METAL CUTTING
Metal cutting, or machining, is a process of cutting off a layer of metal from a
work-piece surface in the form of chips by the cutting tool in order to obtain the
necessary geometry, size accuracy, and surface finish of a part.
Schemes of machining:
1 – processed surface, 2 – cutting surface, 3 – finished surface
METAL CUTTING
Physical phenomena in the cutting process
a
b
c
Types of chips:
Formation of chips
а – continuous chips (plastic metals); b – chips of chopping off
(metals having medium hardness); c – element (brittle metals)
The equation of the thermal balance of a cutting process:
Q1 + Q2 + Q3 = Qch + Qtool + Qw-p + Qrad.
Sources of heat generation
and heat distribution upon
cutting
From a cutting zone heat is removed with chips (25–
85 %), absorbed by the work-piece (10–50 %) and the
tool (2–8 %).
METAL CUTTING
Machining by lathe
Turning machine, or lathe:
1 – bed;
2 – gear box;
3 – quick-change gear box;
4 – headstock with gear box and
spindle;
5 – three-jaw chuck;
6 – carriage;
7 – tool post;
8 – cross slide;
9 – tailstock;
10 – tail cabinet base;
11 – apron;
12 – head cabinet base
Turning cutters:
1 – strait turning cutter; 2 – side cutter; facing cutter; 4
– thread cutter; 5 – left-hand side cutter; 6 – groove
cutter; 7 - parting cutter
METAL CUTTING
Machining by grinding
Speed of cutting for grinding is defined by
the formula
V = ·Dw·n / (103∙60), m/s,
where Dw – external diameter of a wheel, mm;
n – frequency of wheel rotation in rpm.
Circular grinding:
1 – grinding wheel; 2 – work-piece; 3 – driver chuck;
4 – carrier; 5 – tail centre
Internal grinding
METAL CUTTING
Machining by drilling
Twist drill
Drilling machine tool
Core drill