Mechanical Drawing - Paper 2 Flashcards
What type of line is shown in the image?
Continuous thick outline, dark pencil, 0,3-0,5
What type of line is shown in the image?
Continous medium line; medium pencil; 0,15
What type of line is shown in the image?
Continuous thin construction line, light pencil; 0,09
What type of line is shown in the image?
Hidden detail; medium pencil; 0,15
What type of line is shown in the image?
Centre line; medium pencil; 0,15
What type of line is shown in the image?
Cutting plane; medium chain with dark ends; 0,15 or 0,4
What type of line is shown in the image?
Short break or part section line; medium pencil; 0,15
How should mechanical drawings be presented?
In third-angle orthographic projection
What should be included on the drawing with engineering drawings?
It is common practice to include a projection symbol on the drawing.
Where should the projection symbol be placed on an engineering drawing?
The projection symbol should always be placed below the drawing.
What is the rule on linework for centrelines in circles?
The lines extend only a short distance beyond the feature.
What is the rule on linework for hidden detail lines?
The dashes are always slightly longer than the spaces.
What is the rule on linework for centre lines in rectangles?
The long lines always cut the profile of a feature.
What is the rule on linework for hidden detail lines in terms of outlines?
Hidden detail lines start and end in contact with outlines.
What is the rule on linework for centre lines when there are multiple views on one page?
Views are never joined by a centre line.
Should hidden detail lines meet at intersections?
Yes, hidden detail lines meet at intersections.
What are the surface texture of machined components made up of?
Hills and valleys.
How is the roughness of a surface measured?
By taking the average arithmetic deviation of the hills and valleys over a given length.
Why is the surface finish on load-bearing and high speed components very important?
To reduce friction for the correct functioning of the component.
What information is needed when a surface has to be machined to certain specifications?
The roughness, treatment and lay of the surface is needed.
What information does this symbol give you?
The roughness, treatment and lay the surface needs after machining.
What does the machining and surface texture symbol look like?
The basic symbol consists of 2 legs of unequal length inclined at 60 degrees to the horizontal.
When is a horizontal bar added to the longer of the two legs of the machining and texture symbol?
A horizontal bar is added if more than a removal of material is required.
What information needs to be added to the machining and surface texture symbol in order for it to have meaning?
Values defining the surface texture and production surface.
What information is added to the machining symbol in position a?
Roughness value or roughness grade number
What information is added to the machining symbol in position b?
Method: treatment or coating
What information is added to the machining symbol in position c?
Sample length
What information is added to the machining symbol in position d?
Direction of lay
What information is added to the machining symbol in position e?
Machining allowance
What information is added to the machining symbol in position f?
Other roughness value
What is the roughness value (a) given in?
Either in microns or shown by a grade number which represents the roughness value of the surface. Sometimes the value is displayed with an upper and a lower limit.
List 6 treatments of methods that could be listed as (b) on a machining symbol?
Chemical; honing; grinding; machining; lapping; plating; turning.
Why is value (c) needed on a machining symbol?
Sometimes it is necessary to specify a length over which the finish will be measured.
What is the direction of the lay?
The direction of the lay (d) is the direction of the predominant surface pattern, normally determined by the method used to produce the surface finish.
What direction of lay is indicated by this symbol?
Parallel to the plane
What direction of lay is indicated by this symbol?
Multi directional
What direction of lay is indicated by this symbol?
Circular pattern
What direction of lay is indicated by this symbol?
Crossed pattern
What direction of lay is indicated by this symbol?
Radial pattern
What direction of lay is indicated by this symbol?
Perpendicular to plane
How is machining allowance (e) expressed?
It is expressed in mm and is a degree of permissible variance over a specified distance.
How would a machinist read this symbol?
The indicated surface must be finished by machining to a roundness value of 0,8 microns, machined perpendicular to the plane of projection, with a machining allowance of 0,2mm. The roughness of the surface must be measured over a sample length of 4,5 mm.
What do the numbers in this symbol indicate?
The upper and lower roughness value.
Where should the machining symbol be placed on a drawing?
Both the symbol and the inscriptions should be orientated so that they can be read from either the bottom or the right-hand side of the drawing sheet.
How do you avoid the repetition of a symbol when the same machine process and values must be applied to all the surfaces of the component?
Only one symbol should be placed near the drawing
How do you avoid repetition of complicated symbols on a drawing?
Use a reference system that links all surfaces that require the same finish to a single symbol.
What is welding?
Welding is a process that joins metals together by fusing the surfaces of the parts into a single homogenous mass, and the bond can be regarded as permanent.
Which industries make use of welding?
Engineering and manufacturing industries.
How are welds specified on drawings?
A complex symbol describing the weld, its size and length with other processing and finishing information is used.
List 3 types of welding processes.
Gas welding
Arc welding
Resistance welding
Which factors determine which welding process should be used?
The thickness of the metal and the required strength of the join.
List 5 types of welded joints.
Corner joint; butt joint; T joint; lap joint; edge joint
What type of weld joint in shown in the image?
Corner joint
What type of weld joint in shown in the image?
Butt joint
What type of weld joint in shown in the image?
T joint
What type of weld joint in shown in the image?
Lap joint
What type of weld joint in shown in the image?
Edge joint
What does the basic welding symbol consist of?
It consists of an arrow which points at the join and a horizontal reference line. The weld symbol is added to the reference line showing that a weld is required along the joint at the arrow point.
Where should you place the welding symbol if you want the join welded on the same side as the arrow?
The symbol is place below the reference line.
Where should you place the welding symbol if you want the join welded on the opposite side as the arrow?
The symbol is place above the reference line.
List 5 types of welds.
Surface; fillet; groove; plug and slot; square; bead; bevel; single V; single J; single U.
What factors would determine which type of weld should be used on a join?
The relative placement of objects to each other; the required strength of the join; the thickness of the plates and the composition of the material.
What type of weld is shown in the image?
Fillet weld
What type of weld is shown in the image?
Square weld
What type of weld is shown in the image?
Bevel V weld
What type of weld is shown in the image?
Plug of slot weld
What type of weld is shown in the image?
Bead weld
What type of weld is represented by the sectional view and symbol shown in the image?
Square weld
What type of weld is represented by the sectional view and symbol shown in the image?
Bead weld
What type of weld is represented by the sectional view and symbol shown in the image?
Bevel weld
What type of weld is represented by the sectional view and symbol shown in the image?
Single V weld
What type of weld is represented by the sectional view and symbol shown in the image?
Single J weld
What type of weld is represented by the sectional view and symbol shown in the image?
Single U weld
What type of weld is represented by the sectional view and symbol shown in the image?
Plug or slot weld
What type of weld is represented by the sectional view and symbol shown in the image?
Fillet weld
How do you indicate that the weld must extend all the way around the join in a drawing?
It is indicated on the welding symbol by placing a circle on the join where the arrow line meets the reference line.
What is a field weld?
There are occasions when a join cannot be welded during the manufacturing process in the factory and has to be welded on site, or in the ‘field’.
How do you indicate that a weld needs to be made in the field instead of during manufacturing?
This is indicated on the welding symbol by placing a solid circle on the join where the arrow line meets the reference line.
What is the pitch of a weld?
The length and spacing of a weld.
How is the pitch of a weld measured?
It is always measured from the centre of one weld to the centre of the next weld.
Where do you indicate the pitch of a weld on a welding symbol?
On the reference line to the right of the welding symbol.
Study this image carefully so you know how to take the various measurements in the exam.
How long are the legs of a fillet weld usually?
The legs of a fillet weld are usually the same length.
Where should the length of the leg of a fillet weld be indicated on a drawing?
The dimension showing the length of the legs is indicated on the reference line, always to the left of the weld symbol.
What should you do when the length of the legs of a fillet weld need to be different form each other?
You indicate both of the leg lengths in brackets.
When do you add a tail to the end of the reference line on a welding symbol?
Only when a specified welding process needs to be carried out. If the tail is not needed it should be left off the symbol.
What does this resistance weld symbol indicate?
Spot resistance
What does this resistance weld symbol indicate?
Seam resistance
What does this resistance weld symbol indicate?
Flash or upset resistance
List three types of contour symbols.
Flush; concave; convex
What are contour symbols also known as?
Weld surface finishes.
Which type of contour symbols is shown in the image?
Flush contour
Which type of contour symbols is shown in the image?
Concave contour
Which type of contour symbols is shown in the image?
Convex contour
What should accompany the contour symbol?
The intended method of achieving the required finish.
How do you indicate the required method for achieving a finished surface on a contour symbol?
The designated letter is placed above the contour symbol.
Which finishing method is indicated by an M on a contour symbol?
M = Machine
Which finishing method is indicated by an F on a contour symbol?
F = Flame
Which finishing method is indicated by a C on a contour symbol?
C = Chisel
Which finishing method is indicated by a G on a contour symbol?
G = Grinder
Which finishing method is indicated by an R on a contour symbol?
R = Rolling
Which finishing method is indicated by an H on a contour symbol?
H = Hammer
What needs to be specified when a groove weld is used?
The angle of the groove needs to be specified.
How do you specify the angle of the groove on a drawing?
The angle of the groove is placed on top of the weld symbol.
Where do you indicate the depth of penetration on a weld symbol?
Just above the weld symbol
What is the symbol in the image?
A complete welding symbol showing the position of all the information.
Which element of a weld symbol is indicated at arrow 1?
Finish symbol
Which element of a weld symbol is indicated at arrow 2?
Contour symbol
Which element of a weld symbol is indicated at arrow 3?
Groove angle; included angle of countersunk for plug welds
Which element of a weld symbol is indicated at arrow 4?
Root opening; depth of filling for plug and slot welds
Which element of a weld symbol is indicated at arrow 5?
Size or strength; for certain welds
Which element of a weld symbol is indicated at arrow 6?
Tail: may be omitted when reference is not used.
Which element of a weld symbol is indicated at arrow 7?
Welding process
Which element of a weld symbol is indicated at arrow 8?
Basic weld symbol
Which element of a weld symbol is indicated at arrow 9?
Number of spots or projection welds
Which element of a weld symbol is indicated at arrow 10?
Arrow side of weld
Which element of a weld symbol is indicated at arrow 11?
Arrow line
Which element of a weld symbol is indicated at arrow 12?
Field weld
Which element of a weld symbol is indicated at arrow 13?
Weld-all-round
Which element of a weld symbol is indicated at arrow 14?
Centre-to-centre spacing of weld
Which element of a weld symbol is indicated at arrow 15?
Length of weld
Which element of a weld symbol is indicated at arrow 16?
Reference line
Which element of a weld symbol is indicated at arrow 17?
Other side of weld
What is deviation?
The algebraic difference between the limits of size and the corresponding basic size.
What is a zero line?
This is the line of zero deviation and represents the basic size reflected on a drawing without a tolerance.
What are limits?
The maximum and minimum sizes as indicated by a tolerance dimension.
What is an allowance?
The minimum clearance space between the material of mating parts or the tightest permissible fit.
What measurement are the upper and lower deviations of the nominal size expressed in?
Micrometers
Why must ISO values be expressed in mm on a drawing?
Because all dimensions are expressed in mm on engineering drawings.
What is shown in this image?
The image indicates a tolerance on linear dimension.
What does this image show?
The diagram shows a datum surface from which the dimensions for positioning a series of holes should be taken to avoid multiple errors.
What does the method of locating a hole from two surfaces at right angles to each other result in?
The centre of the hole could lie anywhere within a square tolerance zone due to the tolerance of each dimension.
What is shown in this image?
Two methods of constructing the chamfer on a hexagonal fastener.
What does this image show?
Calculating sizes using M
What is shown in this image?
A blind tapped hole
What type of nut is shown in this image?
A lock nut
What type of nut is shown in this image?
A castel nut
What type of nut is shown in this image?
A self-locking nut
What is a half-section?
A half section requires that one half of the view is shown as an outside view while the other half is shown in section.
When can a component or an assembly be represented as a half-section?
When a component or an assembly is symmetrical the section can be presented as a half-section.
What rule applies when you are sectioning components that are too thin for hatching?
They may be filled in solid with a space left between adjacent parts.
When is a revolved section used?
It is used to show the true shape of a cross section on the view of a component.
What is a revolved section?
A section that is drawn by revolving the cutting plane in position to show the true shape of a cross-section.
What is a removed section used for?
To show the true shape of a cross section of a component.
Where do you place a removed section on a drawing?
The section may be placed near the view or connected to the view by the lines of symmetry through the cutting plane.
What type of section is shown in this image?
A revolving section
What type of section is shown in this image?
A removed section
What type of section is shown in this image?
An aligned section
What type of section is shown in this image?
An offset section
What is an aligned section?
In order to include angled elements in a sectioned view the cutting plane may be bent to pass through these features.
How is an aligned section created?
The cutting plane and the feature are first straightened or aligned, by rotating them into a single plane, before the feature is projected to the sectioned view.
What do you do to indicate the bent sections of the cutting plane on an aligned section drawing?
Wherever the cutting plane is bent, these parts of the plane are thickened.
When do you use an offset- section?
When cutting through irregular shaped objects it is often desirable to show the cutting plane passing through several features that do not lie in a straight line.
How is an offset section achieved?
This can be achieved by offsetting or bending the cutting plane. The offsets, or bends, in the cutting plane must be drawn at 90 degrees to each other and are not shown in the sectional view.
What type of section is shown in this image?
Succesive sections
What is the purpose of successive sections?
Successive sections show the true shape of a number of sections through a single component.
How should the sections be placed in successive sections?
The sections should be placed in line with the direction indicated by the arrows, but when space is limited, the sections may be placed as shown in the diagram.
What type of view is shown in this image?
An auxiliary view of a component.
When is an auxiliary view projected?
Components with an inclined part or face may have an auxiliary view projected to show the true shape of the inclined part, with the direction of view shown by an arrow.
Where should an auxiliary view be drawn?
Wherever possible, a view of an inclined face should be drawn in line with the direction of the arrow.
Which feature is shown in this detailed representation?
An interrupted view
Which feature is shown in this detailed representation?
Repeated features
Which feature is shown in this detailed representation?
Holes on a linear pitch and circular pitch.
Which feature is shown in this detailed representation?
Square on a shaft
Which feature is shown in this detailed representation?
Knurling
Which feature is shown in this detailed representation?
Cylindrical helical compression spring.
Which feature is shown in this detailed representation?
Bearings
Which feature is shown in this conventional representation?
An interrupted view
Which feature is shown in this conventional representation?
Repeated features
Which feature is shown in this conventional representation?
Holes on a linear pitch and circular pitch.
Which feature is shown in this conventional representation?
Square on a shaft
Which feature is shown in this conventional representation?
Knurling
Which feature is shown in this conventional representation?
Cylindrical helical compression spring
Which feature is shown in this conventional representation?
Bearings
Which feature is shown in this detailed/conventional representation?
Partial view of symmetrical components.
Which feature is shown in this detailed/conventional representation?
Enlarged auxiliary partial view.
What is a counterbore?
A hole machined below the surface of a part and is used for concealing a bolt head or fastener.
What is a spotface?
A shallow or a raised machined surface used for seating a washer or fastener.
What is a countersunk hole?
A tapered hole machined into the surface of a part and is used to recess the head of a shaped fastener below the surface.
Does this image show correct or incorrect dimensions?
Correct dimensioning.
Does this image show correct or incorrect dimensioning?
Incorrect dimensioning
