The cutting tools selection on machining high chromium cast iron

The cutting tools selection on machining high chromium cast iron

Part 1 Machining High chromium cast iron and the cutting tools selection

High chromium cast iron is a kind of high hardness and high strength alloy white cast iron with high corrosion resistance wear-resistant, high chrome cast iron in the case without any heat treatment, the generally hardness of HRC45 or more, the tensile strength 650 ~ 850MPa.

High chromium cast iron is a kind of difficult to cut materials, carbide cutting tools is difficult to machining, and due to the brittleness of ceramic cutting tool, generally used only for fine finishing; With the advent of new cutting tool materials, high chromium cast iron machining cutting tool industry experienced cemented carbide cutting tools- ceramic cutting tools - cubic boron nitride ceramic composite material cutting tools, to a certain extent, changed the high chromium cast iron machining processes and equipment investment .

Before 2003, due to restrictions by the cutting tool material, carbide insert and ceramic insert is the main stream of machining high chromium cast iron.

High chromium cast iron processing generally: blank-softened processing (lower hardness)---roughing- -heat treatment (to increase the hardness)---finishing.

As can be seen from the above machining process, not only increases the workload, impact machining efficiency, but also increase the machining costs. BN-K1 PCBN insert, due to the hardness higher than carbide and ceramic insert, and fracture resistance and resistance to chipping loss properties higher than ceramic cutting tool, BN-K1 CBN insert used as high hardness cast iron cutting tool grades, is widely used HRC35-HRC68 high hardness cast iron roughing, intermittent machining and finishing.

Compared to ceramic blade, BN-K1 CBN insert hardness generally about HV3500, its hardness is 2 times of ceramic insert and 4 times of carbide insert.

BN-K1 CBN insert heat resistance up to 1400 ~ l500 ℃, when the BN-K1 CBN insert processing high cast iron, its hardness at 1000 ℃ even higher than the hardness of ceramic and carbide. High-speed cutting high hardness white cast iron Cr26, the wear resistance of BN-K1 grades cutting tool is 25 times of silicon nitride ceramic. impact resistant ability is 2000 times of silicon nitride ceramic, cutting tool life can reach the silicon nitride ceramic 22 to 30 times. So BN-K1 CBN insert parameters 3-5 times higher than the carbide cutting tools. It also creates the conditions for PCBN cutting tools high-speed cutting.BN-K1 CBN insert is BN-K1 CBN insert

widely used in high-alloy cast iron rolls, pump parts, high chromium cast iron liners and other wear-resistant castings machining.

In the machining process, in addition to reasonable selection of cutting tools, selection of cutting tool parameter is also an important factor in high-efficiency machining high chromium cast iron. these three factors of in the depth of cut, feed rate, linear speed, the increase in the depth of cut is undoubtedly one of the effective means to improve processing efficiency, but also for some large pump parts, metallurgy, mining machinery wear-resistant castings, cutting the amount large, to improve processing efficiency, the depth of cut to be increased.

Since BN-K1 grade cutting tool anti-break strength and resistance to chipping damage advantage, compared with the ceramic cutting tool, BN-K1 grade cutting tool is more suitable for the use of large depth of cut to reduce the number of feed to improve processing efficiency. BN-K1 grade cutting tool due to the high hardness and excellent high temperature wear resistance, can be used 3-5 times for high-speed cutting higher than cemented carbide and ceramic cutting tools.

The following is BN-K1 CBN insert machining high hardness cast iron cases: 1. BN-K1 grades cutting tool interrupted turning slurry pump outer circle machining case, BN-K1 grade cutting tool cutting parameters: Vc=75m / min, ap = 2.5-5mm, f= 0.1mm/r.

The results show: BN-K1 grade boron nitride cutting tools intermittent processing process did not produce fractured, a piece blade is equivalent 25 pieces ceramic blade, boron nitride cutting tool of impact resistance, not only reduces the cost of the cutting tool, processing efficiency is increased by 5 times.

2. BN-K1 CBN insert milling processing high chromium cast ironďźš Cutting parameters: Rough milling machining Vc=55m/min,ap = 2.5mm, feed per tooth fr=0.25mm / r. Measured both ends the same size, no retract and cutting tool wear and tear. The use of ceramic cutting tool milling takes 5 to 7 blades to complete, and the insert edge when the insert cutting wear faster, leading to increased cutting resistance, resulting in retraction, seriously affecting the quality and efficiency of the processing surface.

BN-K1 CBN insert