tooling & workholding
Chip-breaker geometry is
designed to boost cutting
performance across standard
Air turbine spindles deliver a
package of improvements for
ultra-high-speed micro-machining.
range of over 1000 inserts. Under pressure
Take a
break
LATEST addition to the Horn Supermini range is a
Type 105 insert that offers significantly higher
productivity when machining in bore diameters of
4mm or greater. The tooling incorporates newly
developed HV chipbreaker geometry which allows
much higher feed rates than hitherto.
This development has been enabled by Horn’s
grinding process expertise, and continuous investment
in the most capable insert grinding technology; the
chipbreaker form is ground into the insert close to the
cutting edge during manufacture. More than 1000
standard insert configuration formats are now available
in the Supermini format. Since its introduction in the
early 1990s the system has established itself as a leading
boring, grooving, threading and on-machine
broaching system for machining in bores of 8mm
diameter or less. In fact the minimum entry bore
diameter of Supermini is now 0.2 mm.
Incorporating chipbreakers on Supermini inserts
offers a significant hike in cutting performance. Chip
control is a significant limiting factor when machining
in small diameter bores. The HV chipbreaker form is
designed to minimise stress at the cutting edge while
promoting effective swarf evacuation. Combined with
Supermini’s existing through-tool coolant capability it
offers the opportunity to double feed rates to as much as
0.1 mm without risk of blockage and tool failure.
Versions of the insert are available for machining in
bores up to 30 mm deep and the standard coating is
Horn Type TH35. The standard Supermini ovoid
location/clamping surface of the insert makes it fully
compatible with the wide range of Supermini B105
pattern tool holders, ensuring maximum performance
in a very wide range of applications.
www.phorn.co
TO achieve sufficiently high cutting speeds for efficient metal removal and acceptable tool
life when using very small diameter cutters, BIG Daishowa has introduced two new air
turbine spindles. The RBX5 version operates at 30,000 and 50,000revs/min, RBX7 at 60,000
up to 80,000revs/min. They come with a variety of BIG-PLUS face-and-taper-contact back
ends to fit any BT 30/40/50 or HSK-A63/A100 machining centre spindle. This is held
stationary while compressed air is delivered through a stop block installed on the spindle
face to power the turbine. The air spindle can therefore be exchanged automatically to and
from the tool magazine like other toolholders, allowing micro-machining to be mixed
with other metalcutting operations in one uninterrupted cycle (electrically powered
turbine spindles require a power supply lead to be connected manually, preventing
automatic tool change). The air supply of the RBX is turned on and off by M-code, the air
pressure determining spindle speed. For example, 60 psi of air pressure generates
66,000revs/min while 70 psi delivers 71,000revs/min.
The air spindles can hold shank diameters up to 4mm. Cutting tools down to 1mm diam.
are clamped in a microcollet using a notch-free nut, tightened using a special wrench, to
eliminate unbalance at high speeds. Maximum static TIR (total indicated runout) is one
micron at the collet nose while dynamic run-out is 4 microns at 80,000revs/min, a
combination of precision and speed that is impossible using gear- or belt-driven spindle
speeders due to the vibration and heat that they generate. Moreover, the RBX turbine drive
has less than 17% of the thermal growth in the Z-axis compared with a conventional
spindle, leading to very precise milling, drilling, engraving, slotting, deburring, routing
and boring. The turbine employs ceramic ball bearings and runs quietly at less than 65dB,
allowing operators to hear cutting noise and determine if a cutter has broken.
Dramatic improvements in productivity and tool life are possible:
■ The RBX spindle can be used to cut 63 micron walls in aluminium and drill the material
without a centre drill. Even after drilling 3,500 holes in a test cycle, the cutting tool edge
showed no wear.
■ A 0.5 mm diameter carbide drill in the air turbine has been shown to produce 1,200 holes
at 50,000revs/min, whereas a drill on a machining centre at 12,000revs/min produced only
500 holes.
■ A 0.2mm ball diameter nose end mill in an air turbine cut a complex, 2D shape in
HRC40 tool steel at 80,000revs/min in 120 minutes. With the tool in the spindle of a
20,000revs/min machining centre, the same job took nearly four times longer (450
minutes). www.ncmt.co.uk
New turning insert for heavy industry
TAEGUTEC’S new single sided chip breaker insert (designated HY) was developed
especially for roughing applications on materials commonly used in the heavy industry
sector, in conjunction with customers producing components such as the tower flanges,
main shafts and swing bearings for wind turbines. The HY is available as CNMM and SNMM
inserts and can machine up to 15mm depth of cut at feed
rates exceeding 1.4mm/rev. The chip breaker is integral
to its success, delivering excellent swarf control when
conducting facing, internal facing and general turning
applications. Also, the insert incorporates very strong
edge geometry with negative rake angle to guarantee
stable and sustained tool life. Chip breaker geometry is
designed to generate less heat, whilst a new edge
preparation process also reduces forces and heat.
HY is currently available with TaeguTec’s TT8115 &
TT8125 insert grades.
www.taegutec.co.kr
56 MWP may 2009
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