1.What is Manufacturing? 2.Materials in Manufacturing 3.Manufacturing Processes 4.Production Systems 5.Manufacturing Economics 6.Recent Developments in.
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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
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
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)
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
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
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
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
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
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
Microelectronics Computerization in manufacturing Flexible manufacturing Microfabrication and Nanotechnology Lean production and Six Sigma Globalization and outsourcing Environmentally conscious 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
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
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
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
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%