1.1.2 Turning cast iron parts
When processing hard cast iron, as long as the hardness reaches the medium hardness level (HRc45), the tool with super-hard material will achieve good processing results, which is very suitable for high-speed machining in high-volume production lines, and is widely used in the automotive industry.
The exhaust valve seat on the engine cylinder head is made of copper and molybdenum high chromium alloy cast iron (HRC44). The processing methods generally include milling and car. Most of them are on the automatic line, and processed together with the hinge hole of the hinge, v= 71.6m / min, ƒ = 26.5mm / min, ap = 1.0mm, using PCBN overall blade processing, the average durability is 1,200 valve seat, processing surface roughness Ra0.4μm, cone surface swing ≤ 0.05mm, tool life High and stable quality.
In the automobile engine production line, the cylinder hole finishing of the gray cast iron cylinder requires high dimensional accuracy, small surface roughness and good stability of the cylinder bore; the cutting speed is high due to the fast processing cycle of the production line (usually V≥500m/min) The tool life is long (the number of machining holes is ≥1000), and the blade life of multiple stations such as chamfering, stop, and coarse boring should meet the durability requirements. High-speed cutting and high-stability machining of engine cylinder bore can be realized by PCBN tool; the typical cutting parameters are: V=500m/min, f=0.2～0.4mm/r, ap=0.2～0.7mm; machining surface roughness Ra≤1.6μm, tool life>1,000 pieces.
Boron-containing cast iron cylinder liner is processed by PCBN tool. Cutting parameters: V=200m/min, f=0.1mm/r, ap=0.2～1mm, machining surface roughness Ra≤1.6μm, precision IT6, between two sharpening With a tool life of >100 pieces, it can achieve "car grinding". Due to the dry cutting, the environmental pollution of the cutting fluid and the grinding wheel dust is avoided, and the chips can be recycled and reused, which meets the requirements of clean production.
Cutting the gray cast iron brake disc with PCBN tool, the cutting speed is generally 700 ~ 2,000m / min, such as Shanghai General Motors Co., Ltd. using Seco tool company PCBN300 type blade, cutting speed can reach 2,000m / min.
1.1.3 turning alloy workpiece
Cutting the aluminum alloy wheel with PCD tool, the cutting speed can be V=500~1000m/min, ƒ0.05~0.5mm/r, ap is generally 0.5mm~3mm.
The PCBN tool turns high cobalt chromium molybdenum corrosion resistant alloy with a cutting speed of 160m/min, which is 8 times that of cemented carbide tools.
Generally, an aluminum alloy containing less than 10% silicon can be cut with a cemented carbide tool. However, if the silicon content exceeds 10%, only PCD can be used. Currently, the silicon content of high-silicon aluminum alloys is above 12%, and some of them have exceeded 18%. Therefore, non-PCD such as pistons for turning high-silicon aluminum alloy automobile engines is none other than PCD.
Turning powder superalloy FGH95 also uses PCBN inserts.
1.1.4 Turning other materials
Alumina ceramic density 3.9g/cm3, hardness HV2100～2300, bending strength 300MPa, compressive strength 300MPa, wet cutting with PCD cutter, V=20～70m/min, ƒ=0.025～0.10mm/r, ap= 0.2mm; the processing efficiency is obviously improved, which is 3 to 5 times of the grinding of the diamond wheel, and the tool life can reach 10 to 30 minutes.
The copper commutator for turning the motor commutator with PCD tool has typical cutting parameters: V=300m/min, ƒ=0.08mm/r, ap≤0.15mm; machined surface roughness Ra0.1～0.2μm, tool life> 5,000 pieces. Only a few pieces can be processed with carbide tools.
