IT M4 01 - Factory Layout Planning - September 25th PDF

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Factory Layout Planning

Prof. Luca Fumagalli

Integrated design process

Integrated design process

Layout of a production plant

Layout of a production plant

Layout of a production plant

Owo Voltapile

Officina

Area prepazaione fustelle

Taglio Stampa

Piegatrici

Finestr.

Stampa UV MP

Fustelle

Staccatura Piega incolla

PF

Factory planning models framework

Layout Planning of the production system and its layout

Planning of the handling system and layout Facility Layout Planning Material Handling System Design

Workload Balancing

Capacity

Factory Planning

Material Flow

Planning of the production system and handling system

Factory planning models framework

Stationary deterministic models Stationary stochastic models Dynamic deterministic models Dynamic stochastic models

Capacity WorkLoad Analysis Linear programming Queue network Markov models Simulation DES

Material Flow Mat. Flow Analysis Linear programming Queue network Markov models Simulation DES

Simulation DES

Simulation DES

Layout Mat. Flow Analysis Linear programming --Simulation DES Simulation DES

Factory Layout Planning (FLP) 

FLP consists in the definition of the physical organization of the factory  FLP concerns the search of the most efficient location of the shops (areas of activities) within a given building or area available in a building  Shops might have needs of space very different one from the other  The objective is the minimization of costs of «relation» between the shops, respecting plant constraints (facility physical structural constraints, building constraints, floor maximum load allowed, service infrastructures)



Results of FLP: CAD drawing of the factory layout

Factory Layout Planning (FLP)

General layout, with identification of location of each shop.

2

3

1 4

(a)

(b)

The drawing of the detailed layout in which the following elements are identified: exact position of the shops, structure of corridors/passages, exit and entry points, position of machine and workstations within the shops

Objectives of the FLP problem One of the traditional objective is to optimize the efficiency of material flows and the relation between productive areas (and non-productive areas). The FLP problem is multi-objective!

Objective Function:

min    ( f ij  cij )  d ij  (1   )  rij  xij i

j

– fi,j = material flow between two areas/shops i,j – ci,j = cost per unit of movements between two areas/shops i,j – di,j = distance between two areas/shops i,j

i

j

Models for FLP analysis

Formulate the problem as objective functions with given constraints (linear programming models). Objective function min   ( fij  cij ) dij i

j

– Rectilinear distance – Euclidean distance – Actual distance

Models for FLP analysis Formulate the problem as objective functions with given constraints (linear programming models) Constraints (Example) li  xi  L - li wi  yi  W - wi lbi  2li  ubi lbi  2wi  ubi ...

i i i i

- xi, yi = coordinate of barycentre of the shop i - L, W = geometric dimensions of the building - l i and wi = geometric dimensions of shop i - ubi and lbi = max geometric dimension of shop i (orientation of the shop) ...

FLP Methodology: phases of the project 

Systematic Layout Planning Methodology (Richard Muther)

Analysis

Analysis of products

Analysis of material flows

Analysis of relations between activities

Other needs / constraints Definition of Factory Layout

Evaluation of alternative solutions

Design

Bulding of the graph Alternative solutions evaluation/assessment Areas needed

Areas available

Space diagram definition

Evaluation of alternative solutions

Product analysis 

ABC analysis on products supports strategic definition of factory layout  layout product oriented vs. layout process oriented

LINES

CELLS JOB-SHOP

Mmaterial flow analysis

20

Shop B

100

Shop C

200

50 150

,,, Shop Z

,,,

Sjhop Z

C

B

Shop A

Shop

From to

Shop

A

The flow diagram allows to identify the requirements for movement between shops  from technology diagram (families of) of products to origin/destination matrix of flows

Shop



180

300

fij * cij fij * pij fij

Product and material flow analysis 

Example for high volumes products Main material flow branch Press 1

Form Cutter 1 LINES

Form Cutter 3 CELLS JOB-SHOP

Grinding machine 1

Paint shop Assembly

Store Input

Graph and space diagram

Graph method

Space diagram method

Graph and space diagram

Factory layout drawing Example of CAD factory layout with identification of shops with high density of flows

Tip: shops with high density of flows should be put one close to the other

FLP Methodology: Relationship analysis The method of “Relationship Chart” identify the requirements of «relation» between shops (areas of activity) (between shop i and shop j)  causes and importance of relations are identified by dedicated codes

Scale

Shop A

A E I O U X

Shop B Shop C Shop D

...

rij (A, E, I, O, U,X)

100 50 20 10 0 -50

... ... ... Shop W Shop Z

1 2 3 4 … …

Code Supervision Sharing of tools Division Vibration

Flow analysis vs Relationship analysis

Flow Diagram

Relative importance of procedure analysis

R

A

Large volumes and/or big products

B

Defined and well established flows

C

Shops or offices with high diversity of product (repairing shops, etc.)

D

Office layout

Rel chart

Work characteristics

min    ( f ij  cij )  d ij  (1   )  rij  x ij i

j

i

j

Methods and criteria for FLP planning  Heuristic

techniques for the solution search

Search of a «good» solution Automation of the search vs. interactive search

Objective function

Solutions

Heuristic 

In computer science, artificial intelligence, and mathematical optimization, a heuristic is a technique designed for solving a problem more quickly when classic methods are too slow, or for finding an approximate solution when classic methods fail to find any exact solution. This is achieved by trading optimality, completeness, accuracy, or precision for speed. In a way, it can be considered a shortcut.



The objective of a heuristic is to produce a solution in a reasonable time frame that is good enough for solving the problem at hand. This solution may not be the best of all the actual solutions to this problem, or it may simply approximate the exact solution. But it is still valuable because finding it does not require a prohibitively long time.



Heuristics may produce results by themselves, or they may be used in conjunction with optimization algorithms to improve their efficiency (e.g., they may be used to generate good seed values).

(Wikipedia definition)

Methods and criteria for FLP planning Heuristic MAT (Modular Allocation Technique) – starting from green field Objective function min    ( f ij  cij )  d ij  (1  )  rij  x ij i

j

i

WH finished

POS.1

POS.3

WH raw

POS.2

POS.4

j

Input data Weight of relations between shops WH raw material WH raw Shop - R1 R2 R3 R4 WH finished

fij

Origin/Destination matrix R1 R2 R3 275 225 200

R4

WH finished product 50 25 200 50

Methods and criteria for FLP planning Heuristic MAT • •

Order couple of positions with growing distance Order of couple of shops with decreasing flow

Flow order (MAT) WH raw R1 R1 R2 R2 R3 R3 WH finished R1 R4 R4 WH finished R2 WH finished

275 225 200 200 50 50 25

Linear distance

WH finished

POS.1

POS.3

WH raw

POS.2

POS.4

Methods and criteria for FLP planning Heuristic MAT Flow order (MAT) WH raw R1 R1 R2 R2 R3 R3 WH finished R1 R4 R4 WH finished R2 WH finished

275 225 200 200 50 50 25

Design criteria •

Shops with larger exhanged flow should be positioned one beside the other (to minimize operative costs)

WH finished

POS.1

POS.3

WH finished

R2

POS.3

WH raw

R1

POS.4

WH raw

R1

R2

Methods and criteria for FLP planning U layout

«Linear» layout

WH finished

POS.1

REP.R3

WH finished

REP.R3

POS.3

WH raw

REP.R1

REP.R2

WH raw

REP.R1

REP.R2

Computerized Layout Technique 

Suppose that we are given some space for some departments. How shall we arrange the departments within the given space?



We shall assume that the given space is rectangular shaped and every department is either rectangular shaped or composed of rectangular pieces.



We shall discuss:  a layout improvement procedure, CRAFT, that attempts to find a better layout by pair-wise interchanges when a layout is given and  a layout construction procedure, ALDEP, that constructs a layout when there is no layout given.

Methods and criteria for FLP planning Heuristic

• • •

CRAFT

(Computerized Technique)

Relative

Allocation

of

Facilities

Starting with an existing layout Matrix to exchange position of shops Evaluation of cost of the exchange of position (difference of objective function)

WH finished

WH raw

REP.R2

REP.R1

REP.R3

REP.R4

WH raw R1 R2 R3 R4 WH fin

WH raw 0

R1 Diff. F.o. 0

Matrix R2 Diff. F.o. Diff. F.o. 0

R3 Diff. F.o. Diff. F.o. Diff. F.o. 0

R4 Diff. F.o. Diff. F.o. Diff. F.o. Diff. F.o. 0

WH fin Diff. F.o. Diff. F.o. Diff. F.o. Diff. F.o. Diff. F.o. 0

CRAFT  CRAFT

is one of the first heuristic models (Computerised Relative Allocation of Facilities Technique)

 It

is based on the minimization of moving cost among the departments

 It

needs a starting layout

CRAFT  Input

Initial Layout From-to table Cost of the movements Number of departments to be allocated and their constrains

CRAFT 50 (m)

A

20

30

(25, 30)

B (65, 30)

20

C

D

40

40

CRAFT

Centroid-based distances dAB = |xA, xB| + |yA, yB| = |25 - 65| = 40

From-to table (z = trips/day)

A A

From-to table for single movement (meters/trip))

A

B

C

D

40

25

55

65

25

B

C

D

2

4

4

A

1

3

B

40

2

C

25

65

D

55

25

B

1

C

2

1

D

4

1

0

40 40

CRAFT

From-to table for movement costs (€/meter)

A A

From-to table for the total costs (€)

1 €/metro

A

B

B

C

D

A

1

1

1

B

40

1

1

C

50

65

1

D

220

25

0

Tot

310

170

165

B

1

C

1

1

D

1

1

1

80

C

D

100 220 65

Tot

400

75

180

80

195

245

375

1020

CRAFT 

Given a layout, CRAFT first finds the total distance traveled as illustrated on the previous slides



CRAFT then attempts to improve the layout by pair-wise interchanges  If some interchange results some savings in the total distance traveled, the interchange that saves the most (total distance traveled) is selected  While searching for the most savings, exact savings are not computed. At the search stage, savings are computed assuming when departments are interchanged, centroids are interchanged too. This assumption does not give the exact savings, but approximate savings only



Interchanges can be done on 1 way, with departments of that are next to themselves (one side at least should be connected)

CRAFT 

Le’s change A with B  New distances

New total cost (€)

A d

A

A

B

C

B

C

D

A

40

65

25

B

40

25

55

C

130

25

40

D

100

55

0

Tot

270

160

285

B

40

C

65

25

D

25

55

40

80

D

260 100 25

Tot

440

165

230

80

235

155

345

1060

CRAFT

Possibile exchanges in the initial layout

New total layout cost

A with B

1.060

A with C

955

A with D

1.095

B with C

This is not possibile, since B is not next to C in the original layout

B with D

945

C with D

1.040

CRAFT 50

D

A

20

20

30

C

40

B

30 39

CRAFT  Sometimes,

an interchange may result in a peculiar shape of a department; a shape that is composed of some rectangular pieces

 An

improvement procedure, not a construction procedure

 Estimated

cost reduction may not be obtained after interchange

ALDEP - Automated Layout Design Program  While

CRAFT is an improvement procedure, ALDEP is a construction procedure

 CRAFT

requires an initial layout, which is improved by CRAFT

 ALDEP

does not need any initial layout

 ALDEP

constructs a layout when there is none

ALDEP  Given:

Size of the facility The departments/shops Size of the departments/shops Proximity relationships (activity relationship chart) and A sweep width (defined later)

 ALDEP

constructs a layout

ALDEP 

The size of the facility and the size of the departments are expressed in terms of blocks.



The procedure will be explained with an example. Suppose that the facility is 8 blocks (horizontal)  6 block (vertical).



The departments and the required number of blocks are:  Production area 14 blocks  Office rooms

10

 Storage area

8

 Dock area

8

 Locker room

4

 Tool room

4

ALDEP A: absolutely necessary E: especially important I: important O: ordinarily important U: unimportant Production X: undesirable

area

Office rooms

O A U

I O

Storage A Dock area

X U

U U

U O

O

Locker room Tool room

E

A

ALDEP 

ALDEP starts to allocate the departments from the upper left corner of the facility. The first department is chosen at random. By starting with a different department, ALDEP can find a different layout for the same problem.

 Let’s start with dock rooms (D). On the upper left corner 8 blocks must be allocated for the dock area.  The sweep width defines the width in number of blocks. Let sweep width = 2. Then, dock area will be allocated 2  4 = 8 blocks.

D D D D

D D D D

ALDEP 

To find the next department to allocate, find the department that has the highest proximity rating with the dock area. Storage area (S) has the highest proximity rating A with the dock area.



So, the storage area will be allocated next. The storage area also needs 8 blocks.

 There are only 2 2 = 4 blocks, remaining below dock area (D). After allocating 4 blocks, the down wall is hit after which further allocation will be made on the adjacent 2 (=sweep width) columns and moving upwards.

D D D D S S

D D D D S S S S S S

ALDEP 

See carefully that the allocation started from the upper left corner and started to move downward with an width of 2 (=sweep width) blocks.

After the down wall is hit, the allocation continues on the adjacent 2 (=sweep width) columns on the right side and starts moving up. D D D D  This zig-zag pattern will continue. D D  Next time, when the top wall will be hit, D D the allocation will continue on the adjacent 2 (=sweep width) columns on S S S S the right side and starts moving down. S S S S



Computer-assisted layout using CAD

Centroidbased distances

Computer-assisted layout using CAD

Corridors-based distances

Computer-assisted layout ...