Gas Welding and Hydrostatic Extrusion Quiz

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Questions and Answers

What is the maximum recommended pressure for acetylene from a cylinder through a rubber hose?

2 bar

1 bar (correct)

0.5 bar

3.5 bar

What pressure range is recommended for acetylene at the welding torch in a low-pressure system?

0.06 to 0.5 bar

1.0 to 3.0 bar

0.06 to 1.0 bar (correct)

0.5 to 3.5 bar

What is the purpose of the back pressure valve in the gas welding system?

To prevent an explosion from gas backflow (correct)

To clean the acetylene before usage

To increase the pressure of the gas in the blowpipe

To regulate the temperature of the generated gas

What is the required pressure range for oxygen at the welding torch in a high-pressure system?

0.1 to 3.5 bar Signup and view all the answers

What equipment is replaced in the low-pressure system of gas welding instead of an acetylene cylinder?

Acetylene generator Signup and view all the answers

What is the primary purpose of the high pressure liquid medium in hydrostatic extrusion?

To transmit force to the billet/blank Signup and view all the answers

Which material is mentioned as being extrudable through hydrostatic extrusion, despite its brittleness?

Tungsten Signup and view all the answers

What effect does hydrostatic pressure have on the material during extrusion?

It increases the ductility of the material Signup and view all the answers

What is a significant advantage of using a pressurized fluid in the hydrostatic extrusion process?

Improved surface finish Signup and view all the answers

Which of the following is a potential drawback of hydrostatic extrusion?

Tendency for internal crack formation Signup and view all the answers

What speed range is specified for impact extrusion?

100 to 350 mm/s Signup and view all the answers

What is the main characteristic of a material that can be extruded through hydrostatic extrusion?

It can include brittle materials Signup and view all the answers

Which type of welding is preferable for plates thicker than 20 mm?

Arc welding Signup and view all the answers

What defines a butt joint in welding?

Edges or ends of two pieces are joined. Signup and view all the answers

How much should the members in a lap joint overlap?

From 3 to 5 times their thickness Signup and view all the answers

Which joint is used to connect two pieces at approximately right angles?

T-joint Signup and view all the answers

What type of weld is described as a single run of weld metal?

Bead weld Signup and view all the answers

In which welding type is filler metal deposited at the corner of intersecting surfaces?

Fillet weld Signup and view all the answers

What is the primary purpose of clamping pieces during welding?

To minimize distortion of the materials Signup and view all the answers

Which joint joins the edges of two pieces while keeping surface areas parallel?

Edge joint Signup and view all the answers

Which type of weld has filler material deposited in a groove formed by edge preparation?

Groove weld Signup and view all the answers

What is the primary disadvantage of gas welding for thick materials?

Insufficient heat for large sections Signup and view all the answers

What is a primary advantage of continuous extrusion?

It produces products in an annealed condition directly. Signup and view all the answers

Which materials can be extruded using the continuous extrusion process?

Polymeric materials and fibre reinforced plastics. Signup and view all the answers

In helical extrusion, how is the copper billet initially formed?

By a conical punch driven into the billet. Signup and view all the answers

What is a significant benefit of explosive extrusion?

It allows for very large reductions in cross-section. Signup and view all the answers

What happens to the swarf produced during helical extrusion?

It is trapped and forced out as wire. Signup and view all the answers

Which statement about continuous extrusion is incorrect?

It is exclusively for processing copper alloys. Signup and view all the answers

Which method is specifically designed for enhancing the concentricity and surface quality of tubes?

Three-Roll Piercing Machine Signup and view all the answers

What is a limitation of the Mannesmann process and hot cupping techniques?

Insufficient wall reduction and elongation Signup and view all the answers

During explosive extrusion, what initiates the process?

An explosive is detonated. Signup and view all the answers

In the Assel Elongator method, what design feature do the rolls have?

Conical and inclined to tube axis Signup and view all the answers

What role does the compression disk play in explosive extrusion?

It transmits pressure shock waves to the billet. Signup and view all the answers

Which of the following processes is explicitly limited to non-ferrous metals?

Continuous extrusion. Signup and view all the answers

How does the Pilger rolling mill change the dimensions of the pass during operation?

Through a continuous change in pass groove profiles Signup and view all the answers

Which of the following is NOT a method mentioned for hot reduction of hollow shells?

Suction Process Signup and view all the answers

What is the primary role of the mandrel in the Pilger rolling process?

Support the shell during reduction Signup and view all the answers

Which process is characterized by its use of three driven rolls for hollow shells?

Assel Elongator Signup and view all the answers

What is a unique feature of the Pilger rolling mill's operation?

It has an idle pass with changing dimensions Signup and view all the answers

What is the main advantage of using a three-roll piercing mill over traditional methods?

Smoother surface finish and improved concentricity Signup and view all the answers

What happens to the dimensions of the pass in the Pilger process when the shell is being fed in?

They are gradually decreased Signup and view all the answers

What is the purpose of the pressure regulator on gas cylinders?

To reduce cylinder pressure to a safe working value Signup and view all the answers

How are the oxygen and acetylene cylinders differentiated in terms of threading?

Oxygen cylinders have right-hand threads, acetylene cylinders have left-hand threads. Signup and view all the answers

What component of the gas welding system is responsible for delivering the mixed gas to the nozzle?

Blow pipe or welding torch Signup and view all the answers

Why is the graduated adjusting screw important in the pressure regulation process?

It regulates the pressure by adjusting the compression of the spring. Signup and view all the answers

What role do the control valves on the blowpipe serve?

They control the flow of each gas entering the mixing chamber. Signup and view all the answers

What is the primary reason for using electric resistance welding in tube production?

It is the most widely used process for tube production. Signup and view all the answers

Which electric welding method is specifically mentioned as suitable for thick-walled tubes?

Submerged arc welding (SAW) Signup and view all the answers

What is a critical step that follows the hot piercing method in tube production?

Hot drawing the formed shell through annular dies. Signup and view all the answers

What is the purpose of using a cutter tool after the welding process?

To remove external and internal flashes. Signup and view all the answers

How does the hot drawing process affect the dimensions of the tube being produced?

Increases length and decreases diameter. Signup and view all the answers

For which types of materials is argon-arc welding primarily used?

High-alloy austenitic steel and non-ferrous metals. Signup and view all the answers

What role does the plunger play during the hot piercing process in tube manufacturing?

It pierces and displaces plastic metal to form a shell. Signup and view all the answers

What is a primary reason for the widespread use of welding in construction?

It offers great latitude in design planning. Signup and view all the answers

Which of the following is NOT an advantage of welded joints compared to riveted joints?

Welded joints can weaken the overall structure. Signup and view all the answers

What is a notable drawback of welded joints?

They have poor fatigue resistance. Signup and view all the answers

Why is welding crucial in automotive and aviation industries?

It enables lightweight fabrication methods. Signup and view all the answers

Which challenge can significantly affect the quality of welded joints?

Excessive heat input. Signup and view all the answers

What aspect of welded joints contributes to their strong performance under static loading?

Tightness of welds. Signup and view all the answers

In what scenario is welding particularly advantageous regarding broken parts?

When re-investment costs must be minimized. Signup and view all the answers

What is a significant factor in the choice of welding over casting in modern manufacturing?

Welding enables better utilization of materials. Signup and view all the answers

What defines the future prospects of metals in fabrication?

Their ability to be welded. Signup and view all the answers

Which welding process involves heating parts to a molten state without applying pressure?

Thermit Fusion welding Signup and view all the answers

In which welding classification is no filler metal used at the joint interface?

Autogeneous welding Signup and view all the answers

What characterizes heterogeneous welding compared to other types?

The filler metal is different from the parent metal Signup and view all the answers

Which welding process typically requires a longer preheating period?

Gas welding Signup and view all the answers

Which of the following processes is classified as a pressure process?

Thermit Pressure welding Signup and view all the answers

What is a significant disadvantage of gas welding regarding the crystalline structure of the metal?

It raises adjacent metal temperatures unfavorably Signup and view all the answers

What is the primary composition guideline for filler metal in homogeneous welding processes?

It should be of the same composition as the base metal Signup and view all the answers

Which statement about welding processes is most accurate?

Forge welding is a pressure process. Signup and view all the answers

Which of the following welding processes is NOT typically classified under fusion welding?

Electric Resistance welding Signup and view all the answers

What typically happens to the joint zone in electric arc welding?

It melts instantly due to high temperature. Signup and view all the answers

What is a primary advantage of welding compared to riveting in terms of labor efficiency?

Welding is a less complicated and more productive job than riveting. Signup and view all the answers

Which statement best describes the weight comparison between welds and rivets?

The weight of welds can account for 1 to 1.5% of total work weight compared to rivets at 3.5% to 4%. Signup and view all the answers

What is a noted disadvantage of welding in comparison to casting?

Not all metals can be satisfactorily welded. Signup and view all the answers

In what way does welding provide a significant material advantage over casting?

Welding leads to greater strength than typically found in cast components. Signup and view all the answers

Which classification of welding involves the use of pressure gas for heating the metals?

Chemical welding Signup and view all the answers

What is one of the primary characteristics that makes welding preferable over casting?

Welding processes can often be automated, increasing productivity. Signup and view all the answers

Which of the following options correctly highlights welding's environmental advantage?

Welding joints can be made airtight, preventing leaks. Signup and view all the answers

What is a significant factor when deciding if parts should be welded rather than cast?

The design limitations and economic considerations. Signup and view all the answers

Which welding process utilizes electricity to generate heat for the welding operation?

Electric-Arc welding Signup and view all the answers

Which of the following statements is true regarding the dimensional properties of welded parts versus cast parts?

The wall thickness of welded parts is usually less than that of cast parts. Signup and view all the answers

Study Notes

General Welding Information

Welding is a localized coalescence of metals.
Heat is used to fuse the metals, possibly with filler metal.
The weldment is as strong as the parent metal.

Extrusion

Extrusion ratio is the ratio of billet to product cross-sectional area.
Hot extrusion ratio can be up to 400:1 (aluminum)
Hydraulic or mechanical presses are used for extrusion
High pressure (400 atm) is common
Lubricants reduce friction
Extrusion speed varies from 0.5 m/s for light alloys to 4.5 m/s for copper alloys.

Cold Extrusion

Cold extrusion is similar to hot extrusion, but no heating is needed.
High metal ductility is helpful
Used to improve physical properties, size a part.
The Hooker method, impact extrusion, and hydrostatic extrusion are common methods.
Hooker method uses a punch with a shoulder acting as a mandrel and pushes the metal through.
Impact extrusion is fast, uses a powerful punch blow and is used for thin-walled tubes
Hydrostatic extrusion uses high pressure liquid to force metal through die.

Advantages of Extrusion

Wide variety of extruded objects possible
Easily interchangeable dies
High dimensional accuracy
Improved ductility, especially for metals that do not deform easily
High reduction ratios are possible
Quicker automation, single passing
Creating smaller parts in large quantity
Stronger and lighter than other production methods like castings

Disadvantages of Extrusion

Higher waste percentage than other forms of shaping
More inhomogeneous structure than other methods due to different flows
Short tooling life due to high stresses from operation
High tooling costs
Low productivity compared to methods like rolling
Only constant cross-sectioned products are possible

Other Extrusion Processes

Side Extrusion (Lateral Extrusion) involves material flow perpendicular to ram motion
Continuous Extrusion - continuous feedstock and pressure applied to the back to create a continuous product
Conform process - continuous feedstock in a rod form.

Pipe and Tube Manufacturing

Pipes and tubes can be seamless or with seams.
Seamless tubes are made by extrusion and piercing
Continuous seam welding is used for pipes.
Piercing Method creates thick-walled shells in a rolling mill
Rolling of the shell into the desired pipe shape

Welding Process

General Definition: Localized coalescence of metals using heat, possibly filler material, and pressure
Welding Applications: Wide variety of applications across industries (structural steel, pressure vessels, pipelines, and automobiles) for fabrication and repair of metal components, including machinery frames, parts, and fixing panels.
Welding Advantages: Economical, reliable, high adaptability to shapes and sizes, repair of defective metals.
Welding Disadvantages: Less readily machinable compared to castings, and issues of weld defects like cracks, inclusions, porosity.

Classification of Welding Processes

Pressure Processes (e.g., forge welding, thermit welding, pressure gas welding, electric resistance welding)
Fusion Processes (e.g., gas welding, electric arc welding, thermit fusion welding)
Autogenous welding does not use filler material.
Homogeneous welding means filler metal is the same as the parent metal.
Heterogeneous welding means filler metal is different. Brazing and Soldering are examples, however not strictly welding processes as per some definition

Other Welding Processes

Gas Welding: Uses a gas flame to melt the metal and filler material if used for joining
Electric Arc Welding: Uses an electric arc to melt the metal and filler metal for joining
Thermit Welding: Uses a chemical reaction to melt metal and filler material together, high temperature and possible for thick pieces
Continuous Furnace Butt-Welding; process uses to manufacture water and gas pipes.
Electric Resistance Welding: Uses heat from resistance to electrical current in order to create a weld (spot welding is a type of resistance welding)
Induction Welding: Heat developed by resistance to the induced electric current is used. Suitable for low conductivity materials
Friction Welding: Heat is generated from rubbing metallic parts together, and these parts are then pressed together under force to create a weld.
Ultrasonic Welding: Ultra sonic vibrations cause welding to occur based on the use of high frequency vibrations to produce heat without the use of filler metal
Explosive Welding: Explosives are used to cause heat and pressure in order to weld materials together
Flow Welding: Adds molten filler metal to the joint
Cold Welding: Uses pressure without heat
Plasma Arc Welding: Used for welding materials that have high refractory properties, or for high-precision work,
Stud Welding: Arc welding is used to create welds in studs (fasteners)

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Description

Test your knowledge on gas welding systems and hydrostatic extrusion processes. This quiz covers recommended pressure ranges for acetylene and oxygen, functions of equipment, and characteristics of materials in extrusion. Understand the advantages and drawbacks of various extrusion methods.