Lecture 2 - HVM + Machine Processes Review

Question 1

What is the majority of UK manufacturing

Answer 1

manufacturing of finished goods

Question 2

What is HVM

Answer 2

strategy of UK government to develop UK manufacturing technology and systems High value manufacturing
application of leading edge technical knowledge and expertise to the creation of products, production processes and associated services which have potential to bring sustainable growth and high economic value

Question 3

What does HVM mean in practice

Answer 3

UK never compete on volume, but can compete by adding value to manufactured goods through technological improvement

Question 4

What demands on manufacturing are emphasised in HVM

Answer 4

Decrease product quantity
increase in customer expectations
use new or better materials
maintaining variety on smaller scale by developing new or better processes

Question 5

Does HVM lose jobs

Answer 5

no, generates jobs as required new processes to be developed and enables supply chains to be brought closer to production facilities
local level yes but overall just relocation

Question 6

HVM facilities examples

Answer 6

rolls royce, boeing, mclaren factories in sheffield
JLR plant in wolverhampton
Catapults - uni based industrial research centres e.g. AMRC

Question 7

After HVM what is next

Answer 7

Industry 4.0, applying emerging digital technologies to manufacturing to
improve productivity
improve quality
reduce costs

Question 8

What are the potential benefits of 4IR

Answer 8

factory floor and production systems - autonomous systems, flexible machines
use of AM techniques
digital assisted assembly and 3D visualisation

Question 9

Whats the difference between HVM and 4IR

Answer 9

4IR will impact small and medium enterprises
HVM is mostly large companies and unis
4IR tech becoming cheaper and easier to implement quickly

Question 10

What is the key part of HVM

Answer 10

production process - making the basic shape, making the final shape attaching everything together

Question 11

Types of casting

Answer 11

Making basic shape
traditional - disposable mould casting (sand and investment)
more recently - permanent mould casting (die), continuous, powder metallurgy, sintering, AM (SLS, SLM, EBM)

Question 12

Types of machining

Answer 12

making final shape
Traditional - turning, milling, shaping
more recently - high speed machining, grinding (for bulk material removal)

Question 13

What have been the main developments of machining with HVM

Answer 13

where most of focus has gone
Greatly improving efficiency, removal of lot of cost, removal of whole processes in manufacturing, techniques to deal with very hard materials e.g. electrical discharge machining

Question 14

Types of joining

Answer 14

Traditional - Fusion welding (oxy-feul and arc), brazing and soldering, mechanical fastening
more recently - fusion welding (electron/laser beam), resistance spot welding, solid state (small heat affected zone)

Question 15

What is machining

Answer 15

process of removing unwanted material from a work piece in the form of chips

Question 16

Why is metal cutting a complex process

Answer 16

large variety of inputs
machine tool 
cutting tool
property and parameters of workpiece
cutting parameters
workpiece holding fixtures

Question 17

Types of machine tools

Answer 17

manual lathes and milling machines

multiple axis cutting machining centres

Question 18

What are the types of cutting tools

Answer 18

one piece (solid tools more traditional) HSS
two piece (insert + body) expensive insert that can rotate for fresh edge cheap body

Question 19

Why do modern machines use two piece tools

Answer 19

cheaper (only worn out tips)
tough material for body/hard material for insert
inserts can last longer as indexable
can use more exotic materials (as smaller)

Question 20

Why are cutting tools so important

Answer 20

usually only spend <10% manufacturing cost, have much higher of the success of the machining process

Question 21

Mechanical of chip formation

Answer 21

tool move along shear plane at cutting speed V
Relief/clearence angle exists to minimise contact between tool and workpiece
shearing occurs at shear plane
material under shear plane is not deformed, everything above converted to chips

Question 22

What is chip thickness a function of

Answer 22

tc=f(depth of cut to, rake angle alhpa, shear angle theta)
HVM modify model for max efficiency
and push to the limit

Question 23

What is speed in machining

Answer 23

primary cutting motion, velocity of cutting tool relative to surface of a workpiece

Question 24

What is feed rate in machining

Answer 24

secondary cutting motion, velocity perpendicular to the speed and is usally expressed per revolution or per tooth

Question 25

What is depth of cut in machining

Answer 25

third motion that represents how far tool penetrates per cut

Question 26

What is the material removal rate equation

Answer 26

for single point tools
MRR = speed x feed x depth of cut
for multi point tools
MRR = cross sectional area of cut x feed

Question 27

What are the four types of chips

Answer 27

continuous
serrated
discontinous
built up edge

Question 28

What are continuous chips

Answer 28

ductile materials, high cutting speed and/or rake angles
deformation around primary shear zone
good surface finish but chips wrap around machine parts - need chip breakers (extra cost)

Question 29

What are serrated chips

Answer 29

semi continuous chips with zones of low and high shear strain
chips have a saw tooth like appearance
work piece low thermal conductivity and strength that decrease sharply with temperature (titanium)

Question 30

What are discontinuous chips

Answer 30

segments that may be firmly or loosely attatched to each
brittle workpiece (cannot undergo high shear strain, will happen anyway how do you make better)
very low/high cutting speed, depth of cut
worse surface finish and accuracy

Question 31

What type of chips are used by some tools

Answer 31

build up edge, give protection to tool, reduces surface finish, but where unimportant increases tool life

Question 32

What are built up edge chips

Answer 32

formed at tip of tool during cutting
consists of layers of material from workpiece gradually building up on the tool, then break off
poor surface finish, work hardening of surface, poor geometrical control but small life increase