Page 280 - ISCAR(HOLE_MAKING_CATALOG_65)

USER GUIDE
DEEP DRILLING - BTA SYSTEM

Coolant

Successful deep hole drilling is achieved by an STS - Double tube system
optimal combination of the tool, the machine and Outer Double tube
the coolant. Coolant plays an essential role in Workpiece tube connector
material
achieving secure and cost-efficient deep hole drilling Drill Guide
operations. Therefore, it is very important to choose head bush Inner Chip
the correct type of coolant and use it appropriately. tube box
Coolant
Coolant plays an essential role in lubricating tools,
cooling cutting edges, chips and guide pads, as well
as evacuating chips when drilling. It also improves No need for sealing
tool life, surface finish and cutting accuracy when
continuously supplied during the machining process. Coolant unit
A coolant unit is also important to obtain
1 Lubrication the best effect from the coolant.
Lubrication of cutting edges and guide pads is
necessary in deep hole drilling. For efficient lubrication, 1 Coolant pressure and volume should
it is recommended to use EP (Extreme Pressure) be fixed and continuous.
additives which contain sulfur or chlorine.
An ideal coolant unit should be able to set any valve of
coolant pressure and volume and monitor the condition
2 Temperature reduction with gauges. A system that can detect trapped chips
The ability to cool down the cutting edge and by a pressure gauge and the screw pumps with
chips depends on such characteristics as an inverter controller are both recommended.
thermal conductivity and relative heat. Coolant
with good cooling ability increases tool life, but 2 Coolant temperature should be maintained.
water-soluble coolant is not preferred in deep Coolant is heated by factors, such as:
hole drilling because it reduces effectiveness. If
water-soluble coolant is used, the recommended • Cutting edge
concentration is 10% (dilution rate 1/10) or more. • Friction on guide pad
• Contact time of heated chips and coolant
3 Chip evacuation • Pump
Maintaining coolant temperature is important to
Coolant helps push chips through the back end of the keeping stable cutting conditions, chip formation
boring bar (for STS) or inner tube (for DTS) until the chips and cutting accuracy. The temperature should
are separated from the workpiece in general cutting be lower than 40°C (100°F) for EP additives to
conditions. The flow and the pressure of coolant are provide sufficient lubrication. Therefore, the coolant
also important in order to control chip evacuation. temperature should be kept between 30 - 40°C
STS - Single tube system (90 - 100°F) throughout the cutting operation.
Workpiece
material Oil 3 Filtering
Guide pressure
Drill Drill bush head Bar Chip Unwanted particles are contained in coolant after the
cutting operations, thus filtration is necessary to remove
head tube Sealing rest box
them. The filter size should be selected carefully to catch
particles but not EP additives. Filter size depends on the
coolant, but around 10 - 20 μm is generally suggested.
For iron-based workpieces, a magnetic separator is helpful
as it decreases the frequency of filter maintenance.

Flow chart of coolant in deep hole drilling
Pressure
gauge Flow
gauge
Motor
M Pump P M
Chipbreaker
P
Drill
head Drill tube Filter
Workpiece Chiller
Oil
pressure Chip Dirty tank Clean tank
head box

278 ISCAR