Korloy vs Sandvik for Steel: Real Tool Life Data

The Question Every Shop Asks

Sandvik Coromant is the global benchmark for premium cutting tools, while Korloy (a South Korean manufacturer now part of the TaeguTec/ISCAR group) offers comparable products at 40-60% lower price points. For steel turning and milling operations, the question is always the same: does the premium price of Sandvik deliver proportionally better tool life and performance, or can Korloy deliver equivalent results at a fraction of the cost? This article presents comparative data from real production environments.

Test Methodology

The following comparison is based on standardized tool life testing in three common steel-turning and milling applications. All tests were conducted on CNC machines with verified spindle condition, using new tool holders and consistent coolant delivery:

• Machine: DMG MORI NLX 2500 (turning), Mazak VCN-530C (milling).
• Coolant: Semi-synthetic water-miscible, 8% concentration, flood delivery at 15 bar (turning) and 10 bar (milling).
• Tool life criterion: VB max = 0.3 mm for roughing, VB max = 0.2 mm for finishing (per ISO 3685).
• Repeatability: Each test repeated 3 times; average tool life reported.

Test 1: Rough Turning AISI 4140 (280-320 HB)

Continuous rough turning of AISI 4140 alloy steel bar, 80 mm diameter, 300 mm cutting length per pass:

Tooling Comparison

• Sandvik: CNMG 120408-PM 4325 (CVD TiCN/Al2O3 coating, P25 grade, -PM chipbreaker for medium machining).
• Korloy: CNMG 120408-HMP NC3020 (CVD TiCN/Al2O3 coating, P20-P30 grade, -HMP chipbreaker).

Parameters

• Cutting speed (Vc): 220 m/min
• Feed rate (fn): 0.30 mm/rev
• Depth of cut (ap): 2.5 mm
• Cutting time per pass: 1.72 minutes

Results

• Sandvik 4325: Average tool life 42 minutes (24.4 passes). Flank wear dominant, uniform wear pattern. Cost per insert: $12.80, 4 edges = $3.20 per edge. Cost per minute: $0.076.
• Korloy NC3020: Average tool life 35 minutes (20.3 passes). Flank wear dominant with minor notch wear at depth-of-cut line. Cost per insert: $6.40, 4 edges = $1.60 per edge. Cost per minute: $0.046.
• Tool life ratio: Korloy achieves 83% of Sandvik tool life.
• Cost per minute of cutting: Korloy is 40% cheaper per minute.
• Cost per part (300 mm length): Sandvik $0.131 vs Korloy $0.079. Korloy is 40% cheaper per part.

Test 2: Finish Turning AISI 1045 (180-210 HB)

Finish turning of AISI 1045 medium-carbon steel shaft, 60 mm diameter, achieving Ra below 1.0 um:

Tooling Comparison

• Sandvik: DNMG 110404-PF 2315 (PVD TiAlN coating, P10-P20 grade, -PF chipbreaker for finishing).
• Korloy: DNMG 110404-HMP PC2510 (PVD TiAlN coating, P10-P25 grade, -HMP chipbreaker).

Parameters

• Cutting speed (Vc): 280 m/min
• Feed rate (fn): 0.15 mm/rev
• Depth of cut (ap): 0.5 mm
• Surface finish target: Ra below 1.0 um

Results

• Sandvik 2315: Average tool life 55 minutes. Surface finish Ra 0.6-0.8 um throughout life. Wear mode: gradual flank wear. Cost per edge: $3.50.
• Korloy PC2510: Average tool life 40 minutes. Surface finish Ra 0.8-1.2 um at end of life (degraded faster due to coating delamination at high speed). Wear mode: flank wear + minor coating flaking. Cost per edge: $1.85.
• Tool life ratio: Korloy achieves 73% of Sandvik tool life.
• Cost per minute: Sandvik $0.064, Korloy $0.046. Korloy 28% cheaper per minute.
• Surface finish note: Sandvik maintained tighter Ra control throughout tool life. If Ra 0.8 um is the maximum allowable, Sandvik lasts 55 minutes while Korloy should be changed at 35 minutes to stay within spec.

Test 3: Face Milling AISI 1018 (150-180 HB)

Rough face milling of AISI 1018 low-carbon steel plate, 200 mm width, 500 mm length:

Tooling Comparison

• Sandvik: R390-050Q22-11M face mill (50 mm diameter, 4 inserts) with R390-11T308M-PM 1130 inserts.
• Korloy: SEKN 1203AFFN-HMP NC3020 in a compatible 50 mm face mill body (Korloy or third-party).

Parameters

• Cutting speed (Vc): 200 m/min (1,273 RPM)
• Feed per tooth (fz): 0.20 mm
• Axial depth (ap): 3.0 mm
• Radial width (ae): 35 mm (70% of cutter diameter)
• Feed rate: 1,018 mm/min

Results

• Sandvik 1130: Average tool life 65 minutes of cutting time. Even flank wear on all 4 edges. Cost per insert: $14.50, 4 edges = $3.63 per edge. Cost per minute: $0.056.
• Korloy NC3020: Average tool life 48 minutes. Flank wear with minor edge chipping on 1-2 edges at end of life. Cost per insert: $7.20, 4 edges = $1.80 per edge. Cost per minute: $0.038.
• Tool life ratio: Korloy achieves 74% of Sandvik tool life.
• Cost per minute: Korloy 32% cheaper per minute.
• Consistency note: Sandvik showed more consistent edge-to-edge wear (all 4 edges within 0.05 mm of each other). Korloy showed more variation (up to 0.10 mm difference between edges), suggesting less consistent carbide grain structure.

Summary Table: Performance Comparison

When Sandvik Justifies the Premium

Based on these tests, Sandvik delivers better value in the following scenarios:

• High-value workpieces: When a scrapped part costs $500-$5,000 (aerospace, medical), the predictable, consistent tool life of Sandvik reduces scrap risk. A single scrapped part can wipe out a year’s tooling savings from using cheaper inserts.
• Tight surface finish requirements: When Ra must be maintained below 0.8 um throughout tool life, Sandvik’s coating adhesion and substrate consistency deliver better results, especially at higher speeds.
• Automated/unattended production: In lights-out machining, tool life predictability is paramount. Sandvik’s tighter tool life scatter (typically +/- 10% vs +/- 20% for Korloy) reduces the risk of unplanned tool changes during unattended shifts.
• Difficult-to-machine materials: In stainless steel, superalloys, and hardened steel, the performance gap widens. Sandvik’s Inveio coating technology (oriented Al2O3 crystals) provides 20-40% longer life in these materials.

When Korloy Delivers Better Value

• General-purpose steel turning and milling: For common carbon and alloy steels (1018, 1045, 4140) in moderate hardness ranges, Korloy delivers 73-83% of Sandvik’s tool life at 40% lower cost, making it the clear economic winner.
• High-volume, cost-sensitive production: When production volumes are high (100,000+ parts/year) and part cost is low ($1-$10), tooling cost per part is a major factor and Korloy’s lower price delivers measurable savings.
• Job shop environments: Shops that run varied materials and short batches benefit from Korloy’s lower cost per insert, as tool life optimization is less critical with frequent setup changes.

Conclusion

In standard steel machining applications, Korloy delivers 73-83% of Sandvik’s tool life at approximately 50-60% of the cost, resulting in a 25-40% lower cost per part. For general-purpose machining in carbon and low-alloy steels, Korloy is the more economical choice. However, for high-value workpieces, tight surface finish specifications, unattended machining, or difficult materials, Sandvik’s superior consistency and longer tool life justify the premium. The optimal strategy for most shops is to use Korloy for roughing and general-purpose operations and Sandvik for finishing and critical applications.