Turning With Auto Feed; Thread Cutting; Drilling Operation; Setup And Adjustments - Promac GH-1640ZX Operating Instructions Manual

The correct spindle speed depends
on the type of machining, the cutting
diameter, the material to be
machined and the cutting tool.
These are recommended max.
speeds for a 50mm cutting diameter
with carbide (HM) tools:
Aluminium, brass
Cast iron
Mild steel
High carbon steel
Stainless steel
If high speed steel (HSS) tools are
used about 5 times lower speeds
must be chosen.
Generally speaking, the larger in
relation the cutting diameter, the
smaller the possible RPM.
For example:
Turning mild steel at a diameter of
25mm allows a speed of
1600 RPM max. with carbide tool
320 RPM max. with HSS tool
To change the spindle speed:
The speed may never be changed
when the spindle or motor are still
running.
Move the speed select levers (F, Fig
6) according to the speed you desire.
It may be necessary to turn the chuck
by hand to help the gears to engage.

6.5 Turning with auto feed

Several automatic longitudinal and
cross feeds are readily available by
selection on the gearbox handles
(E, F, H, G, Fig 14).
The feed direction can be chosen
with the feed reversing lever (A, Fig
14).
Move the lever (D, Fig 15):
- in and down longitudinal feed.
- out and up for cross feed.
1500 RPM
1000 RPM
The correct feed depends on the
800 RPM material to be cut, the cutting
operation, the type of tool, the
600 RPM
rigidity of the work piece
chucking, the depth of cut and the
300 RPM
desired surface quality.
For example:
Longitudinal OD-turning, mild steel of
25mm diameter with a carbide tool at
1400 RPM and with rigid chucking.
Stock removal and roughing cut:
Depth of cut
Feed per revolution
(change gear box position 4, G and I )
Finishing cut:
Depth of cut
Feed per revolution
(change gear box position 4, G and II
)
Micro finishing and calibration cut:
Depth of cut
Feed per revolution
(change gear box position 4, G and III
)
When roughing big diameters reduce
the depth of cut!

6.6 Thread cutting

Threading is performed in multiple
passes with a threading tool.
Each depth of cut should be about
0,2mm and become less for the
finishing passes.
The threading direction can be
chosen with the feed reversing lever
(A, Fig 14).
Set the feed rate selectors (E, F, G,
H, Fig 14) in proper position.
A) To cut inch and metric threads
Set the machine up for the desired
threading pitch and first depth of cut.
Engage the halve nut (A, Fig 15).
The halve nut must be engaged
during the entire threading process.
Fig 14
Fig 15
2mm
0,2mm
0,5mm
0.1mm
0,2mm
0.05mm
6
- Start the machine at the lowest
spindle speed.
- When the tool reaches the end of
cut, stop the motor and at the same
time back the tool out of the part so
that it clears the thread (Attention
inertia: Stop the motor in time)
- Reverse the motor direction to
allow the cutting tool to travel back to
the starting point.
Repeat these steps until you have
obtained the desired results.
B) To cut metric threads with
threading dial:
On most metric threads the threading
dial can be used.
The halve nut can be opened at the
end of cut, rather than the motor
being stopped and reversed.
The halve nut may only be engaged
at the corresponding graduation
match on the threading dial.

6.7 Drilling operation

Use a drill chuck with MT-4(MT-5)
arbour (option) to hold centring drills
and twisted drills in the tailstock.
For recommended speeds refer to
section 6.4
To eject the drill chuck, fully retract
the tailstock quill.

7. Setup and adjustments

Warning:
Setup and adjustment work may
only be carried out after the
machine is protected against
accidental starting.
Turn off the main switch and
press the emergency stop button!

7.1 Turning between centres

Mount the workpiece fitted with the
drive dog between centres.
The driver is driven by the face plate
(Fig 18).