-> DEF: definition of the physical oragnization of the factory:

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)

-> OBJ: create a CAD draqing of the factory layout.

Optimize the efficiency of meterial flows and the relation between productive areas (and non-productive areas)
The objective function:

f_i,j: material flow between two areas/shops i, j.
c_i,j: cost per unit of movements between two area/ shops i, j;
d_i,j: distance between two areas/ shops i,j.

❓Which are the element to be considered?

-> Comparing the lead time we can understand if a company is better than another, bacause is a matter of cost.

-> A good layout is a matter of the relationship between the areas.

Good relationship: e.g. maintanence office is near the job shop;
Negative relationship: e.g. have noisy machines near to the office.

-> We can decouple the production system in two part: the system and the product

Factory planning models framework:

LAYOUT DESIGN or FACTORY PLANNING: is the activity of defining a factory.

CAPACITY Design: is the act of defining the number of machiaries.

MATERIAL FLOW:

In the manufacturing cells we saw the material flow analysis.

LAYOUT:

-> Designing a system we should know:

How many machines,
How big is the material flow;

-> Layout can be designed with different techniques:

	Capacity	Material Flow	Layout
Stationary deterministic models	WorkLoad Analysis Linear programming	Mat. Flow Analysis Linear programming	Mat. Flow Analysis Linear programming
Stationary stochastic models	Queue network Markov models	Queue network Markov models	—
Dynamic deterministic models	Simulation DES	Simulation DES	Simulation DES
Dynamic stochastic models	Simulation DES	Simulation DES	Simulation DES

Planning Overview:

Identifies the main areas;
Decide where to put the machineries in these areas:

Models for FLP Analysis:

-> OBJ: formulate problems as objective functions with given constraints (linear programming models)

Rectilinear distance;

Euclidean distance;

Actual distance.

-> CONSTRAINTS: linear programming models

Phases of the project:

-> Using the systematic layout planning methodology of Richard Muther:

1.Product Analysis:

-> ABC Analysis on products supports strategic definition of factory layout;

Layout product oriented vs layout process oriented:

-> From To table or Origin Destination table:

Row: from row…
Colum: … to colum.

3.Relationship Analysis:

-> DEF RELATIONSHIP CHART: identifies the requirements of relation between shops (i.e. areas of activity) (between shop i and shop j).

-> Causes and importance of relations are identified by dedicated codes.

RELATION CHART

->The scale give us the information about how much is strong the relation and the code the type of relation.

4.Graph & Space Diagram:

-> DEF: the processes are converted into graph and in space diagram.

Space diagram is an initial layout: it results from converting the operations in the shops (area of activities) into the area correspondently required.

-> Areas should be adjusted and eventually relocated after verifying the available areas.

Heuristics Techniques for the solution search:

-> DEF: 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.

Seach of a good solution;
Automation of search VS nteractive search;

-> OBJ: produce a solution in reasonable time frame that is good enough for solving the problem at hand.

May produce result by themeselves or may be use in conjunciton with optimization algoritms to improve efficiency.

Heuristic MAT (Modular Allocation Technique):

-> Starting grom green field:

Steps:

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

3. DESIGN CRITERIA: shops with larger exchanged flow should be positioned one beside the other (to minimize operative costs):

4.Reflect on a different method and perspective (different from the heuristic MAT):

Computized Layout Technique:

-> HP:

Given space is rectangular shaped;
Every shop is either rectangular shaped or composed of rectangular pieces.

=> We shall discuss:

Layout improvement procedure (CRAFT) that attempts to find a better layout by pair-wise interchanges when a layout is given;
Layout construction procedure (ALDEP) that constructs a layout when there is no layout given.

CRAFT – Computersed Trelative Allocation of Facilities Technique

One of the first heuristic models;
Based on the minimization of moving cost among the shops;
Needs starting layout;
Working with the objective of which we try to minimize a cost.

-> Given:

Initial existing layout;
From-to table;
Costs of the movements;
Number of shops to be allocated and their constraints.

-> CRAFT need to have a starting layout:

25m: is the distance from 0 to 25 (X axes);
30m is the distance of A from 0 (Y axes).

-> 0 it’s in the bottom/ left side of the chart.

-> So we can build these tables:

-> And then compute…

=> Given a layout CRAFT first finds the total distance traveled and the total cost;

-> CRAFT attempts to improve layout by pair-wise interchanges:

If someone interchange results in some savings in the total distance traveled/ total cost, the interchange that saves the most (total distance traveled/ total cost) is selected;
While searching for the most savings, exact savings are not computed. At the stage, savings are computed assuming when shops are interchanged, centroids are ingerghanged too.

-> Interchanges can be done on 1 way, with shops that are next to themeselves (one side at least should be connected).

-> Down in the table there are the costs to pay for every exchange:

-> Sometimes an interchange result in a peculiar shape of a shop;

-> It is an improvement procedure, not a construction procedure;

-> Estimated cost reduction may not be obtained after interchange.

ALDEP – Automated Layout Design Program:

-> DEF: technique to create a layout

Is a construction procedure;
ALDEP doesn’t need any initial layout.
Constructs a layout when there is none.

-> GIVEN:

Size of facility;
Shops/ areas of activities;
Size of the shops/ areas of activities;
Prodimity relationships (activity relationship chart);
A sweep width (defined later).

-> We need other information:

-> STEPS:

Start to allocate the shops from the upper left corner of the facility;
The first shop is chosen at random (with different shop ALDEP find different layout for same problems).

To find the next shop to allocate find the shop that has the highest proximity rating with the dock area.

-> Storage area S has th highest proximity rating A with the dock area.

-> The storage area will be allocated next. It also needs 8 blocks.

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 adiacent 2 (= sweep width) columns on the right side and starts moving up.