ISE 312 Chapter 10 (Sule)
Spring Semester
Material Handling: Flow Lines, Grouping, and Packaging
Types of Plant Layouts:
1) Fixed Position Layouts:
> Products too big to be moved. Fix position.
> Equipment is moved to the site. (May be removed when completed).
2) Product Layouts: (Product Flow Layout)
> High Volume Standardized Production.
> Flow-Type Mass Production.
> Specialized machines are organized to conform to the sequence of operations.
> Accommodates only a few product and process designs.
> Change over requires great expense & long down times.
3) Process Layouts:
> Groups similar machines having similar functions.
> Wide variation in the product mix.
> Each product has a different routing sequence.
> Flow patterns are highly variable.
> High queue at machining centers.
> Designs changes are common. Part Routings changes frequent.
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ISE 312 Chapter 10 (Sule)
Material Handling: Flow Lines, Grouping, and Packaging
4) Group Technology Layouts:
> Wide variety of parts in moderate to high volumes.
> Parts identified and grouped based on similarities in mfg. function or design.
> Each family requires similar processing (on same machines).
> Layout (cell) is based on needs on the family of parts.
> Reduce WIP inventories.
> Reduced setup times.
> Reduced materials handling costs.
> Better scheduling.
Disadvantages: Duplication of machines. May be difficult to identify suitable part families.
5) Flexible Manufacturing System Layout:
> Low volume & high customization.
> Collection of numerically controlled machines connected by a computer-controlled materials flow
system.
> Large variety of parts. Each routings programmed into computer.
> Small batch sizes.
> Reduced WIP inventories with increased machine utilization.
> Quick tooling change and product design with minimal additional investment in new equipment.
> Disadvantage: Extremely expensive. Equipment, Space, Software.
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ISE 312 Chapter 10 (Sule)
Spring Semester
Material Handling: Flow Lines, Grouping, and Packaging
Conveyor Systems:
> Serial: Assembly line developed along a single conveyor or connected together with separable
segments.
Intermittent speeds for station cycle time; length adjusted to provide input on time.
> Modular: Assembly line with general-purpose equipment with return path for multi-sequence jobs.
Banking:
> Allows for absorption of fluctuations in production rates (repairs, breaks, meetings, problems)
> A space for in-process inspection between stations
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ISE 312 Chapter 10 (Sule)
Spring Semester
Material Handling: Flow Lines, Grouping, and Packaging
Banking Controlled By:
1) Changing the Product Flow
2) Providing for Overlapping Operations or Moving Operator
Finding the Correct Banking Space:
Example: Rotary Table Capacity (M,M,1)
Parts arrive at a station following a Poisson distribution with mean () = 2 parts/minute
Station Service Time Mean: u = 3 parts/minute (Poisson)
[Exponential Service in minutes/part]
Incoming items are stored on a rotary table.
Find the required capacity of the Banking system so that the probability of not being able to accommodate a
part on the table is less than 0.03.
For  < u (Service rate higher than arrival)
Pk = ( / u)k P0 for k = 0, 1, 2…
Probability that Bank is Empty P0 = 1 –  / u
State Probability
0
1
2
3
4
5
6
7
8
Cumulative Probabilities
Expect number of parts in Bank =
Rotary Table Capacity with Modification:
Example: Machine stops periodically for at most 3 minutes.
What is the probability of not accommodating an incoming part if Bank Size = 8?
Machine Down = No Service:
t = 2 parts/minutes x 3 minutes = 6 parts
Probability on k units in system Pk(t)= e-t
(t)k/k! (Poisson Process)
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ISE 312 Chapter 10 (Sule)
Spring Semester
Material Handling: Flow Lines, Grouping, and Packaging
Accumulation Line:
Single Server
M/M/1/k
Accumulation line has limited queue. If the queue is full during an arrival, the arrival
continues past the system and the arrival is lost to the system.
M = interarrival & service probability distributions are Exponential
A = mean arrival rate (units/time)
S = mean service rate (units/time)
(1) worker servicing units
Worker service rate:
S = 4 units / minute
(1) conveyor line (Input)
Arrival rate:
A = 3 units / minute
1 = Single Server System
k = “system” capacity
(Note: zero queue implies k = 1 for this system)
(System can not be “Full” at k = 0)!
For: A/S  1
P(0) = (1 – (A/S)) / (1 – (A/S))k + 1
P(k) = (1 – (A/S))x(A/S)k / (1 – (A/S)k + 1)
Not all arrivals enter system so effective arrival rate is recalculated.
Probabilities of having k units in the system; k – 1 on the accumulator.
k capacity
0
1
2
3
4
5
P(k) “Full”
X
0.429
0.243
0.154
0.104
0.072
Effective Arrival Rate
X
1.713
2.271
2.538
2.688
2.784
If the system being found full 7.2 % of the time is considered reasonable.
How many lost units do you expect to send to the relief worker?
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ISE 312 Chapter 10 (Sule)
Spring Semester
Material Handling: Flow Lines, Grouping, and Packaging
Accumulation Line:
Multi-Server M/M/C/k
(2) workers servicing units
Each worker service rate: S = 2 units / minute
(1) conveyor line (Input)
Arrival rate:
A = 3 units / minute
Determine the size of the needed accumulator:
Constraint: The probability that the system will be full on arrival must be less than 2%.
C-1
P(0)=1 / [ (A/S)n/n! + {(A/S)C/C! x (1-(A/CS))k -C + 1/1-(A/CS)}]
n=0
P(k) = (/u)k P(0) / k!
if 0  k  C
P(k) = (/u)k P(0) / C!Ck-C
if k > C
zero queue implies k = 2
(System can not be full at k = 0 or 1)
k
P(k) “Full”
Effective Arrival Rate t
0
1
2
3
4
5
6
7
8
9
10
11
12
X
X
.3101
.1888
.1240
.0851
.0600
.0430
.0313
.0229
.0170
.0130
.0090
2.069 <<< 3 arrivals * (1-.3103) able to service
2.434
2.628
2.745
2.820
2.871
2.906
2.931
2.949
2.961
2.973
How many do we expect to see on the floor for the whole day (8 hours)?
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ISE 312 Chapter 10 (Sule)
Spring Semester
Material Handling: Flow Lines, Grouping, and Packaging
Horizontal Main Production Flow Issues:
> Physical Structure of Plant & Machines
> Location of Receiving Department
> Location of Shipping Department
> Size of Parts
> Utilization of Machines
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ISE 312 Chapter 10 (Sule)
Spring Semester
Material Handling: Flow Lines, Grouping, and Packaging
Packaging Functions:
> Protect from Damage
> Allows flexibility in locating plant
Three Major Categories of Packaging:
1) Consumer
2) Industrial
3) Military
Packaging Issues:
> Structure
> Aesthetics
> Appeal
> Style
> Ability to communicate information
> Adherence to Specifications
> Safety (if hazardous)
Packaging Materials:
> Glass
(Bottles, Jars, Tumblers, Vials)
> Metal
(Steel Drums, Aluminum Cans)
> Strapping
(Bands of Steel or Plastic)
> Paper
(Corrugated cardboard cartons, burlap/cotton bags)
> Wood
(Boxes, Pallets)
> Plastic Film
(Shrink Wrap-heat source, Stretch Wrap-no heat)
Cellophane, Cellulose, Nylon, Polyester, Styrene, Polypropylene, Polyethylene,
Rubber Hydrochloride, Saran, Ethyl Acetate.
Stretch & Shrink Design Issues:
> Density of Wrap
> Surface Hardness
> Heat Seal Temperature
> Flexibility
> Impact Strength
> Moisture, Gas, & Grease Resistance
Packaging Equipment:
> Automatic Adhesive Sealers
> Automatic Tape Sealers
> Stitchers
> Staplers
> Strappers
> Wrappers
> Palletizers
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