1. Cylinder Liner General Materials
Cylinder liner general adopts wear resistant alloy cast iron with phosphorus or boron such as ductile iron, high phosphorus cast iron and alloy cast iron.
Ductile Iron Cylinder Liner
Ductile iron has dense and tough pearlite matrix and spherical graphite, and its strength is twice as high as that of ordinary cast iron. Its cavitation resistance and wear resistance are also better than that of ordinary cast iron. However, its casting process is more complex and cost is higher than that of ordinary cast iron.
High Phosphorus Cast Iron
Horous cast iron has better hardness and wear resistant. Its wear resistant is similar to ductile iron. Its arts are better than that of ductile iron. Meanwhile, it saves labor hours. Phosphorus can also change corrosion resistance. However, high phosphorus cast iron is brittle due to the increase of phosphorus content, and easy to produce shrinkage, resulting in waste products.
Alloy Cast Iron Cylinder Liner
Various alloy cast iron obtained by adding nickel, chromium, copper and other alloying elements into cast iron which can make material structure uniformity, pearlite denseness , or promote the formation of carbides with high hardness, further improve strength, wear resistance and corrosion resistance. Its shortcoming is precious metals consumables, the complex smelting and casting process , the hard processing and the high cost.
The materials to making cylinder liner have others such as boron-bearing cast iron, rare earth calcium cast iron, titanium-vanadium cast iron, phosphorus-vanadium cast iron and austrian cast iron. The manufacture adopt the nitriding steel to making cylinder liner in some Intensified internal combustion engine due to the nitriding steel has better heat resistance and corrosion resistance. Nitrided layer hardness decreases little to assure the wear resistant under the 500℃.
2. the Processing Arts of Cylinder Liner
（1）Dry Cylinder Liner
Casting blank--rough turning--rough boring--turning process cylindrical--finishing boring-semi--finishing turning--finishing turning--rough honing--turning end face and cylindrical--rough grinding cylindrical--finishing grinding cylindrical--finishing honing
（2）Wet Cylinder Liner
Casting blank--rough turning--rough boring--turning process cylindrical--finishing boring--finishing turning--finishing turning water gear--grooving--rough honing--finishing turning--finishing honing
3、CBN Tools for Cylinder Liner Processing
At present, wear-resistant cast iron such as boron cast iron and alloy cast iron are mostly used in cylinder liner. Because these cast iron have very high hard spots, the tool wear is relatively large. When cutting with cemented carbide tools, the cutting speed is low and the tool wear is fast. It is difficult to improve working efficiency and machine efficiency, but some materials are difficult to grind.
CBN inserts are a new super hard inserts which provide the economical and efficient cutting methods for hard processing materials. A large number of facts proved the development direction that increasing life, improving cutting efficiency, reducing processing costs, ensuring high accuracy and low roughness, and meeting the processing requirements of hard to processing materials.
Halnn superhard as a pioneer to provide two materials: BN-S300 and BNK30. The BN-S300 materials belong to solid PCBN inserts that can apply both the finish turning and rough turning and can process blank with large margin to promote the work efficiency. The BNK30 materials belong to brazing CBN inserts that only the edge part is made of CBN material, so it is generally used in finishing process to ensure the dimensional accuracy and surface finish of cylinder liner. The mainly parts as following:
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Replacing grinding by turning, high-speed cutting wet cylinder liner upper and lower waistband;
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High-speed cutting cylinder liner outer circle, water jacket wall, sealing tank, chamfer, flat end surface;
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Finishing the outer circle of dry cylinder liner to reduce the machining margin and working procedure of centerless grinding
A Case Study on Processing Boron Cast Iron Cylinder Liner with BNK30 Material
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Materials
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Cutting speed
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Inserts life
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Efficiency
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Work pieces:Boron alloy cast iron cylinder liner
Select inserts: BNK30 SNGA120412-8S
Cutting parameter: ap=0.3mm，Fr=0.2mm/r，Vc=850m/min, wet-cutting
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Halnn BNK30
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850m/min
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120p/b
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Twice
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Coating Carbide tool
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400m/min
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25p/b
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25p/b
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