Ch 5 Material Handling

8/10/2019 Ch 5 Material Handling

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Chapter 5: Material Handling

5.1 Introduction- Historically, material handling is to move the materials around. Since manufacturing is a

value-added operation and move materials around does not add any value, the simple rule

for material handling is the less (cost, time, labor and etc.) the better.- oday, it is recogni!ed that material handling is an integrated part of any manufacturing

system as sho"n in the figure belo".

#ig. 1$ %aterial handling and manufacturing systems

- In most manufacturing plants, materials spend more time being moved and stored thanbeing processed (it could be as much as &' of the time). herefore, analysis and designof material handling system is very important.

- his chapter corresponds to hapter * in the te+tboo and hapters & and 1' in eference/0. It is interesting to no" that there is a course in the ept. of Systems 2ngineering and2ngineering %anagement that discuss only the material handling.

- %aterial handling involves a rather broad body of no"ledge. Ho"ever, "e "ill focus ononly some fundamental issues including basic principles, various material handlinge3uipment such as conveyor and 46 (4utomated uided 6ehicle), material route

planning, and 4utomatic Storage and etrieval Systems (4S7S).

5.8 9asic oncepts and :rinciples of %aterial Handling(1) Some important concepts- 4 material system is an integrated system involving such activities as handling, storing,

and controlling of materials- In material handling, material has a rather broad meaning, covering all inds of ra"

materials, "or in progress, sub-assemblies, assemblies, and finished assemblies- he primary ob;ective of using a material handling system is to ensure that the material in

the right amount is safely delivered to the desired destination at the right time "ithminimum cost.

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customer customer

esignanalysis

:rocessplanning

9ill ofmaterials

%aterialhandling

oolingdesign andanalysis

%achinetool andcontrol


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(8) he :rinciples of material handling- he handling of materials must be performed safely, efficiently (at lo" cost), in a timely

manner, accurately (the right materials in the right location), and "ithout damage to thematerial.

- he %aterial Handling Institute has complied 8' basic guidelines for designing and

operation material handling systems. hese guidelines are referred to as the principles ofmaterial handling. hese principles are listed belo".- Orientation principle. Study the system relationships thoroughly prior to preliminary

planning in order to identify e+isting methods and problems, physical and economicconstraints, and to establish future re3uirements and goals

- Planning principle. 2stablish a plan to include basic re3uirements, desirable options,and consideration of contingencies for all material-handling and storage activities.

- Systems principle. Integrate the handling and storage activities that are economicallyviable into a coordinated system of operation including receiving, inspection, storage,

production, assembly, pacing, "arehousing, shipping and transportation.- Unit load principle. Handle product in as large a unit load as practical.

-Space utilization principle. %ae effective utili!ation of all cubic space.

- Standardization principle. Standardi!e handling methods and e3uipment "heneverpossible.

- Ergonomic principle. ecogni!e human capabilities and limitations by designingmaterial handling e3uipment and procedures for effective interaction "ith the peopleusing the system.

- Energy principle. Include energy consumption of the material handling systems andmaterial handling procedures "hen maing comparisons or preparing economic

;ustifications.- Ecology principle. %inimi!e adverse effects on the environment "hen selecting

material handling e3uipment and procedures.

-Mechanization principle. %echani!e the handling process "here feasible to increaseefficiency and economy in handling of materials.

- Flexibility principle. =se methods and e3uipment that can perform a variety of tassunder a variety of operating conditions.

- Simplification principle. Simplify handling by eliminating, reducing, or combiningunnecessary movements and7or e3uipment.

- Gravity principle. =tili!e gravity to move material "henever possible, "hilerespecting limitations concerning safety, product damage, and loss.

- Safety principle. :rovide safe material-handling e3uipment and methods that follo"e+isting safety codes and regulations in addition to accrued e+perience.

-

omputerization principle. onsider computeri!ation in material handling and storagesystems, "hen circumstances "arrant, for improved material and information control.- System flo! principle. Integrate data flo" "ith the physical material flo" in handling

and storage.- "ayout flo! principle. :repare an operational se3uence and e3uipment layout for all

viable system solutions, then select the alternative system that best integratesefficiency and effectiveness.

- ost principle. ompare the economic ;ustification of alternative solutions ine3uipment and methods on the basis of economic effectiveness as measured bye+pense per unit handled.

- Maintenance principle. :repare a plan for preventive maintenance and scheduled

repairs on all material-handling e3uipment.

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- Obsolescence principle. :repare a long-range and economically sound policy forreplacement of obsolete e3uipment and methods "ith special consideration of after-ta+ cycle costs.

- o begin "ith, "e usually use an e+isting design.- onsidering the situation in Hong >ong, "e probably should pay special attention to

planning principle, the simplification principle, and the cost principle.(/) %aterial handling e3uipment- here are many different inds of material handling e3uipment. hese e3uipment can be

classified into the follo"ing categories$- onveyors such as belt, trolley, and feeders (scre", vibrating and pneumatic),- %onorails and cranes (bridge, gantry, to"er, and stacer)- Industrial trucs and forlifts, both hand-lift and po"ered,- 46s such as carrier, pallet trucs and for trucs- 4utomated storage and retrieval systems

- he choice to these e3uipment depends on a number of factors such as the amount ofmaterials to move, the type of materials, the cost and etc. 4s sho"n in #igure 8, conveyor

and for truc are t"o types of material handling e3uipment. he former providesma+imum capacity but no fle+ibility. ?n the other hand, the later provide limitedcapability but very good fle+ibility.

#ig. 8$ he spectrum of material handling e3uipment

(@) he analysis or design of a material handling system begins "ith capacity planning, by"hich "e can determine "hat ind of material handling e3uipment "ill be used.

5./ Selection of %aterial Handling 23uipment(1) he selection of material handling e3uipment starts "ith an analysis of the materials to be

moved. he analysis includes- he characteristics of the material. In general, materials can be classified as follo"s$

- physical forms$ solid, li3uid, gas- si!e$

- length, "idth, and height- volume

- "eight$- "eight per piece,- "eight per unit volume

-shape$ long and flat, round, s3uare

- ris of damage$ fragile, brittle, sturdy

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onveyor 46

ontinuous production Single parts productionHigh volume production iscrete production

Aimited batches Ao" volume production4 large number of batches

%onorail rane #or truc


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- safety ris$ e+plosive, to+ic, corrosive- condition$ hot, "et, dirty, sticy

- ?ther factors- he 3uality of material to be removed (a dedicated system "ill be needed for large

3uality)

-he rate of flo" re3uired (a dedicated system "ill be re3uired for high rate of flo")

- he scheduling of the moves (continuous, in batch, or one at a time)- he route by "hich the materials are to be moved (the longer the distance, the greater

the cost)- %iscellaneous factors$

- government regulations- loading and unloading e3uipment- BB

(8) %aterial handling analysis- %anufacturing facilities may be layout in many different "ays. here is a topic of study,

called facility layout. Ho"ever, "e "ill not be able to study its details.

-In general, a layout should provide the follo"ing information$- Aocations "here materials must be piced out (loading stations)- Aocations "here materials must be delivered (unloading stations)- :ossible routes bet"een these locations- istances that must be traveled to move the materials- #lo" patterns, opportunities to combine deliveries, possible places "here congestion

might occur- otal area of the facility and areas "ithin specific departments in the layout- 4rrangement of e3uipment in the layout.

(/) %aterial handling e3uipment selection model- he basic mathematical model for material handling e3uipment selection is a

mathematical programming model.- 4ssuming that

- Me3uipment types are available,- #product moves are to be planned.- he unit load si!e is no"n for each part type- 4 factory layout is no".- Hence, the fre3uency and distance re3uired for each move, $,$C 1, B,#is no"n.

- he decision variables are$

=other"ise'

moveforusedistypee3uipmentif1 $i%i$

&iC number of units of e3uipment type iac3uired.- he cost factors$

- ci$C total variable operating cost per period for e3uipment type ito perform move$- iC fi+ed cost per unit-period for e3uipment type i- ti$C time per move for e3uipment ito perform move$- 'iC available time per unit-period for e3uipment type i

- he model$

= = =

+=M

i

#

$

#

iiii$i$ &%c

1 1 1

dcost7periomin

sub;ect to$

= =M

i

i$%1

1 , for all$

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=

#

$iii$i$ &'%t

1, for all(

%i$C D', 1E and &iis integer

- his is model is an integer programming model.

-4n e+ample- hree alternatives (pushcart, po"er truc, and conveyor) are being considered for si+

inter-department moves.- he move data and cost are as follo"s$

23uipment type

1 8 /

%ove c1$ t1$ c8$ t8$ c/$ t/$1 18FG.@ '.*8 G@'.' '.8@ F&'.' 1.'8 8GF'.' 1.5' 1///./ '.5' /G''.' 1.'

/ 8GF.' '.15 /8'.' '.18 /85.' 1.'@ /*5.8 '.81 1FG.* '.'* 18''.' 1.'5 8GF.' '.15 1//./ '.'5 1'5'.' 1.'G G/@.8 './G /8'.' '.18 &&&&.' 1.'

i *5.' /F&.5 '

- ote that since the conveyor are fi+ed, its time is fi+ed 1 indicating. Ho"ever, itcannot be used for more than one point-to-point move. So, for move G, the cost is setto very large.

- =sing the data above, the optimi!ation model becomes$

min 18FG.@%11 8GF'.'%18 B &&&&.'%/G *5.'&1 /F&.5&8s.t. %11%81%/1C 1

)

%G1%G8%G/C 1

'.*8%11 1.5%18 '.15%1/ '.81%1@ '.15%15 './G%1G&1

'.8@%81 '.5'%88 '.18%8/ '.'*%8@ '.'5%85 '.18%8G&8

- Solving this optimi!ation problem resulting in$x81Cx88Cx8@Cx85Cx8GCx//C 1, &8C 1.

"ith all other variables e3ual to !ero. his indicates that "e shall purchase a conveyor formove / and lift trucs for the rest moves. he total cost is //8*.F/.(@) 4 modified model- he model presented above is an integer programming model, "hich is difficult to solve

(%4A49 does not support that). herefore, the follo"ing modification is introduced.- he modification is to allo" the model solution, &i, to tae fractions ("hich means the

number of e3uipment purchased "ill have to round up to nears integer).- Aet$

i

#

$

i$i$

i'

%t

&

== 1

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#ig. /$ Single-direction conveyor

-he time re3uired to move the carrier from the load station to the unload station is$

'lC"d- +c.

-he carrier flo" rate cannot be greater than the reciprocal of the loading time, that is$

"c

c

'S

+ 1

"here, Scis the spacing bet"een the carriers.

-he time re3uired to unload the carrier, 'u, must be less than or e3ual to the loading timeMor the conveyor must be slo" do"n

-If each carrier holds npparts, the flo" rate of the parts "ill be$

l

p

c

cpf

'

n

S

+n, =

-he single-direction conveyor has a relatively high efficiency since there "ill be no trafficcongestion along the conveyor, and conveyor does not stop for loading and unloading.

-Ho"ever, it also has the least fle+ibility.

(5) ontinuous loop conveyor

-omparing to the single-direction conveyor, the continuous loop conveyor has a returnloop as sho"n in #igure @.

#ig. @$ ontinuous loop conveyor

-4ssuming that

-he spacing bet"een the carriers is Sc

-2ach carrier holds npparts

- he length of delivery loop is"d-

he length of return loop is"e

5-*

Aoad

station

=nload

station

"d

onveyor path

+c

Aoadstation

=nloadstation

elivery loop

+c

eturn loop


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#ig. 5$ an e+ample of "orstation layout

able 1$ #rom-to chart sho"ing the flo" rate (number of deliveries re3uired in unit time)bet"een different stations

o

#rom 1 8 / @ 5

1 ' & 5 G '8 ' ' ' ' &/ ' ' ' 8 /@ ' ' ' ' F5 ' ' ' ' '

able 8$ #rom-to chart sho"ing the distances bet"een different stations (4 indicates that thedistances are not applicable to this layout)

o

#rom 1 8 / @ 5

1 ' 8'' @'' *'' 48 4 ' 4 4 /''/ 4 4 ' /'' G''@ 4 4 4 ' /''5 1'' 4 4 4 '

- 9ased on the from-to chart, "e can find the so-called transport "or, '.$

'.C,f"d

"here,,frepresents the flo" rate (piece 7 hour) and"drepresents the length of delivery- 4ggregate the transport "or for all the deliveries, "e obtain the total transport "or,

''.$

'.C ,f"d

-#or e+ample above, the '.s are sho"n in a flo" diagram as sho"n in #igure / and the''.is$

''.C &N8'' 5N@'' GN*''' 8N/'' &N/'' /NG'' FN/'' C 15,5''

5-&

Station 1

Station /

Station 8 Station 5

Station @

Aoading duc


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#ig.G$the

flo"

diagram corresponding to the e+ample$ nodes represent loading and unloading "orstationsand arro"s "ith number represent indicate the material flo" rate

-In practice, the actual O is usually higher because of the losses during the operations.In fact, the total amount of time for material handling include$

-he time of the delivery$ ("d7 +c), "here,"dis the distance bet"een the origination tothe destination, and +cis the speed of the material handling system.

-he time of loading and unloading, 'h.

-he time of empty travel, ("e7 +c), "here,"eis the distance of the empty move.

-he time traffic factor,Eh.

-Hence, "e can define an efficiency measure$

thcecd

cdh F

'+"+"

+"E

++=

-he re3uired handling system capability is$

hm

E

''. =

Ohen there are npparts are needed to handle, the re3uired handling system capability is$

hpm

En

''. =

-ote that in the above study, the "orstation layout and the material delivery paths arefi+ed. o design a better "orstation layout and 7 or a material delivery path, "e must use

the group techni3ues described in hapter G.-

he te+tboo presents another formal, "hich "ill be discussed in the tutorial.

5.G 4utomated Storage and etrieve Systems(1) 4lthough many manufacturing companies are driving for the so-called Pust-In-ime (PI)

manufacturing ("hich "ill be discussed in hapter *), it is inevitable that the materialshave to be stoced or stored for use. herefore, there are "arehouses, and automatedstorage and retrieve systems (4S7S) in various level.

(8) In a "arehouse, many activities may occur as sho"n belo"$

able /$ Oarehouse facilities and activities

#acilities 4ctivitiesStorage racs 7 slots Storage

5-1'

1

8

/

@

5

G

&5

&

/8

F


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13/15


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in other "ords, :roduct 8 is most important follo"ed by :roduct / and then 1.Step /$ assign :roduct 8 to the best 48 C 5 position, follo"ed by :roduct / and 1. he

unassigned position is mared as Q6R (vacancy). he final result is sho"n inthe table above.

(G) Aocation assignment L open storage

- he location assignment in open storage (also called random storage) is made possible bythe use of computers

-he space re3uirement calculation is the same as that of the dedicated storage

-Since the parts "ould be randomly stored, there is no need for the location assignment.

-Oe can calculate the e+pected stocing 7 retrieving time by averaging.

(*) :icing up the orders

-Suppose "e "ant to pic up an order consisting of ;ust 1 product, all "e have to do is toallocate the storage position and go there to pic it up.

-Ho"ever, suppose "e "ant to pic up an order consisting of nproducts stored in ndifferent places, then it is difficult to find the optimal solution. In fact, it is e3uivalent tothe travel salesman problem. It is called :-incomplete problem and "e cannot find the

optimal solution "hen nis large. 9ut, as you can image, a simple sub-optimal solution"ill do the ;ob ;ust fine.

-?ne of the simple methods for sub-optimal solution is the minimum distance algorithm asdemonstrated belo". Suppose there are n locations, and each location is mared by itscoordinate"i(x,y,z), iC 1, 8, B, n, and the picup list is mared by$

=other"ise1

locationfromuppic,edllproduct "inoif&&&&& iai

Step 1$ start from the initial "orstation (the loading 7 unloading doc), set it as the currentposition, c(x,y,z).

Step 8$ calculate the distances bet"een the current position to all the locationsM3iC c(x,y,z) L"i(x,y,z) ai, iC 1, 8, B, n.Step /$ add the location "hose distance is the minimum to the to go listStep @$ set the selected location as the current position, repeat Step 8 until all the locations are

searched.

-his algorithm is simple, and you may try a simple e+ample by yourself.

(F) 4utomated Storage 7 etrieval Systems (4S7S)

-4S7S is a basic component in "arehouse and modern manufacturing systems.

-In manufacturing systems, in addition to store and retrieve materials, 4S7S also carry ontransportation tass sending the parts to specific areas.

- here are several types of 4S7S-

=nit load 4S7S$ used to store and retrieve large or palleti!ed loads in standard si!econtainers and it is usually automatic (#igure *.* in the te+tboo)

-%iniload 4S7S$ used to small loads such as tools and supplies

-:erson on-board 4S7S$ a person rides "ith the S7 machines

-eep lane 4S7S$ a variation of unit load system for high density storage andretrieval and it usually has many racs in one lane

-he design of an 47S. In order to design a 47S system, follo"ing factors shall beconsidered

-he load si!es

-he dimensions of an individual storage space

- he number of storage spaces, note that$-

he F5 rule

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-It "ould be different for dedicated storage and random storage

-he system throughput and the number of 4S7S machines

-he si!e parameters of the space

-he number of ro"s, columns, layers, aisle, B

-he bay "idth, rac length, B

- ycle time-

=tili!ation of S7 machines

-hese factors can be 3uantitatively measured using simple calculations as sho"n in thee+amples in the te+tboo, "hich "ill be covered in the tutorial.

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Ch 5 Material Handling