Choosing the Right Cutting Tools
for Roll Machining​

1. Core Consideration: Tool Material

This is the most decisive factor. The choice mainly depends on the roll material and machining process. Due to the high hardness of rolls—especially high-chromium cast iron and HSS rolls—roll machining falls into the category of hard cutting and wear-resistant material machining.

Modern roll machining mainly uses the following tool materials:

1.1. Cemented Carbide (Carbide Tools)

Currently the mainstream and preferred choice. It can be further divided into:

Standard Carbide:

• Features: Made of tungsten carbide with a cobalt binder; cost-effective and versatile.
• Best for: Spheroidal graphite iron rolls and indefinite chilled rolls with relatively lower hardness; ideal for roughing and semi-finishing.

Ultrafine/Submicron Carbide:

• Features: Grain size <0.5μm, combining high hardness and toughness.
• Advantages: Excellent wear resistance, sharp and durable edges, strong resistance to chipping.
• Best for: Finishing of high-chromium cast iron rolls and high-nickel-chromium cast iron rolls.

Coated Carbide:

• Features: A thin (several microns) hard coating (TiCN, TiAlN, AlCrN, etc.) applied via CVD or PVD on the carbide substrate.
• Advantages: Greatly improves surface hardness, wear resistance, and thermal stability—extending tool life and cutting speed.
• Best for: All types of roll machining, especially high-chromium cast iron finishing. TiAlN and AlCrN coatings perform excellently in high-temperature environments.

1.2. Cubic Boron Nitride (CBN)

• Features: Hardness second only to diamond, with much better thermal stability and chemical inertness toward ferrous materials.
• Advantages: 1) Extremely high wear resistance—tool life can be dozens of times that of carbide. 2) Enables “turning instead of grinding,” achieving superior surface finishes and reducing the need for grinding.
• Disadvantages: Expensive, less tough, requires high machine rigidity.
• Best for: High-precision finishing of high-chromium cast iron and HSS rolls; when carbide tool life is insufficient, CBN provides a cost-effective long-term solution.

2. Tool Geometry and Type

2.1. Indexable Insert Tools

• Features: The modern mainstream approach—mechanically clamped inserts on toolholders.
• Advantages: 1) No regrinding required, short tool change time, high efficiency. 2) Consistent geometry ensures stable machining quality. 3) Coating remains intact, maintaining optimal performance.
• Key point: Select insert shape (e.g., rhombic, triangular, round) and chipbreaker design based on the roll pass profile and machining stage (roughing or finishing).

2.2. Brazed or Form Tools

• Features: Carbide tips are brazed onto steel shanks, then ground manually into shape.
• Advantages: Low cost, highly flexible, suitable for complex or non-standard pass profiles.
• Disadvantages: Dependent on operator skill; inconsistent regrinding quality; low efficiency; cannot use advanced coatings.
• Best for: Small-batch, multi-variety, or special-shape roll machining, or when budget is limited.

3. Summary of Tool Selection Strategies

4. Additional Recommendations

Cutting Parameters:

• Cutting speed: Use medium-to-high cutting speeds for hard rolls.
• Feed rate: Use small feeds for finishing to achieve better surface finish.
• Depth of cut: Should exceed the hardened or worn surface layer of the roll.

Machine Rigidity: Machining rolls requires excellent machine rigidity—vibration can cause edge chipping and poor surface quality.

Conclusion

Indexable coated carbide tools offer the best cost-performance ratio for most roll machining tasks. When dealing with the most challenging high-chromium cast iron rolls that demand extreme precision and durability, CBN tools are worth the investment. For traditional or special-shaped passes, brazed tools remain irreplaceable.

The best approach is to work with professional tool suppliers—provide your roll material and machining details, and let them recommend the most suitable tool grade, geometry, and cutting parameters, followed by trial cutting for verification.