Drill: Nickel-based superalloy material and its cutting

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Superalloys can be subdivided into nickel-based alloys, iron-based alloys, and cobalt-based alloys. Superalloys still have good mechanical strength and ability to maintain surface properties without degradation in high temperature environments above 780 °C. This is because high-temperature alloys have high tensile strength, creep rupture strength, good ductility and toughness, and excellent oxidation resistance and hot corrosion resistance.

Nickel-based and cobalt-based superalloys are mainly used in aerospace, oil and gas exploration, petrochemical and other industries, and their use accounts for about 90% of high-temperature alloys. The method of correctly processing nickel-based alloys includes high-rigidity machine tools and high-pressure cooling. Mode, positive rake angle, appropriate lead angle and optimum chip thickness. As long as these five key elements are well grasped, the processing of nickel-base superalloys is successful.

Nickel-based superalloy cutting characteristics:

1. The cutting resistance is large (containing a large amount of alloying elements, serious work hardening, and large plastic deformation), which is 1.5-2 times that of steel.

2. The cutting temperature is high and the cutting temperature is 1.5-2 times that of 45 steel under the same conditions.

3. Tool wear is severe, mechanical wear, bond wear, diffusion wear and oxidative wear are more serious, resulting in significantly reduced tool life.

4. The work hardening phenomenon is serious, and the degree of surface hardening has reached 1.5-2 times the hardness of the substrate.

5. The cutting is hard and tough, and it is not easy to break, which makes the cutting process of the chip process difficult.

Nickel-based superalloy cutting tools:

When turning nickel-base superalloys, the tool must be sharp and ensure sufficient blade tip strength. The cutting edge must be carefully sharpened to maintain the good surface roughness of the tool, ensuring smooth edge and no chipping. Notches, cracks and burrs prevent blade chipping damage during processing. The wear resistance of the blade is good to ensure the surface quality when processing high temperature alloys.

During turning, there are a variety of tool wear mechanisms, such as built-up edge, groove wear, chip hammering, etc. The two main wear mechanisms that adversely affect the chip are chipping pain and because the surface of the workpiece is cold. Groove wear caused by hardening (also known as wear or scoring at the depth of cut).

Groove wear of the tool occurs on the primary and secondary cutting edges. On the main cutting edge, the groove wear appears to be chipped at the depth of cut and is primarily mechanical wear. The grooves appearing on the secondary cutting edge are mainly caused by chemical wear and have an adverse effect on the surface finish of the workpiece. In order to minimize this wear, it is recommended to use Al2O3 and PVD tool coatings.

Chip hammering is a form of mechanical wear caused by the impact of chips on the outer edge of the cutting zone, mainly in the processing of nickel-based alloys with lower hardness and better toughness. Chip hammering can occur at the top and bottom of the blade, and by changing the feed rate and depth of cut, the chip changes direction, which may help reduce wear. It is recommended that PVD coated inserts be preferred for processing nickel-based alloys (especially during roughing) because PVD coated inserts have better edge toughness.

Our company's YBG105/YBG202 series PVD coated grades achieve excellent surface quality in nickel base alloy processing. YBG105 grade, the new TiALN-based multi-component coating, has higher wear resistance and high temperature oxidation resistance, and is suitable for fine and semi-finishing of difficult-to-machine materials such as high-temperature alloys and heat-resistant alloys.

With a positive cutting angle, a reinforced geometry, a reasonable insert geometry and a tool configuration, the built-up edge and groove wear on the primary and secondary cutting edges can be minimized. When machining, try to avoid the use of typical CNMG inserts to process superalloys, because this blade will form a 95° lead angle, which will increase the groove wear of the insert.

Our company's -NF groove cutting edge is sharp, -NM groove type cutting edge is high, -NF/-NM groove type surface is smooth, the chip guide is smooth, and the cutting edge is specially treated to have high wear resistance. When the base superalloy is used, good surface quality and processing precision can be obtained.

The basic requirements for milling are accuracy and surface quality. Therefore, there must be sharp tools, rigid machine tools and fixtures. Milling of nickel-based superalloys is interrupted cutting. The milling cutters are required to have sufficient strength during machining to withstand the deformation resistance and chipping of high-temperature alloy cutting. load. When milling superalloys, downward cutting helps to increase stiffness and reduce vibration. The cutting problems in milling and turning are the same, so standard milling cutters must provide sufficient chip pockets.

Our company-APF slot milling inserts are precision ground and have a new PVD coated grade YB9320. The atomic rearrangement technology perfectly matches the hardness, toughness and thermal stability of the coating. Optimized structure, greatly improved surface quality and excellent anti-collapse performance. Suitable for processing of heat resistant alloy materials.

SMP three-faced series of milling cutters, in the processing of steel, alloy steel, stainless steel, heat-resistant alloy materials, cutting light, excellent surface quality, a wide range of applications.

The general common milling cutter has very low cutting parameters, and the tool life is very low. The tool change is frequent, the machine takes up time, and the high-performance solid carbide vertical milling cutter can achieve high efficiency, smooth chipping and less vibration. Our UM/VSM series solid carbide end mills can achieve good results when processing nickel-based superalloys.

UM series unequal pitch, variable edge inclination design, greatly improve vibration resistance, more stable cutting, deep groove design, and both tool rigidity and chip space, enabling greater feed and smoother chip removal.

VSM series unequal pitch cutting angle end mills can achieve excellent results in cutting difficult materials such as stainless steel and heat resistant alloys.

Drilling and reaming of superalloys is very difficult. Generally, carbide drills such as shallow hole drills, solid or inlaid carbide drills are used. In the drilling of superalloys, in addition to the correct feed rate, sharp cutting edges and positive rake angle tools should be used to achieve shear processing of nickel-base alloys.

The geometry geometry also helps reduce chatter. The helix angle also plays a crucial role in the chipping. In addition to the 45° helix angle, in order to reduce the cutting force, the chip control can be improved by forming smaller chips, and a double helix angle (composite helix angle) of 20° can also be used.

Our new generation of universal series GD twist drills have a stable and long-lasting tool life. Excellent processing accuracy and good chip breaking performance. Straight cutting edge, high strength, optimized tip structure for better cutting performance. Double-edged belt design improves processing stability and professional post-treatment technology to ensure low-resistance and efficient processing.

Nickel-based superalloy processing method:

The use of cycloidal milling and cycloidal turning to machine nickel-base alloys is quite effective, greatly reducing blade-to-work contact and preventing tool curling.

The cycloidal tool path is very similar to the oscillating tool path. Instead of snapping into the workpiece, the insert is cut with an optimized smooth tool path to avoid sudden impact on the tool. Especially when using a small depth of cut, cycloidal cutting can increase the feed rate and facilitate chip breaking. In order to control wear,