Chapter 9web.utk.edu/~kkirby/IE527/Ch9.pdfProduct-Process Matrix Volume Low Low High High Projects...

1Ch8 Pull Production Systems

Chapter 9

Focused Factories and GroupTechnology


Processes

vProject– produce a product or service one-at-a-time to customer

order– unique, large-scale work effort directed at one or a few

end-items which are tailored to fit unique requirements– ex: buildings, dams, highways, ships

v Job– small-volume, somewhat small-scale work effort where the

output is one or a few identical items, custom-made to fitan order

– ex: custom furniture, special airplane parts– often performed in a job shop by craftsmen


Processes (cont.)

vBatch production– process many different jobs at the same time in batches– producing several or many identical end-items– more-standardized (less diverse) products– take advantage of scales of economies resulting from:

• fewer changeovers• quantity discounts on procured materials•greater work proficiency


Process (cont.)

vRepetitive production– produce a commodity product or service continuously in

very high volume– equipment is designed for single-purpose, high-efficiency

operation– workers are narrowly trained and perform one or a few

tasks each– ex: cars, computers, VCRs, pens


Process (cont.)

v Continuous production– produce a commodity product or service continuously in very

high volume– products and materials actually flow through the process– the product seldom changes– production is scheduled and controlled by volume output– ex: paint, steel, paper, coal, petroleum

v Hybrid– one type of process within another– ex: Candy is made in a continuous process until it is packaged

which is a repetitive process


Product-Process Matrix

Vo

lum

e

LowLow High

High

Projects

Jobproduction

Batchproduction

Continuousproduction

Standardization


Processes (Volume vs. Size andVariations of Product)


Variety/Efficiency Trade-off Craft/Project Job Batch Repetitive

Product Unique Made to order Made to stock Commodity

Customer Single Few individuals Mass market Mass market

Demand Infrequent Fluctuates Stable Very stable

Volume Very low Low to med High Very high

Variety Infinite Many, high Low Very low

System Long-term Intermittent Flow lines Process industry

Equipment Varied General Special Highly automated

Type of work Contracts Fabrication Assembly Mix, treat, refine

Skills Experts, Wide range Limited range Equipment

craftspeople monitors

Advantages Custom work, Flexibility, Efficiency, Highly efficient

quality speed, low cost large capacity

Disadv. Nonrepeating Costly, slow Capital invest. Difficult to change

Example Construction Printing, bakery Autos, TV’s Paint, oil, food


Craft/Project Job Batch Continuous

volume increasesmaterial flow is more continuous, less intermittent, and more steady

work task efficiency increasesunit time and cost of production decrease

processes are more standardizeddemand volume increases

products are more standardizedmore capital intensive

more automatedless flexible

customers less involved


Variety/Efficiency Trade-off (cont.)

v Factors for high efficiency and variety production:– Product design– Planning and scheduling of jobs– Arrangement of operations and equipment in the factory– Grouping of products for production

Facilities LayoutvThree type of facility layouts:

– Fixed-position layout– Process layout– Product Layout


Fixed-Position Layout

vEnd-item remains in a fixed or stationary positionduring production

vCommon for large products that are difficult to move– ex: ships, hydroelectric turbines, electrical transformers,

aircraft, large CNC machines

vCommon for product made by many craftspeople– ex: racing cars, machine tools


Process Layout

vUses departments with similar equipment and toolsand workers with similar expertise

vEach job is routed through areas using a routingsequence

vUsed in job shopsv Sometimes necessary when there is a large piece of

machinery that many lines must use– ex: heat treatment

HeatTreatmentFurnace

Line 1

Line 2


Process Layout (cont.)

v Can readily process any product that requires work in anydepartment, regardless of volume or routing sequence

v Can increase capacity by using overtime or new machinesv Many possible routing sequencesv May move material over long distances (non-value added)v Scheduling, routing, sequencing, and tracking of jobs requires a

lot of effortv Possibility of large amounts of WIPv Probable long setups from non-standardized operationsv Flexible from standpoint of producing many different types of

products


Process Layout (cont.)

vCannot eliminate waste unless unless product mix is:– Small quantity– Custom designed– One-of-a-kind products

Product Operation Sequence Annual VolumeX J-B-L-T-P 100,000Y T-L-P-T 8,000Z P-L-B-J 20,000W J-L-P 11,000


Product Layout

vUsed for repetitive or continuous processesvProduct line is made up by all of the operations

required to make a productv Facilities using this procedure are called flow shopsvOne or a few kinds of end-items are producedvAll products follow the same routingv Schedule work by determining the flow rate or cycle

time required to satisfy demandvLittle or no inventory between operations


Product Layout (cont.)

v Capacity is constrained since the production rate is designedinto the layout

v Easiest to increase capacity by running overtimev Decrease capacity by stopping the linev Potential large capital investment

– Custom-made, one-of-a-kind equipment– Expensive to design, fabricate, install, and maintain

v Workers have narrowly defined and boring tasks


Variety/Volume Trade-off

vGoal of manufacturing:– Increase product appeal– Broaden market scope– Production agility to offer many kinds of products– Reduce production waste– Increase profits

** Must make a choice between variety and volume **


Group Technology

If products can be reduced in number and made morestandardized, and if the processes that make thoseproducts can also be reduced in number, thenproduction waste will be reduced and efficiency willbe increased.


Group Technology (cont.)

v Start with many different products

⇒Then collapse the number of products into a more manageable number

⇒Use this to produce products more easily

vGroup technology provides capability of producingin a repetitive environment

vDoes not try to reduce the number of productsoffered to customers– Group technology reduces the number of products

produced by the manufacturer


Group Technology (cont.)

v Identify and exploit the similarities between differentproducts

vEven though product may appear very different,they may be manufactured the same way


Product Coding and ClassificationSchemes

vProduct code - multi-digit, alphanumeric code– Each digit and letter may represent a feature on the

product– Used to group the products by:

• design categories• similarity of manufacturing processes

vThree types of product code:– Hierarchical (monocode) structure– Chain (polycode) structure– Hybrid Structure


Hierarchical Structure

v Interpreted as an inverted tree hierarchyv Sequence of digits created by starting at the top or

trunk of the tree, then moving downward throughwhatever branches apply

v Each digit’s interpretation depends upon thepreceding digit

vAdvantage: It is compact and assigns only the numberof digits necessary

vDisadvantage: More difficult to read because of thechanges in length of the code for different products


Hierarchical Structure (cont.)

The product shown above has code 0011•0 because it is a cylinder•0 because L/D = 1”/1.25” = 0.8 < 1•1 because I/D = 1”/1.25” = 0.8 > 0.5•1 because Inside Tolerance = 0.00005 > 0.0001


Hierarchical Structure (cont.)

The product shown above has code 11314111•1 because it is a Maxima•1 because the model is GXE•3 because the car’s color is gold•1 because it has a sun roof (this number isadded because the feature is not on all cars)•4 because the interior is leather•1 because the radio is AM/FM•1 because the tires are 15”•1 because the display is digitalThis code has two more digits than the next pagesince the sunroof and digital displays are notoffered on all cars.


Chain Structure

vEach digit’s position in the sequence represents thesame attribute or feature of a part

vAdvantage: Easy to interpretvDisadvantage: Less efficient than hierarchical codes

Interpretation1 Type of car 1 = Maxima2 Car package 1 = GXE3 Car color 3 = Gold4 Interior 4 = Leather5 Radio 1 = AM/FM6 Tires 1 = 15"

Digit PositionFeature/Attribute Type of car Car package Car Color Interior Radio Tires

1 = Maxima 1 = GXE 1 = White 1 = Black 1 = AM/FM 1 = 15"2 = Altima 2 = XE 2 = Black 2 = Gray 2 = CD 2 = 17"3 = Sentra 3 = SE 3 = Gold 3 = Brown 3 = CD changer

4 = GLE 4 = Blue 4 = Leather 4 = Premium5 = Red6 = Dark Gray


Hybrid Structure

vConsists of subgroupings that contain eitherhierarchical or chain structures

vVersatile because they can be tailored to representboth general attributes of parts as well as process-specific or company-specific features

9833-39423-3982First two codes have chain structureLast code has hierarchical structure


Product Families

vProducts with similar manufacturing characteristicsas identified by Group Technology coding

vGenerally:– Made from the same material– Have similar overall dimensions– Require similar machines– Require similar tooling– Require similar routing sequences


Focused Factory

v Exclusively produces products in a family when there isenough demand

v Enables production on a repetitive basis by clusteringtogether the:– Required equipment– Tools– Workers

v Achieves high volume by producing different, but similar,kinds of items

v Combines the variety and flexibility of a job shop with thesimplicity and efficiency of a flow line


Group Technology and Product Design

vWhen a new part is required, the designer can accessthe GT database to see if a similar part already exists

vThe new part may be used as-is or with a littlemodification


To Code or Not To Code

v Coding for existing parts may be costly, complex, andfrustrating

v Coding for new products is simplev Commercial software codes for:

– Product design– Physical attributes

v But not for:– Forming part families– Processing attributes– Machine attributes

v May be easier to develop internal software


Focused Factory

v Portion of plant is devoted to making a group of severalsimilar products

v Supported by maintenance, purchasing, and engineeringstaff

vOperators perform PM, housekeeping, and simple setupsvHas a manager or supervisorvHas better cost and quality than job shopsvManager and workers have more responsibility for

planning, scheduling, and controlling output and for costand quality


Focused Factory (cont.)

v Required information for developing a focused factory:– Demand– Number of products– Number of part families– Routing sequence– Operations required– Capacity of operations– Machines required

v Three types– Focused flow line– Workcell– Focused workcenter


Focused Flow Line

v Similar to product layoutv Can produce all of the parts in a part familyv Useful when every part follows the same routing sequencev Good for balanced linev Uses

– Similar parts for assemblies– Quick changeover machines– Multi-skilled workers– Conveyors, gravity slides, or other automated

transportation


Workcell

vMakes products with similar routingvUnneeded operations are skippedvActually a dedicated job shopvMostly uses unidirectional routingsvRoutings may be omni-directionalvUsually arranged in a U-shaped pattern to minimize

distance


Focused Workcenter

v Similar to a process layout (machines are clustered into areasby functional type)

v Some machines are dedicated to certain part familiesv Simplifies machine schedulingv Saves setup timev Improves product qualityv Useful when:

– Machines are hard to move– Machines are hard to setup– Product volumes and mix changes rapidly– Each department has multiple machines


Focused Factory


Shapes of Production Lines

v Flexible flow line– Made up of benches that may be moved, added, or taken away

easily– Workers sit in close proximity to each other– Provides good communication

v U-lines and S-lines– Workers walk a short distance within the curved line– Promotes communication– Utilizes workers better– S-lines are for longer lines and area around the line may be

increased by stretching the line


Shapes of Production Lines (cont.)

Using a flexible flow line.

May stretch the S-line to increase the area around the line***** Always consult the workers about new layout proposals *****


Product-Quantity Analysis

v The volume of production output of each focused factory must justify thecost of dedicating workers and equipment to producing that output

v Pareto analysis: 80% of volume comes from 20% of products– Determine which of these products could be made in focused factories– Could also be used for product families


Establishing Product and MachineGroups

v Focused factory involves:– Clustering products or parts that have similar processing

requirements (product family)– Clustering operations, machines, workers, and tools (to

produce a product family)vGoal: Maximize the independence between groupsvTwo approaches:

– Parts coding and classification– Cluster analysis

v Start by using information about product routingsthrough operations


Coding and Classification

vUseful when the product code includes informationabout the production process

vEasy to classify products into groupsvOnly used to classify productsvAfter products are classified, then machines have to

be assigned to the groupv If not available, use cluster analysisvOften impractical and unnecessary


Cluster Analysis

vGroups by similarities in product features andproduction requirements

vDoes not require codesvUses simple information that is easily obtainedvUse visual methods if there are a small number of

products and machines


Visual Analysis

vUse pareto analysis to determine the items in highestdemand

vDisplay the routings of the items

⇒

Product Volume Process RoutingA3 15000 E g GB6 13500 A g C g DC2 12500 C g DD9 8000 E g F g GE3 7000 G g FF4 4000 B g A g D g EG1 1000 B g C

Product Volume Process RoutingB6 13500 A g C g DC2 12500 C g DF4 4000 B g A g D g EG1 1000 B g CA3 15000 E g GD9 8000 E g F g GE3 7000 G g F


Production Flow Analysis (PFA)

v Forms groups of part families and machinesvDo not assume current routings are fixed,

particularly for machining operations.vWhat parts / assemblies consume capacity at a given

work center?vWhat percent of total workcenter capacity is

consumed by parts/assemblies that are not nowbeing considered for inclusion in cells for theidentified product family? How will this affect theoverall layout for the product family?


PFA (cont.)

v Factory Flow Analysis– Divides a factory into mostly independent focused factories– Enable products to flow in a unidirectional fashion

vGroup Analysis– Divides each department into mostly independent

workcells– Workcells perform almost all necessary operations for a

product family– Highly used technique


Group Analysis

vUses process matrix– Provides relationships between products and the machines

required to make the products– Does not provide routing information– Type: Binary ordering algorithm

Machine B6 C2 F4 G1 A3 D9 E3A 1 1B 1 1C 1 1 1D 1 1 1E 1 1 1F 1 1G 1 1 1

Product

Outlier


Binary Ordering Algorithm

vGoal: Rearrange the 1s so they line up in a diagonalin the process matrix

v Information needed in the cells with 1s– Position in routing sequence.– Average demand per time period.– Hours of machine capacity consumed by the part.

vLimitations:– Does not take capacities into account.– Does not consider alternative routings of parts.– Does not consider the routing sequence.


Binary Ordering Algorithm (cont.)

v Assign a value of one to each cell (i,j) if machine i processes part j.v Step 1. Reorder the columns:

a. Assign a power value of 2(row number) to each row.b.Compute a weight for each column by summing its cell values times

the corresponding row power values.c. Sort the columns in descending order of their weights.

v Step 2 .Reorder the rows:a. Assign a power value of 2(column number) to each column.b.Compute a weight for each row by summing its cell values times the

corresponding column power values.c. Sort the rows in descending order of their weights.

v Repeat steps 1 and 2 until no more changes occur.


BOA Example

Original Process Matrix


BOA Example (cont.)

Performing Step 1


BOA Example (cont.)

Performing Step 2


BOA Example (cont.)

Repeating Step 1


BOA Example (cont.)

Repeating Step 2


BOA Example (cont.)

Repeating Step 1


BOA Example (cont.)

Repeating Step 2


BOA Example (cont.)

Repeating Step 1 (no changes needed)

Repeating Step 2 (proof that no changes are needed)


BOA Example (cont.)

Visually inspect the process matrix.Then,

switch parts A-60, F-190, A-110 with F-730, A-70, H-230Move machines E, F, C above A, D

outlier


PFA

vMore efficient than GT codingv Identifies product families by processing

requirementsvDoes not guarantee good final answers (may need to

be fudged)vMay need duplicate machinesvDoes not incorporate the direction of workflow


PFA (cont.)

vMay have to:– Redesign the part so certain operations are no longer

needed– Add machines– Combine workcells into one workcell– Route parts through different workcells

v If a machine is used for two workcells, install themachine in the workcell that will preventbacktracking of the part

vMay put the machine in a workcell if that workcellhas similar machines with similar setups


Key Machine Approach

v Form groups around certain machines– Ex: heat treat– This idea may lead to one large workcell (not efficient)

v Develop a similarity coefficient between two machines i and j

j machine visiting parts of number

i machine visiting parts of number

j and i machines visiting parts of number

==

=−+

=

j

i

ij

ijji

ij

ij

P

P

P

PPP

PS


Key Machine Approach (cont.)

vChoose a key machine, then group machines with itthat have a coefficient > 0.5– Machine B is a key and will be grouped with G and H since

their coefficients are 0.6 > 0.5– Machine E is key and will be grouped with F– Machine I is key and will be grouped with J– Machines A, C, and D may be put together or separated

vDisadvantage:– Coefficients will not be significant if used by many parts


Machine Utilization Approach

v Groups machines to maximize utilizationv Procedure:

– Use the Binary Ordering Algorithm to develop the processmatrix

– Replace the 1s with the utilization– Add the total utilization per machine– Keep track of the minimum number of machines required– Products, and their associated machines, are grouped until

they have adequate utilization– Add machines when more capacity is required– Develop a new group when the maximum allowable

machines is exceeded


Machine Utilization Approach (cont.)

How many groups and machines are necessary ifwe limit ourselves to a maximum of eight machines?



Group Parts Assigned Machines Assigned No. Machines Remain. Util.1 F-720 B, G, H, A 4 B=.25,G=.85,H=.85,A=.7

M-50 B, G, H 4 B=.1,G=.65,H=.65,A=.7A-50 B2, G, H 5 B=.3,G=.3,H-.3,A=.7F-700 B3 6 B=.8,G=.3,H=.3,A=.7

H-2000 G, H 6 B=.8,G=.05,H=.05,A=.7H-90 E,F,C,A,D 10 (exceeds max)

2 H-90 E,F,C,A,D 5 E=.75,F=.85,C=.5,A=.8,D=.85F-730 E,F,C 5 E=0,F=.35,C=.5,A=.8,D=.85A-70 E2,C 6 E=.7,F=.35,C=.4,A=.8,D=.85

H-230 C 6 E=.7,F=.35,C=.25,A=.8,D=.85A-100 E3,F,D 7 E=.8,F=.15,C=.25,A=.8,D=.65A-320 E3,F2,D 8 E=.2,F=.8,C=.25,A=.8,D=.35F-134 E3,F2,D 8 E=.05,F=.4,C=.25,A=.8,D=.3F-670 C,D 8 E=.05,F=.4,C=.1,A=.8,D=.2M-56 D2,I,J 11 (exceeds max)

3 M-56 D,I,J 3 D=.75,I=.2,J=.8F-131 D,I2,J 4 D=.55,I=.6,J=.7A-110 A,D,I2,J 6 A=.9,D=.4,I=.7,J=.55F-190 A,D 6 A=.8,D=.35,I=.7,J=.55A-60 A,I2,J 6 A=.55,D=.35,I=.15,J=.2



Answer:Three groups and twenty machines resulted from

the example on the previous page.

How many groups and machines will result if we onlyallow a maximum of five machines in each group?





Answer:Six groups and twenty-seven machines resulted

from the example on the previous page. Thisresults in many more machines having a greatamount of extra capacity

Note: The fewer machines allowed in a workcell, themore groups and machines will be required witheven more wasted capacity


Focused Factories - Advantages

v Results:– 70-90% reductions in lead times– 96% reduction in late orders– 70-95% reduction in WIP– 60% reduction in finished goods inventory– 75-90% reduction in material handling– 20-56% reduction in required floor space– 65-80% reduction in machine setup time– 50-85% decrease in quality-related problems– Simpler shop-floor procedure and reduced paperwork– Greater worker involvement, productivity, flexibility, and satisfaction– Reduced overhead costs

v Note: All of this cannot happen without other pull philosophiesimplemented first.


Focused Factories - Disadvantages

vPotential low machine utilizationvMay need more flexible machinesvMay need more machinesvLoss of flexibilityvMust have good customer demand datavOften have to work with the union and adjust

contractsvRequires considerable effort and expensevDisruptive to ongoing operations

Chapter 9web.utk.edu/~kkirby/IE527/Ch9.pdfProduct-Process Matrix Volume Low Low High High Projects...

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