R. Wertheim. IWU.Fraunhofer , Germany wzm-g-vl-01-1/69. Cutting Processes –
Overview with Defined Edges. • Turning. • Milling. • Others ...
Cutting Processes – Overview with Defined Edges • Turning • Milling • Others
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-1/69
Categories of Material Removal/ Machining Processes
Material Removal Processes
Cutting
Abrasive
Nontraditional
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-2/69
The Abrasive Cutting Process
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-3/69
Machines for Bonded Abrasive - Surface Grinder
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-4/69
Basic Cutting Processes
•
Rotating part - turning – Creates round shapes
•
Stationary part - milling, drilling, sawing, etc – Creates all other shapes
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-5/69
Basic Lathe
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-6/69
Basic Turning
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-7/69
Basic Turning
V =
p Dn
[m/min] n [R.P.M] D [mm]
1000 f [mm/rev] % feed
d [mm]
% depth of Cut R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-8/69
Turning Process Parameters
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-9/69
Turning Parameters
Volume of material removed per unit time:
•
Material Removal rates = p Davg d f N [(mm)(mm)(mm/rev)=mm3/min] • Where Davg is the average diameter
Cutting Time
l t [sec] fN
Force
Fc K s f d [N]
fN - feed rate
K s resistance of the material for machinabil ity Power
u Fc Vc [Watt]
1HP=736Watt
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-10/69
Machining Processes for Round Shapes
• • • • • • • •
Turning Facing Boring – Produces circular internal profiles In hollow workpieces Drilling – Produces round holes Reaming Parting Threading Knurling
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-11/69
Machining Processes for Round Shapes
Kalpakjian p 517 R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-12/69
V
Dn 1000
[m/min]
In straight turning V=const
In facing turning D->0 where n=const
1000V n [RPM] D
V=0 -> n=0 D=0 -> n=Inf.
n Desired V=const D R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-13/69
Basic Milling Non Round Machining - Slab Milling
n
•
Milling – Slab/Peripheral – Cutter rotation axis parallel to workpiece surface
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-14/69
Milling - Parameters
•
Cutting speed, – D is the cutter diameter – n its rotational speed
•
Feed per revolution, f = v/n – v [m/min] is the linear speed or feed rate of the workpiece,
•
Feed per tooth, – z is the number of teeth
n
fz = v/n z
V
Dn 1000
[m/min]
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-15/69
Slab Milling types
•
Conventional/up – Maximum chip thickness at end of cut
•
Climb/down – Maximum chip thickness at beginning of cut
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-16/69
Face milling
•
Axis of rotation perpendicular to work piece surface
•
Large multi-insert cutter
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-17/69
Face milling - Parameters
Action of an insert in face milling
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-18/69
Face milling
Climb Milling
Conventional milling R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-19/69
Non Round Machining
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-20/69
Milling formula (cont’)
•
Cutting time, t = (l + lc) / v – where l is the length of the work piece and lc is the extent of the cutter’s first contact with the work piece f = v/n z
=>
v=f n z =>
t=(l+lc)/(f n z)
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-21/69
Other Non Round Machining Processes
•
Drilling
•
Straddle milling
•
Planing
•
Broaching
•
Sawing – Generally used for cutting off pieces to be worked on by other processes
•
Filing and finishing
•
Gear machining
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-22/69
Forces
q
h=h(q) h(q)=fz cos(q) Fc Fc=Ks h(q) w [N] 900
1800 2700
q
900
1800 2700
q
Fc Fc=Ks h1(q) w+ Ks h2(q) w R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-23/69
Drilling Operations and Drill bits
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-24/69
Machining Economics
R. Wertheim IWU.Fraunhofer , Germany wzm-g-vl-01-25/69
