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CoroBore® BR20

Twin-edge rough boring tools for flexible boring

Application test: Differential pitch

®CoroBore BR20 and DuoBore™ * comparison

Material:42CrMo4 soft, P2.1.Z.AN
Machine:Vertical milling machine
Machine interface:ISO 50
Coolant:No
Diameter range:55–70 mm (2.17–2.76 inch)
Insert:CCMT 12 04 08-PM 4325
Kappa (Kr):90°

+30%

INCREASED OVERHANG


DuoBore™CoroBore® BR20
Basic holderC5-390.00-50 030C5-390.00-50 030
ExtensionC5-391.01-50 080AC5-391.01-50 080A
Boring tool assembly821-70CC12-C5BR20-71CC12F-C5

LF (mm)LU (mm)vc (m/min)fz (mm/z)ap (mm)n (min-1)vf (mm/min)Surface finish
DuoBore™260244.8166.80.182.3900500Heavy vibration marks
CoroBore® BR20316300.8166.80.182.3900500Shining

Results

Thanks to the differential pitch, CoroBore® BR20 could increase the overhang with 30% compared to DuoBore™. Comparing the same cutting data, DuoBore™ stopped to perform at LF = 260 mm (10.2 inch), while CoroBore® BR20 reached an LF = 316 mm (12.4 inch) with a shiny surface finish.

*DuoBore is part of the previous generation of rough boring tools from Sandvik Coromant.

Case: CoroBore® BR20

Challenge: Machining a connecting rod in weak machining conditions. The customer required a stable and secure machining process, good chip control and long insert life and tool life, while obtaining a high surface quality.

Component:Connecting rod
Material:C70S6; CMC: 02.2, MC: P2.5.Z.HT, hardness HB280~310
Operation:Semi-finishing after an initial rough boring operation performed with a combination tool with chamfer
Machine:Feeler VMP-40A, BT40
CoolantInternal coolant, 15 bar
Output power11 kW
DC, mm (inch)59.6 (2.35)

+75%

INCREASED TOOL LIFE


Competitor tool®CoroBore BR20
Total length:120 mm120 mm
Machine interface adaptor
C5-390B.555-40 050
Boring tool assembly
BR20-71SP12Y-C5
Insert
SPMT 12 12 – BR 4325 (CoroBore® 111)
Kappa (Kr)75°84°
Cutting data
zn2
n, rpm1500 rep/min
vc, m/min (ft/min)280 (919)
fz mm/rpm (in/rev)0.09 (0.0035)
ap mm (inch)1.2 mm (0.047)
Depth of hole, mm (inch)31 (1.22)

Results

CoroBore® BR20 together with CoroBore® 111 inserts achieved good surface finish, excellent chip breaking and 70% increased tool life compared to existing tooling solution. The customer can now produce 700 pieces instead of 400 pieces within the same time.

Customer case: CoroBore® BR20 with CoroBore® 111 inserts

Customer demands:Large cutting depths
Component:Connecting rod
Material:C70S6BY; CMC: 02.2, MC: P2.5.Z.HT
Hardness:HB280~310
Operation:Rough boring
Machine:HYUNDAI WIA F650, BT50
Coolant:Internal coolant 30 bar
Output power:22 KW
Machining conditions:Interrupted cut, uneven allowance
DC:56 mm (2.20)

+20%

TOOL LIFE


Reference tool 140 mm®CoroBore BR20 190 mm
Basic holder
C5-390B.58-50 040
Extension
C5-391.01-50 080A
Boring toolSolid boring tool with BT50 spindle couplingTool assembly code: BR20-71SP12Y-C5 Adaptor: C5-BR20-E-048 Slide: BR20-EA-SP12Y-18 & BR20-EB-SP12Y-18
Insert
CoroBore 111
Kappa (Kr)75°84°
Cutting data
zn2
n, rpm1100 rep/min
vc, m/min (ft/min)190 (623)
fn mm/rev (in/rev)0.11 (0.004)
ap mm (inch)5 (0.197)

Results:

  • Customer is very satisfied with CoroBore® BR20 and the CoroBore® 111 insert, as it can take large cutting depths, gives a good surface finish, ensures good chip control and tool life can be increased by +20%.
  • Customer can now produce 350 pieces instead of 280 pieces within the same time. Notch wear pattern (after 350 pieces) was achieved with the CoroBore®
  • The customer could produce in total 1400 components with the CoroBore® BR20 tool.
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