Sumitomo General Catalog 2025-2026

SUMIBORON for Hardened Interrupted Steel Machining BNC300 / BN350

Hardened Steel

The Ultimate in Interrupted Cutting of Hardened Steel

■ General Features BNC300

BNC300

A CBN substrate that emphasizes toughness is coupled with a highly wear-resistant TiAlN-based coating layer that has improved adhesion strength. With a good balance of fracture and wear resistance, this grade achieves a long, stable tool life in interrupted cutting or in a mixture of continuous and interrupted cutting. BN350 CBN - SUMIBORON with the highest fracture resistance and toughest CBN. Reliable grade for achieving stable tool life in heavy interrupted cutting conditions.

L

BN350

■ Features

· Long, stable tool life in interrupted cutting Achieving long, stable tool life in heavy interrupted cutting, with superior fracture resistance. · Superior dimensional tolerance TiAlN-based high-wear-resistance coating with good adhesion strength. Achieves superior dimensional tolerance even in interrupted cutting. · Supports various work material shapes Achieves long, stable tool life even in workpieces requiring both continuous and interrupted cutting. · Superb stability with regard to fracture Superior fracture resistance, preventing the fractures that commonly occur during interrupted cutting. Achieves a long, stable tool life.

● BNC300

● BN350

■ Cutting Performance

Continuous + Mid Interrupted Cut (Interrupted Cutting 50%)

Heavy Interrupted Cutting: (Interrupted Cutting 100%)

Competitor's CBN: Fracture

Competitor's Coated CBN: Fracture

BN350

.0039

.0039

D

BNC300 : Fracture

D

Coating chip-off

D

F D D

D

D

.0019

D

.0019

BNC300 Able to Continue

D D

BN350 Able to Continue D

D D

D

D

0

8

16

24

32

0

20 Time in Cut (minutes) 10

30

Time in Cut (minutes)

Part Material: 5120 Chromium Steel (58 to 62 HRC) Tool Cat. No.: 4NC-CNGA432 Cutting Conditions: v c = 400 SFM, f = .0039 IPR, a p = .0079” Dry

Part Material: 5120 Chromium Steel (58 to 62 HRC) Tool Cat. No.: 2NU-CNGA432 Cutting Conditions: v c = 330 SFM, f = .0039 IPR, a p = .0079” Dry

● BNC300 has a superior balance of fracture and wear resistance.

● BN350 exhibits very good fracture resistance.

■ Application Range

■ Recommended Cutting Conditions (BNC300/BN350 common)

● CBN (SUMIBORON)

● Coated CBN (SUMIBORON)

1000

1000

BNC100

165 265 330 400 500 Cutting Speed v c (SFM)

BN1000

BNC160

BNC2010

660

660

BNC2020 BNC200

BNX25

BN2000

BNX20

400 330

BN350

330

Feed Rate f (IPR) Depth of Cut a p (inch) .0012 - .0079 .0012 - .0118 Coolant: Dry

BNC300

Light Interrupted Medium Interrupted Heavy Interrupted Continuous

Light Interrupted Medium Interrupted Heavy Interrupted Continuous

Small

Impact Force on Cutting Edge Large

Small

Impact Force on Cutting Edge Large

L15

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