Joining of Materials

cypriotcamelUrban and Civil

Nov 29, 2013 (3 years and 8 months ago)

52 views

Materials Technology




Joining Processes

Overview


Joining Materials


OPTION

The student will learn about…


The methods by which materials are joined


permanent and semi
-
permanent techniques


The student will be able to…



Demonstrate a knowledge of the main methods
of joining materials


metallurgical processes,
mechanical joining and adhesive/chemical
bonding



Overview


Joining Processes


JOINING TECHNIQUES




Metallurgical

Brazing

Soldering

Mechanical

Screw Fasteners

Compression Joints

Riveting

Sheet Metal Folding

Adhesive

Natural

Elastomer

Thermoplastic

Thermoset

Toughened

P

P

NP

NP

P

P

P

P

P

P

P

P = Permanent

NP = Non
-
permanent

JOINING PROCESSES

MECHANICAL

Screw Fasteners

These are non
-
permanent methods of joining
materials. There is a very wide variety of screw
fasteners available they include;


Woodscrews


Self
-
drilling/tapping screws


Machine screws


Furniture screws


Bolts


Compression Joints



JOINING PROCESSES

MECHANICAL

Screw Fasteners

Woodscrews



JOINING PROCESSES

MECHANICAL

Screw Fasteners

Woodscrews



Wood Screw Pozi Head CSK

Wood Screws Round Head Slotted

JOINING PROCESSES

MECHANICAL

Screw Fasteners

Furniture Screws



Furniture Screws & ‘Knock Down’ fittings

JOINING PROCESSES

MECHANICAL

Screw Fasteners

Knock Down Fittings



JOINING PROCESSES

MECHANICAL

Self Drilling/Tapping Screws




JOINING PROCESSES

MECHANICAL

Machine Screws




JOINING PROCESSES

MECHANICAL

Bolts





Hexagon Socket Head

Hexagon Flange Bolts

Chrome Hexagonal Bolts

JOINING PROCESSES

MECHANICAL

Nuts & Washers





JOINING PROCESSES

MECHANICAL

Compression Fittings






Straight Coupling

Equal Tee

Used primarily in plumbing applications

JOINING PROCESSES

MECHANICAL

Pop Rivets







Pop Riveting Tool with Threaded Inserts

This is a permanent joining process

JOINING PROCESSES

MECHANICAL

Rivets







These are used for permanent joints in steel plate

Snap Head Rivet

Countersunk Rivet

JOINING PROCESSES

METALURGICAL

Soldering






Electric Cable

Replaceable Tip

Insulated Handle

Electric Soldering Iron

JOINING PROCESSES

METALURGICAL

Soldering






Soldering Iron Stand

Soldering Wire

JOINING PROCESSES

METALURGICAL

Soldering a Component on

A Circuit Board






Soldering Iron

Circuit Board

Foil

Component Lead

The soldering iron tip is placed against the lead and the circuit board
foil. Both are heated for 3 or 4 seconds

JOINING PROCESSES

METALURGICAL

Soldering a Component on

A Circuit Board






Cored Solder
Wire

The solder is applied to the lead opposite the soldering iron. It is the
heated lead and circuit board foil that melts the solder

JOINING PROCESSES

METALURGICAL

Soldering a Component on

A Circuit Board






Molten Solder

As the solder melts it flows around the connection and forms a good
conductive joint with the foil. The soldering wire and the soldering iron are
then withdrawn and the joint is allowed to cool

JOINING PROCESSES

METALURGICAL

Brazing






Brazing Hearth

Brazing Torch

Firebrick

JOINING PROCESSES

METALURGICAL

Brazing






Brazing Torch

Brazing Rod (Spelter)

Whole of joint
area is heated
and it is the
heated joint
that melts the
Spelter

JOINING PROCESSES

METALURGICAL

Brazing






Typical Brazing Applications

JOINING PROCESSES

Adhesives

Natural Adhesives

These are made from natural ingredients
rather than being fabricated synthetically
from chemicals.


Sources


Animal based


Fish based


Vegetable based








JOINING PROCESSES

Adhesives

Natural Adhesives

Some natural adhesives have the following
properties, they can be;


Strong


Flexible


Waterproof


Soluble in water


Transparent











However they are not as strong as synthetic
adhesives and are usually more expensive

JOINING PROCESSES

Adhesives

Natural Adhesives

Are often used in furniture and architectural
restoration projects


They are also friendlier to the environment;


No chemicals released into the soil or
atmosphere in production or use


No aggravation of chemical based allergies


Manufactured from renewable resources










JOINING PROCESSES

Adhesives

Elastomer Adhesives

Are based on natural and synthetic rubbers. They
set by solvent evaporation or heat curing. Used
for flexible bonds in plastics and rubber











Type

Description

Materials

Natural Rubber

Water resistant

Rubber, plastics, steel,
fabrics, wood, glass

Neoprene

Contact adhesive

Wood, metal, leather,
plastics

Butyl Rubber

Tyre repairs

Rubber products

Polyurethane

High strength joint

Glass, polyurethane,
plastic, metals

Silicone Rubber

Sealant, space filling,
water resistant, glazing

Silicone, glass, metals

JOINING PROCESSES

Adhesives

Thermoplastic Adhesives

Are fusible, soluble but with poor heat and creep
resistance











Type

Description

Materials

Polyvinyl Acetate (PVA)

Emulsion type wood glue,
poor resistance to water

Wood, metal, glass,
ceramics

Cyanoacrylates

Hardens in seconds
based on catalytic action

Metal, plastics, ceramics,
etc

Polyamines

Applied hot


sets on
cooling (hot glue gun)

Metal, wood, plastics,
laminates

Anerobic Acrylic Acid
Diesters

Locking and sealing nuts
and threaded parts

Metals

JOINING PROCESSES

Adhesives

Thermoset Adhesives

High strength, suitable for high load assemblies
and resistant to heat and cold. Comparable with
the strength of welded or riveted joints











Type

Description

Materials

Resorcinol Resins

Used in exterior plywood

Wood and other porous
materials

Polyesters (unsaturated)

Hardens by chemical
reaction, not evaporation


very little shrinkage

Binder for fibre glass

Epoxy Resin

2
-
part, high strength, little
shrinkage

Metal, glass, elastomers,
some plastics

Redux© adhesive (brand
name)

High performance,
aerospace, marine,
automobiles

Metals

JOINING PROCESSES

Adhesives

Toughened Adhesives

Research has led to the development of
high strength, toughened adhesives.


They have small rubber
-
like particles
dispersed throughout the glassy matrix.


This gives the adhesive a high resistance
to crack formation