Exam Flashcards
If conforming to BS8888 what projection would a drawing be done in?
First or Third angle orthographic
What are the purposes of an engineering drawing?
To describe the part required by the designer
To be a manufacturing instruction, describing how the part is to be made
Allows the part to be inspected
Definitions of Factor of Safety
The ratio of the material yield strength to design load
The ratio of the materials ultimate tensile strength to the design load
When a component is designed for a higher load due to uncertainties in the desgin
What is the purpose of a bearing?
To support and transmit a load while allowing relative motion
What is the difference between Pugh’s and Pahl and Beitz model of design?
Pugh does not make a distinction between concept and embodiment design
What is the difference between punching and blanking?
In punching the slug is discarded where as in blanking the slug is retained
What is the difference between a fixture and a jig?
Jig guides the cutting tool positions the work and guides the tool.
Fixture doesn’t guide the tool
Define design methodology
The theory of the procedures fro solving design problems which are intended to be valid for all types of engineering design
What is Abstracting product requirements and which Pahl and Beitz task does it relate to?
Ignoring what is particular or incidental and emphasizing what is general and essential about a problem.
It is a principal technique in identifying essential problems
What are drilling and reaming used for?
The creation of blind or through holes by cutting process
How is milling carried out?
Normally the work piece is clamped to a moveable table and the tool is rotated about the vertical or horizontal axis
In the manufacturing processes drilling and milling what is the difference?
In drilling the fluted cutting tool has the cutting edges at the tip, in milling the cutting edges are down the shank
Why are coolants used in machining processes?
to inhibit corrosion
to reduce friction
to reduce built up edge on tools
What is the purpose of a bearing?
To support and transmit a load while allowing relative motion
In the context of design shafts why do critical speeds occur?
Critical speeds occur because the centre of mass of a rotating system never coincide with the centre of rotation due to manufacturing and operational constraints
Definition of design methodology
The theory of the procedures for solving design problems which are intended to be valid for all types of engineering design
According to Pahl and Beitz’s what category of design do most design activities fall into?
Variant Design
Which task in Pahl and Beitz’s process does abstracting take place?
Identifying essential problems
Define solution neutral statement
it is a statement of what the product is to do without specifying how it is to do it
Define function structure
It is the representation of the function and sub functions of the system in terms of the flow of energy materials and signals in a block diagram using the solution neutral statements
Define combination matrix
the first column lists the solution neutral, verb-noun phrases from the function structure and the rows contain solution principles
Define selection matrix
the first column lists the requirements and constraints from the product specification against which solution principles in the rows of the matrix are evaluated
Describe Pugh’s method of controlled convergence
It is a matrix based concept selection technique in which concepts are qualitatively compared with a datum concept against criteria from the product specification
what should be the outcome for controlled convergence?
The design concepts should be improved
Describe the weighting and rating method for concept selection
It is a matrix based concept selection technique in which concepts are quantitatively evaluated against criteria from the product specification
What is the tragedy present in Tragedy of the Commons by Hardin?
What is rational for the individual is not rational for the collective
What is the tragedy of the commons about
Managing limited resources over time
How does Hardin think appealing to people’s conscience will work to motivate people?
Definitely won’t work
What is Hardins paper a rebuttal to?
The invisible hand by Adam Smith
What was Hardins concerns regarding the popularity of Adam Smiths idea od the invisible hand?
It has contributed to peoples tendencies to assume that the decisions reached by individuals about what is best for themselves will turn out to be the best decision for society as a whole
According to Hardin what is pollution a consequence of?
Population
According to Hardin what does he consider to be the least defensible as a reaction to the problem of global warming?
Have a publicity campaign to explain the importance of driving less and encouraging people to drive less
What does Hardin say about the freedom to breed?
It is intolerable
What are the simplest types of bearing?
Journal or plain bearing
3 facts about spur gears
They are inexpensive
Allow ratios up to 6:1
Can be 98-99% efficient
How is turning usually carried out?
Normally the work piece is rotated and the tool moves in one plane
How is spring back prevented in sheet metal bending?
Over bending or using punches that promote the plastic deformation in the work piece
What manufacturing process is used on most inexpensive general purpose bolts and screws?
Cold rolling
What does a continuous wide line (solid line) on an engineering drawing mean?
Visible edges and outlines of parts
What does a long dashed dotted narrow line mean on an engineering drawing?
Lines of symmetry and centre lines
What are assembly drawings used for?
It is an orthographic engineering drawing
it can be used as an instruction to create job cards
It contains a list of parts
In which projection systems are the x and y axes receding?
Isometric Projection
In the context of machines and shafts what is the purpose of a bearing
to support and transmit a loads while allowing relative motion
In the tragedy of the commons what are the cases that can be discussed from it?
The population problem
over fishing
free access to national parks
