METAL CUTTINGMetal 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

Sources of heat generationand heat distribution upon

cutting

Types of chips:а – continuous chips (plastic metals); b – chips of chopping off(metals having medium hardness); c – element (brittle metals)

Formation of chips

METAL CUTTINGPhysical phenomena in the cutting process

a b c

The equation of the thermal balance of a cutting process: Q1 + Q2 + Q3 = Qch + Qtool + Qw-p + Qrad.

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

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

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

Machining by lathe

Circular grinding:1 – grinding wheel; 2 – work-piece; 3 – driver chuck;

4 – carrier; 5 – tail centre

METAL CUTTINGMachining by grinding

Internal 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.

METAL CUTTING

Drilling machine tool

Machining by drilling

Twist drill

Core drill