Part a – Layout Design
1. Introduction
1.1.
Production process concepts.
In dealing with the analysis and management of a production system, a “management engineer”
must be able to approach the following main problems:
1°. Analyze a manufacturing plant, where a production process is implemented in order to
manufacture one or more final products;
2°. Manage personnel and tool-machines that operate in the plant, respectively controlling and
executing production operations.
Typically, the number of types of production systems is so large that a selection has to be done: no
engineer neither any manager can be so able to really manage other than a specific type of
manufacturing plant.
Then, our approach will only deal with discrete production processes, that means processes dedicated to
final products in the sectors of: automotive, electronics, home fornitures, agro-food.
Before to start, two questions have to be considered:
1st question: what does it mean “plant”?
2nd question: what does it mean “process. Let us try to answer the first question, by looking at a real
industrial plant, illustrated by a map in the following Figure 1:
Any plant is a regular space where a number of tool machines, of different types, are located.
To understand the use of tool machines and their links, one needs to have an illustration of some
production flows, as in Figure 2:
Fig. 2. Some production flows showing the movements of parts from a machine to the following one.
This plant is is a department of a company whose production process produces special bolts for the safety
systems of car seats and for air bags, with cold pressing, using a stainless steel wire.
Having information of the production flows and of the final product to be manufactured, one can
understand the type of some tool machines, as shown in the following:
n. 1 - cold straightener (input stage)
n. 2 - eight ram press (rough component) as well as n. 3, 4, 5 – 6 & 7 (smaller), 18
n. 15 – steam cleaner as 14 & 16
n. 9 – rolling machine (roll forming of slots)
n. 10 – threading machine as 10, 1, 12, 13
Now, one can also have a more evident idea of the concept of “production flow”.
In Figure 2, the production flows are the paths along which the product components are moved from a
Tool machine (in the following denoted “resource”) to the downstream one, such that the production
process can be implemented.
Just as an example, in the Figure 2, the production process:
1. begins with the cutting of the stainless steel wire, obtaining rods of fixed length
2. then, the cold molding of the rod,
3. and then, the washing of the raw product,
4. the threading of the raw product,
5. the sandblasting of the threaded product,
6. the testing of dimensions and quality.
In our study of production processes, we will analyze simpler processes, in which the sequence of
production operations to be done in order to obtain the final product, could be performed by using simple
machining units.
A self-explained example of final product is the following “barbeque”…..
The formal and detailed description of the final product “barbeque” can be obtained ba giving a
representation of the product itself in terms of “product tree”, i.e. the organized set of components (inside
the blocks) and operations (connecting blocks), as shown in the following…
Finite product
(PF)
Plate bearing
(PA)
Grate
(GR)
Painted
legs (GV)
Painted side
panels (CG)
legs(G)
Side panels
(SF)
Steel bar
(P)
Sheet
(L)
The “Product tree”, as we will see in the following, is the detailed description of the transformation of raw
materials (in the case, Steel bar, Sheet, and a grate) into the finite product, through a number of
operations.
The complete description of all the operations required to manufacture the “barbeque” must be detailed
in a list, that can be fully understood if it is accompanied b y the list of “resources” where the production
operations (sometimes denoted also “functions”) have to be implemented.
n°
1
2
3
4
5
6
7
8
Production Function
Steel bar cutting
Sheet cutting
Legs painting
Side panels painting
Plate bearing assembling
Final assembling
Quality Control (QC)
Production Activity Control (PAC)
Resource
R1
R2
R3
R4
Task to be executed
Steel bar cutting
Sheet cutting
Painting
Assembling
Finally, the completion of the set of information describing the production process mus also take into
account the “personnel” who will be involved in either the execution of some production operations, or in
the control of the activities done by the resources. Do, the third list of data will contain the “agents”, that
means the types of personnel icharged of some production operations.
Agent
DM1
DM2
DM3
DM4
Duty assigned
Cutting
Painting
Assembly
QC & PAC
Type
LO
LO
LO
PAC
With responsibility on
Center (manufact)
Center (manufact)
Center (assembly)
System
Subordinated to
PAC
PAC
PAC
---
1st IMPORTANT REMARK: Note that an “agent” is NOT a person, but a qualification, that means a set of
operations (one or more) that a group of personnel is abilitated to execute.
In the following, we will see a set of standardized definitions of the introduced terminology.
Example for students: The final product (“abajour”) to be manufactured, its product tree, and the set of
data concerning production operations/functions, resources to be used, personnel to be involved:
Finite product
(PF)
Abatjour without
electrical circuit (BCF)
Lamp post
(BC)
Base
(C)
Switch
(E)
Rough
base
Electric circuit
(AD)
Stem
(B)
Wood rod
Lamp
shade
(F)
Wire
(D)
Lamp
holder (A)
The Data set of the Production Functions to be executed, Resources to be used, and Agents charged of the
work activities, for producing the “abajour”, are the following:
Agent
DM1
DM2
DM3
DM4
n°
1
2
3
4
5
6
7
Duty assigned
Wood cutting
and turning
Electic circuit
assembling
Final
assembling
QC & PAC
Type
LO
With responsibility on
Center (manufact)
Subordinated to
PAC
LO
Center (manufact)
PAC
LO
Center (assembly)
PAC
PAC
System
---
Production Function
Base cutting and turning
Stem cutting and turning
Lamp post assembling
Electric circuit assembling
Final assembling
Quality Control (QC)
Production Activity Control (PAC)
Resource
R1
R2
R3
R4
R5
Task to be executed
Base cutting and turning
Stem cutting and turning
Lamp post assembling
Electric circuit assembling
Final assembling
Application example: Students are required to analyze the final porduct and recognize, from the product
tree, how the production operations should be implemented. Then, they should also to verify the links
between the resources, and the attribution of tasks t o the agents.
Referring to the above example, the following table can give some help:
Example of simple production process data:
Object obtained
Material to be processed
by material removal
- Circular-section object
Wood or iron
& axis of rotation
- Plane object, with shape
Wood or iron
dug inside or modeled externally
-. Object with hole
Wood or iron
- Object with a cut part
Wood or iron
Object obtained by
Material to be processed
Material deformation
- Linear deformation
Iron
- Linear bending
Iron
Object obtained by
Material to be processed
material addition
- Welding (continuous,
Iron
spot, friction…)
- Bonding / Glueing
Wood
- Nailing
Wood
- Screwing up
Iron and wood
Production Operation
& Tool machine
Turning / Lathe
Milling/ Milling machine
Drilling/ drilling machine
Sawing/ Saw
Production operation
& Tool mach ine
Rolling/ Rolling mill
Bending / Bender
Assembing operation
Welder (electric, gas-using,
pression-based…
Glueing machine
Hammer and nails
Wrench
2nd IMPORTANT REMARK: How to estimate the machining time of a manufacturing unit: (this data should
be already known by students, from the course on “Integrated Manufacturing Processes”:
1) Turning t = L / (a * v)
L = length of the workpiece [mm]
a = tool feed [mm / revolution]
v = rotation speed of the work piece [revolution per minute = rpm]
2) Drilling t = p / (a * v)
p = depth of the hole
a = feed of the drill bit [mm/rev]
v = rotation speed of the drill bit [rpm ]
3) Milling t = L / va
L = length of the part to be milled [mm]
Va = feed of the milling cutter [mm/min]
4) Sawing → as milling
5) Bending t = fixed value, usually very short
6) Welding t = milling, with proper meaning
7) Bonding /Glueing t = above
8) Screwing up t = value depending on the screw lenght
1.2.
From the production process concepts to the performance evaluation needs
The three main phases of the analysis and management of a production system can be stated through
three words: ANALYZE – EVALUATE – MANAGE.
In principle, these three words define the both the type of models of a real system that any manager must
have , the ability to clearly recognize the reality, and the capability to select the most convenient planning
or control procedure. In practice, these three words gives us the possibility to “measure” a good manager.
Then:
a) ANALYZE …
a.1) the structure of a production process inside a plant, composed by resources (i.e. tool-machines)
a.2) and its management organization (links moving components of the final product from a resource to
a downstream one, i.e. production flows) , dedicated to manufacture a given final product;
a) EVALUATE--- the performance of the process (e.g. efficiency, effectiveness, economic
convenience…), by using data collected from resources and applying statistical procedures;
b) MANAGE… the production flows (physical movements of components from a resource to another)
and the internal orders, by applying “production planning and control” procedures.
Remark for students: pay attention to the bold terms !!!
Now the problem is to obtain a good definition of “performance analysis”, and to see how to obtain a
performance analysis evaluation.
The first idea is the following:
Assumimg to have a description of a production process, in terms of plant (good if the analyst is already
gifted with good experience) then, the meaning of “performance analysis” corresponds , In practice, to
one of the following actions:
➢ FIRST, identify the critical points of the production plant structure, through an accurate analysis
of the plant, the location of machining units, the links among them, and the production flows (as
we see in the first two Figures)
➢ THEN, evaluating if the production plant operations are performed at a good level of efficiency –
effectiveness – economic convenience.
Here you can have some “measures” of “performance evaluation” in case of a production process:
critical point == critical resource, critical path of products,… on which the production rates are strictly
conditioned.
efficiency = high utilization of resources
effectiveness = good satisfaction of the demand for products
economic convenience = high earnings from product market
Surely, these four “measures” are a good suggestion for the new analyst, but some more details are
necessary. That means to be informed of the relations between any “measure” and either the process
structure (the plant) or the process (production) operations.
This further information can be obtained by looking at this two aggregation of more detailed “measures”,
one related to the process structure, and the other to the process operations:
a) Plant Structure Evaluation (1° Part )
critical points ➔ “bottleneck” = production resource with the lowest rate
“critical path” = longest route of items from raw
materials to final products
“units’ line unbalancing” = different rates at prod. units
b) Performance Evaluation of the Plant Operations (2° Part)
ex. of KPI – Key Performance Indicators
- Throughput = n° of products per time-unit leaving the plant;
- Flow Time = time it takes an item to travel through the plant
- Utilization = fraction of time a plant is processing items
- Work In Process (WIP) = number of items in the plant
These more detailed “Measures of performance” are usually denoted – in any enterprise – Key
Performance Indicators – KPI.
Then, in practice, the evaluation of the performance should be done and reported in terms of values
measured for the considered KPIs.
In order to apply KPIs for performance evaluation, one have to do a sequence of steps as follows:
1° Step. describe the production operations and identify input & output (demand & supply),
2° Step. adopt a proper mathematical model of the manufacturing system
→ either structural or functional model
3° Step. estimate critical points, by analyzing the adopted mathematical model of the plant structure AND
the values of the Key Performance Indicators, by simulating that model
4° Step. compare the KPI estimated values with the expected ones, to evaluate if the manufacturing
system is operating well.
Intuitively, the critical point is the selection of a mathematical model of thep roduction process under
evaluation…
REMARK for students: We will have all the course time for learning how to select sufficiently good
mathematical model of production processes… Now we are only defining the basic concepts…
1° Step. describe the production operations and identify input & output (demand & supply),
By only considering basic concepts that can derive us from our small experience, we can say that:
A production system is a complex reality,
- made up by many “agents” (personnel) acting either inside and outside its socio-economic context,
- composed by a network of resources (“production units”),each one applying proper
technologies and controlled by one or more agents;
- and operating such as to satisfy demands (for products and work) from outside.
Then, when dealing with the first step of adopting/selecting a sufficiently good (i.e., able to give a good
description of the process), we have to take account of three typical aspects of a production system,
→ its Operational Structure (SO), likewise the production of goods and goods services furnishing,
→ its Organizational Arrangement (AO), that is the governance,
→ its Interaction with external Social-Economic Context (ICSE), that are the markets of goods and
services, but also with the labour market.
To simplify notations, in order to illustrate a general model of production process, the following notations
are used:
OS ➔ modeling the network of the production units, connected by production flows
OA ➔ modeling the network of the agents, each one with proper attributed production functions and
responsibility;
ISEE ➔ modeling the management of the dynamics of production loads (from suppliers) and flows (to
clients), up to final product delivery.
By using such notations, the general model of a production process can be illustrated as in Figure 3:
Demand of goods
Suppliers
Demand of work
OA
ISEE
New
Resources
Offered goods
Work
plans
OS
Offered resources
New Resources
Customers orders
Figure 3. Scheme of general
model of a production
process
The above sketched general model of a production process makes clear the three dimensions of the KPIbased evaluation of the performance of the modeled process, by focusing the three blocks that compose
any production process:
First: Analyze the constraints that manufacturing techniques and resources (blocks OS) needs to verify in
order t o produce goods and services, such as to identify critical points of the plant structure, which can
generate “bottlenecks”
Second: Analyze the constraints imposed by the management of personnel (OA) operating in the firm, in
order to identify if functions and responsibilities have been correctly attributed;
THIRD: Analyze the ability of the whole enterprise to respond to the demand dynamics (ISEE), in order to
evaluate if the balance of costs and income is assured properly.
2° Step. adopt a proper mathematical model of the manufacturing system
This second step will be widely discussed during the next lessons of the course.
Now, only a rough classification of models of production processes is presented, just to push students to
revise concepts already seen in previous courses.
Three basic types of mathematical models can be used for production process representation:
a)
Structural model. A typical example is a network of connections among resources: in theoretical
terms , a graph.
b) Evaluative model. Often this type refers to a statistical formula e.g. connecting the produced
volumes of final product with the time (regression line…)
c) Generative model. A typical example is the description of the change versus time of the level of
products stored in a buffer, at the output of a machining unit.
3° Step. estimate the values of the Key Performance Indicators, by analyzing the adopted mathematical
model
Also this third step will be widely discussed in the near future.
Now, some examples of KPIs could help the student to understand the types of evaluations that could be
done, by using the model – for instance, by simulating the production operations at every resource:
•
•
•
•
•
•
•
Count (Good or Bad): the amount of product produced. Important to evaluate the plant efficiency
Reject Ratio: bad products or parts to be rejected. Measure that the system is very critical
Rate: production speed of a machine.
Target: expected value for output, rate and quality.
CycleTime: the amount of time, or cycle time, for the completion of a task.
Overall Equipment Effectiveness (OEE): global resource utilization.
Downtime: the result of a breakdown or simply a machine changeover.
4° Step. compare the KPI estimated values with the expected ones
This last step requires to pay attention to the word “compare”… as you can see in the following three
possibilities:
First possibility: to do any comparison, one must have reliable values of the considered KPIs. To this aim,
one have to search and collect data…BUT: WHICH TYPE OF DATA????
Only PUBLIC data can be used to estimate target KPI. A possibility is to analyze web sites of an industrial
sector to which the production system under evaluation belongs: in this way, one can compute the
benchmark of the industrial sector to which the system pertains.
Second possibility: identify a production process of the same sector of the one under evaluation, as well as
of similar dimension, and try to collect the main data describing this process (that will be the best process
i.e. the benchmark for the evaluation).
Third possibility: use table of target KPI values, and apply them the comparison.
FINAL REMARK: at this point, we have seen all the basic introductory concepts.
========== &&& ==========
2. Introduction to the Analysis of the Operation Structure
The analysis of a production process develops in three phases:
1° PHASE= PRODUCT ANALYSIS: develop a model of a product , called product tree, specifying, for every
component of the product and for the final product, which group of simpler components is
needed to build it, and which operation is necessary for this purpose;
2° PHASE = PROCESS ANALYSIS: recognize, from the product tree, a model of the working and assembly
process called “working sequence”, pointing out on one side, a group of working and assembly
operations; on the other side, the sequence in the same operations; and finally the deployment
of some technological resources to perform such operations.
3° PHASE = LAYOUT ANALYSIS: consider the set of the technological resources, that should be used to
implement the requested Working Schedule, and formulate a Map of Resources, describing
the layout; in this way, you can recognize the organization of the technological resources
whose deployment would be finalized to perform the sequence of operations composing the
Working Schedule to do.
In terms of an IDEF0 scheme, the three phases can be illustrated by the following FIGURE 4:
This figure contains the three phases of the Analysis of the Operational Structure.
a. The Product Analysis must be based on the “customer needs”, that give to the process manager the
specifications of the desired product, in terms of the various “dimensions” of the product
performance. In addition, The Product Analysis must include an evaluation of the economic
constraints, that reflects on several process parameters : the raw material cost; the utilization cost
of the process; the personnel cost, etc.
b. The Process Analysis has to be based on the Product Tree, since the analyst must know the data on
production operations, on the resources to be used, and on the agents to be incharged of the
different operations and controls. The result of this Phase will be the “Working Sequence”, i.e. the
sequence of production operations to be performed, and the “Map of Resources”, that means the
connections of Resources together, showing how components and materials will be addressed
from a resource to the downstream one.
c. Finally, the Layout Analysis must give to the manager the possibility to evaluate the utilization of
the Production Plant, that means the organized set of Resources and their connecting links, from
which one cal estimate the Production Volumes (number of final products per unit time), together
with the Production Flows (frequency of completing Final Products).
This figure will also give us the sequence according to which the three basic analysis phases will be
approached in the following paragraphs.
Figure 4
Technological
constraints
Economic
constraints
Average
demand
estimates
Customer
needs
Product
Analysis
Map of
Resources
Product tree
(what must
be done)
Process
Analysis
Working Sequence
(how must be done)
Resources
Layout
Analysis
Flows & volumes
(how much)
. REMARK: Before to proceed, let us summarize the basic Definitions:
• Elementary Operations = basic operations contributing to a production activity, i.e. elementary
connection between two Components in the Product Tree
• Production Operation = A group of (or an individual) Elementary Operations, which are executed
in a Resource.
• Resource = a manufacturing or an assembling center, that performs one (or more) Production
Operations
• Agent = personnel with the duty of controlling/executing a Production Operation or of
managing/controlling other personnel.
• Agent’s Duty = set of Production Operations which execution can be controlled by an Agent
• Resource Task = set of Production Operations which can be executed by an individual Resource
• Working Sequence = table of sequences of the Production Operations for working a product,
• Layout = Graph of Resources, connected by physical links, which are trucks or conveyors that
carry pieces from one resource to the next
3. Analysis of the Product Tree
In this third Section we are going to analyze the model of a final product in terms of “graph” of its
components, and our goal is to obtain a formal model of the Product Tree:
a. in terms of a matrix that gives us a clear view about how any component, including the final
product, is obtained by the simpler components or by the raw materials, this matrix will be denoted
“Map of Operations”;
b. In terms of a graph that will illustrate us how any component is obtained by the simpler ones, thus
representing the Map of Operations in terms of the Graph of Components.
The structure of a Product can be represented by graph , where N points the nodes group, and A the set of
arcs (oriented links).
The Graph describing a Product is just the representation of the PRODUCT TREE.
The basic characteristics of a Product Tree are the following:
➔ A Product Tree has a unique Final Node, representing the Final Product, and a given number of
Initial Nodes, representing the Raw Materials or Basic Components, purchased from Suppliers.
➔ Each Internal Node is a Tree Component, produced by the Production System.
➔ Each Link is an Elementary Operation, to be applied to one simple Component such to produce – or
contribute to assemble - a more complex Component.
REMARK: Each Component can be obtained by applying one or more Elementary Operations, each one
being applied to a simpler Component.
In order to understand the concept and use of Product Tree, we can refer to an example already discussed:
the set of data specifying all information on the “abajour”.
Finite product
(PF)
Abatjour without
electrical circuit (BCF)
Lamp post
(BC)
Base
(C)
Switch
(E)
Rough
base
Electric circuit
(AD)
Stem
(B)
Wood rod
Lamp
shade
(F)
Wire
(D)
Lamp
holder (A)
Considering the Product Tree, it is possible to intuitively recognize the sequence of Production Operation
necessary to manufacture the Abajour
1st Prod. Operation Turning = Elementary Operation ➔ (a) Turning the base; (b) Turning the wood rod
2nd - Prod. Operation Assembling = Group of Elementary Operations ➔ assembling the lamp post
3rd - Prod. Operation Assembling = Group of Elementary Operations ➔ assembling the electric circuit
4th - Prod. Operation Assembling = Group of Elementary Operations ➔ assembling the abajour without the
electric circuit
th
5 - Prod. Operation Assembling = Group of Elementary Operations ➔ assembling the Final Product
What we have reported is a practical description on how to produce an abajour.
BUT now we need to… Translate this practical description into a Formal Model…
A formal representation of the Product Tree is provided by a Map of Elementary Operations.
By denoting with i and j two components of the product under examination, and with MOij the link
between them, the Map of Elementary Operations is described by:
MOij ➔ such that element (i,j) = 1 if the connection from i to j exists;
= 0, otherwise.
In theoretical terms, the matrix Moij is the “adiacency matrix” of the graph representing the product itself.
In a real firm, this description corresponds to a list of the components, structured in order to underline
their interactions, called Bill of Materials (BOM).
REMARK: We will see in the following how the BOM could be recognized by the Map of Elementary
Operations.
Now we have to compose the Map of Operations in terms of matrix.
To this aim, we will use the other example discussed in previous paragraph, that is the description of the
barbeque.
Finite product
(PF)
Plate bearing
(PA)
Grate
(GR)
Painted
legs (GV)
Painted side
panels (CG)
legs(G)
Side panels
(SF)
Steel bar
(P)
Sheet
(L)
The Map of Operations contained in the Product Tree of the barbeque must describe the graph of links
(Elementary Operations) connecting all Components.
Let us put a code “1” in each box <raw I; column j> of the matrix referred to the link between two
Components, as follows:
PF
PF
PA
GV
CG
G
SF
GR
P
L
PA
GV
CG
G
SF
GR
P
L
1
1
1
1
1
1
1
1
Looking at the Product Tree, you can see that the Final Product PF will be obtained by connecting
(“assembling”) the Plate Bearing PA with the Grate GR. In the Map of Operations, you will find code “1” in
the following boxes:
- The box referred to the line GR and column PF;
- The box referred to line PA and column PF.
REMARK: The student can complete the location of the other codes “1” in the other boxes, each one
referred to a link between a component and a simpler one (that in the Product Tree appears in a lower
level).
Now, based on the Map of Operations, one can transform the Map itself into a “Graph of Components”.
Indeed, a Product Tree can also be represented by a “traditional graph”, whose nodes correspond to
components, while arcs correspond to Elementary Operations.
The following Graph will be the second formal representation (model) of the Product Tree of the
“barbeque”, in the Figure 5.
P
G
GV
PA
L
GR
SF
CG
PF
VERY IMPORTANT REMARK:
Note that (as in the Product tree) an Elementary Operation can be:
- a manufacturing operation
(turning, cutting, milling...)
- One of the operations contributing to an assembling..
We can now summarize some intermediate preliminary results:
➢ A product tree is described by a graph in which only one (final) component exists without
downstream components (= the final product PF), as well as by a set of components without
upstream components (= the original raw materials).
➢ Any intermediate component is linked either to one lower-level component (i.e. the former is
obtained by manufacturing the latter), or to a set of lower-level components (the former is
obtained by assembling the latter ones): each link is an Elementary Operation.
➢ Then, a product tree is the graphical representation of all information describing a product: its
Components & the Elementary Operations that must be applied to manufacture the product itself.
➢ The Map of Operations is the table of: all Components of the product and all links existing among
them; this is the “adiacency matrix” of the Graph of Components, ordered from the Final Product
down to intermediate components, and then to the original “raw materials”.
The next step is to represent the Map of Operations by making evidence of the Elementary Operations.
Assign a number n=1,2,…,NO, as the index of each Elementary Operation, previously indicate with the
oriented pair (i,j).
In this way, the arcs of the graph in the previous Figure 5 will be numbered progressively, starting from
the final product (PF) and moving backward... up to the raw materials.
Figure 6.
8
6
4
P
G
GV
1
PA
7
PF
5
3
L
SF
CG
2
GR
The Map of Operations can be rewritten by including in each box, previously identified by a code “1”, the
number of the respective link, each number corresponding to an Elementary Operation:
PF
PF
PA
GV
CG
G
SF
GR
P
L
PA
GV
CG
G
SF
GR
P
L
1
4
3
6
5
2
8
7
As before, but now with a better evidence, you can see that three column do not include any number.
These column are referred to the three raw materials that the production process will receive from outside
(either the input storage of the enterprise, or from some supplier).
At the end of this Chapter, one problem remains open:
 how to recognize any precedence among two Elementary Operations ?
This problem will be approached in the next chapter.
========== &&& ==========
4. Organization of the Working Sequence
4.1. Preliminary considerations
In order to make the production process able to perform the necessary production operations to complete
a given product, one have to answer to the above question, that now will be reformulated as follows:
Given two work centers (resources), such that one will receive parts to be processed by itself from the
other, located upstream, the following situations could occur:
The work center under consideration will perform a production operation such that
➢ Either the part will be obtained by removing material or by deformation of its own shape,
that means trough a “Manufacturing Operation”;
➢ Or the part will be obtained by connecting itself with other parts, trough some devices (e.g.
bolts) or other material (e.g. glue), thus obtaining a new part including the one received by
the mentioned upstream work center and other work centers; that means trough an
“Assembling Operation”.
In the first case, a Manufacturing Operation will correspond to a unique connection between two
work centers, and then a Manufacturing Operation can be associated to an “Elementary
Operation”.
In the second case, an Assembing Operation will be viewed as set of links, each one starting from
an upstream work center and ending to the considered work center. Then, an Assembling
Operation must be associated to a set of Elementary Eperations. In this case, each Elementaru
Operation – in practice - corresponds to the transfer of a part from downstream to the Assembing
Center AND to the union of same part with the others, coming from different upstream work
centers.
This concepts of Manufacturing Operation and Assembling Operation are VERY IMPORTANT for the
definition of a Working Sequence.
4.2. Modelling a Working Sequence
In order to define a simple but comprehensive model of oa Working Sequence, we have to mode along two
phases:
Phase 1.
Move from the Product Tree to the Working Sequence concept, by using the procedure to recognize the
precedence first among the Elementary Operations, then among the Production Operations, each one
referred to a proper “Working Phase”.
Phase 2:
Represent the Working Sequence as the set of pairs <Production Operations; Work Phase>, such as to
generate the Working Sequence in the form of a Table of above pairs.
The two statements seem to be rather unclear ... but this depends on the two concepts that have yet to be
defined: Working Sequence and Working Phase.
Therefore we try to use the usual example: the barbeque, of which we remember the Product Tree.
Finite product
(PF)
Plate bearing
(PA)
Grate
(GR)
Painted
legs (GV)
Painted side
panels (CG)
legs(G)
Side panels
(SF)
Steel bar
(P)
Sheet
(L)
Then, Let us refer to the Product Tree of the “barbeque”, above reported.
Assign a number n=1,2,…,NO, as the index of each Elementary Operation, previously indicated with the
oriented couple (i,j).
In this way, the arcs of the graph in the following Figure 7 will be numbered progressively, starting from the
Final Product (PF) and moving backward.
8
6
4
P
G
GV
1
PA
7
PF
5
3
L
SF
CG
2
GR
Let us refer again to the above represented Product Tree of the “barbeque”.
As one can verify , most of the representations of the Product Tree of a discrete Production Product, In
general, are characterized as follows:
→ The Product Tree is a Graph defined by the set of pairs:
<Components=node; Elementary Operations =link>.
→ The Product Tree Graph is a “folding fan” of Paths.
- It means that, starting from the node associated to the Final Product, frequently some arrows –
directed to the Final Product node, comes from some Components; and the same happens for any
node internal to the Graph.
- By connecting a node with an upstream one and with the downstream node, one can obtain a Path:
each Path will be characterized by the following pattern: each Path will start from an Initial Node
and end to the Final Node.
→ Each Path is a sequence of :
- Components, with their own code = the Component name;
- Elementary Operations, with their own code = the Elementary Operation number
Let us refer again to the above represented Product Tree of the “barbeque”.
In general,
→ The Product Tree is a Graph of [Components=node; Elementary Operations =link].
→ The Product Tree Graph is a “folding fan” of Paths, each one starting from an Initial Node and ending to
the Final Node
→ Each Path is a sequence of :
- Components, with their own code = name;
- Elementary Operations, with their own code = number
Then, to find the Working Sequence, given the Product Tree, one have to perform the following steps:
Step 1: Recognize, by starting from one Initial Node (related to a raw material), the “Precedence Relations”
between each pair of Component Nodes, one after the other, utill to reach the Final Product node.
Then, put in the boxes of a raw of a matrix the code of each node, according to the sequence
previously recognized, starting from the final node and going back along the sequence (or Path
associated to the considered initial node)
The “Map of Paths” (MP) results, as you can see in the following matrix:
MP =
GR
PF
L
SF
CG
PA
PF
P
G
GV
PA
PF
REMARK:
- In the above Map of Paths, you can see three paths, starting from the three raw materials.
- Considering each consecutive pair of components (for example, <CG; PA> or <PA; PF>), each pair of
Components corresponds to an Elementary Operation, with the respective number in Figure 7.
Step 2: List all links, with thir own numbers, and associate to each link both the pair od Components,
connected by the link, and the link position in the Path to which it belongs.
The following Table of Paths will result:
LO =
n=1
n=2
n=3
n=4
n=5
n=6
n=7
n=8
Elementary
Operation
PA→ PF
GR→ PF
CG→PA
GV→PA
SG→CG
G→ GV
L→SF
P→G
Position in
the Path
4
4
3
3
2
2
1
1
Step 3: The position of a given Elementary Operation in its Path is denoted Work Phase:
LO =
n=1
n=2
n=3
n=4
n=5
n=6
n=7
n=8
Elementary
Operation
PA→ PF
GR→ PF
CG→PA
GV→PA
SG→CG
G→ GV
L→SF
P→G
Work
Phase
4
4
3
3
2
2
1
1
Step 4: Then, the pairs <Elementary Operation; Work Phase> is the basic element for a description of any
Work Path in the Tree Graph.
Step 5: All pairs <Elementary Operation; Work Phase> can be represented in a table with
as many lines as the Elementary Operations, and as many columns as the
Work Phases:
Elementary
Operation
n=1
n=2
n=3
n=4
n=5
n=6
n=7
n=8
Work Phases
1
2
3
4
PA→ PF
GR→ PF
CG→PA
GV→PA
SG→CG
G→ GV
L→SF
P→G
The obtained table is the Work Sequence of the Elementary Operations.
REMARK: The table above obtained is NOT a definite result, because it represent only sequences of
Elementary Operations.
In any enterprise, personnel could have a confused idea of “Elementary Operations”.
They have a clear idea of PRODUCTION OPERATIONS, that are the operations performed by working
machines and controlled by Line Operators.
Then, we have to translate this Preliminary Table into a form usable in the firm, where the enterprise
operators use the term “Production Operations”…
REMEMBER:
- Elementary Operation (EO) = elementary connection between two Components of a Product in the
Product Tree
- Production Operation (PO) = a group of Elementary Operations or a single Elementary Operation,
which can be really executed by a Resource.
Step 6. Having obtained the Work Sequence of Elementary Operations, now we have to derive the Work
Sequence of the Production Operations, by applying the following Points:
Point 6-a. In order to use a terminology that can be understood by industrial people, since, in a real plant,
the basic data is the Production Operations, the analyzer has to show the relations between the List of
Elementary Operations(EO) and the List of Production Operation (PO) through an EO-to-PO
Correspondence Matrix, as shown in the following Figure 8.
Figure 8.
E O (j)
PO(i)
EO-to-PO Correspondence Matrix CM s.t.
CM(i,j)= 1 if PO(i) includes EO(j)
It is not immediate to have clear the content of the EO-to-PO Correspondence Matix.
So, we will try to have a simpler view of this same matrix by considering – again – the example of the
barbeque.
- By the data set of the barbeque, we can see the list of Production Operations (see the list on the
left side).
- Given the product described by the Product Tree of the previous page, We remember the List of
Elementary Operations, including the EO numbers.
Production Operations
Code
Operation type
PO1
Steel Bar Cutting
PO2
Sheet Cutting
PO3
Legs Painting
PO4
Side Panel Painting
PO5
Plate Bearing Assembling
PO6
Final Assembling
PO7
Quality Control
PO8
PAC
Elementary Operations
Code Pair of Components
1
PA → PF
2
GR→ PF
3
CG→ PA
4
GV→PA
5
SG→CG
6
G→GV
7
L→SF
8
P→G
Now the next step is to create Matrix of Coppespondences among Production Operations and
Elementary Operations.
VERY IMPORTANT REMARK; To this aim, one has to look at the Graph of Elementary Operations and, FOR
EACH PAIR OF COMPONENTS, to RECOGNIZE which type of Production Operation has to be done in order
to manufacture the upstream Component such to obtain the downstream Component, of the pair
considered.
This is the typical basic reasoning of the engineer who is analyzing the Product Tree and its Graph model.
In simple terms, the above REMARK prescribes:
a. Either, to recognize the correspondence between an Elementary Operation and a Production
Operation, both referred to the same pair of Components,
b. Or, to recognize the correspondence between a Production Operation and a set of Elementary
Operations, the ones which contribute to the same Assembling Operation; in this case, a set of
pairs of Components are considered, all having the same downstream component.
The application of these prescriptions will generate the following Matrix of Coppespondences among
Production Operations and Elementary Operations.
:
Eos
POs
PO1
PO2
PO3
PO4
PO5
PO6
PO7
PO8
1
2
3
4
5
6
7
8
1
1
1
1
1
1
1
1
REMARK: In this matrix, you can find some charateristics:
a. No relation exists between the Quality Control Operation and any Elementary Operation, since
Quality Control is performed without any use of work machines.
b. The same happen for the Production Operation “PAC”.
c. The Assembing Operation numbered 6 in the left column is related to two Elementary Operations,
as shown by the Graph of Elementary Operations.
Point 6.b. By using this PO-vs-EO Correspondence Matrix, one can represent the Graph of Production
Operations (the “dual graph” w.r.t. the EO one), where
- each node is a Production Operation;
- each link is a Product Component
Figure 9: GRAPH OF PRODUCTION OPERATIONS
P
G
GV
3
1
PA
5
PF
6
SF
L
2
4
CG
GR
REMARK: This Graph of Production Operations is an important, even if not definite, Result, since
- Each node corresponds to a Production Operations, thus showing how any component will be
processed step by step, along a Path;
- Each link corresponds to a Production Flow, showing as parts are moved from a Production
Operation, once executed, to the next one, to be executed after the previous one.
Using the Graph of Production Operations, one can represent the Table of Production Operations versus
Work Phases, that is the Professional Work Sequence of Production Operations.
Production
Operations
Work Phases
1
2
3
4
PO1
PO2
PO3
PO4
PO5
PO6
Important Remarks related to the PO Graph and PO Work Sequence:
A) A Production Operation must be allocated in a unique Work Phase.
B) In case a same Production Operation must be performed to manufacture two different
Components, said Production Operation PO must be considered as “subdivided” into POa and
POb: each one for processing a Component.
Exercise for Students:
By using all data describing the Final Product “Abajour”,
5. Organization of the Plant Layout
5.1. Preliminary Considerations
IN order to obtain a complete formal – even graphical – description of the Plant Layout, one must
implement two further steps:
1s Step:
By using
- the Graph of Production Operations
- Professional Work Sequence of Production Operations
- the matrices describing the Product Tree
one has to transform the Graph of Production Operations into the Graph of Resources.
Rule to be used: Looking at the table “List of Resources” and considering one Resource,
one must recognize the correspondence between the Task of the
considered Resource and one or more Production Operations. All
recognized Production Operations - by such a correspondence – must be
assigned to the considered Resource.
Result: the obtained graph is denoted the Preliminary Layout.
Indeed, this graph will only show the links among the Resources, denoted Production Flows.
2nd Step:
Considering now the Preliminary Layout, for each Production Flow addressed to a Resource, one has to
EVALUATE if, for that Production Flow it is necessary to allocate at the Resource input, a BUFFER to store
parts arriving along the considered Production Flow, thus allowing the Resource to process parts without
“idle times” (i.e. stops due to lack of parts to be rocessed).
Rule to be used:
- In case of a pair of Resources, that means two Manufacturing Resources, the
downstream Resource needs to have an input buffer if its own Processing Time is
surely longer than the processing time of the upstream Resource.
- In case of an Assembling Resource, it needs to have one buffer for each Production
Flows addressed to itself.
5.2. Given the Product Tree and the Working Sequence, find the Graph of Resources
GIVEN the Data Set:
1) Map of Elementary Operations, MOp, which for every operation On/p points to the elements of the
product tree on which it operates (see Lect. 2)
2) Graph of the Production Operations, showing the precedence relations among POs (see Lect. 3)
3) Professional Work Sequence, i.e. The Table of all pairs <Production Operation; Work Phase>
4) List of Resources, each Resource able to execute a Task, which denotes either one or a set of
Production Operations, and it is defined “Resource Task”:
FIND:
→ the Network of Resources, that describes how resources (in a real plant, each Resource can be either
one machining unit, or a set of machining units or an assembling unit) are connected together by links =
Production Flows, where materials, parts, components flow from the input storage to the final product
storage.
A better understanding of these two steps – that are the “core” of the analysis of a Production Process
done by an engineer – we will use the example previously introduced: the production of the “abajour”,
according to the following sequence of points.
1st Point : represent the Product Tree and put in correspondence to each Production Operations
its own code….. And take account of the list of Production Operations.
Finite product
(PF)
Figure 10
PO5-b
Abatjour without
electrical circuit (BCF)
PO5-a
Lamp post
(BC)
PO3
Base
(C)
PO4
Stem
(B)
PO1
Switch
(E)
Electric circuit
(AD)
Rough
base
PO2
Wood rod
Lamp
shade
(F)
Wire
(D)
Lamp
holder (A)
Production Operations
Code
Operation type
PO1 Steel Bar Cutting
PO2 Sheet Cutting
PO3 Legs Painting
PO4 Side Panel Painting
PO5 Plate Bearing Assembling
PO6 Final Assembling
PO7 Quality Control
PO8 PAC
VERY IMPORTANT REMARK: Note that, as shown in Figure 10, a Production Operation
can be applied in two or more different steps (Production Phases) of the Work Sequence;
in this case the Production Operation (PO) must be decomposed in 2 (or more) POs, as
PO/a and PO/b, each one in a given phase.
2nd Point: By considering the above illustrated Product Tree and the “Graph of Production
Operations”, and noting –from the Product Tree - the necessity of duplicating some POs, the
following “Map of Production Operations” can be stated:
PF
PF
E
BCF
AD
BC
F
C
B
RB
WR
D
A
E
BCF
AD
BC
F
C
B
RB
WR
D
A
5/b
5/b
5/b
5/a
5/a
3
3
1
2
4
4
REMARK: The Map of Operations is a squared matrix with as many raws & columns as
the Product Components.
RULE: In boxes of this matrix, you have to allocate codes of the Production Operations,
depending on the information given by the Product Tree
Considering a column, referred to a given Product Component (for instance, BCF = Abajour without electric
circuit) , in some boxes you will find the codes of more than one Production Operations.
In case of Component BCF, two times the code 5-a, because said Component is obtain ed by the Assembling
Operation 5, applied to obtain the Component BCF by assembling Components BC = Lamp post and F =
Lamp shade).
NOTE THAT: the Production Operation 5 = Assembling will be used in two consecutive
assembling operations: the above considered, and the final assembling, i.e. the assembling
of the Final Product.
3rd Point: By using the above stated Map of Production Operations, the Graph of the Production
Operations can be represented, as in Figure 11.
RB
PO1
PO1
C
PO3
BC
WR
BCF
B
PO2
PO5/a
PF
PO5/b
F
D
AD
A
PO4
E
FIGURE 11: Note that that Production Operation F5 is subdivided into two Production Operations: F5/a and
F5/b, according to the Product Tree organization
3rd Point: Now the Map of Resources can be created, by using the tables of Production Operations
and of Resource Tasks, as well as the Map of Production Operations.
n°
1
2
3
4
5
6
7
Production Function
Operations PO1 to PO7
Production
Base cutting and turning
Stem cutting and turning
Lamp post assembling
Electric circuit assembling
Final assembling
Quality Control (QC)
Production Activity Control (PAC)
Resource
R1
R2
R3
R4
R5
Task to be executed
Base cutting and turning
Stem cutting and turning
Lamp post assembling
Electric circuit assembling
Final assembling
By using the Graph of Resources illustrated in Figure 11, one can associate to each Production Operation,
the Resource that will execute such a Production Operation.
As a consequence, to each Resource to one or more Product Components will be addressed and to each
Resource, one or more specific Production Operation will be assigned.
Then, by using the Map of Production Operations, the List of Production Operations and the List of Tasks, a
“Map of Resources” can be compiled:
PF
PF
E
BCF
AD
BC
F
C
B
RB
WR
D
A
E
BCF
AD
BC
F
C
B
RB
WR
D
A
R5
R5
R5
R5
R5
R3
R3
R1
R2
R4
R4
REMARK: This squared matrix exactly correspond to the previously created Map of Production Operations,
with the only substitutions in some matrix boxes the Production Operation with the Resoiurce
implementing said Production Operation.
5.3. Given the MAP and Graph of Resources, find the Preliminary Layout
The goal of this Section is to obtain a result of important practical utilization, namely a graphical
representation of the Layout of the Production Process under analysis.
Also for getting this result, we have to use some points.
Point A: By using the Graph of Production Operations, the previous Map of Resources can be transformed
into the Network of Resources, i.e. the Preliminary Layout
VERY IMPORTANT REMARK: Note that, in the Figure 12, Resource R5 includes the Production Operation
F5, that has been decoupled into two parts F5/a and F5/b, to be executed in different Phases
R1
RB
PO1
BCF
C
PO3
R
BC
R2
WR
B
PO2
PO5/a
PF
PO5/b
PO /b
R5
F
D
R4
AD
PO 4
A
FIGURE 12
E
E
Important General RULES for Layout organization:
Given the Graph of Resources (see previous Figure):
1) The Graph of Resources makes evidence of a number of Production Lines, each one
starting from the loading of a Raw Material (= basic component) on an Input Resource,
received by the enterprise input store or by a supplier.
2) A given Production Operation must be assigned to a unique Resource.
3) If a same Production Operation must be performed by two different Resources, either in
the same Production Line or in two different Production Lines, said Production
Operations must be duplicated.
4) If a same Production Operation must be performed in two different Work Phases, said
Production Operation must be duplicated.
5) If two (or more) Production Operations are assigned to the same Resource, the
Production Operations must be organized (and then, represented inside the Resource
image) depending on the way in which they must be executed: in series, if the output of
one Production Operation is used as input by the other Production Operation; in
parallel, if the two Production Operations have to process different Components.
5.4. Given the Preliminary Layout find the FINAL LAYOUT with Bufferized Resources
The completion of the Final Layout definition requires to develop two more Points:
1st Point: Given the Graph of Resources – i.e. the Preliminay Layout – allocate buffers to some Resources,
such to obtain the Bufferized Layout (Final version)
2nd Point: Recognize the Production Process elements which could be either Weakness or Strength
situations.
To perform these two Points, we have to refer to the Graph of Resources (the above illustrated Preliminary
Layout, in Figure 12, and to the Data-set of the Final Product, with the characterization of each Resource.
First Point: Criteria to recognize the utility of equipping a Resource with an input buffer:
a) If the Resource is an assembly center, to which two or more components have to be supplied;
b) If the Resource is either a machine-tool with long processing time, or a painting center for groups
of components;
c) If the Resource is an intermediate center in a process line, so that the input buffer located at that
Resource input could avoid blocking/starving situations
By applying these criteria, we can derive the Bufferized Layout from the Figure 12:
R1
RB
PO1
1
BCF
R3
C
PO3
R3
BC
R5
R2
WR
B
PO2
D
PF
PO5/a
R5/b
PO5/b
R4
AD
A
PO4
E
E
Figure 12
Second Point: Recognize situations of weakness and Strength.
Recognize points of strength and weakness” can be done by using some simple considerations, well
known from books of Productions Systems...
a. Nodes with a large number of incoming flows could be subjected
to congestion → potential bottlenecks.
b. Nodes dedicated to special operations (= long working time) could
induce unbalances in the work line.
c. Longer sequences of resources define the flow time of the plant
→ critical paths….
The effective recognition of critical points will be easily done having at disposal a specific example.
For instance, in case of the Production Process to manufacturing abajour, by Figure 12 one can recognize as
Bottleneck the Resource R5, owing to the number of assembling operations to be done.
6. Simplified Organization of the Information Pattern
As we have seen in the two maps of a real department of an enterprise, the usua evident representation of
the Production Process is given in terms of a Graph od Machining Units (Research) and of the links
connecting each pair of Resource, eventually equipped with an input buffer.
BUT the Production Operations in a plant can only be done if each Resource will receive, from the OA –
Organizational Arrangement, specific internal Production Orders – based on the requests of Customers.
The dissemination, inside the plant towards each Resource, of the internal Production Orders is done by
the Enterprise Information System, namely an internal network of internet connections.
For our goals of describing the Production Process, we only deal with the network connecting the
Production Activity Controller (PAC) to each Line Operator (LO) and, eventually, to the Quality Controller
(QC).
This network is simply denoted Information Pattern.
A simple but complete description of the Production System, from the point of view of the persons
operating inside it, include the following Personnel , denoted “Agents”, with three types of Qualification (*)
1. PAC, Production Activity Controller, i.e. manaager of the Production System to be analyzed;
2.STAFF, i.e. personnel who must perform auxiliary operations, as quality monitoring (QC);
3. Line Operator (LO), i.e. personnel who must control the Task execution of a Work center or contribute
to an assembly task control.
Then, the Information Pattern stands for the networks of information exchange among Agents operating
inside the Production System, information such to condition the receiving actor.
6.1.
Rules to organize an Information Pattern,
Let us refer to the third table od the Data-set associated to a Final Product description:
In case of the “abajour”, the table of Agents and their own Duties is the following:
Agent
DM1
DM2
DM3
DM4
Duty assigned
Wood cutting
and turning
Electic circuit
assembling
Final
assembling
QC & PAC
Type
LO
With responsibility on
Center (manufact)
Subordinated to
PAC
LO
Center (manufact)
PAC
LO
Center (assembly)
PAC
PAC
System
---
Given:
- the list of Agents, with the Duties assigned to each one, being the Agent’s Duty = the set of Production
Functions to be controlled by the Agent himself;
- the production system Layout.
Step 1: Find a link between an Agent and the Resource that is controlled by Agent.
To this aim:
a) Find the Table of Production Operations assigned to the Agent as Duty:
MFA = Map of Operations assigned
b) Find the Table of Links between each Agent and a Resource
MAR = Map of Agents to Resource
Let us first consider the MAP of Operations Assigned to Agents (MFA).
To specify which Operation has to be Assigned to an Agent, the analyst has the following information:
→ the List of Production Operations, PFn, n=1,…,NF,
→ the List of Agents’ Tasks, DMδ, δ=1,…, ND,
Note that an Agent’s Task can correspond to one or more Production Operations.
As an example, the Agent’s Task stated when the Agent has to control metal cutting operations
within a workshop implies Production Operation as “steel channel cutting”, “plate cutting”, etc.
The set of Production operations included in an Agent’s Task is formally described by the table <Agents;
Prod. Operations> denoted Map of Assigned Operations MFA:
MFAδ,n =
1, if the Production Operation PFn is included in the Agent’s Task DMδ ;
0, otherwise.
In case of the Abajour, the Map of Assigned Operations tp Agents id the following:
PO1
Pf1
MFA =
DM1
DM2
DM3
DM4
1
PO2
Pf2
PO3
PF3
PO4
PF4
PO5
PF5
PO6
PF6
PO7
PF7
1
1
1
1
1
1
Rule: MFA can be easily obtained by looking at the Duty assigned to each Agent, and comparing it with the
Production Operations stated in the left-high side of the Data-Set. Each time you find a correspondence, a
code “1” must be signed in the matrix box referred to the Agent and the Production Operation.
In a similar way a Map M(r,n), for the Task r and the Production Operation n, of the Tasks to be executed
by a Resource can be filled by using the list of Resources and their Tasks, and the list of Production
Functions.
MTR(r,n) = 1, if the Production Operations PFn is included in the Resource Tasks Rr , r=1,.., NR,
= 0, otherwise.
By using the above two matrices, MFA and MTR, one can obtain the map MAR(I,j), linking the Agent I to the
Resource j:
MAR(i,j) = 1, if Agent i has to control the Resource j;
= 0, otherwise
In theoretical approach, this last matrix could be obtained by the first two trough a Boolean operations.
However, a simpler way can be used, as shown in the following example, again referred yo the Data-Set of
the Abajour:
DM1
DM2
DM3
DM4
MFA =
MTR
MRA
PO1
Pf1
1
=
PO3
PF3
PO4
PF4
PO5
PF5
PO6
PF6
PO7
PF7
1
1
1
1
PO1
PF1
1
R1
R2
R3
R4
R5
=
PO2
Pf2
1
PO2
PF2
PO3
PF3
PO4
PF4
PO5
PF5
PO6
PF6
1
PO7
PF7
1
1
1
1
DM1
DM2
DM3
DM4
R1
1
R2
1
R3
R4
R5
1
1
1
To obtain the Map of Resources assigned to Agents, the following reasoning can be done:
IF an Agent (as DM1) has to execute/control a given Production Operation (as PO1) AND the same
Production Operation PO1 must be executed by the Resource R1, THEN the considered Agent DM1 is
incharged to control the Resource R1.
REMARK: Students are required to complete the MRA – MAP of the Resource assigned to an Agent.
Step 2. Find a link between two Agents of the same type LO:
In several situations, considering two Agents operating on two consecutive Resource inside a Production
Line, it happens that the downstream Agent could has the necessity of asking for new parts to the
upstream Agent, because parts are arriving late and the downstream Agent needs to work.
In this type of situation, it is necessary that the two Agents be connected by a link, such as to transfer from
downstream to upstream, NOT orders, BUT requests for parts.
REMARK: Given two Agents DMa and DMb, a “precedence condition” between them, i.e. a link from DMb
to Dma for requeest of parts, exists
IF the Resource Ra, controlled by DMa, sends parts – for further processing – to the Resource Rb,
controlled by Agent DMb.
This situation is illustrated by Figure 13 in the following:
where the links have the following meanings:
Where:
denotes a flow of parts
denotes a flow of internal request for parts
illustrates a link stated by the matrix MAR(Agent; Resource>
VERY IMPORTANT REMARK: Remember that
(a) A Resource can execute a number of Production Operations; then it can be a complex work center
(not a simple machine-tool…)
(b) The Duty assigned to an Agent can include a number of Production Operations, that can also be
executed by different Resources.
Then, to have a clear view of the links between an Agent and a Resource, the best approach is to include –
within the Resource symbol – the codes of the Production Operations to be executed there.
And to link the Agent controlling the Resource, with the Production Operations that are assigned to
himself.
His suggestion (prescription…) is clearly illustrated in the following Figure 14:
DM1
DM3
R1
RB
PO1
1
BCF
R3
C
PO3
BC
R5
R2
WR
PO5/b
PO2
D
PF
PO5/a
B
R4
AD
A
PO4
DM2
E
Figure 12
Step 3. Find a link between an Agent PAC and an Agent LO or STAFF.
In case an Agent Production Activity Controller – PAC exists, it has to control all the Line Operators – LO and
Staff Operators – STAFF that are included in the production management organization of the Plant.
To define the connections from the PAC and any LO or STAFF is the simplest case:
RULE: For each pair of Agents <PAC;LO> or <PAC;STAFF>, there exists also a link from PAC to LO or from
PAC to STAFF, by which the Agent PAC sends production orders to the managed Agents.
7. Two Simplified Organizational Charts.
7.1. Generalities on Organizational Structures
The management of the Info Pattern, that is the addressing of internal order to the Agents operating in the
Production Process, requires an organization of the responsibilities, asyou can see in the last table of the
Data-Set, fourth column: “With responsibility on…”
Agent
DM1
DM2
DM3
DM4
Duty assigned
Wood cutting
and turning
Electic circuit
assembling
Final
assembling
QC & PAC
Type
LO
With responsibility on
Center (manufact)
Subordinated to
PAC
LO
Center (manufact)
PAC
LO
Center (assembly)
PAC
PAC
System
---
Depending on the types of Agents operating inside the Plant , the different types of process management
responsibilities can generate two types of Management Methodologies:
Coordination:
A management function of coordination implies the presence of an Agent with a higher level of
responsibility, the coordinator, in whose duty is included the search for a global strategy viz. valid for the
Agents set at the lower level of responsibility, Agents assigned to it.
Cooperation:
The cooperation among many Agents operating at the same level of responsibility and with partially
overlapping functions, implies each one of them look for with any other the best possible agreement, such
that both of them get a good profit, and have all the same responsibility, including the Production Activity
Control.
The Coordination Management Method is applied when a Hierarchical control of activities is used to drive
the Production Process.
A general scheme of Hierarchical Management is the following Figure 13…
In practical terms, a hierarchical organizational has the following features:
a. pulverizing (i.e. great subdivision) tasks, generating the need for a strong coordination;
b. hierarchization of the professional figures;
c. resulting remuneration of responsibility, activating an individual relation between enterprise and
individual Agent (employee).
It follows that, in the analysis of a hierarchic organizational structure at almost two levels of responsibility,
there is the need to be able to recognize:
→ for every Agent of superior level, which rules sent to the inferior level in order to perform the
coordination actions;
→for any Agent of inferior level, which information he was commanded to transmit to the superior level
decision maker (coordinator) in order to allow to verify the effect of the coordination.
FIGURE 13
If the Cooperation Management Method is applied, a simple illustration of how it performs is to consider
that a group of Agents, with similar qualifications, interact together as in a market place.. as in Figure 14.
Now, each Agent is interchangeable within their work group, and the aim is to obtain a flat organizational
structure in which every Agent could talk with all the other Agents in the group, having the authority of
proposing his own decisions to a set of equi-level Agents and also the necessity of hearing alternative
proposals, with same authority, from the others.
In practice, a Collaborative Organizational Arrangement shows the following features:
a. work organization for products or group of personnel located in production cells (teams) ➔ see
Group Technology;
b. attribution to the team, as composed Agent, of a collective responsibility for the production
mission including the Production Activity Control
c. remuneration on the basis of the result quality, by opening a reporting connection between the
interpersonal group and the enterprise.
Assuming to adopt a Team-based Organizational Arrangement:
→ an active cooperation rule has to be valid inside the team through a “joint substitution” criterion, viz.
cooperation of an Agent with another with partially overlapping competences.;
→ towards the exterior, the team has to interact by adopting the rule of the “spokesman”, viz. of the
primus inter pares transferring agreed decisions.
7.2. From the Agents’ responsibilities to the Organizational Chart schemes
In the industrial world, the concept of Responsibility associated to a Production Operation comes from the
rationale of the ISO standard certifications and related manuals.
The Quality Manual in an industrial department states that the correct and accurate execution of any
Production Operation will assure the Quality Level of the final product. That means, it’s the enterprise’s
responsibility to guarantee the product quality.
As a consequence, the “quality level” of a product corresponds to the “responsibility level” in executing a
required Production Operation.
So, the enterprise management assigns to an Agent δ who will operate/control a Production Duty, a
responsibility level corresponding to the Agent’s Qualification = Duty.
Referring again to the last Table of the Data-Set, we can make evidence of the responsibilities of each type
of Agent, that will be considered in our examples:
Agent Type
PAC
STAFF
LO
Responsibility on
System (management)
Data (monitoring)
Center (manufacturing or
assembling)
Subordinated to
-----PAC
PAC
From this Table, one can easily recognize the two types of Organizational Charts, that in general describes:
-
either the subordination relations between any two Agents <PAC; STAFF> or <PSC; LO>, in case the
PAController is present in the Process;
-
or the lean organization of pairs <LO; LO> included in the same Team, if no PAC is involved; in this
case, the STAFF dedicated to Quality Control will have links with the whole group of LoOs-
As a consequence,
(a) If a PAC is present in the process; then the Organizational Chart will be Hierarchical,
(b) If no PAC will be involved, then the Organizational Chart will has only one layer.
The two cases corresponds, in the simplest situation, to the following two schemes:
PAC
STAFF
LO
LO
(a) Hierarchical Organizatin Chart
LO
LO
STAFF
(b) Simplified scheme of a TEAM.
The presentation of the two types of Organizational Charts will concludes the analysis of the Production
Process.