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USER GUIDE
DEEP DRILLING - BTA SYSTEM

Coolant

Successful deep hole drilling is achieved by an DTS - double tube system
optimal combination of the tool, the machine and Workpiece material
the coolant. Coolant plays an essential role in Outer tube Double tube connector
achieving secure and cost-efficient deep hole drilling Drill Guide Inner Chip
bush
head
operations. Therefore, it is very important to choose tube box
the correct type of coolant and use it appropriately.
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 sets the coolant pressure
valves and volume while monitoring the codition with
2 Temperature reduction 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 • Cutting edge
water-soluble coolant is used, the recommended • Friction on guide pad
concentration is 10% (dilution rate 1/10) or more. • Contact time of heated chips and coolant
3 Chip evacuation • Pump
Coolant helps push chips through the back end of the Maintaining coolant temperature is important to
boring bar (for STS) or inner tube (for DTS) until the maintain stable cutting conditions, chip formation
and cutting accuracy. The temperature should
chips are separated from the workpiece under general
cutting conditions. The flow and the pressure of coolant be lower than 40°C (100°F) for EP additives to
provide sufficient lubrication. Therefore, the coolant
are 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 Guide Oil 3 Filtering
Drill Drill bush pressure Bar Chip Unwanted particles are contained in coolant after the
head
head tube Sealing rest box cutting operations, thus filtration is necessary to remove
them. The filter size should be selected carefully to catch
particles but not EP additives.
Filter size depends on the coolant, but around
400 - 800 μinch 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
head Chip box Dirty tank Clean tank

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