6/3/2014 ieng 471 facilities planning 1 ieng 471 - lecture 04 - 3 schedule design: the sequels...

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06/17/22 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequel’s Sequel

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Page 1: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 1

IENG 471 - Lecture 04 - 3

Schedule Design:

The Sequel’s Sequel

Page 2: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 3

Assignments

Current Assignment: HW: (HW 3) See Assignment Link

required input for each of the workstationsequipment necessary for each machinesteady state cycle time for each machineideal machine assignment for each machinecompute the idle time unit cost at each workstationtotal cost per good unit square footage for each workstation and the total space required

We will use class time next period to work this problemSo sit with the people that you want to work with on this

assignment!

Page 3: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 4

Ex: Injection Mold Rubber Feet

We obtain one set of feet per cycle

Machine time is 35 s (steady state) after the operator starts the process

At the start of each cycle, the operator will spend 5 s unloading moldings from the machine and spraying release agent on the mold halves before starting a machine cycle

During automatic injection cycle, operator trims feet (15 s) and feeds re-grind & virgin material into machine hopper (10 s)

Page 4: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 5

Ideal Machine Assignment

Neglects idle time:

Where:a = concurrent activity time (both op & mach tied up)b = independent operator activity timet = independent machine activity time

)(

)('

ba

tan

Page 5: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 6

Cycle Time:

Cycle time (Tc):

Where:a = concurrent activity time (both op & mach tied up)b = independent operator activity timet = independent machine activity timem = number of identical machines assigned to op.n’ = ideal number of identical machines assigned to op.

')(

')(

nmbam

nmtaTc

Page 6: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 7

Idle Machine Time:

Idle time for machine (Im):

Where:a = concurrent activity time (both op & mach tied up)b = independent operator activity timet = independent machine activity timem = number of identical machines assigned to op.n’ = ideal number of identical machines assigned to op.

')(

'0

nmtaT

nmI

cm

Page 7: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 8

Idle Operator Time:

Idle time for operator (Io):

Where:a = concurrent activity time (both op & mach tied up)b = independent operator activity timet = independent machine activity timem = number of identical machines assigned to op.n’ = ideal number of identical machines assigned to op.

'0

')(

nm

nmbamTI co

Page 8: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 9

Total Cost per Unit:

Based on assigning m machines per operator, total cost (TC(m)) is:

Where:Co = cost per operator-hourCm = cost per machine-hour a = concurrent activity time (both operator & machine tied up) b = independent operator activity time t = independent machine activity time m = number of identical machines assigned to operator n’ = ideal number of identical machines assigned to operator

'))((

'))((

)(

nmbamCC

nmm

tamCCmTC

mo

mo

Add this to the material cost total from the BOM!

Page 9: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 10

Idle & Costing Example (cont.)

Assume t = 35sCase A: Operator is assigned 1 machineCase B: Operator is assigned 2 machinesCase C: Operator is assigned 1.3

machines

Page 10: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 11

Example: Ideal Machine Assign.

Neglecting idle time:

Where:a = 5s (load/unload)b = 15s (trimming) + 10s (feeding) = 25st = 40s (cycle time) – 5s (load/unload) = 35s

operatorpermachines

ba

tan

3.1

30

40

)255(

)355(

)(

)('

Page 11: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 12

Cycle Time: 1 Machine/Operator

Cycle time (Tc):

Where:a = 5sb = 25st = 35sm = 1n’ = 1.3

sssnmbam

nmtaTc 40)355(

')(

')(

M#1

Page 12: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 13

Cycle Time: 2 Machines/Operator

Cycle time (Tc):

Where:a = 5sb = 25st = 35sm = 2n’ = 1.3

sssnmbam

nmtaTc 60)255(2

')(

')(

M#2

M#1

Page 13: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 14

Cycle Time: 1.3 Machines/Operator

Cycle time (Tc):

Where:a = 5sb = 25st = 35sm = 1.3n’ = 1.3

sssnmbam

nmtaTc 40)355(

')(

')(

4 machines3 operators

M#3

M#1= 1.3

Page 14: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 15

Idle Machine Time: 1 Mach/Op

Idle time for machine (Im):

Where:a = 5sb = 25st = 35sm = 1n’ = 1.3

snmtaT

nmI

cm 0

')(

'0

M#1M#1

I’m faster than one machine, so the machine is always busy!

Page 15: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 16

Idle Machine Time: 2 Mach/Op

Idle time for machine (Im):

Where:a = 5sb = 25st = 35sm = 2n’ = 1.3

ssssnmtaT

nmI

cm 20)355(60

')(

'0

M#2

M#1I’m slower than two machines, so now I’m always busy!

Page 16: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 17

Idle Machine Time: 1.3 Mach/Op

Idle time for machine (Im):

Where:a = 5sb = 25st = 35sm = 1n’ = 1.3

snmtaT

nmI

cm 0

')(

'0

4 machines3 operators

M#3

M#1= 1.3

3 of us are just as fast as 4 machines, so everything is always busy!

Page 17: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 18

Idle & Costing Example (cont.)

Assume the Following Costs:Operator Wage = $15/hrOperator Overhead = 40%Electricity Cost/Machine = $6/hrMaintenance Cost/Machine = $1/hr

Computing the Cost per Unit Components:Co = Cost per Operator-Hour:

$15/hr + (.40)($15/hr) = $21/hr

Cm = Cost per Machine-Hour:$6/hr + $1/hr = $7/hr

Page 18: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 19

Total Cost per Unit:

Based on assigning 1 machine per operator:

Where:Co = cost per operator-hour

Cm = cost per machine-hour

'3600

1)255(

7$)1(

21$

???/$

'1

36001

)355(7$

)1(21$

)(

nms

hrss

hrhr

unit

nms

hrss

hrhr

mTC

Page 19: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 20

Total Cost per Unit:

Based on assigning 2 machines per operator:

Where:Co = cost per operator-hour

Cm = cost per machine-hour

'3600

1)255(

7$)2(

21$

???/$

'2

36001

)355(7$

)2(21$

)(

nms

hrss

hrhr

unit

nms

hrss

hrhr

mTC

Page 20: 6/3/2014 IENG 471 Facilities Planning 1 IENG 471 - Lecture 04 - 3 Schedule Design: The Sequels Sequel

04/10/23 IENG 471 Facilities Planning 21

Total Cost per Unit:

Based on assigning 1.3 machines per operator:

Where:Co = cost per operator-hour

Cm = cost per machine-hour

'3600

1)255(

7$)3.1(

21$

???/$

'3.1

36001

)355(7$

)3.1(21$

)(

nms

hrss

hrhr

unit

nms

hrss

hrhr

mTC