1 WHAT IS MANUFACTURING Manufacturing is the process of converting raw materials into products. It encompasses the design and manufacturing of goods using various production methods and techniques. The word manufacturing is derived from the Latin manu factus meaning made by hand. Modern manufacturing involves making products from raw materials by various processes machinery and operations following a well-organized plan for each step. 2 Type of Course
Manufacturing is an integration course
It integrates your knowledge of
Nature of materials
Stress strain behavior
Forces torques pressures vectors
Resolution of forces/vectors
Phase changes/crystal growth
Fluid flow statistics control etc
3 Examples of Knowledge Integration
Crystal growth in pure metals and alloys
Relationships among force power and energy
Effect of deformation on crystal structure
Effect of temperature on microstructure (heat treating)
4 Why is traditional engineering so expensive
The typical cost for each change made during the development of a major product
When changes are made Cost
During Design Testing 10000
During Process Planning 100000
During Test Production 1000000
During Final Production 10000000
5 (No Transcript) 6 (No Transcript) 7 The basic goals of CE are
to minimize product design and engineering changes.
to minimize time and cost involved in taking product from design concept to production and introduction of the product into the marketplace.
utilizes a database representing the engineering logic used in the design of each part of a product.
If a design modification is made on a part DE will determine the manufacturing consequences of that change.
In order to implement CE it should be provided
the full support of upper management
a multifunctional and interactive work team
utilization of all available technologies
Product design involves preparing analytical and physical models of the product as an aid to analyze factors such as
optimal part shape
Computer-aided design engineering and manufacturing simplifies construction and analyses of analytical models.
On the basis of these models the product designer selects and specifies the final shape and dimensions of the product its dimensional accuracy and surface finish and the materials to be used.
A powerful and effective tool is COMPUTER SIMULATION in evaluating the performance of the product and planning the manufacturing system to produce it.
Computer simulation helps in
early detection of design flaws
identifying possible problems in a particular production system
optimizing manufacturing lines for minimum product cost
Computer simulation predicting tool performance 10 Overview of the Manufacturing Processes
The final shape of the manufactured component can be achieved by
Changing the shape of the raw stock without adding material to it or taking material away from it.
Metal forming processes Rolling extrusion forging drawing sheet metal forming
Obtaining the required shape by adding metal or joining two metallic parts together
Welding brazing metal deposition
Molding molten or particulate metal into a cavity that has the same shape as the final product
Casting powder deposition
Removing portions from the stock material to obtain the final shape
turning milling drilling etc.
11 Factors involved in the processes
Shear stress strain behavior
Relationships among force power and energy and shearing energy
Thermodynamics and material expansion
Powder Processing for metals ceramics and plastics
Effect of heat on microstructure
Flow and rheology of powders
12 Fundamentals of Manufacturing Concepts
The ability to create shapes components and assembled products relies on several physical phenomena
The liquid to solid phase transformation
Create the required shape in the liquid form then solidify
The ability of certain materials to flow under stresses greater than some limit
soften the material by heating it then shape it
The ability of powders to flow like liquid and for powders to sinter and densify under heat and/or pressure
Useful for brittle materials
The method chosen depends on the material and the required properties.
Liquid to solid phase transformation
Create a negative mold of the same shape
Pour the liquid material in the mold
extracting heat or liquid (e.g. water)
reactions heat induced photon induced or by reagents
Remove the solid part from the mold
Casting conditions determine the properties
Most metals and many plastics flow when stress exceeds the yield stress
The stress-strain curve has three regions elastic yield stress and flow regime.
Flow regime - mechanical energy transformed into deformation and heat
cutting machining turning
Combined Stress States
Mostly compressive with some shear
Extremely complex stress states
Combination of high compressive and shear stresses
Mostly shear with tensile and compressive components
Stretching with bending
Mostly shear with only tensile components
Highly complex stress combination with high levels of shear causing fracture in a controlled manner
Takes advantage of the ability of powders to flow like a liquid and fill complex shapes
can be dry or slurry
can be compacted by pressure or extraction of liquid from the slurry
this process forms a green body which is pliable and weak
heating to high temperatures causes the powder particles to sinter together for a strong nearly 100 dense product
impossible to obtain the desired nominal dimension when processing a workpiece
inaccuracies inherent in the machine tool
elastic deformation of the workpiece and/or fixture
temperature effects during processing
skill of the operator
establish a permissible degree of inaccuracy with respect to the nominal dimension that will not affect the proper functioning of the manufactured part
the nominal dimension is referred to as the the basic size of the part
the deviations from the basic size to each side determine the high and low limits
the difference between these two limits of size is called the tolerance
The International Standardization Organization (ISO)
the magnitude of the tolerance is dependent upon the basic size and is designated by an alphanumeric symbol called the grade
there are 18 standard grades of tolerance in the ISO system
the relationship between the dimensions of the mating surfaces must be specified
this determines the degree of tightness or freedom for relative motion between the mating surfaces
clearance fit the upper limit of the shaft is always smaller than the lower limit of the mating hole
interference fit the lower limit of the shaft is always larger than the upper limit of the hole
transition fit is an intermediate fit
means that identical parts must be able to replace each other without the need for any fitting operation
it is achieved by establishing a permissible tolerance beyond which any further deviation from the nominal dimension of the part is not allowed
standardization limits the diversity and total number of varieties to a definite range of standard dimensions
e.g. For wires and sheets the sheet thickness is limited to only 45 (in US standards)
The Production Turn
The main goal of a manufacturing project is to make a profit
22 Product Life Cycle 23 Technology Development Cycle
A new technology emerges as a result of active RD and is then employed in the design and manufacturing of several different products.
Technology is concerned with the industrial and everyday applications of the results of the theoretical and experimental studies that are referred to as engineering
24 (No Transcript) 25 Rapid Prototyping
Rapid prototyping relies on CAD/CAM and various manufacturing techniques to produce prototypes in the form of a solid physical model of a part rapidly and at low cost.
These techniques can be used for low-volume economical production of parts.
Tests on prototypes must be designed to simulate as closely as possible the conditions under which the product is to be used.
Computer-aided engineering techniques are now capable of comprehensively and rapidly performing such simulations.
After this phase has been completed appropriate process plans manufacturing methods equipment and tooling are selected with the cooperation of manufacturing engineers process planner and all others involved in production.
27 Design for Manufacturing Assembly Disassembly and Service
Design for manufacturing (DFM) is a comprehensive approach to production of goods and integrates the design process with materials manufacturing methods process planning assembly testing and quality assurance.
Designers should acquire a fundamental understanding of the characteristics capabilities and limitations of materials manufacturing processes and related operations machinery and equipment.
Expert system expedites the traditional iterative process in design optimization.
28 (No Transcript) 29 Selecting Materials 30 (No Transcript) 31 Properties of Materials
electric and magnetic properties
Manufacturing properties of materials determine whether they can be cast formed shaped machined welded or heat-treated with relative ease.
Another important consideration is that the methods used to process materials to the desired shapes ma adversely affect the products final properties service life and cost.
Cost and Availability
The economic aspects of material selection are as important as the technological considerations of properties and characteristics of materials.
Appearance Service Life and Recycling
time and service dependent phenomena such as wear fatigue creep and dimensional stability are also important.
Compatibility of materials
34 Selecting Manufacturing Processes
There is usually more than one method of manufacturing a part from a given material.
Casting expandable mold and permanent mold
Forming and Shaping rolling extrusion drawing sheet forming powder metallurgy and molding.
Machining turning drilling milling planning shaping broaching grinding ultrasonic machining chemical electrical and electrochemical machining and high-energy beam machining.
35 (No Transcript) 36 Dimensional and Surface Finish Consideration
Size thickness and shape complexity of the part have a major bearing on the process selected to produce it.
Flat parts with thin cross-sections cannot be cast properly. Complex parts cannot be formed easily and economically.
Tolerances and surface finish obtained in hot-working operations cannot be as fine as those obtained in cold-working operations. Dimensional changes warpage and surface oxidation occur during processing at elevated temperatures.
The size and shape of manufactured parts cary widely.
Nanotechnology and nanofabrication
Ultraprecision manufacturing techniques and machinery is coming into more common use. Highly sophisticated techniques such as molecular-beam epitaxy and scanning-tunneling engineering will be implemented to obtain accuracies on the order of the atomic lattice
38 Operational and Manufacturing Cost Considerations
the design and cost of tooling the lead time required to begins production and the effect of workpiece materials on tool and die life
availability of machines and equipment and operating experience
environmental and safety implications
the safe use of machinery
39 Net-shape Manufacturing
The parts are made as close to the final desired dimensions tolerances and specifications as possible.
Typical examples are near-net shape forging and casting of parts stamped sheet-metal parts components made by powder metallurgy techniques and injection molding of plastics.
40 Computer Integrated Manufacturing
The major goals of automation in manufacturing facilities are
to integrate carious operations
to improve productivity
increase product quality and uniformity
minimize cycle times
reduce labor costs
Computers are used for
optimization of manufacturing processes
automated inspection and testing of products.
41 (No Transcript) 42 Machine Control Systems
Numerical Control (NC) of machines is a method of controlling the movements of machine components by direct insertion of coded instructions in the form of numerical data.
In adaptive control (AC) process parameters are adjusted automatically to optimize production rate and product quality and minimize cost. Parameters such as forces temperatures surface finish and dimensions of the part are monitored constantly.
43 Computer Technology
Computers allow us to integrate virtually all phases of manufacturing operations which consist of various technical as well as managerial activities.
Computer-integrated Manufacturing (CIM) is characterized with
responsiveness to rapid changes in market demand product modification and shorter product cycles
high quality products at low cost
better use of materials machinery and personnel and reduced inventory
better control of production and management of the total manufacturing operation
Computer-aided Design (CAD) allows the designer to conceptualize objects more easily without having to make costly illustrations models or prototypes.
Computer-aided Engineering provides
simulation analyses and testing of the performance of structures subjected to static or fluctuating loads and temperatures.
Computer-aided Manufacturing (CAM) involves all phases of manufacturing by utilizing and processing further the large amount of information on materials and processes collected and stored in the organizations database.
Some of the tasks are programming numerical control of machines programming robots for material handling designing tools dies and fixtures and maintaining quality control.
Computer-aided Process Planning (CAPP) is capable of improving productivity in a plant by optimizing process plans reducing planning costs and improving the consistence of product quality and reliability. Functions such as cost estimating and time required to perform a certain operation can also be incorporated into the system.
Group Technology and Cellular Manufacturing (CM)
The concept of group manufacturing is that parts can be grouped and produced by classifying them according to similarities in design and manufacturing processes. In this way part design and process plans can be standardized and families of parts can be produced efficiently and economically.
46 Quality Assurance and Total Quality Management
Traditionally quality assurance has been obtained by inspecting parts after they have been manufactured.
Quality must be built into a product from the design stage through all subsequent stages of manufacture and assembly.
We control processes not products.
Product integrity is a term that can be used to define the degree to which a product
is suitable for its intended purpose
fills a real market need
functions reliably during its life expectancy
can be maintained with relative ease.
Total quality management (TQM)
becomes the responsibility of everyone involved in designing and manufacturing a product
prevents defects from occurring rather than detecting defective products
Important developments in quality assurance include the implementation of design of experiment a technique in which the factors involved in a manufacturing process and their interactions are studied simultaneously.
ISO 9000 series on quality management and quality assurance standards
this is a quality process certification not a product certification
It is becoming the world standard for quality
48 Global Competitiveness and Manufacturing Costs
Typically manufacturing costs represent about 40 of a products selling price
design principles for economic production are
the design should be as simple as possible to manufacture assemble disassemble and recycle
materials should be chosen for their appropriate manufacturing characteristics
dimensional accuracy and surface finish specified should be as broad as permissible
because they can add significantly to cost secondary and finishing processes should be avoided or minimized
The total cost of manufacturing a product consists of
by-products sand with additives for casting water oild and other fluids from heat-treating facilities and plating operations slag from foundries and welding operations scrap of all kinds
800000 metric tons of old TV sets radios and computer equipment are discarded in Germany each year.
Certain guidelines can be followed
reducing waste of materials at their source by refinements in product design and reducing the amount of materials used
conducting research and development of manufacturing technologies
reducing the use of hazardous materials in products and processes
ensuring proper handling and disposal of all waste
making improvements in recycling waste treatment and reuse of materials
Design for the environment
Design for recycling
51 Flexible Manufacturing Systems (FMS)
FMS integrate manufacturing cells into a large unit containing industrial robots and automated guided vehicles (AGVs) serving several machines all interfaced with a central computer.
Just-in-Time Production (JIT) is a concept in manufacturing in which supplies are delivered just in time to be used parts are produced just in time to be made into subassemblies and assemblies and products are finished just in time to be sold.
Artificial Intelligence (AI) involves the use of machines and computers to replace human intelligence
expert systems - intelligent computer programs
artificial neural networks (ANN) simulate the thought processes of the human brain.
ANN have the capability of modeling and simulating production facilities monitoring and controlling manufacturing processes diagnosing problems in machine performance conducting financial planning and managing a companys manufacturing strategy.
Factory of the future in which production takes place with little or no direct human intervention.
53 Lean Production and Agile Manufacturing
Lean production involves major assessment of each of the companys activities
efficiency and effectiveness of each operation
necessity of retaining operations and managers
efficiency of the machinery and equipment used while maintaining quality
number of personnel involved in each operation
reduce cost and waste of each activity
requires a fundamental change in corporate culture
Agile manufacturing is ensuring flexibility in the manufacturing enterprise so it can quickly respond to changes in product variety demand and customer needs.
Lean Flexible Agile
54 Product Liability
Designing and manufacturing safe products is an important and integral part of a manufacturers responsibilities.
Examples that could involve liability are
a grinding wheel that shatters and blinds a worker
a cable that snaps allowing a platform to drop
brakes that become inoperative due to failure of one component
machines with no guards or inappropriate ones
electric or pneumatic tools without proper warnings
Human factors engineering and ergonomic considerations are important aspects of the design and manufacture of safe products.
55 Organization for Manufacture
Complex interactions among the carious factors involved in manufacturing - materials machines people information power and capital - requires the proper coordination and administration of diverse functions.
Responsibilities of manufacturing engineers
Plan the manufacture of a product and processes to be utilized
identify the machines equipment tooling and personnel needed to carry out the plan
interact with design and materials engineers to optimize productivity and minimized production costs
Cooperate with industrial engineers when planning plant floor activities such as plant layout machine arrangement material handling equipment time-and-motion study production method analysis production planning and scheduling and maintenance.
Manufacturing engineers in cooperation with industrial engineers also are responsible for evaluating new technologies their applications and how they can be implemented.
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