production technology (ind 006) - fayoum production tech… · 12 joining processes 3-1- arc...
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Production Technology(IND 006)
Preparatory Year,
Faculty of Engineering,
Fayoum University
Dr. Ahmed Salah Abou Taleb
Lecturer, Industrial Engineering Dept.,
Faculty of Engineering, Fayoum University
Lecture No. 6
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Joining and Fastening Processes
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Introduction
Why using joining and fastening processes?
1- Products are impossible to be manufactured as a single piece due to size or transport constraints.
2- Repair of products during their service life.
3- Products made of different materials.
Joining and Fastening Processes
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Joining and Fastening Processes
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1- Mechanical Fasteners:
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Fastening Processes
Permanent Non-permanent
riveting, press or shrink fitting
assembly with threaded fasteners
2- Adhesive Bonding (gluing or glue bonding):
Natural Inorganic Synthetic
These are made from natural ingredients.e.g.: Starch, dextrin, soya flour, animal
products
There are made from inorganic
chemical materials
e.g.: sodium silicate,
magnesium oxychloride
Are based on natural and synthetic rubbers.
They set by solvent evaporation or heat
curing. e.g.: thermoplastic and
thermosetting plastic
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Adhesive Bonding
– Welding is a materials joining process which produces coalescence of materials by heating them to suitable temperatures with or without the application of pressure, and with or without the use of filler material.
– Welding is used for making permanent joints.
– Applications: ships, pressure vessels, automobile bodies, off-shore platform, welded pipes, sealing of nuclear fuel, explosive, aircraft frames, railway wagons, machine frames, structural works, tanks, furniture, boilers, and general repair work.
3- Welding Process:
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Joining Processes
welding processes could be classified according to the type of energy used in performing the process.
3- Welding Process:
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Joining Processes
Welding Process
Heat Energy
Mechanical Energy
Both Energy
Fusion Welding
Friction Welding
Resistance Welding
3-1- Arc Welding (Fusion Welding):
• The heat is obtained from electrical energy.
• The arc is produced between tip of electrode & workpiece.
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Joining Processes
Joining Processes
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3-1- Arc Welding (Fusion Welding):
The basic elements involved in arc welding process:
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Joining Processes
3-1- Arc Welding (Fusion Welding):
The heat generated in arc melts a portion of the tip of electrode, its coating and base metal.
Function of electrode coating:
1- Stabilize the arc.2- Generate gases to act as a shield against
atmosphere.3- Control the rate which the electrode melts.4- Produce slag which protects the molten weld pool.5- Add alloying elements to the weld zone to enhance
the properties.
Joining Processes
Advantages Most efficient way to join
metals.
Most simple method.
Lowest-cost joining method
Portable equipment useful in remote area
Affords lighter weight through better utilization of materials
Joins all commercial metals
Provides design flexibility
Workpiece thickness range from 3 to 20 mm
Limitations• Manually applied, therefore
high labor cost.
• Need high energy causing danger
• Not convenient for disassembly.
• Defects are hard to detect at joints.
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3-1- Arc Welding (Fusion Welding):
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Joining Processes
3-1- Arc Welding (Fusion Welding):
Applications:General constructions, ship building, pipelines, and maintenance work.
Other arc welding processes1- Submerged arc welding: The weld arc is shielded by
granular flux.2- Gas metal arc welding: The weld area is shielded by
inert gas.3- Flux-cored arc welding: Tubular electrode filled with
flux.4- Gas tungsten arc welding: Non-consumable electrode
plus filler wire plus inert gas.
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Joining Processes
3-2- Gas ”Oxy Fuel” Welding (Fusion Welding):
A fusion welding process which joins metals, using the heat of combustion of an oxygen and fuel gas (i.e. acetylene, hydrogen propane or butane).The intense heat (flame) thus produced melts and fusestogether the edges of the parts to be welded, with the addition of a filler metal.
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Joining Processes
3-2- Gas ”Oxy Fuel” Welding (Fusion Welding):
Joining Processes
• Maximum temperature reached at tip of inner cone, while outer envelope spreads out and shields work surface from atmosphere.
• Oxyacetylene can also be used for cutting metals
• Shown below is neutral flame of oxyacetylene torch indicating temperatures achieved
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3-2- Gas ”Oxy Fuel” Welding (Fusion Welding):
1- Oxygen is turned on, flame immediately changes into a long white inner area (Feather) surrounded by a transparent blue envelope is called Carburizing flame (30000c)
• Used for welding: high carbon steel.
Joining Processes
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3-2- Gas ”Oxy Fuel” Welding (Fusion Welding):
2- Addition of little more oxygen give a bright whitish cone surrounded by the transparent blue envelope is called Neutral flame (It has a balance of fuel gas and oxygen) (3200 0C)
• Used for welding: mild steel, stainless steel, cast iron, copper, and aluminum.
Joining Processes
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3-2- Gas ”Oxy Fuel” Welding (Fusion Welding):
3- If more oxygen is added, the cone becomes darker and more pointed, while the envelope becomes shorter and more fierce is called Oxidizing flame
• Has the highest temperature about 34000c
• Used for welding: copper base and zinc base metals.
Joining Processes
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3-2- Gas ”Oxy Fuel” Welding (Fusion Welding):
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Advantages
Portable.
Low cost equipment.
Suitable for all welding positions.
Can be used in cutting and preheating.
Flux:
used to remove the oxide film and to maintain a clean surface.
Joining Processes
Limitations
Together, acetylene and oxygen are highly flammable.
C2H2 is colorless and odorless.
3-2- Gas ”Oxy Fuel” Welding (Fusion Welding):
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Terminological elements of welding process used with common welding joints
Joining Processes
3-3- Weld Joint (Fusion Welding):
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For welding the edges of joining surface of metals are prepared first.
Joining Processes
3-3- Weld Joint (Fusion Welding):
Joining processes
4- Brazing & Soldering:
• Filler metal distributed by capillary action
• Only filler metal is melted, not base metal
• Strength of joint typically
– Can join dissimilar metals
– Less heat - can join thinner sections (relative to welding)
– stronger than filler metal itself
– weaker than base metal
– Excessive heat during service can weaken joint
• Pros & Cons
• Lower temperatures in all welding processes.
• Metallurgical bond formed between filler & base metals
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Joining processes
4-1 Soldering:Solder = Filler metal
Applications:
• Printed Circuit Board (PCB) manufacture
• Pipe joining (copper pipe)
• Jewelry manufacture
Easy to solder: copper, silver, gold
Difficult to solder: aluminum, stainless steels
• Alloys of Tin (silver, bismuth, lead)
• Melt point typically below 300 0C.
Flux used to clean joint & prevent oxidation
• Typically non-load bearing
Tinning = pre-coating with thin layer of solder
• separate or in core of wire (rosin-core)
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Joining processes
4-2 Brazing:
Applications:
• Pipe/Tubing joining (HVAC)
• Filler metals Cu alloys (silver, zinc & phosphorus)
• Melt point typically above 300 0C)
• Automotive - joining tubes
• Electrical equipment - joining wires
• Jewelry Making
• Flux also used
• Types of brazing classified by heating method:
– Torch, Furnace, Resistance
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Workshop This Week (4-7/4/2015)
Day Time Slot 3 Time Slot 4
Saturday Workshop 5 Workshop 5
Sunday Reparation
Monday Reparation Workshop 5
Tuesday Workshop 5 Workshop 5
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Lecture Power Point, Assignments, & Grades
www.fayoum.edu.eg/ahmedsalah
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