Title: Manufacturing Systems Modeling, Analysis and Design IME 452 IME 545 Modeling and Analysis of Manufac
1Manufacturing SystemsModeling, Analysis and
DesignIME 452 / IME 545Modeling and Analysis
of Manufacturing Systems
Amy Thompson Instructor
2Chapter 1 Manufacturing Models
- The anatomy of manufacturing operations
- Product design
- Process planning
- Tools and fixtures
- Operating conditions, ...
- Production planning
- What type of process
- Facility layout
- Material flow
- Production scheduling
- Operations
- Production monitoring and control
- Quality control, ...
- Role of information
- Drives the interrelated functions
- Measures compliance to corporate objectives
3Chapter 1 Manufacturing Models
- Manufacturing Classifications
- Discrete parts or continuous processing
- Manufacturing Operations
- Fabrication or Assembly
- Manufacturing process and manufacturing system
- manufacturing process deals with machinery such
as stamping press, CNC machining center,
injection molding machine, - manufacturing system it is an integration of
various machinery with material handling,
network, control, ... - Manufacturing process and manufacturing system is
often inseparable today.
4Chapter 1 Manufacturing Models
- A step back from the level of individual
processing, in this course, we will focus on
manufacturing systems how to make them - better (more reliable)
- faster (more efficient)
- cheaper (more cost-effective)
5Types of Manufacturing Systems According to
Factory Layout
- Product (production line)
- Process (job shop)
materials
product
materials
products
6Types of Manufacturing Systems According to
Layout Group/Cell
Machines
Material handling system
7Group Technology History
- In 1925, R.E. Flanders use product oriented
departments to make standardized products - In 1937, A.P. Sokolovski parts with similar
features manufactured together - In 1960s J.L. Burbidge developed a systematic
approach based upon these concepts - Complete History see Snead (1989)
- Currently evolved into small focused factories
8Group Technology
- Group Technology is a Management Theory
- The basic principle of GT
- many problems are similar, and that by grouping
similar problems, a single solution can be found
to a set of problems and thus saving time and
effort
9Group Technology on theManufacturing Floor
- Cellular Manufacturing
- Divide manufacturing facility into small cells
that manufacture a specified set of part types - Cells usually contain no more than 5 machines,
but can have only one or two machines - Configuring machines with different capabilities
into a cohesive group is an alternative to
process layout - Larger groups departments with many cells
- Lessons to be gained from GT for all
manufacturing Small is beautiful?
10Group vs. Other Organization
- Group vs. process for medium-volume,
medium-variety products - If volumes large, pure item flow line
- If volumes are small and only slight similarities
exist, then less gained by grouping - Method for gaining advantages of flow line in
shops previously organized by process - GT can be used for
- Design whenever possible, new parts should be
designed to be compatible with the processes and
tooling of an existing part family - GT is an attempt to standardize products and
process plans. - Items with similar geometric features should have
similar designs - SKU reductions, partial SKUs
11Group vs. Other Organization
- Setup time reduction is an important benefit of
cellular manufacturing on the shop floor - Work center produce similar products with similar
features which allows development of generic
fixtures and tools. - Tools can be stored locally, reducing retrieval
time. - Some machines can be loaded with all the tools
for all the products in the families, so tool
change is only required due to wear, not
production changes. - The same universal fixture can be designed to
hold any part in the family by simple adjustment
to the fixture. - Reduced setup time allows for smaller batches to
be produced, which significantly reduces WIP,
thus throughput time. - Lower setup time and lower WIP inventory, smaller
batch sizes allow products to be made JIT. This
in turn, reduces finished product inventory. - Less floor space, less inventory cost, shorter
lead times.
12Group vs. Other Organization
- Management Orientation Changes
- Process-based department
- In a process based department, the blueprint and
written specifications are the target, and the
focus of work is placed directly on the part
being made. - Customers are rarely consulted
- The final use of the part is rarely understood,
there are too many different types of parts going
through the area to understand the purpose or
problems of each type. - Cellular-based department
- Focused product type means smaller group of
suppliers, producers, and customers. - Communication can be verbal and personal.
- More common for customers to visit supply cell
group and better understand requirements.
13Group Technologyon the Manufacturing Floor
- For manufacturing systems, the basic steps of GT
include - Coding assigning a symbolic or a numerical
description to the parts based upon product
characteristics - Classification (group formation) use the part
code and other information to assign parts to
families based upon similarities - Layout group machines to produce the parts with
best efficiency. (Assign families to groups.)
Part routings must be known.
14Characteristics of Successful Groups
- Size is important. Group must be small enough to
act as a close-knit structure good
communication, good cooperation. Social
scientists have determined that groups of 6 to 12
best, 7 being optimal. - Level long-run utilization between groups to
match production plans. What major/typical
problems could this cause? - Consider safety when combining operations into a
cell. - Layout machines in cell to minimize material
movement. - Physically separate cells within a facility with
an input and output buffer. (Establish
independence/autonomy.) - Reside group tooling locally.
- All documents and drawings reside locally.
- Organize business around groups.
- Workers must be empowered.
- Independent profit center.
15Introduction to a Flexible Manufacturing System
(FMS)
- The definition of the FMS
- Flexible Manufacturing System (FMS) refers to a
set of computer numerically controlled (CNC)
machine tools and supporting workstations that
are connected by an automated material handling
system and are controlled by a central computer.
16- A sample of flexible manufacturing systems
Parts loading and unloading
Machines
Material handling system
17Introduction to a Flexible Manufacturing System
(FMS)
- The basic components of FMS
- Machines
- they are the backbone of the FMS
- various machines can be used, such as vertical
and horizontal machining centers - machines must be programmable
- Supporting workstations
- they are used for loading, unloading, storage and
inspection (such as gages and Coordinate
Measurement Machine (CMM)) - Part transportation system
- it is used to transport the parts between
workstations - commonly used transportation devices include
conveyors, tow cars, rail cars, and AGV
(automated guided vehicle) - System controller
- it is a computer that controls the entire system
18Introduction to a Flexible Manufacturing System
(FMS)
Plant
Shop 2
Shop 1
- Control in FMS
- Five-level control hierarchy
- plant
- shop
- cell
- workstation
- equipment
Cell 2
Cell 1
Cell 3
Station 2
Station 1
Station 3
Robot
Machine
I/O
19Introduction to a Flexible Manufacturing System
(FMS)
- Problems to be solved
- System design problems
- Is FMS beneficial?
- Capacity of the FMS
- Hardware machining centers, tool changers,
pallet and pallet loaders, cutting tools,
fixtures, and etc. - Software computer language, communication
protocol, - System setup problems
- Part selection
- which parts are to be made by the FMS
- which part shall be made by which machine
- Tooling assignment
- Machine setup and operation sequencing
- Task assignment
- Operation sequencing
20Chapter 1 Manufacturing ModelsCharacteristics
of Mfg. Systems
21Chapter 1 Manufacturing Models
- Application examples (production line)
- Product layout shops automobile assembly line
- Process layout shops tool and die shop
- Applications can also be found in our daily life
- Product shop McDonalds
- Process shops Make-to-order restaurant.
- New McDonalds stores change to a Process Shop,
Why? - Different manufacturing systems require different
ways to organize and to run.
22Chapter 1 Manufacturing Models
- Production planning
- What type of process
- Facility layout
- Material flow
- Production scheduling
- Actual production planning and control process
takes market demand, production capacity, and
inventory levels to determine quantities of
product families to make over different time
spans. This plan is then disaggregated to
schedule machines, jobs and resources on a daily
basis. - Designing systems for optimal performance, given
a production plan, versus learning process of
production scheduling.
23Chapter 1 Manufacturing Models
- Modeling Assumptions in this Text Minimize
complexity - Assume product design and process plans are known
- An information system is assumed to exist
- All data is reliable and no inconsistencies exist
- Why are these assumptions not always true in
reality?
24Chapter 1 Manufacturing Models
- Assume Product Design/Process Plans Exist
- Product Design Levels of Available Data
- 3D CAD model with all information available to
user - 3D CAD model available, but designer must access
- CAM program available, but no other details
- 2D representational model (orthographic drawing)
- Written summary of critical design criteria
- Jigs or tool available
- No information available. When would this occur?
- Process Routing/Planning Levels of Data
- Complete description of processes, equipment, and
parameters - Complete BOM and routing information
- Routing complexity (alternate routes, FMS, etc.)
25Chapter 1 Manufacturing Models
- Data gathering
- Does the data exist that you need?
- Where or who has the data?
- If the data doesnt exist, how do you get it and
what issues are involved? - Type of data available depends upon traditional
use - Aggregated/averaged data
- What if you cant get the data, what do you do,
what are the issues? - Ignore the data. How important is the data to the
model outcome? - Sensitivity Analysis.
- What industries are most likely to have the data
you need?
26Chapter 1 Manufacturing Models
- Model components
- Objectives
- Efficiency versus effectiveness
- 7 types of waste (Suzaki, 1987)
- Waste from overproduction, Waste of waiting time,
Transportation waste, Processing waste, Inventory
waste, Waste of motion, Waste from product
defects - Meet customer satisfaction in a profitable
manner. Think globally. - An efficient modeler builds a model that finds an
optimal solution. - An effective modeler builds a model that is used
to understand the important factors in the system
and uses it to find a very good/improved solution
to a real system or an important problem. - Not much value in finding optimal solutions to
trivial sub-problems which ignore system
interactions on a higher level.
27Chapter 1 Manufacturing Models
- Inputs and Outputs to a Production Activity (from
A. Thompson, Unattended and Lights-Out
Manufacturing, 2003 adapted and modified from S.
Nakajima, Introduction to TPM, 1988)
28Chapter 1 Manufacturing Models
- Objects in building manufacturing system models
- Physical Objects
- Materials
- Resources (Human, Machine, Tool, Energy)
- Organizational Objects
- Tasks
- Production and Process Plans
- Events point in time when a resource starts or
completes a task
29Chapter 1 Manufacturing Models
- Model Types
- In order to understand and then better control
complicated manufacturing systems, we need models - The types of models
- Physical models prototype, 2D or 3D
- Mathematical models
- Set of mathematical or logical relationships
- Use parameters to define process and system
- Use decision variables
- Descriptive models
- Simulation
- Prescriptive models
- Linear Programming
- Heuristics
- Analytical and experimental
- Computer simulation
30Chapter 1 Manufacturing Models
- Model Uses
- insight understanding
- prediction
- justification
- optimization
- control
31Chapter 1 Manufacturing Models
- Model building Process
- The model building process
- define the problem
- define the objectives
- define the decision variables
- define the solving method
- objective functions
- constraints
- verification and validation
- Verification and validation criteria
- structure
- operation conditions
- behavior
32Chapter 1 Manufacturing Models
- Most models in the real world (and discussed in
the class) are simple and straightforward. - An example job assignment
- The job costs data
- The objective find the minimum cost assignment
33Chapter 1 Manufacturing Models
- The decision variables machine assignments
- The solving method
- A heuristic starting from job 1, find the
machine with minimum cost and assign it. - Evaluation the total cost is 36
- Question
- Is there a better assignment?
- Is there a systematic method by which we can find
the best assignment?
34Chapter 1 Manufacturing Models
- Summary in this course, we will focus on
- modeling
- model solving
- model evaluating
- Problems
- Facility layout
- Material flow systems
- Process planning
- Machine setup
- Operation optimization
- Scheduling
35Chapter 1 Principles of Mfg. Systems
- The first law (Littles law)
- the formula
- work_in_process production rate ? throughput
time - an illustration
- Interpolation the production rate is X, the
number of part in process in the system is N,
then the total processing time is - T N(1/X) or NXT, and (1/X) is the arrival
rate to the system. - Implication if the production rate is fixed,
then merely putting more parts into the system
will only increase throughput time
36Chapter 1 Principles of Manufacturing Systems
- An example
- There are six people going to a drive through
window of a McDonald (i.e., N 6) - The service rate of the clerk is 2
minutes/customer (X 2) - Therefore, the total processing time is (6)(2)
12. - Note that at any give time, there is only one
customer being served while the other five are
waiting (assuming they have to leave all
together). - Implications
- If someone else joins the group the waiting will
be longer - Increase the service rate or add another service
window can reduce the waiting time
37Chapter 1 Principles of Manufacturing Systems
- The second law matter is conserved.
- The formula material in material out storage
(disposal) - A stable system cannot have storage accumulation.
In other words, input materials shall equal to
the output materials. The storage includes
scraps, chips, wastes, and etc., which must be
cleared out as well - Examples
- Your garage
- Just-In-Time Manufacturing (i.e., zero inventory
manufacturing) in Toyota.
38Chapter 1 Principles of Manufacturing Systems
- The third law the larger the system, the less
reliable it becomes - The formula suppose the system has N components
connected in series and the availability of
component i is ri, then the system availability
is - An example there are 5 machines connected in
series, each has an availability (i.e., the
reliability in operating) of 0.9, then, the
system availability is (0.9)5 0.59. - Solutions of the problem
- Buffer
- Parallel system
39Chapter 1 Principles of Manufacturing Systems
- The fourth law objects decay
- The causes of failures
- wear
- fatigue
- Corrosion, etc.
- Implications conditions may change and
maintenance is necessary
40Chapter 1 Principles of Manufacturing Systems
- The fifth law exponential growth in complexity
- The formula if a system has N components and
each component has M states, then the system will
have NM states in total. - Implication consider six components with four
states 4096 possible system states - Limit the number of system components and
- Limit states of these components
41Chapter 1 Principles of Manufacturing Systems
- The sixth law technology advances
- Implication continuous improvement
- The seventh law system components may behave
randomly - Implication 1 we may only find the expected
value - Implication 2 be prepared for unusual events
42Chapter 1 Principles of Manufacturing Systems
- The eighth law limits of human rationality
- Human limits
- Linear thinking concerning a single task at a
time - Short term memory is limited to seven items
- Difficult to view more than 3D
- Implication simplify the design, the process and
the system
43Chapter 1 Principles of Manufacturing Systems
- The ninth law combining, simplifying, and
eliminating tasks will save time, money, and
energy - Note that this is the founding principle of
scientific management