The diagram shows the most common
indexable insert shapes from round
tips right down to 35º indexable
inserts.
The arrow on the scale shows that
the greater the stability of the cutting
edge (S), the higher the point angle
on the left is. With regard to accessibility
(2), the indexable inserts shown on
the right are the most suitable..
The arrow on the scale shows that
the tendecy to vibration (V) on the
left increases, where as the power
required (P) is lower.
When copy turning shapes the maximum
approach angle must not be exceeded
for inward copying. The clearence
angle between the secondary cutting
edges and tbe workpiece shape produced
should be at least 2º.
Corner
radius and feed:
The
corner radius of the indexable insert
is a key factor with regard to;
Stability during rough cutting,
Surface quality during finishing.
Roughing
Use the largest possible corner
radius to ensure the greatest degree
of stability for the cutting edge.
A large corner radius permits
a greater feed rate.
Use a smaller corner radius if
there is a risk of vibration.
When selecting the feed rate for rough
turning work, the maximum feed rates
given above must not be exceeded in
any circumstances. The basic rule
is:
fn
ROUGHING = 0,5 x CORNER RADIUS
Maximum feed rate for various corner
radii
Corner
radius (r)mm
0.4
0.8
1.2
1.6
2.4
Recommended
max. feed rate (fn)mm/dev.
0.25-0.35
0.4-0.7
0.5-1.0
0.7-1.3
1.0-1.8
The most frequently used radii for
rough machining are between 1,2 and
1,6 mm.
The table is based on the max. recommended
feed rate of two thirds of the corner
radius.
Greater feed rates are possible in
the following cases;
Indexable inserts have a stable
cutting edge and a point angle
of at least 60º;
Single-sided indexable inserts;
Indexable inserts which are
used with a approach angle less
than 90º;
Working easily machinable workpiece
materials at moderate cutting
speeds.
Tools
and Indexible Inserts for TURNING
