WIDAX -GW Toolholder are now
available with full form ground
inserts having three cutting edges, which give concentric and
burr free threads due to tapping action of the inserts.The clamping of
insert is done by means of a clamp which rests
on the counter sink provided on the insert which apart from
clamping the insert from top also pulls the insert into the pocket
(fig 1).
A separate insert is required for each pitch of thread. Our present
programme includes inserts for ISO-metric threads and whitworth
threads only.
Inserts with partial profile are also available, for a range of pitches
which can be used on the same toolholder.
RECOMMENDED CUTTING DATA
The cutting forces on the insert increase as the profile is made
deeper . It is, therefore, recommended that a reducing series of
infeed should be used. However infeed should not be less than
0.05 mm and not more than 0.2 mm per pass. In Table 1 given
below, higher cutting speed should be chosen for lower feeds.
CUTTING SPEED
Recommended cutting speeds are given in the following
Table 1.
TABLE1
| Material |
Tensile strength
Kg/mm2 |
Speed m/min. |
| TTX |
TTS |
TH20 |
Plain carbon
steels |
45 - 70 |
190 - 230 |
80 - 100 |
- |
| 70 - 90 |
160 - 190 |
70 - 80 |
- |
Alloyed and high
tensile steels |
85 - 110 |
130 - 160 |
70 - 80 |
- |
| Stainless steel |
- |
- |
70 - 90 |
70 - 90 |
| Cast Iron |
180 - 250
BHN |
- |
- |
70 - 100 |
| Non Ferrous |
- |
- |
- |
130 - 200 |
|
|
TOOL GEOMETRY When the
insert is fitted to the toolholder, the following geometry
is obtained:
Side rake +10
Point clearance angle  is
(i) For external toolholders: 100
(ii) For internal toolholders: 150
Clearance Angle
,:30 to 60
To calculate the helix angle of the thread, the following equation
can be used:
tan  = p
 x D
where P is pitch of thread and D is pitch diameter in mm
If the helix angle of the thread is larger than 10 because of
the
large pitch of the thread or small diameters, the side rake angle
of the tool has also to be changed. Fig.3 gives the values of helix
angle for different pitch and diameters.
It is possible to change the side rake angle (corresponding to
helix angle) by changing the shim of the toolholder. (Please refer
to table II).
TABLE II
Shim
Form |
Shim
Angle |
-30 |
-20 |
-10 |
00 |
+10 |
Tool
Holder
angle |
+10 |
+10 |
+10 |
+10 |
+10 |
Result-
ant helix
angle |
-20 |
-10 |
00 |
+10 |
+20 |
| Application |
Reverse Threading
(LH threads) |
Normal Threading
(RH threads) |
|
Type of Thread-
ing |
Ext. |
Int. |
Ext. |
Int. |
Ext. |
Int. |
Ext. |
Int. |
Ext. |
Int. |
Shim
Ordering Number
73 332... |
164 |
175 |
162 |
173 |
160 |
171 |
161 |
172 |
163 |
174 |
|
