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CoroBore® BR20

Twin-edge rough boring tools for flexible boring

Application test: Differential pitch

CoroBore® BR20 and DuoB​ore™ * 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 holder C5-390.00-50 030 C5-390.00-50 030
Extension C5-391.01-50 080A C5-391.01-50 080A
Boring tool assembly 821-70CC12-C5 BR20-71CC12F-C5 ​
​​

  LF (mm) LU (mm) vc (m/min) fz (mm/z) ap (mm) n (min-1) vf (mm/min) Surface finish
DuoBore™ 260 244.8 166.8 0.18 2.3 900 500 Heavy vibration marks
CoroBore® BR20 316 300.8 166.8 0.18 2.3 900 500 Shining

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
Co​olant Internal coolant, 15 bar
Output power 11 kW
DC, mm (inch) 59.6 (2.35)

+75%
INCREASED TOOL LIFE​​

  Competitor tool​ CoroBore® BR20
Total length: 120 mm 120 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​​
zn 2
n, rpm 1500 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)

Resul​ts​

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)

+2​0%
TOOL LIFE​​

Reference tool 140 mm CoroBore® BR20 190 m​m
Basic holder C5-390B.58-50 040
Extension C5-391.01-50 080A
Boring tool Solid boring tool with BT50 spindle coupling Tool 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​​​
zn ​ 2
n, rpm 1100 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 in​stead 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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