P2 and
2
plac e to T2
travel fr. T2 to T1
take part fr. T2, load to
4
P3 and hit buttons
P3 c yc le
5
take part f. P3 and
2
plac e to T3
travel fr. T3 to T2
take part fr. T3, load to
5
P4 and hit butons
P4 c yc le
5
take part fr. P4 and
4
plac e to T4
travel from T4 to T3
take part fr. T4, load to
3
P5 and hit buttons
P5 c yc le
6
take part fr. P5 and
2
plac e to Cart
travel fr. Cart to T4
TOTAL
33
28
No. Element - Non-Cyc licalQty
1
2
3
4
Ex change Pallet
Ex change Cart
200
72
Wlk
1
5
10
15
20
25
30
35
40
45
50
55
60
65
2
2
2
3
61
2
11
Time
Rate
600
300
3
4.17
63
Steps of Cell Design
1. Document the current process
2. Define the product family and
calculate TAKT Time for the cell
3. Balance the work to create flow
between work-stations that meets
demand
4. Design the cell for ergonomics
5. Test and de-bug the cell design
Balance the Work to Create Flow
• Use the operator balance chart
• Use the standard work combination
chart
Cycle Time / Takt Time Bar Chart
# Operators =
80
Takt Time
Time (Seconds)
70
50
30
20
10
0
Takt Time
70 Sec.
12
60
40
 Cycle Time
43 Sec.
33 Sec.
27
34 Sec.
15
6
5
9
10
8
5
10
4
3
10
9
5
4
6
Operator 1
Operator 2
Operator 3
Operator 4
10
18
6
Cycle Time / Takt Time Bar Chart
# Operators =
 Cycle Time
Takt Time
=
182 Sec.
60 Sec.
= 3.03 Operators
70
Time (Seconds)
60
50
58 Sec.
59 Sec.
4
5
10
27
40
15
30
6
5
12
9
6
8
10
5
4
Operator 1
Operator 2
20
10
0
59 Sec.
9
10
18
3
10
6
Operator 3
Operator 4
Standard Work Combination Sheet
Used to:
• Provide adherence to Standardized
Work in the cell.
• Train operators.
• Display the best combination of
operator and machine.
• Displays the sequence of steps for an
operator.
Standard Work Combination Sheet
OPERATOR
NUMBER
MODEL NUMBER
AND NAME
WORK
SEQUENCE
12345 - 67890 master cylinder
Master cylinder machining
STEP
NUMBER
Standardized
Work
STANDARD
WORK
CombinationSHEET
Sheet
COMBINATION
1/5
QUOTA PER
SHIFT
Man.
Auto.
TAKT TIME
Pick up blank
2
2
M110
Unload/load/switch on
L210
Unload/load/switch on
4
28
2
5
29
2
4
D310
Unload/load/switch on
4
27
2
5
T410
Unload/load/switch on
3
12
2
6
Measure thread diameter
6
2
7
Put down finished piece
2
2
26
14
TOTAL
OPERATION TIME (IN SECONDS)
Walk
2
+
=
CT
690
Manual
Automatic
DEPT.
TIME
OPERATION NAME
1
3
DATE
PREPARED
40
Walking
wwwwww
Standardized Work Layout
• Visually displays the process at a glance
– Machine Layout
– Order of Operations
– Work Sequence for a single operator
1
2
3
4
– Standard Work in Process
– Quality Checks
– Safety Precautions
Standardized Work Layout
L210
4
2
5
1
6
Safety
Precaution
Standard Workin-Process
Raw Material
Finished Product
7
Inspect
T420
Quality
Check
4-14-03
M110
3
L310
Date prepared
or revised:
Master Cylinder
12345-678909
From Pick up raw material
To Finished product
Scope of
Operations
# of Pieces of Std.
Work-in-Process
5
TAKT
Time
40”
Cycle
Time
40”
Operator
Number
Design the Cell for Flow and
Ergonomics
Team brainstorming to improve
these 4 elements
•
•
•
•
Method
Machines
Materials
People
Designing the Cell
Plan Possible Layouts
–
–
–
–
Use the process sequence as basic principle.
Place everything as close together as possible.
Select cell configuration: U, C, Straight line, …, etc.
Counterclockwise is preferred flow for better control and
efficient handling.
Move the Machines
– For a smooth transition, team needs to discuss with
production, maintenance, transport, engineering, and
housekeeping.
Documenting the New
Process
• Revise the Standard Work Combination
Chart to reflect the new cell staffing plan
• Draft new standard operating
procedures
Steps of Cell Design
1. Document the current process
2. Define the product family and
calculate TAKT Time for the cell
3. Balance the work to create flow
between work-stations that meets
demand
4. Design the cell for ergonomics
5. Test and de-bug the cell design
Testing the New Process
• Test run parts through the cell
• Observe operation steps and timing
• Re-distribute work to achieve balance
De-bugging
• Monitor the new cell every day for 2-3
weeks
• Provide a means to collect feedback
from operators: flip chart, white board
• Fix problems every day
• Monitor performance against standard