Fabrication and Welding Engineering

For information on all Newnes publications, visit our website at http://books.elsevier.com. I trust that Fabrication and Welding Engineering will be a worthy addition to my previous books on the fundamentals of general engineering and mechanical engineering.

Acknowledgements of ﬁ gures and tables

Health, safety and the law

Health and Safety at Work etc. Act

Adhering to safe work practices is important not only to protect yourself, but also to protect the people you work with.

The employer

The employee (that means you)

Health and Safety Commission
Health and Safety Executive

In addition to serving a Prohibition Notice or an Improvement Notice, the inspector can prosecute any person (including an employee – you) for breaching a relevant statutory provision. Finally, the inspector may seize, render harmless or destroy any substance or article which the inspector considers to be the cause of imminent danger or personal injury.

Obey all the safety rules and regulations of his or her place of employment

Thus, every employee must be a fit and qualified person who is able to perform the assigned task correctly and safely.

Understand and use, as instructed, the safety practices incorporated in particular activities or tasks

Not proceed with his or her task if any safety requirement is not thoroughly understood, guidance must be sought

Keep his or her working area tidy and maintain his or her tools in good condition

Draw the attention of his or her immediate supervisor or the safety ofﬁ cer to any potential hazard

Report all accidents or incidents (even if injury does not result from the incident) to the responsible person

Understand emergency procedures in the event of an accident or an alarm

Co-operate promptly with the senior person in charge in the event of an accident or an incident such as ﬁ re

Further legislation and regulations concerning safety

Factories Act

Safety Representatives and Safety Committees Regulations

Notiﬁ cation of Accidents and General Occurrences Regulations

The Management of Health and Safety at Work Regulations

The Protection of Eyes Regulations

Electricity at Work Regulations

Low Voltage Electrical Equipment (Safety) Regulations. This includes voltage ranges of 50 volts to 1000 volts (AC) and 75 volts to 1500 volts (DC)

Abrasive Wheels Regulations

Noise at Work Regulations

Employers ’ responsibilities

Working practices and systems are safe and that, where necessary, protective clothing is provided

A safe, healthy and comfortable working environment is provided. That the temperature and humidity is maintained at the correct levels for the work being

There is an adequate supply of fresh air and that fumes and dust are either elim- inated altogether, or are reduced to an acceptable and safe level

There is adequate and suitable natural and artiﬁ cial lighting in the workplace, particularly over stairways

There is adequate and convenient provision for washing and sanitation

There are adequate fi rst aid facilities under the supervision of a qualifi ed person. This can range from a fi rst aid box under the supervision of a person

Provision is made for the safe handling, storing, and transportation of raw materials, work-in-progress and ﬁ nished goods awaiting delivery

There is a correct and legal system for the reporting of accidents and the log- ging of such accidents in the accident register

There is a company policy for adequate instruction, training and supervision of employees. This must not only be concerned with safety procedures but also

The Act is contained in section 2(4) which provides for the appointment of safety representatives from among the employees who shall represent them in consultation with the employers and shall have other prescribed functions. When an employer receives a written request from at least two safety representatives to form a safety committee, the employer, after consulting with.

Where an employer receives a written request from at least two safety representatives to form a safety committee the employer shall, after consulting with the

Membership of the safety committee should be settled by consultation. The number of management representatives should not exceed the number of safety

Management representation is aimed at guaranteeing the necessary knowledge and expertise to provide accurate information on company policy, production needs and

Employees ’ responsibilities

Learn the safe way of doing each task. This is also the correct way

Use the safe way of carrying out the task in practice

Ask for instruction if you do not understand a task or have not received previous instruction

Be constantly on your guard against careless actions by yourself or by others

Report all accidents to your instructor or supervisor

Draw your instructor’s or your supervisor’s attention to any potential hazard you have noticed

Electrical hazards
Fire ﬁ ghting

Fire extinguishers
General rules governing the use of portable extinguishers

Fire precautions and prevention

Fire precautions
Fire prevention

Accidents

Accident procedure
Warning signs and labels

First aid

In the event of an emergency

Personal protection

Appearance
Head and eye protection
Hand protection
Hand cleansing
Foot protection

Hazards in the workplace

Health Hazards Noise
Personal hygiene
Behaviour in workshops
Hazards associated with hand tools
Hazards associated with machine tools

Manual lifting

Individual lifting
Team lifting
Moving loads that are too heavy to lift

Mechanical lifting equipment

Manual (muscle power)
Powered
Mobile cranes
Safety

All moving objects that form dangerous obstacles must be moved to a safe place before the movement of the load is started. Before taking the weight off the load, your back should be straightened and as close to vertical as possible.

Check the lifting equipment is suitable for the load being raised. All lifting equip- ment should be clearly marked with its SWL

Even after you have been instructed in the use of lifting equipment, always carry out the following checks before attempting to lift a load. Never leave a load unattended while it is supported by lifting equipment and ensure that it rests in a stable before releasing it from the lifting equipment.

Never leave a load unattended whilst it is supported by lifting equipment, and ensure that before it is released from the lifting equipment, it is resting in a stable

Pendulum Switch Control: if the pendulum switch controls a running lift, you must check the direction of travel and check which buttons raise and lower.

Pendant switch control: if the pendant switch controls a travelling hoist, check the direction of travel as well as checking which buttons raise and lowers the

Use of lifting equipment

Lifting a load
Traversing a load on a travelling crane
Lowering a load
Hand signals

Accessories for lifting gear

Hooks
Slings
Rings
Eyebolts and shackles
Special purpose equipment

Useful knots for ﬁ bre ropes
Inspection (lifting equipment)
Oxy-acetylene welding

Safety in the use of gas cylinders
Testing for leaks

Both should be familiar with the standard code for hand signals, as shown in figure. Rope and strap slings themselves must be protected from being cut or frayed by sharp edges, as shown in Figure 1.32 Standard code for hand signals for crane operation.

Figure 1.31 Care when lowering a load: (a) lower onto timbers; (b) guide by hand; (c) never work under a suspended load

Open the control valves on the torch

Release the pressure-adjusting control on the regulators

Open cylinder valves to turn on the gas

Set the working pressure by adjusting the regulator controls

Having established the correct pressure for each gas, close the control valves on the torch

Fire hazards
Explosion risks
Protective equipment (goggles)
Protective equipment (overalls)
Arc-welding equipment (mains operated)

Hazards associated with mains-operated arc-welding equipment

However, overalls worn while welding must be made of flame retardant fabric and must be buttoned or zipped up to the neck to prevent particles of hot metal and slag from becoming lodged in them. In addition, a fireproof headgear and a chrome-plated leather apron should be worn along with Figure 1.41 Cylinder bursting.

The primary (mains-voltage) circuit which should be installed and maintained by a qualiﬁ ed electrician

The external welding circuit
Protective clothing
Working on site

Primary circuit (current-voltage) which must be installed and maintained by a qualified electrician. Properly constructed scaffolding should be provided with guard rails and toe boards for safety as shown in Fig.

Figure 1.45 Manual metal-arc welding circuit diagram Neutral

Basic relationships

Confrontation
Cooperation

Relationship with managers, supervisors and instructors
Attitude and behaviour

Attitude
Behaviour

Implementing company policy

Communication
Recording and ﬁ ling

Creating and maintaining effective working relationships with other people As has been stated previously, you cannot work in isolation. Sooner or later you

Positive attitudes
Teamwork
Personal property

It's no use being the best apprentice or intern if you're also the most temperamental. If you are a member of such a team and you believe you have discovered a potential hazard in the work to be done, it is your duty to bring it to the attention of the team leader.

Figure 2.1 Structure of relationships There is no law that

States of matter

Almost all matter can exist in three physical states by changing its temperature under appropriate conditions. On cooling, they first return to a liquid and then return to a solid at room temperature.

Properties of materials

Strength properties Tensile strength
Forming properties Elasticity
Heat properties
Corrosion resistance
Hot and cold-working

Provided that no chemical change takes place (eg the oxidation of the metal by contact with air at high temperatures), we can change substances back and forth through the three states by heating and cooling as often as we like. too cool It is the ability of a material to withstand an offset load without breaking (shearing).

Figure 3.1 Mechanical properties – strength: (a) tensile strength;

Classiﬁ cation of materials

Metals
Non-metals

Ferrous metals (plain carbon steels)

Plain carbon steels
Low carbon steels
Medium carbon steels
High carbon steels

It is slightly weaker than the next group of low carbon steels to be considered. Medium carbon steel with a carbon content in the range of 0.3% to 0.5% is used for products such as drop hammer nozzle blocks, laminated springs, wire ropes, screwdriver blades, wrenches, hammer heads and heavy duty forgings.

Figure 3.7 The effect of carbon content on the properties of plain carbon steels

From 1.2% to 1.4% carbon where extreme hardness is required for wood-work- ing tools and knives where a very keen cutting edge is required

Ferrous metals (alloy steels)

High-speed steels
Stainless steels

Ferrous metal (cast irons)
Abbreviations
Non-ferrous metals and alloys

Aluminium and its alloys
Copper and its alloys

The identiﬁ cation of metals
Non-metals (natural)

Unfortunately, it is relatively weak in its pure state and is difficult to join and solder. In this book we are only interested in brass alloys and tin-brass alloys.

Rubber is used for anti-vibration mountings, coolant and compressed air hoses, transmission belts, truck wheel tyres

It is essential that all materials are stored carefully so that they are not damaged or spoiled before use. Because of the similarity in appearance between many metals with different physical properties, it is imperative that they be marked with some form of permanent identification (eg color coding) so that they can be quickly and accurately identified.

Glass is used for spirit level vials (the tube that contains the bubble), lenses for optical instruments

Mistakes, resulting in the use of an incorrect material, can be very costly through waste. Rubber is used for anti-vibration mounts, coolant and compressed air hoses, transmission tires, truck wheel tires.

Emery and corundum (aluminium oxides) is used abrasive wheels belts and sheets, and as grinding pastes. Nowadays it is usually produced artiﬁ cially to

It can also cause serious accidents if, for example, a weak metal is used instead of a strong one for heavily loaded components.

Wood for making casting patterns

Ceramics for cutting tool tips and electrical insulators

Non-metals (synthetic)

Thermosetting plastics

They can be used in environments that are chemically hostile to even the most corrosion-resistant metals. Solvents used in the processing of plastics are often highly toxic and should not be inhaled, but used in well-ventilated areas.

Shredded paper and shredded cloth provide good strength and reasonable electrical insulating properties at a low cost.

Forms of supply
Heat treatment processes (introduction)
Heat treatment processes (safety)

Protective clothing

It can be sheared on continuous rotary shears to the customer's specification where accurate control of the width is required. However, some of the more important processes for the heat treatment of copper-based and aluminum-based alloys will be included in this chapter.

Splashes from the molten salts when using salt bath furnaces

In addition, you must wear a leather apron to prevent contact of the overall with hot workpieces and hot equipment. These should be made of leather or other heat-resistant materials and should have gloves to protect your wrists and the sleeve ends of the coveralls.

Splashes from hot liquids when quenching

Coveralls used in heat treatment workshops must be made of flame-resistant or flame-retardant material and labeled accordingly. Headgear, safety glasses and visors, as described in Chapter 1, should be worn when there is a risk of danger to your eyes, the skin of your face and your hair and scalp.

The accidental ignition of oil quenching baths due to overheating

However, heat treatment can involve large pieces of metal at high temperatures and powerful furnaces.

The radiated heat from large furnaces when their doors are opened

Safety notices
Fire
The heat treatment of plain carbon steels

Through-hardening
Quenching, distortion and cracking Quenching and distortion
Tempering
Annealing
Normalizing

The heat treatment of non-ferrous metals and alloys

Solution treatment
Precipitation treatment

Heat-treatment furnaces

Semi-mufﬂ e furnace
Mufﬂ e furnace (gas heated)
Mufﬂ e furnace (electric resistance)

Temperature measurement

Thermocouple pyrometer
The radiation pyrometer

Atmosphere control

The carbon content of the steel (the higher the carbon content, the harder and more brittle the steel is). Process annealing, as the hardening of the metal is the result of cold working (forming) processes.

Figure 3.9 Safety notices must be placed by hot objects

Selection of information sources

Production instructions, such as the name of the parts to be produced, the number required, any special finishes required and the date by which they are required. This involves teamwork within organizations and close liaison with their customers and suppliers, and can only be achieved by choosing to communicate effectively and handle engineering information effectively.

Interpretation of information (graphical)

Line graphs
Histograms
Bar charts
Ideographs (pictograms)
Pie charts

From E to F the vehicle resumes its journey at a reduced speed because the line is less steep. In this graph, it is correct that the points are connected by separate lines, since each leg of the journey is not connected to the previous or to the next leg.

Figure 4.1 Line graphs: (a) points connected by a smooth curve (points related mathematically); (b) points connected by straight lines

Interpretation of information (tables, charts and schedules)

Manufacturers ’ catalogues
British and European Standards
Production schedules
Product speciﬁ cations

For example, the production specification may be a manufactured road bridge, which requires a complex document covering such things as the materials to be used, the method of production of the various components and sub-assemblies, the sequence of production, the planned dates and times of on-site delivery to to ensure smooth progress and the methods of assembly and testing. On a simpler basis, the work order is issued in a series production or in a workshop.

ABC Engineering Co. Ltd

Conversion tables for fractional to decimal dimensions in inch units, and conversion tables for inch to metric dimensions. Not only are these more convenient for the user than having to open a book with greasy hands, but they are also good publicity for the manufacturers who release them.

Drawings and diagrams

Evaluating engineering information

Recording and processing engineering information

Quality control
Health and safety
Legal and ﬁ nancial reasons

They must publish their memorandum and articles of association and file a copy at the company house when the company is incorporated. They must keep accurate minutes of all board meetings and produce annual reports, including a current list of directors and other information, immediately after each annual general meeting (AGM) of the company.

Figure 4.7 Quality control chain (each stage is a customer of the previous stage and a supplier to the next stage, i.e

Methods of record keeping

Computer ﬁ les
Micro-ﬁ lm and microﬁ che
Registers and logbooks

Communications (miscellaneous)

Safety and hazard notices
Safety and hazard signs
Colour coding
Posters

These are internationally recognized and combine geometric shape, color and a pictorial symbol to convey the message. The picture reinforces the caption so that the message is clear even to people who cannot read the words for some reason.

Table 4.3 Colour codes for pipe contents

Engineering drawing (introduction)

Finally, we can add the sizes (measurements) that we need to make the clamp. A drawing that shows and displays all the components together is called a general arrangement drawing.

First angle orthographic drawing

Third angle orthographic drawing

In the first angle projection, the end view, looking towards the nose of the aircraft, would be drawn somewhere beyond the tail. An end view, looking towards the tail of the aircraft, would be drawn somewhere beyond the nose.

Figure 4.13 (a) Principles of drawing in third angle projection; (b) projection symbol

Conventions

Types of line
Abbreviations for written statements

In the UK we use the British Standard for Engineering Drawing Practice as published by the British Standards Institute (BSI). Dashed lines should consist of lines of equal length and spacing, approximately in the ratio shown in the figure.

Figure 4.15 Types of line and their applications

Redundant views

When thin warp lines are used as center lines, they must cross each other at fixed parts of the line. They should not extend through the spaces between the views and should not end at another line in the drawing.

Dimensioning

Correct dimensioning
Incorrect dimensioning
Dimensioning diameters and radii

Dimension lines must be well spaced so that the numerical value of the dimension can be clearly read and so that it does not obscure the outline of the drawing. Points are used where the front line ends within the outline of the component or feature to which it refers.

Figure 4.17 Typical conventions for some common featuresExternal screw

Welding symbols

Additional weld information

When the weld symbol is above the reference line, the weld is made on the side of the joint opposite the arrowhead. When the weld symbol is below the reference line, the weld is made on the same side of the joint as the arrowhead.

The development of surfaces

Parallel line developments
Radial line development
Development by triangulation

However, the sloping corners of the pyramid in the plan view are not perpendicular to the height. Therefore, the actual length of the connecting line is equal to the slope height shown in the elevation.

Interpenetration

Angled co-axial interpenetration

Get the true length of the diagonal 2.A on the plan by drawing it in vertical elevation and swing an arc from 2 on the pattern to find point A. Take 3.1 on the plan view and swing an arc from point 1 on the pattern.

Figure 4.38 Two cylinders unequal diameters oblique interpenetration

Pictorial views

Oblique projection
Isometric projection

You can do this by erecting a grid over the feature in orthographic projection as shown in Figure 4.41(a). The points where the circle intersects the grid in the orthographic drawing are transferred to the isometric grid as shown in Figure 4.41(b).

Introduction
Linear measurement

Steel rules (use of)
Line and end measurement
Calipers and their use
The micrometer caliper (use of)
Micrometer caliper (care of)
Vernier calipers

One instrument can be used for measurements ranging over the full length of its main (beam) scale. Figure 5.7(a) shows a vernier caliper
It can be used for both internal and external measurements as shown in Fig
One instrument can be used for taking measurements in both inch units and in metric dimensional systems

Angular measurement

5.2(a), the accuracy of measurement depends on the visual alignment of a mark or surface on Figure 5.1 Standards of measurement - the ruler and the steel tape. This instrument depends on the principle that the distance a nut moves along a screw is proportional to the number of revolutions made by the nut and the tip of the screw thread.