INTRODUCTION AND OVERVIEW OF MANUFACTURING. What is Manufacturing? Materials in Manufacturing Manufacturing Processes Production Systems Trends in Manufacturing Organization of the Book. What is Manufacturing?.
What is Manufacturing? Materials in Manufacturing Manufacturing Processes Production Systems Trends in Manufacturing Organization of the Book
What is Manufacturing?
The wordmanufacture is derived from two Latin wordsmanus (hand) and factus (make); the combination means “made by hand” “Made by hand” accurately described the fabrication methods that were used when the English word “manufacture” was first coined around 1567 A.D. Most modern manufacturing operations are accomplished by mechanized and automated equipment that is supervised by human workers
Manufacturing is Important
Making things has been an essential human activity since before recorded history Today, the term manufacturing is used for this activity Manufacturing is important to most developed and developing nations a) Technologically b) Economically
Technology - the application of science to provide society and its members with those things that are needed or desired. Technology provides the products that help our society and its members live better. What do these products have in common? They are all manufactured Considerthelist of products in Table 1.1. They represent various technologiesthat help society and its members to live better. Manufacturing is the essential factor that makes technology possible
TABLE 1.1 Products representing various technologies, most of which affect nearly everyone. Athletic shoes Fax machine One-piece molded plastic patio chair Automatic teller machine Flat-screen high-definition television Optical scanner Automatic dishwasher Hand-held electronic calculator Personal computer (PC) Ballpoint pen High density PC diskette Photocopying machine Cell phone Home security system Pull-tab beverage cans Compact disc (CD) Hybrid gas-electric automobile Quartz crystal wrist watch Compact disc player Industrial robot Self-propelled mulching lawnmower Compact fluorescent light bulb Ink-jet color printer Supersonic aircraft Contact lenses Integrated circuit Tennis racket of composite materials DigitalcameraMagneticresonanceimaging Video games Digital video disc (DVD) (MRI) machine for medical diagnosis Washing machine and dryer Digital video discplayerMicrowaveoven
a) Manufacturing - Technological
Application of physical and chemical processes to alter the geometry, properties, and/or appearance of a starting material to make parts or products The processes to accomplish manufacturing involve acombination of machinery, tools, power, and labor, as depicted in theFigure
b) Manufacturing - Economic
Economically, manufacturing is the transformation of materials into items of greatervalue by means of one or more processing and/or assembly operations, as shownintheFigure . The key point is thatmanufacturing adds value to thematerial by changing itsshape or properties, or by combining it with other materials that have been similarly altered.
Industry consists of enterprises and organizations that produce or supply goods and services Industries can be classified as: Primary industries - cultivate and makeuse of natural resources, e.g., agriculture, mining Secondary industries - take the outputs of primary industries and convert them into consumer and capital goods Tertiary industries - service sector Alist of specific industries in these categories is presented inthenextTable
Specific Industries in Each Category
(giysi) (meşrubat) (legal= hukuki, retail= perakende wholesale= toptancılık) Quarries = Taş Ocağı
Manufacturing Industries - continued
Wewill be concerned mainlywith the secondary industries in theprevioustable Secondary industries include manufacturing, construction, and electric power generation Manufacturing is the principal activity in this category Manufacturing includes several industries whose products are not covered in this book; e.g., apparel, beverages, chemicals, and food processing For our purposes, manufacturing means production of hardware Examplesare : Nuts and bolts, forgings, cars, airplanes, digital computers, plastic parts, and ceramic products
Final products divide into two major classes: Consumer goods - products purchased directly by consumers Ex: Cars, clothes, TVs, tires, tennis rackets Capital goods - those purchased by companies to produce goods and/or provide services Ex: Aircraft, computers, communication equipment, medical apparatus, trucks, machine tools, construction equipment
Production Quantity Q
The quantity of products Q made by a factory has an important influence on the way its people, facilities, and procedures are organized Production quantity Q (üretim miktarı)refers to the number of units produced annually of a particularproducttype Annual quantities can be classified into three ranges: Production rangeAnnual Quantity Q Low production 1 to 100 units Medium production 100 to 10,000units High production 10,000 to millions of units
Product variety P (üretim çeşitliliği) refers to different product types or models produced in the plant Different products have different features They are intended for different markets Some have more parts than others When the number of product types made in the factory is high, this indicates high product variety
Product VarietyP - cont
There is an inverse correlation between product variety P and production quantity Q interms of factory operations. If a factory’s product variety is high, then its production quantityis likely to be low; but if production quantity is high, then product variety will be low, asdepicted inthenextFigure. Manufacturing plants tend tospecialize in a combinationof productionquantity and product variety that lies somewhere inside the diagonal band inthenextFigure
P vsQ in Factory Operations
More About Product Variety
Although P(productvariety) is quantitative, it is much less exact than Q because details on how much the designs differ is not captured simply by the number of different designs Soft product variety- small differences between products, e.g., between car models made on the same production line, with many common parts Hard product variety- products differ substantially, e.g., between a small car and a large truck, with few common parts (if any)
Materials in Manufacturing
Most engineering materials can be classified into one of three basic categories: Metals Ceramics Polymers Their chemistries are different, and their mechanical and physical properties are different These differences affect the manufacturing processes that can be used to produce products from them
Venn diagram of three basic material types plus composites Composites Nonhomogeneous mixtures of the other three basic types rather than a unique category
Usually alloys, which are composed of two or more elements, at least one of which is metallic. Two basic groups: a. Ferrous metals - based on iron, comprises about 75% of metal tonnage in the world. e.g. Steel and cast iron b. Nonferrous metals - all other metallic elements and their alloys. e.g. Aluminum, copper, nickel, silver, tin, etc.
a. Ferrous Metals Ferrous metals are based on iron; the group includes steel and cast iron. These metals constitute the most important group commercially, more than three fourths ofthe metal tonnage throughout the world. Pure iron has limited commercial use, but whenalloyed with carbon, iron has more uses and greater commercial value than any othermetal. Alloys of iron and carbon form steel and cast iron.
Steel can be defined as an iron–carbon alloy containing 0.02%to 2.11%carbon. It is themost important category within the ferrousmetal group. Its composition often includes otheralloyingelements as well, such as manganese, chromium, nickel, andmolybdenum, toenhancethe properties of the metal. Applications of steel include construction (bridges, I-beams, andnails), transportation (trucks, rails, and rolling stock for railroads), and consumer products (automobilesandappliances).
Cast iron is an alloy of iron and carbon (2% to 4%) used in casting (primarily sandcasting). Silicon is also present in the alloy (in amounts from 0.5% to 3%), and otherelements are often added also, to obtain desirable properties in the cast part. Cast iron isavailable in several different forms, of which gray cast iron is the most common; itsapplications include blocks and heads for internal combustion engines.
b. Nonferrous Metals Nonferrous metals include the other metallic elements and theiralloys. In almost all cases, the alloys aremore important commercially than the puremetals. The nonferrous metals include the pure metals and alloys of aluminum, copper, gold,magnesium, nickel, silver, tin, titanium, zinc, andothermetals.
Charging a basic oxygen furnace in steelmaking: molten pig iron is poured into the BOF (BasicOxygenFurnace). Temperatures are around 1650C (3000F).
Compounds containing metallic (or semi-metallic) and nonmetallic elements. Typical nonmetallic elements are oxygen, nitrogen, and carbon For processing, ceramics divide into: a. Crystalline ceramics – includes: Traditional ceramics, such as clay, and modern ceramics, such as alumina (Al2O3) b. Glasses – mostly based on silica (SiO2)
Compounds formed of repeating structural units called mers, whose atoms share electrons to form very large molecules. Three categories: a. Thermoplastic polymers - can be subjected to multiple heating and cooling cycles without altering molecular structure (ex: polyethylene, polystyrene, polyvinylchloride, andnylon) b. Thermosetting polymers - molecules chemically transform into a rigid structure – cannot reheat (ex: resins,epoxides) c. Elastomers- shows significant elastic behavior. (ex: natural rubber, neoprene, silicone, and polyurethane.
Compositesare materials consisting of two or more phases that are processed separately and then bonded together to achieve properties superior to its constituents. Phase - homogeneous mass of material, such as grains of identical unit cell structure in a solid metal. Matrix - Usual structure consists of particles or fibers of one phase mixed in a second phase calledmatrix. Properties of a compositedepends on components, physical shapes of components, and the way they are combined to form the final material.
Two basic types: A. Processing (işleme) operations - transform a work material from one state of completion to a more advanced state. Operations that change the geometry, properties, or appearance of the starting material(e.g., painting a spot-welded car body) B. Assembly(montaj)operations - join two or more components to create a new entity (e.g., a welded assembly)
( İşlemek ) ( montaj )
A. Processing Operations
A processingoperation alters a material’s shape, physical properties, or appearance in order to add valuetothematerial. Three categories of processing operations: Shaping processes- alter the geometry of the starting work material (casting, forging, andmachining) Property‑enhancing processes- improve physical properties without changing shape (heattreatment) Surface processing operations - clean, treat, coat, or deposit material on surface of work (platingandpainting)
1- Shaping Processes – Four Categories
Most shape processing operations apply heat, mechanical force, ora combination of these to effect a change in geometry of the work material. (a) Solidificationprocesses, in which the starting material is a heated liquid or semifluid that cools andsolidifies to form the part geometry; (b) Particulate processing, in which the startingmaterial is a powder, and the powders are formed and heated into the desired geometry; (c) Deformation processes, in which the starting material is a ductile solid (commonlymetal) that is deformed to shape the part; (d) Material removal processes, in whichthe starting material is a solid (ductile or brittle), from which material is removed so that the resulting part has the desired geometry.
a. Solidification Processes
In this category, the starting material is heated sufficiently to transform it into aliquid or highly plastic (semifluid) state. Nearly all materials can be processed in this way. Metals, ceramic glasses, and plastics can all be heated to sufficiently high temperatures toconvert theminto liquids. With thematerial in a liquid or semifluid form, it can be poured orotherwise forced to flow into amold cavity and allowed to solidify, thus taking a solid shapethat is the same as the cavity. Most processes that operate this way are called casting or molding. Casting is the name used for metals, and molding is the common term used forplastics. This category of shaping process is shownin thenextFigure.
a. Solidification Processes
Casting process at left and casting product at right
b. Particulate Processing
In particulate processing, the starting materials are powders of metals or ceramics. Although these twomaterials are quite different, the processes to shape themin particulateprocessing are quite similar. The common technique involves pressing and sintering, illustrated in thenextFigure, in which the powders are first squeezed into a die cavity underhigh pressure and then heated to bond the individual particles together.
b. Particulate Processing
Starting materials are (1)metal or ceramic powders, which are (2) pressed and (3) sintered
c. Deformation Processes
In deformation processes, the starting workpart is shaped by the application of forcesthat exceed the yield strength of the material. For the material to be formed in this way, itmust be sufficiently ductile to avoid fracture during deformation. To increase ductility (andfor other reasons), theworkmaterial is often heated before forming to a temperature belowthe melting point. Deformation processes are associated most closely with metalworkingand include operations such as forging and extrusion, shown in thenextFigure.
c. Deformation Processes
Somecommondeformationprocesses: forging, in which two halves of a diesqueezetheworkpart, causing it to assume theshape of the die cavity;and extrusion, in which a billet is forced toflow through a die orifice,thustakingthecrosssectionalshape of theorifice.
d. Material Removal Processes
Materialremovalprocessesareoperationsthatremoveexcessmaterialfromthestartingworkpiece so that the resulting shape is the desired geometry. The most important processes inthis category are machining operations such as turning, drilling, and milling, shown inthenextFigure. These cutting operations are most commonly applied to solid metals, performedusing cutting tools that are harder and stronger than the work metal.
d. Material Removal Processes
Excess material removed from the starting piece so what remains is the desired geometry Examples: (a) turning, (b) drilling, and (c) milling
Turning, Drilling, Grinding WheelVideos
Metal chips fly in a high speed turning operation performed on a computer numerical control turning center (photo courtesy of Cincinnati Milacron).
Waste in Shaping Processes
It is desirable to minimize waste in part shaping Material removal processes are wasteful in the unit operations, but molding and particulate processing operations waste little material Terminology for minimum waste processes: Net shape processes - little or no waste of the starting material and no machining is required Near net shape processes - when minimum machining is required
2. Property‑Enhancing Processes
The second major type of part processing is performed to improve mechanical or physical properties of the work material. These processes do notalter the shape of the part. The most importantproperty-enhancing processes involve heat treatments, which include various annealingand strengthening processes for metals and glasses. Sintering of powdered metals andceramics is also a heat treatment that strengthens a pressed powder metal workpart.
A batch of silicon wafers enters a furnace heated to 1000°C (1800°F) during fabrication of integrated circuits under clean room conditions (photo courtesy of Intel Corporation).
3. Surface Processing Operations
Surface processing operations include Cleaningandsurface treatments, b. coatingandthin film depositionprocesses.
a. Cleaningandsurface treatments
a. Cleaningincludesbothchemicalandmechanical processes to remove dirt, oil, and other contaminants from the surface. Surfacetreatments include mechanical working such as shot peening and sand blasting, and physicalprocesses such as diffusion and ion implantation.
b. coatingandthin film depositionprocesses
b. Coating processesapply a coating ofmaterial to the exterior surface of theworkpart. Commoncoating processesexamples: electroplating, anodizing of aluminum, organic coating (ex: painting), andporcelain enameling. Thin film deposition examples: physical vapor deposition andchemical vapor deposition to form extremely thin coatings of various substances.
Photomicrograph of the cross section of multiple coatings of titanium nitride and aluminum oxide on a cemented carbide substrate (photo courtesy of Kennametal Inc.).
B. Assembly Operations
Two or more separate parts are joined to form a new entity Types of assembly operations: Permanent joining processes – create a permanent joint ex: welding, brazing, soldering, adhesive bonding Mechanical assembly – fastening by mechanical methods ex: threaded fasteners (screws, bolts and nuts); press fitting, expansion fits
Two welders perform arc welding on a large steel pipe section (photo courtesy of Lincoln Electric Company).
Assembling: Production Machines and Tooling
Manufacturing operations are accomplished using machinery and tooling (and people) Types of production machines: Machine tools - power-driven machines used to operate cutting tools previously operated manually Machine tools are among the most versatile of allproductionmachines. Other production machines include presses for stamping operations, forge hammersfor forging, rollingmills for rolling sheet metal, weldingmachines for welding, and insertionmachines for inserting electronic components into printed circuit boards.
Automated dispensing of adhesive onto component parts prior to assembly (photo courtesy of EFD, Inc.).
A robotic arm performs unloading and loading operation in a turning center using a dual gripper (photo courtesy of Cincinnati Milacron).
Production systems consist of people, equipment, andprocedures designed for the combination of materials and processes that constitute a firm’smanufacturing operations. Production systems can be divided into two categories: production facilities and manufacturing support systems, as shown in thenextFigure. Production facilities refer to the physical equipment and the arrangement of equipmentin the factory. Manufacturing support systems are the procedures used by the company tomanage production and solve the technical and logistics problems encountered in orderingmaterials, moving work through the factory, and ensuring that products meet quality. Bothcategoriesincludepeople. People make the systems work.
Facilities vs Product Quantities
A company designs its manufacturing systems and organizes its factories to serve the particular mission of each plant Certain types of production facilities are recognized as most appropriate for a given type of manufacturing: Low production – 1 to 100 Medium production – 100 to 10,000 High production – 10,000 to >1,000,000
1. Low Production
Job shop is the term used for this type of production facility (1-100 units/year) A job shop makes low quantities of specialized and customized products A job shop must be designed for maximum flexibility to deal with the wide productvariations encountered (hard product variety). - Products are typically complex, (e.g., space capsules, prototype aircraft, special machinery) - Equipment in a job shop is general purpose - Labor force is highly skilled - Designed for maximum flexibility
Fixed-Position Plant Layout
2. Medium Production
In the medium-quantity range (100–10,000 units annually),two different types of facility, depending on product variety: Batch production Suited to medium and hard product variety Setups required between batches Cellular manufacturing Suited to soft product variety Worker cells organized to process parts without setups between different part styles
Batch (parti) Process Plant Layout
Cellular (hücre) Plant Layout
3. High Production
The high-quantity range (10,000 tomillions of units per year) Referredto as massproduction. High demand for product Manufacturing system dedicated to the production of that product Two categories of mass production: a. Quantity production(involves the mass production of single parts on singlepieces of equipment) b. Flow line production(involves multiple pieces of equipment or workstations arrangedin sequence, and the work units are physically moved through the sequence to complete theproduct.
a. Quantity Production
Mass production of single parts on single machine or small numbers of machines Typically involves standard machines equipped with special tooling Equipment is dedicated full-time to the production of one part or product type Typical layouts used in quantity production are process layout and cellular layout
2. Flow Line Production
Multiple machines or workstations arranged in sequence, e.g., production lines Product is complex Requires multiple processing and/or assembly operations Work units are physically moved through the sequence to complete the product Workstations and equipment are designed specifically for the product to maximize efficiency
FlowLine (Band) Product Plant Layout
Assembly workers on an engine assembly line (photo courtesy of Ford Motor Company).
Trends in Manufacturing
Lean production and Six Sigma Globalization and outsourcing Environmentally conscious manufacturing Microfabrication and Nanotechnology
Lean Production and Six Sigma
These are two programs aimed at improving efficiency and quality in manufacturing. Lean production Doing more work with fewer resources, yet achieving higher quality in the final product Underlying objective: elimination of waste in manufacturing Six Sigma Quality-focused program that utilizes worker teams to accomplish projects aimed at improving an organization’s organizational performance
The recognition that we have an international economy in which barriers once established by national boundaries have been reduced. This has enabled the freer flow of goods and services, capital, technology, and people among regions and countries. Once underdeveloped countries such as China, India, and Mexico have developed their manufacturing infrastructures and technologies, so that, they are now important producers in the global economy.
Globalization is closely related to outsourcing. In manufacturing, outsourcing refersto the use of outside contractors to perform work that was traditionally accomplished inhouse. Local outsourcing Jobs remain in the country Outsourcing to foreign countries - Offshore outsourcing - production in other overseas locations - Near-shore outsourcing - production in nearbycountries
Environmentally Conscious Manufacturing
Determining the most efficient use of materials and natural resources in production, and minimizing the negative consequences on the environment Associated terms: green manufacturing, cleaner production, sustainable manufacturing Basic approaches: Design products that minimize environmental impact Design processes that are environmentally friendly
Microfabrication and Nanotechnology
Microfabrication Processes that make parts and products whose feature sizes are in the micron range (10-6 m) Examples: Ink-jet printing heads, compact disks, microsensors used in automobiles Nanotechnology Materials and products whose feature sizes are in the nanometer range (10-9 m) Examples: Coatings for catalytic converters, flat screen TV monitors