INDUSTRIAL PROCESSES II INDEN 3313

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INDUSTRIAL PROCESSES IIINDEN 3313

• Lecture 8 Completion of Joining
• (Adhesives and Mechanical)
• Introduction to Part Location

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OVERVIEW

• Adhesives
• Mechanical Fastening
• Part Location Theory

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QUESTIONSTO START ??
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ADHESIVES

• Adhesive Joining (Definition)
• Joining Process in Which Physical Bonds are Used
  to Hold Two (or More) Base Materials (Which May
  be Different) Fast
• Adhere - (From The Random House Dictionary)
• 1. to stick fast, cleave, cling, ... 3. to
  hold closely or firmly. from the Latin
  adhaerere meaning to stick/cling.

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ADHESIVE PROCESSES

• Adhesive Wets Surfaces to be Joined
• Dry -gt 1 of Surface in Contact
• Emollient May be Used to Reduce Surface Tension
  of Adhesive
• Bonding Strength is a Function of Surface Tension
  of Adhesive
• Achieved via Change of State
• Solidification (Fusion, Chemical Change, Loss of
  Solvent, ...

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ADHESIVE PROCESSES

• Major Consideration
• Physical Performance of Bond
• Strength
• Relative Strength (to Adherents)
• Which Breaks First
• Setting Time
• Life
• Toxicity
• Ease of Cleaning (Spills, Equipment)
• Compatibility with Base/Contacting Materials
• Insulator/Conductor

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ADHESIVE PROCESSES

• Considerations
• Design Considerations
• Properties of Adhesive, Adherents, and Operating
  Environment
• Porosity of Substrate (Higher Porosity, Weaker
  Joint)
• Fixturing Required, Ability to Clean
• Known Service Requirements
• Economics
• Application Costs
• Acquisition Costs
• Cost of Failure

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ADHESIVE JOINTS STRESSES

• Groover,
  Figure 30.10 p. 783
  

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ADHESIVE PROCESSES

• Considerations
• Application
• Compatible Method/Product
• Spread Lower Surface Tension on Higher
• Processing Rate/Curing Time
• Temperature/Pressure Requirements
• Ability to Automate (Production Rate, Toxicity)
• Joint
• Cleanliness
• Area of Contact
• Thickness of Adhesive Layer

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ADHESIVE JOINTS

• Groover,
  Figure 30.11 p. 783
  

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APPLICATION METHODS

• Roller
• Brush
• Extrusion
• Trowel
• Spray
• Roll Coaters
• Dip Emersion

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ROLL COATING

• Groover,
  Figure 30.14 p. 786
  

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CLASSES OF ADHESIVES

• Class I -- Chemically Reactive
• Set by Cross-Linking of Polymers
• Generally, Endothermic (Thermosetting) Plasitic
• High Shear Strength, Low Peel Strength
• Three Sub-classes
• IA -- Plural Component
• Epoxies, Phenolic Resins
• IB -- Heat Activated
• Endothermic Reactions
• Pre-mixed, Short Shelf Life
• IC -- Moisture Activated
• Silicone/Urethanes, Cynoacrylates, Concrete

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CLASSES OF ADHESIVES

• Class II -- Evaporative Adhesives
• Cures as Solvent Evaporates
• One Substrate Must Absorb the Adhesive
• Generally, Long Drying Times
• Examples
• Acrylics, Vinyl Resins, Asphalt
• Elmers Glue
• Airplane Glue
• Class III -- Hot Melt Adhesives
• Melted, Allowed to Cool/Fuse
• Rapid Setting
• Ethylene Copolymers, Polymides, Polyesters,
  Polyethylene, Polyvinyl Buteral

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CLASSES OF ADHESIVES

• Class IV -- Delayed Tack Adhesives
• Non-tacky Solids that Upon Heating Become Tacky
  and Remain so for Extended Periods (up to Days)
• Polyvinyl Acetate, Polystyrene
• Class V -- Film Adhesives
• One or More Layers of Adhesives
• Individual Layers May Also Belong to Another
  Class
• Class VI -- Pressure Sensitive Adhesives
• Pressure Used to Wet Surface
• PolyAcrylates, Polyvinyl (With Plasticizers),
  Alkyl Ethers

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CLASSES OF ADHESIVES

• Class VII -- Electrically and Thermally
  Conductive
• Fillers added to Adhesive to Improve/ Change
  Electrical Resistance or Heat Transfer Properties
  (Typically Add Metals)
• Used for Electronic Device Attachment (Surface
  Mount Technology)

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INTRODUCTION TO JOINING PROCESSES

• Mechanical Fastening - Definition
• Processes in Which a Mechanical Device or
  Deformation (Elastic or Plastic) is Introduced to
  Hold Two or More Components Together.
• Why Use ?
• Can Join Any Materials
• Easier/More Economical/Lower Skill Requirements
  Than Other Joining Methods
• Use of Fasteners Allows Disassembly for
  Maintenance/Repair
• May Be Made Permanent
• No Temperature, Chemical Processes Introduces
• Other Joining Method Unavailable, Inaccessible

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INTRODUCTION TO JOINING PROCESSES

• Mechanical Fastening - Key Elements in Definition
• Mechanical Devices -- Specifically Designed
  Devices, Commonly Referred to As Fasteners, e.g.,
  Nails, Nuts and Bolts, Screws, Rivets, ... .
• Elastic Deformation -- Material Displacement
  (Strain) in Reaction to an Applied Force (Stress)
  Which Returns to Its Original Position/Condition
  Upon Removal of the Force.
• Plastic Deformation -- Material Displacement
  (Strain) in Reaction to an Applied Force (Stress)
  Which Does Not Return to Its Original
  Position/Condition Upon Removal of the Force.

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MECHANICAL ASSEMBLY/JOINING

• Definition
• Use of One or More Fastening Methods or Devices
  to Attach Parts to One Another
• Reasons
• Ease of Assembly
• Ease of Disassembly
• Low Skill Requirements
• Can Be Automated
• Low cost

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MECHANICAL ASSEMBLY/JOINING

• Types
• Threaded Fasteners
• Rivets and Eyelets
• Press Fits
• Shrink and Expansion Fits
• Snap Fits
• Stitching, Stapling, and Sewing
• Cotter Pins
• Molding Inserts
• Integral Fasteners

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THREADED - SCREWS, NUTS, BOLTS

• Groover,
  Figure 31.1 p. 791
  

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FASTENERS - HEAD STYLES

• Groover,
  Figure 31.2 p. 791
  

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FASTENERS - SET SCREWS

• Groover,
  Figure 31.3 p. 792
  

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FASTENERS - SELF TAPPING

• Groover,
  Figure 31.4, p. 792
  

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FASTENERS - STUDS

• Groover,
  Figure 31.5, p. 792
  

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FASTENERS -THREADED INSERT

• Groover,
  Figure 31.6, p. 793
  

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FASTENERS -CAPTIVE THREADED INSERT

• Groover,
  Figure 31.7, p. 793
  

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FASTENERS - WASHERS

• Groover,
  Figure 31.8, p. 794
  

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FASTENERS - RIVETS

• Groover,
  Figure 31.10, p. 797
  

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FASTENERS - EYELETS

• Groover,
  Figure 31.11, p. 797
  

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FASTENERS - INTERFERENCE FITS

• Groover,
  Figure 31.12, p. 799
  

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FASTENERS - SNAP FITS

• Groover,
  Figure 31.13, p. 800
  

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FASTENERS - RETAINING RINGS

• Groover,
  Figure 31.14, p. 801
  

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FASTENERS - STITCHING

• Unclinched Std.Loop ByPass Loop Flat
  Cinch
• Groover,
  Figure 31.15, p. 801
  

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FASTENERS - COTTER PINS

• Groover,
  Figure 31.16, p. 802
  

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FASTENERS - MOLDED IN INSERTS

• Groover,
  Figure 31.17, p. 803
  

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FASTENERS - INTEGRAL

• Groover, Figure
  31.19 a-c, p. 804
  

Single Lock Seam
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FASTENERS - INTEGRAL

• Groover, Figure
  31.19 d-e, p. 804
  

BEADING
DIMPLING
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PART LOCATION THEORY

• Part in Space Has Six/Twelve Degrees of Freedom
  (Possible Movements)

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PART LOCATION THEORY

• To Arrest Motion, Six Contact Points are
  Sufficient
• Three Points to Define First Datum Plane and
  Arrest One Translational and Two Rotational Modes
• Two Points to Arrest One Additional Translational
  Mode and One Additional Rotational Mode
• One Point to Arrest Final Translational Mode
• This is the 3-2-1 Principle for Jigs/Fixture
  Design

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PART LOCATION THEORY

• Minimize Area of Contact
• Least Likelihood of Hitting Irregularity
• Minimize Area for Inspection, Dirt/Chip
• Maximize Distance Between Locators
• Minimizes Impact of Dirt/Irregularity on Surface
  Location
• Other Two Major Jig/Fixture Design Principles

SHIFT LOCATOR
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EXAMPLE

• In Class Demonstration
• Location of Red Box in Space

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OTHER DESIRED JIG/FIXTURE DESIGN FEATURES

• Allow for Wear
• Slip Renewable Bushings
• Replaceable Locator Pins
• Part Visibility
• Hinged Tops
• Minimum Enclosure
• Fool Proofing
• Ease of Attachment to Machine Tool
• Use of Legs and Feet (Attach/Clearance)
• Cleaning/Drain Holes

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OTHER DESIRED JIG/FIXTURE DESIGN FEATURES

• Use Standard Parts
• Locators
• Correct Size
• Use Shims as Necessary
• Drill Bushings
• Chips Clear Before Bushing
• Chip Pass Through Bushing
• Clamps
• Quick Acting
• Accommodate Part Size Variation
• Simple, Reliable

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QUESTIONSOR CLARIFICATIONS ???
Reminder