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Determination of Number of Kanbans

Bhaskara PI semester PEST

National Institute of Engineering, Mysore-08

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SupplyingProcess

Assemblyprocess

part

Production Card

Finished parts

Store

Withdrawal Card

part

Kanban Information system

Kanban (pull) SystemWithdraw/Pull only what is neededReplenish what is withdrawn

Overall BenefitsPrevents overproductionReduces inventory

Fig.1. 2 kanban card information system10/22/2013 5:57 AM 2

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Kanban Information system

Fig.2. kanban card10/22/2013 5:57 AM 3

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Process of Kanban sizing

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Determine the daily demand

Calculate No. of kanban cards

or

quantity per kanban

Print Kanban

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Withdrawal Systems

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Withdrawal system

Constantquantity,

non constant cycle

Constant cycle,

non constant quantity

Constant cycle systemforsupplier kanbans

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Used within the plant

Shorter lead time

Improved processes

where,

S = safety co efficient (should not be less than 0.1)

C = container capacity

D = daily demand

lead time (days)= Tprocess+Twaiting+Tconveyance+Tkanban collecting

i). The constant quantity, non-constant cyclewithdrawal system

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Avg. D X lead time X (1+ S)

Total No. of kanbansC

economic lot size+ (D X S)Total No. of kanbansC

Larger lots

Smaller lots

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E.g.: 1. D=100

lead time=0.5 day

C=10

S=0.2

No. of kanban = [100*0.5*(1+0.2)]/10

= 6

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i). The constant quantity, non-constant cyclewithdrawal system.

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ii). The constant cycle, non-constant quantitywithdrawal system

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Kanban No. is fixed

Demand doubles then, only kanban circulation doubles

Quicker problem identification

D X (order cycle + lead time + safety period)

Total No. of kanbans C

Used within the plantRelatively larger lead time (process/conveyance)

Order quantity No. of kanban detached by regular collection X C

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ii). The constant cycle, non-constant quantitywithdrawal system.

E.g.: 2. D=500

order cycle= 0.2

lead time=0.5

Safety period=0.2

C=40

No. of kanban = [500* (0.2+0.5+0.2)]/40

= 11.25 ~ 12

Order quantity = 3 * 40

= 120

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iii). The constant withdrawal cycle system forSupplier kanbans

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100 1+ 2Total No. of kanbans [[1]] * 0.2

5 6

Total No. of kanbans 14

D 1+ conveyance intervalTotal No. of kanbans [[No. of days spent for conveyance]] *

C No. of convey/dayS

Used forSupplierkanbans

geographical distance

longer lead time

slightly varying quantity

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