Chapter 1 - Introduction Manufacturing Technology Note PDF

Manufacturing Technology BDA 31403 Prof. Ir. Dr. Yusri Bin Hj Yusof  INTRODUCTION AND OVERVIEW OF MANUFACTURING 1. What is Manufacturing? 2. Materials in Manufacturing 3. Manufacturing Processes 4. Production Systems 5. Manufacturing Economics 6. Recent...

Manufacturing Technology BDA 31403 Prof. Ir. Dr. Yusri Bin Hj Yusof  INTRODUCTION AND OVERVIEW OF MANUFACTURING 1. What is Manufacturing? 2. Materials in Manufacturing 3. Manufacturing Processes 4. Production Systems 5. Manufacturing Economics 6. Recent Developments in Manufacturing ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  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 the United States and most other developed and developing nations ▪ Technologically ▪ Economically ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Technological Importance ▪ Technology - the application of science to provide society and its members with those things that are needed or desired ▪ Technology affects our daily lives, directly and indirectly, in many ways ▪ Technology provides the products that help our society and its members live better ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Technological Importance ▪ What do these products have in common? ▪ They are all manufactured ▪ They would not be available to our society if they could not be manufactured ▪ Manufacturing is the essential factor that makes technology possible ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Economic Importance U.S. Economy Sector: %GDP Agriculture and natural resources 5 Construction and public utilities 5 Manufacturing 12 Service industries* 78 100 * includes retail, transportation, banking, communication, education, and government ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e PRODUCTIVITY PERFORMANCE OF MAIN ECONOMIC SECTORS (2019 – 2021) What is Manufacturing? ▪ The word manufacture is derived from two Latin words manus (hand) and factus (make); the combination means “made by hand” ▪ “Made by hand” 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 ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  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 ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Manufacturing - Economic ▪ Transformation of materials into items of greater value by one or more processing and/or assembly operations ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Manufacturing Example: Artificial Heart Valve Left: Heart valve Right: Starting titanium billet ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Manufacturing Industries ▪ Industry consists of enterprises and organizations that produce or supply goods and services ▪ Industries can be classified as: 1. Primary industries - cultivate and exploit natural resources, e.g., agriculture, mining 2. Secondary industries - take the outputs of primary industries and convert them into consumer and capital goods 3. Tertiary industries - service sector ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Specific Industries in Each Category ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Manufacturing Industries - continued ▪ Secondary industries include manufacturing, construction, and electric power generation ▪ 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 ▪ Nuts and bolts, forgings, cars, airplanes, digital computers, plastic parts, and ceramic products ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Manufactured Products ▪ Final products divide into two major classes: 1. Consumer goods - products purchased directly by consumers ▪ Cars, clothes, TVs, tennis rackets 2. Capital goods - those purchased by companies to produce goods and/or provide services ▪ Aircraft, computers, communication equipment, medical apparatus, trucks, machine tools, construction equipment ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  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 ▪ Annual quantities can be classified into three ranges: Production range Annual Quantity Q Low production 1 to 100 units Medium production 100 to 10,000 units High production 10,000 to millions of units ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Product Variety P ▪ Product variety P 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 ▪ The number of different product types made each year in a factory can be counted ▪ When the number of product types made in the factory is high, this indicates high product variety ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e P vs Q in Factory Operations ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  More About Product Variety ▪ Although P 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) ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Manufacturing Capability ▪ A manufacturing plant consists of processes and systems (and people) to transform a certain limited range of materials into products of increased value ▪ The three building blocks - materials, processes, and systems - are the subject of modern manufacturing ▪ Manufacturing capability includes: 1. Technological processing capability 2. Physical product limitations 3. Production capacity ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  1. Technological Processing Capability ▪ The set of available manufacturing processes in the plant (or company) ▪ Certain manufacturing processes are suited to certain materials, so by specializing in certain processes, the plant is also specializing in certain materials ▪ Includes not only the physical processes, but also the expertise of the plant personnel ▪ A machine shop cannot roll steel ▪ A steel mill cannot build cars ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  2. Physical Product Limitations ▪ Given a plant with a certain set of processes, there are size and weight limitations on the parts or products that can be made in the plant ▪ Product size and weight affect: ▪ Production equipment ▪ Material handling equipment ▪ Production, material handling equipment, and plant size must be planned for products that lie within a certain size and weight range ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  3. Production Capacity ▪ Defined as the maximum quantity that a plant can produce in a given time period (e.g., month or year) under assumed operating conditions ▪ Operating conditions refer to number of shifts per week, hours per shift, direct labor manning levels in the plant, and so on ▪ Usually measured in terms of output units, e.g., tons of steel or number of cars produced ▪ Also called plant capacity ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Materials in Manufacturing ▪ Most engineering materials can be classified into one of three basic categories: 1. Metals 2. Ceramics 3. Polymers ▪ Their chemistries are different, and their mechanical and physical properties are different ▪ In addition, there is a fourth category: 4. Composites ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Classification of engineering materials ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  1. Metals ▪ Usually alloys, which are composed of two or more elements, at least one of which is metallic. Two basic groups: 1. Ferrous metals - based on iron, comprises about 75% of metal tonnage in the world: ▪ Steel and cast iron 2. Nonferrous metals - all other metallic elements and their alloys: ▪ Aluminum, copper, nickel, silver, tin, etc. ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  2. Ceramics ▪ Compounds containing metallic (or semi-metallic) and nonmetallic elements. ▪ Typical nonmetallic elements are oxygen, nitrogen, and carbon ▪ For processing, ceramics divide into: 1. Crystalline ceramics – includes traditional ceramics, such as clay, and modern ceramics, such as alumina (Al2O3) 2. Glasses – mostly based on silica (SiO2) ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  3. Polymers ▪ Compound formed of repeating structural units called mers, whose atoms share electrons to form very large molecules. Three categories: 1. Thermoplastic polymers - can be subjected to multiple heating and cooling cycles without altering molecular structure 2. Thermosetting polymers - molecules chemically transform into a rigid structure – cannot reheat 3. Elastomers - shows significant elastic behavior ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  4. Composites ▪ Material consisting of two or more phases that are processed separately and then bonded together to achieve properties superior to its constituents ▪ Phase - homogeneous material, such as grains of identical unit cell structure in a solid metal ▪ Usual structure consists of particles or fibers of one phase mixed in a second phase ▪ Properties depend on components, physical shapes of components, and the way they are combined to form the final material ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Manufacturing Processes: Two Basic Types 1. Processing 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 2. Assembly operations - join two or more components to create a new entity ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Classification of Manufacturing Processes ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Processing Operations ▪ Alters a material’s shape, physical properties, or appearance in order to add value ▪ Three categories of processing operations: 1. Shaping operations - alter the geometry of the starting work material 2. Property-enhancing operations - improve physical properties without changing shape 3. Surface processing operations - clean, treat, coat, or deposit material on surface of work ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Four Categories of Shaping Processes 1. Solidification processes - starting material is a heated liquid or semifluid 2. Particulate processing - starting material consists of powders 3. Deformation processes - starting material is a ductile solid (commonly metal) 4. Material removal processes - starting material is a ductile or brittle solid ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Solidification Processes ▪ Starting material is heated sufficiently to transform it into a liquid or highly plastic state ▪ (1) Casting process and (2) casting product ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Particulate Processing ▪ (1) Starting materials are metal or ceramic powders, which are (2) pressed and (3) sintered ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Deformation Processes ▪ Starting workpart is shaped by application of forces that exceed the yield strength of the material ▪ Examples: (a) forging and (b) extrusion ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e 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 ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e 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 ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Property-Enhancing Processes ▪ Processes that improve mechanical or physical properties of work material ▪ Examples: ▪ Heat treatment of metals and glasses ▪ Sintering of powdered metals and ceramics ▪ Part shape is not altered, except unintentionally ▪ Example: unintentional warping of a heat treated part ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Surface Processing Operations ▪ Cleaning - chemical and mechanical processes to remove dirt, oil, and other surface contaminants ▪ Surface treatments - mechanical working such as sand blasting, and physical processes like diffusion ▪ Coating and thin film deposition - coating exterior surface of the workpart ▪ Examples: ▪ Electroplating ▪ Painting ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Assembly Operations ▪ Two or more separate parts are joined to form a new entity ▪ Types of assembly operations: 1. Joining processes – create a permanent joint ▪ Welding, brazing, soldering, adhesive bonding 2. Mechanical assembly – fastening by mechanical methods ▪ Threaded fasteners (screws, bolts and nuts); press fitting, expansion fits ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e 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 ▪ Other production equipment: ▪ Presses ▪ Forge hammers, ▪ Plastic injection molding machines ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Production Systems ▪ People, equipment, and procedures used for the materials and processes that constitute a firm's manufacturing operations ▪ A manufacturing firm must have systems and procedures to efficiently accomplish its production ▪ Two categories of production systems: ▪ Production facilities ▪ Manufacturing support systems ▪ People make the systems work ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Model of the Production System ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Production Facilities ▪ The factory, production equipment, and material handling systems ▪ Includes the plant layout ▪ Equipment usually organized into logical groupings, called manufacturing systems ▪ Examples: ▪ Automated production line ▪ Machine cell consisting of three machine tools ▪ Production facilities "touch" the product ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e 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: 1. Low production – 1 to 100 2. Medium production – 100 to 10,000 3. High production – 10,000 to >1,000,000 ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Low Production ▪ Job shop is the term used for this type of production facility ▪ A job shop makes low quantities of specialized and customized products ▪ 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 ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e CLASS ACTIVITY (W2) Identify and discuss the process to produce a Spur Gear Fixed-Position Plant Layout ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Medium Production ▪ 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 ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Process Plant Layout ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Cellular Plant Layout ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e High Production ▪ Often referred to as mass production ▪ High demand for product ▪ Manufacturing system dedicated to the production of that product ▪ Two categories of mass production: 1. Quantity production 2. Flow line production ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e 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 ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Flow Line Production ▪ Multiple machines or workstations arranged in sequence, as in a production line ▪ 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 ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Product Plant Layout ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e  Manufacturing Support Systems ▪ A company must organize itself to design the processes and equipment, plan and control production, and satisfy product quality requirements ▪ Accomplished by manufacturing support systems ▪ The people and procedures by which a company manages its production operations ▪ Typical departments: ▪ Manufacturing engineering, Production planning and control, Quality control ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Typical Cost Breakdown for a Manufactured Product ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Recent Developments in Manufacturing ▪ Microelectronics ▪ Computerization in manufacturing ▪ Flexible manufacturing ▪ Microfabrication and Nanotechnology ▪ Lean production and Six Sigma ▪ Globalization and outsourcing ▪ Environmentally conscious manufacturing ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Microelectronics ▪ Electronic devices that are fabricated on a microscopic scale: Integrated circuits (ICs) ▪ Today’s fabrication technologies permit billions of components to be included in a single IC ▪ A large proportion of the products manufactured today are based on microelectronics technology ▪ About 2/3 of the products in Table 1.1 are either electronics products or their function and operation depend on electronics ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Computerization of Manufacturing ▪ Direct Numerical Control (DNC) was one of the first applications of computers in manufacturing (1960s) ▪ Mainframe computer remotely controlling multiple machine tools ▪ Enabled by advances in microelectronics, the cost of computers and data processing has been reduced, leading to the widespread use of personal computers ▪ To control individual production machines ▪ To manage the entire enterprise ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Flexible Manufacturing ▪ Although mass production is widely used throughout the world, computerization has enabled the development of manufacturing systems that can cope with product variety ▪ Examples: ▪ Cellular manufacturing ▪ Mixed-model assembly lines ▪ Flexible manufacturing systems ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e 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 ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Lean Production and Six Sigma ▪ 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 ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Globalization ▪ 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 now developed their manufacturing infrastructures and technologies to become important producers in the global economy ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Outsourcing ▪ Use of outside contractors to perform work that was traditionally accomplished in-house ▪ Local outsourcing ▪ Jobs remain in the U.S. ▪ Outsourcing to foreign countries ▪ Offshore outsourcing - production in China and other overseas locations ▪ Near-shore outsourcing - production in Canada, Mexico, and Central America ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e 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: 1. Design products that minimize environmental impact 2. Design processes that are environmentally friendly ©2012 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 5/e Examples 1 (A) A company invests $750,000 in a piece of production equipment. The cost to install the equipment in the plant = $25,000. The anticipated life of the machine = 12 years. The machine will be used eight hours per shift, five shifts per week, 50 weeks per year. Applicable overhead rate = 18%. Assume availability = 100%. Determine the equipment cost rate if (a) the plant operates one shift per day and (b) the plant operates three shifts per day. ▪ Solution: (a) For a one-shift operation, hours of operation per year H = 50(1)(5)(8) = 2000 hr/yr. Using Eq. (1.8), Ceq = (750,000 + 25,000)(1.18)/(60 x 12 x 2000) = $0.635/min = $38.10/hr ▪ (b) For a three-shift operation, hours of operation per year H = 50(3)(5)(8) = 6000 hr/yr. ▪ Ceq = (750,000 + 25,000)(1.18)/(60 x 12 x 6000) = $0.212/min = $12.70/hr ▪ Note the significant advantage the company has if it runs three shifts per day rather than one shift. Example 2 1 A stamping press produces sheet-metal stampings in batches. The press is operated by a worker whose labor rate = $15.00/hr and applicable labor overhead rate = 42%. Cost rate of the press = $22.50/hr and applicable equipment overhead rate = 20%. In one job of interest, batch size = 400 stampings, and the time to set up the die in the press takes 75 min. The die cost $40,000 and is expected to last for 200,000 stampings. Each cycle in the operation, the starting blanks of sheet metal are manually loaded into the press, which takes 42 sec. The actual press stroke takes only 8 sec. Cost of the starting blanks = $0.43/pc. The press operates 250 days per year, 7.5 hours per day, but the operator is paid for 8 hours per day. Assume availability = 100% and scrap rate = 0. Determine (a) cycle time, (b) average production rate with and without setup time included, and (c) cost per stamping produced. ▪ Solution: (a) Cycle time Tc = 42 + 8 = 50 sec = 0.833 min ▪ (b) Including setup time, Tp = 75/400 + 0.833 = 1.021 min ▪ Rp = 60/1.021 = 58.78 pc/hr ▪ Excluding setup time, Rc = 60/0.833 = 72.03 pc/hr ▪ (c) Equipment cost rate Ceq = 22.50(1.20)/60 = $0.45/min. ▪ Die cost per piece Ct = 40,000/200,000 = $0.20/pc ▪ Labor cost rate CL = 15.00(1.42)/60 = $0.355/min ▪ This labor cost should be adjusted for the fact that although the press operates 7.5 hr/day, the operator is paid for 8 hr. CL = 0.355(8/7.5) = $0.379 ▪ Finally, cost per stamping Cpc = 0.43 + (0.379 + 0.45)(1.021) + 0.20 = $1.48/pc Example 3 1 (A) During a particular 40-hour week of an automated production operation, 336 acceptable (non-defective) parts and 22 defective parts were produced. The operation cycle consists of a processing time of 5.73 min, and a part handling time of 0.38 min. Every 60 parts, a tool change is performed, and this takes 7.2 min. The machine experienced several breakdowns during the week. Determine (a) hourly production rate of acceptable parts, (b) scrap rate, and (c) availability (proportion uptime) of the machine during this week. ▪ Solution: (a) Production rate of acceptable parts Rp = 335/40 = 8.40 pc/hr ▪ (b) Total parts processed during the week Qo = 336 + 22 = 358 pc ▪ Scrap rate q = 22/358 = 0.0615 = 6.15% ▪ (c) Cycle time of the unit operation Tc = 5.73 + 0.38 + 7.2/60 = 6.23 min ▪ Total uptime during the week = 358(6.23) = 2230.34 min = 37.17 hr ▪ Proportion uptime A = 37.17/40 = 0.929 = 92.9%