288064948-Chapter-9-Solutions.doc

CHAPTER 9 DISCUSSION QUESTIONS 4.

(a )

(b) (b)

$.

(a )

(b) (b)

The advantages of a product layout  are:  are: The use of special purpose equipment can make the th e overall process more efficient efficient n Individual workloads can usually be made to be relatively equivalent n It usually results in low variable cost per unit n It tends to keep material handling costs relatively relatively low n It reduces workinprocess inventories n It makes training and supervision easier than with other layout strategies n The The dis disad adv vanta antage gess ar are: !igh volume is required because of the large investment needed to setup t he process n "ork stoppage at any point ties up the whole operation n There is a lack of fle#ibility fle#ibility in handling a variety of products or production rates n The advantages of a process layout  are:  are: It can simultaneously handle a wide variety of products or services% services% especially in terms n of &batches' or &ob lots' It has considerable fle#ibility with respect to equipment and labor assignments n The disa disadv dvant antag ages es of of a pro proce cess ss lay layou outt are: are: The use of general general purpose purpose rather than special special purpose equipment equipment tends to make the n overall process somewhat less efficient rders take more time and money to move through the system because of the difficult n scheduling% scheduling% setting up the process for a wide wide variety of orders% and considera considerable ble material handling *abor skill requirements tend to be high because of the use of general purpose n equipment "orkinprocess inventories tend to be high n

+.

The advantages of work cells are: cells are: ,eduction in workinprocess inventory n ,eduction in required floor space n ,educed raw material and finished goods inventory n ,educed direct labor cost n !eightened sense of employee participation n Increased utili-ation of equipment and machinery n ,educed investment in machinery and equipment n The disadvantages are: imilar to a product layout n !igh volume is required because of the large investment needed to setup t he process n There is a lack of fle#ibility fle#ibility in handling a variety of products or production rates n ,equires the use of group technology n ,equires a high level of training and fle#ibility fle#ibility on the part of employees employees n /ither /ither consi consider derabl ablee staff staff suppor supportt or imagina imaginativ tivee emplo employe yees es are needed needed for the initial initial n development of the work cells

01.

2 heuristic is heuristic is a &rule of thumb' method of problem solving. *ine balancing heuristics include: longest task time% most following tasks% ranked positional weights% shortest task time% and least number of following tasks.

END-OF-CHAPTER PROBLEMS 9.1

Chapter 9: Layout Strategy

Interstation Activity Matrix Pickup

Pickup

Veri fication

1

Class Cards C! $$6 866 6 6

of Status and Payment #! $6 6 1$6 6

Interstation #istance Matrix$%riginal &ayout Pickup Pickup Paperwork Advising Class and Forms Station Cards A! "! C! 3aperwork5orms (2) 6 <6 +6 2dvising (7) <6 6 <6 9lass 9ards (9) +6 <6 6 erification3ayment (;) =6 +6 <6

Verification of Status and Payment #! =6 +6 <6 6

3aperwork5orms (2) 2dvising (7) 9lass 9ards (9) erification3ayment (;)

Paperwork and Forms A! 6 8$6 6 6

Advising Station "! 4$6 6 6 6

&oad #istance 2  7: 4$6 ´ <6  0<%$66 2  9: $$6 ´ +6  <<%666 2  ;: $6 ´ =6  4%$66 7  2: 8$6 ´ <6  1%$66 7  9: 866 ´ <6  +%666 9  ;: 1$6 ´ <6  88%$66 >1%666

Initial layout:

2

'

7

9

;

 Instructor’s Solutions Manual t/a Operations Management 

Interstation #istance Matrix$Improved &ayout Pickup Pickup Paperwork Advising Class and Forms Station Cards A! "! C! 3aperwork5orms (2) 6 <6 <6 2dvising (7) <6 6 +6 9lass 9ards (9) <6 +6 6 erification3ayment (;) +6 =6 <6 &oad #istance 2  7: /?7/; /quation 4$6 ´ <6  2  9 : /?7/; /quation $$6 ´ <6  2  ;: /?7/; /quation $6 ´ +6  7  2: /?7/; /quation 8$6 ´ <6  7  9: /?7/; /quation 866 ´ +6  9  ;: /?7/; /quation 1$6 ´ <6 

Verification of Status and Payment #! +6 =6 <6 6

0<%$66

0+%$66

<%666

1%$66

08%666

88%$66

1$%666 Improved layout:

7

9.2

2

9

;

This matri# includes movements in both directions:

? " ; * @ 7

? A

Chapter 9: Layout Strategy

" 08$ A

; 1$ 6 A

* 6 1$ 6 A

@ $6 6 0$6 86 A

7 +6 6 86 6 6 A 

(

!ere are two optimal layouts: ,oom 0

,oom 8

,oom <

7

?

"

;

@

*

,oom 4

,oom $

,oom +

,oom 0

,oom 8

,oom <

"

?

7

*

@

;

,oom 4

,oom $

,oom +

or 

?  ": ?  ;: ?  @: ?  7: "  *: ;  @: ;  7: *  @:

9.3

08$ ´ 86  1$ ´ 46  $6 ´ 86  +6 ´ 86  1$ ´ 86  0$6 ´ 86  86 ´ 86  86 ´ 86 

Movement$#istance Calculations 8%$66 <%666 0%666 0%866 0%$66 <%666 466 466 0<%666 B ?inimum distance movement for both (symmetrical layouts)

9urrent layout:

/ntrance

0

/#am I

8

/#am II

<

Dray

4

*ab% /C@

$

.,.

+

,.,.

1

9asts

>

3atient movement B +%166 feet

)

 Instructor’s Solutions Manual t/a Operations Management 

Improved layout:

/ntrance

0

/#am I

8

*ab% /C@

$

.,.

+

/#am II

<

Dray

4

,.,.

1

9asts

>

3atient movement B 4%>66 feet (shown in 5igure =.01 of te#t) Improved layout:

/ntrance

0

/#am I

8

*ab% /C@

$

.,.

+

/#am II

<

Dray

4

9asts

>

,.,.

1

3atient movement B 4%166 feet ?ore improved layout (with /#am rooms swapped):

/ntrance

0

/#am II

<

*ab% /C@

$

.,.

+

/#am I

8

Dray

4

9asts

>

,.,.

1

3atient movement B 4%$66 feet  Eote that this final solution reflects &common sense%' or the result of oneFs intuition. "e simply allocate the spaces in the order in which the tasks are usually performed. "e usually start at the &entrance%' proceed to an e#amination roomG from the e#amination room% proceed for either # rays or lab tests% then (a) leave the facility% (b) go to get a cast put on% or (c) go for surgery.

Chapter 9: Layout Strategy

*

9.

*ayout 0:

,efrig. (0)

0 6 $ < < 6

0 8 < 4 $

9ounter  (8)

Trip ?atri# 8 < 4 > 0< 6 6 < < 08 6 4 6 6 6 > 4 06

ink  (<)

$ 6 > 6 $ 6

torage (4)

0 8 < 4 $

0 6 4 > 08 0+

tove ($)

;istance ?atri# 8 < 4 4 > 08 6 4 > 4 6 4 > 4 6 08 > 4

$ 0+ 08 > 4 6

  Tij ´ Dij  +66  with rooms fi#ed ($64% if not fi#edG $+6% if the sink is fi#ed in one location) *ayout 8:

ink  (<)

,efrig. (0)

0 8 < 4 $

0 6 $ < < 6

torage (4)

9ounter  (8)

Trip ?atri# 8 < 4 > 0< 6 6 < < 08 6 4 6 6 6 > 4 06

$ 6 > 6 $ 6

tove ($)

0 8 < 4 $

0 6 1 > 08 04

;istance ?atri# 8 < 4 1 > 08 6 $ + $ 6 4 + 4 6 1 = +

$ 04 1 = + 6

  Tij ´ Dij  +68  (if rooms are fi#edG $++ if notG and $=$ if sink is fi#ed at one location) 9.!

*ayout <:

,efrig. (0)

9ounter  (8)

ink  (<)

torage (4)

tove ($) Trip ?atri#

+

;istance ?atri#

 Instructor’s Solutions Manual t/a Operations Management 

0 8 < 4 $

0 6 $ < < 6

8 > 6 08 6 >

< 0< < 6 6 4

4 6 < 4 6 06

$ 6 > 6 $ 6

0 8 < 4 $

0 6 4 > 08 04

8 4 6 4 > 06

< > 4 6 < >

4 08 > < 6 4

$ 04 06 > 4 6

  Tij ´ Dij  $+4  (if rooms are fi#edG 414 if unfi#ed) 9." 

(a)

*ayout 4:

9ounter  (8)

ink  (<)

torage (4)

,efrig. (0)

0 8 < 4 $

tove ($)

0 6 $ < < 6

Trip ?atri# 8 < 4 > 0< 6 6 < < 08 6 4 6 6 6 > 4 06

$ 6 > 6 $ 6

0 8 < 4 $

0 6 $ > 00 0<

;istance ?atri# 8 < 4 $ > 00 6 4 > 4 6 4 > 4 6 00 > $

$ 0< 00 > $ 6

  Tij ´ Dij  +6=

Chapter 9: Layout Strategy

,

(b)

*ayout $

ref0 coun8 sink< stor4 stov$

Trip ?atri# 8 < 4 > 0< 6 6 < < 08 6 4 6 6 6 > 4 06

0 6 $ < < 6

$ 6 > 6 $ 6

ref0 coun8 sink< stor4 stov$

0 6 4 08 08 4

;istance ?atri# 8 < 4 4 08 08 6 < 4 < 6 4 4 4 6 4 4 <

$ 4 4 4 < 6

  Tij ´ Dij  41> olution: ,efrig in ,oom < (where sink was)G 9ounter in ,oom 4 (where storage was)G ink  in ,oom 8 (where counter was)G torage in ,oom 0 (where ,efrig was)G tove in ,oom $ (no change)

9.#  -ask 2 7 9 ; / 5

Performance -ime in minutes! 0 0 4 0 8 4 0<

466 minutes

(b)

9ycle time 

(c)

?inimum number of stations 

>6 units

(a)  (d)

-ask Must Follow -.is -ask   H  H  2% 7 7% 9 ; /

 $ minutes unit

 t i  0<  8.+  < stations 9T

$

Station '

(0) 7

(0) 2

Station )

(0) ;

(4) 9

(8) /

(4) 5

Station (

Station 1

(e)

/fficiency 

0< minutes 4 stations ´ $ minutes

 6. +$  +$J

?ultiple layouts are possible.

/

 Instructor’s Solutions Manual t/a Operations Management 

9.$

Performance -ime in minutes! 4 1 + $ + 1 > + 4=

-ask 2 7 9 ; / 5 @ !

-ask Must Follow -.is -ask   H  H  2% 7 9 ; / / 5% @

9ycle time  ?inimum number of stations 

4>6 minutes $6 units

 t i cycle time



 =.+ minutes

4= =.+

 $0 .  + stations

Station '

(1) 7

Station 1

Station )

Station *

Station ,

Station /

(4) 2

($) ;

(+) /

(1) 5

(+) !

(+) 9

(>) @

Station (

Station +

/fficiency 

4= minutes > stations ´ =.+ minutesK

 6+<> .

or /fficiency B +<.>J K

9.9

(a)

*ongest operation time

2

7

9

;

/

5

@ (b)

!

There are multiple alternatives. !ere is one that does not violate any procedures. Station 0

Chapter 9: Layout Strategy

-asks 2% ;

0

8 < 4 (c)

7% @ 9% 5 !% /

/ach alternative has an overall efficiency of =8.$J.

9.1% -ask  2 7 9 ; / 5 @ ! I L

Performance -ime in minutes! 0 < 8 4 0 < 8 $ 0 < 8$

-ask Must Follow -.is -ask  H  2 7 7 9% ; 2 5 @ /% ! I

9ycle time  ?inimum number of stations 

466 minutes +6 units

 t i cycle time



 +.+1  minutes unit

8$ +.+1

 <.1$ or 4 workstations

 Eote: 5our stations with a 1minute cycle time is possible. !owever% efficiency becomes 8$ 4´1

 >=
and production drops to $1 from the required +6 units. ne fivestation solution (there are multiple answers) is: Station '

(0) 2

(8) 9

(<) 7

(0) / (4) ;

Station 1

Station *

(<) 5

(0) I

(<) L

Station (

(8) @

($) ! Station )

Theoretical: /fficiency 

1

8$ minutes $ stations ´ +.+1 minutes

 6.14=  1$J

 Instructor’s Solutions Manual t/a Operations Management 

2ctual: /fficiency 

9.11

8$ minutes

Performance -ime in minutes! 0 0 8 0 < 0 0 8 0 0<

-ask  2 7 9 ; / 5 @ ! I

(0) 7

 6.><1  >4J

$ stations ´ +.66 minutes

-ask Must Follow -.is -ask  H  2 2 9 9 9 ;% /% 5 7 @% !

(8) !

Station (

(0) 2

(0) I

(0) ; (8) 9

Station '

(<) /

Station 1

(0) 5

/fficiency 

(0) @ Station *

Station )

0< minutes $ stations ´ <.<< minutes

 6.1>

or /fficiency B 1>J. ?ultiple layouts with this efficiency e#ist. 9.12

(a)

,esolving 3roblem =.00 with a production time of <66 minutes per day: 9ycle time  ?inimum number of stations 

Chapter 9: Layout Strategy

<66 minutes +6 units  t i cycle time



 $ minutes unit

0< $

 8.+ or < workstations

11

(0) 7

(8) !

(0) 2

(0) I

(0) ; (8) 9 (<) /

Station 1 Station '

(0) @ Station (

(0) 5 /fficiency 

0< minutes < stations ´ $ minutes

 6>+1 .

or /fficiency B >+.1J. ?ultiple layouts with this efficiency e#ist.

(b)

,esolving 3roblem =.00 with a production time of 466 minutes per day: 9ycle time  ?inimum number of stations 

466 minutes +6 units

 t i cycle time



(0) 7

 +.+1  minutes unit

0< +.+1$

 0.=$ or 8 workstations

(8) ! Station (

(0) 2

(0) I

(0) ; Station 1

(8) 9

(<) /

Station '

(0) @

(0) 5 /fficiency 

0< minutes < stations ´ +.+1 minutes

 6+4= .

or /fficiency B +4.=J. ?ultiple layouts with this efficiency e#ist. 9.13

utput 

operating time

9T min. cycle time B < minutes (2ctivity / time) 466  0<<<< .  or 0<< output  <

9.1 -ask 

1'

Performance -ime in minutes!

-ask Must Follow -.is -ask 

 Instructor’s Solutions Manual t/a Operations Management 

2 7 9 ; / 5 @ ! I L C * ?

6.0 6.0 6.0 6.8 6.0 6.8 6.0 6.0 6.8 6.0 6.8 6.8 6.0 0.> 9ycle time 

?inimum number of stations 

H 2 7 7 7 9% ;% / 2 @ ! I 5 L% C *

 

 

$ hours ´ $ days ´ +6 minutes hours <%666 bottles

 t i cycle time (6.0) /



0> . 6.$



0%$66 <666 %

B 6.$ minutes bottle

 <.+ or 4 workstations

Station (

Station )

(6.0) 2

(6.0) 7

(6.8) ;

(6.8) 5

(6.0) @

(6.8) *

(6.0) ?

(6.0) L

(6.0) 9

Station 1

(6.8) C 

(6.8) I (6.0) !

/fficiency 

Station '

0> . minutes 6.$ minutes ´ 4 stations

 6.=6

or /fficiency B =6J 9.1!

,esolving 3roblem =.04 with double the original demand: 9ycle time  ?inimum number of stations 

Chapter 9: Layout Strategy

$ hours ´ $ days ´ +6 minutes +%666 units

 t i cycle time



0> . 6.8$

 6.8$ minutes unit

 1.8 or > workstations

1(

Station +

(6.0) / Station 0

(6.0) 2

(6.0) 7

(6.8) ;

Station 1

(6.8) 5

Station '

(6.8) C 

Station ,

(6.0) 9

(6.8) *

Station /

(6.0) ? Station 1

(6.0) L

Station *

(6.8) I (6.0) @

(6.0) !

Station )

Station (

/fficiency 

0> . minutes 6.8$ minutes ´ 06 stations

 6.18

or /fficiency B 18J. ?ultiple layouts e#ist with the same efficiency.

9.1" 

Performance -ime in minutes! $ < 4 < + 0 4 8 8>

-ask  2 7 9 ; / 5 @ !

-ask Must Follow -.is -ask  H  2 7 7 9 9 ;% /% 5 @

?inimum number of stations 

 t i cycle time



8> 1

 4 workstations

The work activities may be grouped% however% into no fewer than five workstations without violating precedence requirements. (4) 9

Station )

Station 1

($) 2

(+) /

(<) 7

(0) Station ( 5

(4) @

(8) ! Station *

(<) ; Station '

1)

 Instructor’s Solutions Manual t/a Operations Management 

/fficiency 

8>



$´ 1

8> <$

 6.>6

or /fficiency B >6J everal other balances are also possible. ne of them is to place 2 alone% tasks 7 and 9 together% ; and 5 together% / by itself% and @ and ! together.

9.1#  -ask  2 7 9 ; / 5 @ ! I L C *

Performance -ime in minutes! 0< 4 06 06 + 08 $ + 1 $ 4 0$ =1

-ask Must Follow -.is -ask  H 2 7 H ; / / 5% @ ! ! I% L 9% C  

9ycle time  ?inimum number of stations 

8$%866 seconds 0%466 units

 t i cycle time



=1 0>

 

 

 0>  seconds unit  $.4 or + workstations

Station 1

Station +

(0<)

(4)

(06)

(0$)

2

7

9

*

(08) 5

Station )

(1) I

Station '

(06)

(+)

;

/

(+) !

Station (

(4) Station *

($)

($)

@

L

C 

Total idle time  00 seconds /fficiency 

Chapter 9: Layout Strategy

=1 seconds + stations ´ 0> seconds

 6>=> .

1*

or  /fficiency   >=>J . 9.1$

There are three alternatives: Station 0 8 < 4 $

Alternative 1 -asks Alternative ' -asks Alternative ( -asks 2% 7% 5 2% 7 2% 5% @ 9% ; 9% ; !% 7 / 5% @ 9% ; @% ! / / I !% I I

/ach alternative has an efficiency of >+.+1J. 9T 

1+

T ;emand

 implies < 

4>6 output

% so output



0+6

 Instructor’s Solutions Manual t/a Operations Management