No Chipping or Sticking! CBN Inserts Provide a High-Speed Dry Cutting Solution for Ductile Iron

Ductile iron is widely used in the manufacture of key components such as automobile crankshafts and gears due to its high strength, high toughness, good wear resistance and machinability.

I. Machining Characteristics of Ductile Iron

1. Wide Hardness Range: The hardness of ordinary ductile iron is HB180-250, while that of quenched and alloyed ductile iron can reach HB280-380.

2. Significant Work Hardening: During cutting, the plastic deformation of the metal leads to a significant increase in the surface hardness of the workpiece, easily causing tool edge wear and chipping.

3. Abrasiveness of Graphite Particles: Although spheroidal graphite can improve the toughness of the material, it will continuously abrade the tool edge during cutting, accelerating tool failure.

4. Precision Machining Requirements: Industries such as automotive and construction machinery have stringent requirements for the dimensional accuracy and surface roughness (Ra≤0.8μm) of ductile iron parts, requiring tools with excellent dimensional stability.

II. Core Advantages of CBN Tools for Machining Ductile Iron

1. Ultra-long service life: CBN tools have 5-10 times the wear resistance of cemented carbide tools, and their single-edge machining life can reach 8-12 times that of cemented carbide tools, significantly reducing tool change frequency and downtime, and lowering production costs;

2. High-efficiency cutting capability: CBN tools can withstand higher cutting speeds, and feed rates can be increased by 30%-50%, significantly improving machining efficiency and shortening production cycles in roughing and semi-finishing;

3. Precision Machining Effect: CBN tools have sharp and stable cutting edges, resulting in minimal vibration during cutting. This effectively controls workpiece dimensional accuracy and surface roughness, leading to a high-gloss finish on the machined workpiece.

4. Green and Environmentally Friendly Machining: CBN tools have high heat resistance, allowing for machining under dry cutting or minimum quantity lubrication (MQL) conditions. This avoids the use and treatment costs of cutting fluids, reducing environmental pollution.

Application Case: The Practice of CBN Tools in Automotive Crankshaft Machining

An automotive parts manufacturer produces ductile iron crankshafts. Previously, they used carbide tools for machining, which presented the following problems: cutting speed was only 180 m/min, single-edge life was only 80 pieces, frequent tool changes led to low production efficiency; the workpiece surface roughness Ra=1.2 μm required subsequent grinding, increasing production costs.

After switching to SCBN brand integral PCBN inserts and optimizing cutting parameters: cutting speed Vc = 600 m/min, feed rate f = 0.15 mm/r, depth of cut ap = 0.3 mm, dry cutting. The application results are significant:

1. Single-edge machining life increased to 800 pieces, 10 times that of the original carbide inserts

2. Cutting efficiency increased by 233%, production line capacity increased by 40%

3. Workpiece surface roughness Ra = 0.4 μm, dimensional accuracy reached IT6 level, directly eliminating the grinding process and reducing production cost per piece by 15 yuan

4. Dry cutting reduces cutting fluid consumption, saving approximately 120,000 yuan annually in environmental treatment costs.