Part I OVERVIEW OF MANUFACTURING Chapters: 2.Manufacturing Operations 3.Manufacturing Models and...

Part I OVERVIEW OF MANUFACTURING

Chapters:

2. Manufacturing Operations

3. Manufacturing Models and Metrics

©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems,

and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 1

Ch 2 Manufacturing Operations

Sections:

1. Manufacturing Industries and Products

2. Manufacturing Operations

3. Production Facilities

4. Product/Production Relationships

5. Lean Production



Manufacturing Defined - Technological Definition

““Application of physical and chemical processes to Application of physical and chemical processes to alter the geometry, properties, and/or appearance of alter the geometry, properties, and/or appearance of a given starting material to make parts or productsa given starting material to make parts or products””

Manufacturing also includes the joining of multiple parts to make assembled products

Accomplished by a combination of machinery, tools, power, and manual labor.

Almost always carried out as a sequence of operations



Manufacturing Defined - Technological Definition

Fig. 2.1.a



Manufacturing Defined - Economic Definition

““Transformation of materials into items of greater value Transformation of materials into items of greater value by means of one or more processing and/or assembly by means of one or more processing and/or assembly operationsoperations””

Manufacturing adds value to the material Examples:

Converting iron ore to steel adds value Transforming sand into glass adds value Refining petroleum into plastic adds value



Manufacturing Defined -Economic Definition

Fig. 2.1.b



Classification of Industries

1. Primary industries – cultivate and exploit natural resources Examples: agriculture, mining

2. Secondary industries – convert output of primary industries into products Examples: manufacturing, power generation,

construction

3. Tertiary industries – service sector Examples: banking, education, government, legal

services, retail trade, transportation



Manufacturing Industries

ISIC Code

Food, beverages, tobacco 31 Textiles, apparel, leather and fur products 32 Wood and wood products, cork 33 Paper, printing, publishing, bookbinding 34 Chemicals, coal, petroleum and their products 35 Ceramics, glass, mineral products 36 Basic metals, e.g., steel, aluminum 37 Fabricated products, e.g., cars, machines, etc. 38 Other products, e.g., jewelry, toys 39



More Industry Classifications

Process industries, e.g., chemicals, petroleum, basic metals, foods and beverages, power generation Continuous production Batch production

Discrete product (and part) industries, e.g., cars, aircraft, appliances, machinery, and their component parts Continuous production Batch production



Process Industries and Discrete Manufacturing Industries



Manufactured Products

Consumer goods: products purchased directly by consumers

Ex: cars, personal computers, Tvs, toys...

Capital goods: products purchased by other companies to produce goods and supply services

Ex: commercial aircraft, mainframe computers, machine tools, construction machinery...



Manufacturing Operations

There are certain basic activities that must be carried out in a factory to convert raw materials into finished products

For discrete products:

1. Processing and assembly operations

2. Material handling

3. Inspection and testing

4. Coordination and controlA processing operation transforms a work material from one state of

completion to a more advanced state using energy to alter its shape,

properties or appearance to add value to the material.



Fig. 2.3

Classification of manufacturing processes



Processing Operations

A processing operation transforms a work material from one state of completion to a more advanced state that is closer to the final desired part or product.

Adds value to the material using energy to alter a work part’s shape, physical properties or appearance.




Shaping operations apply mechanical force and/or heat or other forms and combinations of energy to change the geometry of the work material. Classification is based on the state of the starting material.




Shaping operations

1. Solidification processes Casting (metal) Molding (plastic/glass)

2. Particulate processing – pressing then sintering powder material (ceramics)

3. Deformation processes – forging/extrusion/rolling

Starting material is ductile metal

4. Material removal processes – turning/drilling/milling/grinding Starting material is solid Excess material is removed so that resulting product

has the desired geometry ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems,



Property-enhancing operations are designed to improve mechanical or physical properties of the work material heat treatments (sintering)

Surface processing operations Cleaning (remove contaminants) Surface treatments – mechanical work Coating and thin-film deposition – coating of

material to exterior surface



Assembly Operations

Joining processes Welding Brazing and soldering Adhesive bonding

Mechanical assembly Threaded fasteners (e.g., bolts and nuts, screws) Rivets Interference fits (e.g., press fitting, shrink fits) Other

An assembly operation joins two or more components to create

a new entity which is called an assembly, subassembly, etc.



Other Factory Operations

Material handling and storage Inspection and testing Coordination and control



Material Handling

““A means of moving and storing materials between processing A means of moving and storing materials between processing and/or assembly operations”and/or assembly operations”

Material transport Vehicles, e.g., forklift trucks, AGVs, monorails Conveyors Hoists and cranes

Storage systems Unitizing equipment Automatic identification and data capture (AIDC)

Bar codes RFID Other AIDC equipment



Time Spent in Material Handling

Fig. 2.4 A typical part in a batch production machine shop



Inspection and Testing

Inspection – examination of the product and its components to determine whether they conform to design specifications Inspection for variables - measuring Inspection of attributes – gaging

Testing – observing the product (or part, material, subassembly) during actual operation or under conditions that might occur during operation



Coordination and Control

Regulation of the individual processing and assembly operations Process control Quality control

Management of plant level activities Production planning and control Quality control



Production Facilities

A manufacturing company attempts to organize its facilities in the most efficient way to serve the particular mission of the plant

Certain types of plants are recognized as the most appropriate way to organize for a given type of manufacturing

The most appropriate type depends on: Types of products made Production quantity Product variety



Production Quantity

Number of units of a given part or product produced annually by the plant

Three quantity ranges:

1. Low production – 1 to 100 units

2. Medium production – 100 to 10,000 units

3. High production – 10,000 to millions of units



Product Variety

““Refers to the number of different product or part Refers to the number of different product or part designs or types produced in the plantdesigns or types produced in the plant””

Inverse relationship between production quantity and product variety in factory operations

Product variety is more complicated than a number Hard product variety – products differ greatly

Few common components in an assembly Soft product variety – small differences between

products Many common components in an assembly



Product Variety vs. Production Quantity

Manufacturing plants tend to specialize in a combination of production quantity and product variety that lies somewhere inside the diagonal band in the figure.



Low Production Quantity

Job shopJob shop – makes low quantities of specialized and customized products

Also includes production of components for these products

Products are typically complex (e.g., specialized machinery, prototypes, space capsules)

Equipment is general purpose



Low Production Quantity

Plant layouts: Fixed position: The product remains in a single location

during its entire fabrication and workers/equipment are brought to the product rather than moving the product. Ex: ships, aircraft, heavy machinery

Process layout: The equipment is arranged according to function or type.

Different parts, each requiring a different operation sequence, are routed through the departments in the particular order needed for their processing, usually in batches.



Fixed-Position Layout

Fig. 2.6 (a)



Process Layout

Fig. 2.6 (b)



Medium Production Quantities

1.1. Batch productionBatch production – A batch of a given product is produced, and then the facility is changed over to produce another product Changeover takes time – setup time Typical layout – process layout Hard product variety

2.2. Cellular manufacturingCellular manufacturing – A mixture of products is made without significant changeover time between products Typical layout – cellular layout Soft product variety



Cellular Layout

Fig. 2.6 (c)

Each cell is designed to produce a limited variety of part configurations; that is, the cell specializes in the production of a given set of similar parts or products (group technology).



High Production (mass production)

1.1. Quantity productionQuantity production – Equipment is dedicated to the manufacture of one product Standard machines tooled for high production (e.g.,

stamping presses, molding machines) Typical layout – process layout

2.2. Flow line productionFlow line production – Multiple workstations arranged in sequence and parts or assemblies are physically moved through the sequence to complete the product Product requires multiple processing or assembly

steps Product layout is most common



Product Layout

Fig. 2.6 (d)



Relationships between Plant Layout and Type of Production Facility

Fig. 2.7



Product/Production Relationships

Parameters that influence to determine how the products are manufactured:

1.Production quantity

2.Product variety – number of products

3.Product complexity (of assembled products) – number of parts

4.Part complexity – number of operations




Total number of product units = Qf =

Qj: annual quantity of style j

Qf: total quantity of all parts/products made in the factory

P: total number of different part or product styles

P

jjQ

1




Let

P1: number of distinct product lines produced-hard variety

P2: number of models in a product line-soft variety



1

12 21 22 21

...P

j Pj

P P P P P


Product variety Hard product variety = differences between

products Soft product variety = differences between models

of products Product and part complexity

Product complexity np = number of parts in product

Part complexity no = number of operations per part



Product and Part Complexity

npj: number of parts in product j

npf: total number of parts manufactured by the plant per year (pc/yr)

nof: total number of operation cycles performed (ops/yr)

nojk: number of processing operations for each part k for all parts of product j



1

P

pf j pjj

n Q n

1 1

pjnP

of j pj ojkj k

n Q n n

Factory Operations Model

Simplified for purposes of conceptualization: Total number of product units Qf = PQ

Total number of parts produced npf = PQnp

Total number of operations nof = PQnpno



Production Plants

no>1Parts producer: makes individual components, each component requires multiple processing steps, no assembly.

Vertically integrated plant: makes all its parts and assembles them into its final products.

no=1Handicraft shop: not really a production plant, makes one part per year.

Assembly plant: produces no parts, purchases all parts from suppliers, one operation is required to assemble each part to the product.

np=1 np>1



Limitations and Capabilities of a Manufacturing Plant

Manufacturing capabilityManufacturing capability - the technical and physical limitations of a manufacturing firm and each of its plants

Three dimensions of manufacturing capability:

1. Technological processing capability - the available set of manufacturing processes

2. Physical size and weight of product

3. Production capacity (plant capacity) – max production quantity that can be made in a given time under assumed operating conditions



Lean Production

““Operating the factory with the minimum possible Operating the factory with the minimum possible resources and yet maximizing the amount of work resources and yet maximizing the amount of work accomplishedaccomplished””

Resources include workers, equipment, time, space, materials

Also implies completing products in the minimum possible time and achieving a very high quality level to completely satisfy the customer

In short, lean production means doing more with less, and doing it better



Lean Production and Manufacturing Activities

Manufacturing activities can be divided into three categories:

1. Value-adding activities - contribute real value to the work unit. Ex: processing/assembly operation

2. Auxiliary activities - support the value-adding activities but do not contribute value to the product. Ex: loading/ unloading machines

3. Wasteful activities - do not add value nor do they support the value adding activities If not performed, there would be no adverse effect on

the product “ELIMINATE !”



Programs Associated with Lean Production

Just-in-time delivery of parts: refers to the manner in which parts are moved through the production system when a sequence of manufacturing operations is required to make them.

Worker involvement: Workers with greater responsibility and training that allow them to be flexible.

Continuous improvement: Search for ways to make improvements in products and manufacturing operation (Kaizen)

Reduced setup times: Minimize the time needed to change over from one setup to the next in batch production



Programs Associated with Lean Production

Stop the process when something is wrong Error prevention: Refers to the use of low-cost devices and

design features at each workstation that prevent errors occuring.

Total productive maintenance: A program that includes preventive maintenance and other procedures to avoid machine breakdowns that disrupt production operations.



Part I OVERVIEW OF MANUFACTURING Chapters: 2.Manufacturing Operations 3.Manufacturing Models and...

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