Foreword
With the development of CBN powder, the development of hard polycrystalline cubic boron nitride (PCBN) has made it an ideal material for efficient machining tools. In addition to its inherent durability, PCBN also has excellent thermal shock resistance and chemical resistance; PCBN is also suitable for very high cutting speeds, the focus of the user's attention.
Iskar offers a wide range of polycrystalline cubic boron nitride (PCBN) grades for hardened hardware turning (HPT). The so-called quenching hardware turning (HPT) usually refers to the turning of hard-to-machine materials such as hardened steel of Rockwell hardness HRC45-68, high-temperature alloys, sintered metal and gray cast iron.
Throughout the global industry, the Iskar PCBN insert is the first choice for high-speed turning hardened workpieces. It will be described in detail next.
Iskar offers the following two main forms of PCBN tools: Welded PCBN, with CBN tip or surface soldered CBN for finishing on carbide inserts; Monolithic PCBN for more demanding and harsher processing conditions under.
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In addition, Iska released a new generation of PCBN inserts with effective chipbreakers designed to improve chip control. When using a flat-topped standard blade with a brazed PCBN tip as shown in Figure 6, there is often an uncontrolled long and constant chip. Such long coils may cause damage to the surface quality of the workpiece and even interrupt the machining process.
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Iska's new PCBN inserts with HF chipbreakers and HM chipbreakers enable good chip control at different depths of cut. Isca's PCBN insert with chipbreaker solves the problem of long crumbs.
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1. Why is the Isca PCBN blade the best solution for hardened hardware turning (HPT)?
Boron nitride has a hardness of up to 4500 HV, which is very close to the hardness of synthetic diamond; at high temperatures, PCBN also has high thermal conductivity and high chemical stability. The above advantages make it possible to machine the quenching hardware under high cutting parameters. In addition, the excellent wear resistance of PCBN greatly extends tool life, meets stringent dimensional tolerance requirements, and maintains excellent surface quality standards.
All of Isca's PCBN inserts are machined in a peripheral finish with very high precision.
The very important advantage of using a PCBN insert is that it can replace the less efficient and more expensive quenching hardware grinding process. Compared to grinding, turning with a PCBN insert can significantly reduce the cost per piece.
Isa's global sales data confirms that users are turning the finishing process from grinding to PCBN inserts. The trend of car grinding is becoming more and more popular in the global automotive industry and has greatly changed the process of manufacturers. PCBN inserts for hardened hardware finishes shorten the manufacturing cycle and increase productivity while increasing user productivity.
2. Isca PCBN grade
Iskar offers a wide range of PCBN grades. Each grade is specifically developed to provide high performance for a wider range of applications from continuous cutting to heavy interrupted cutting.
2.1. PCBN grades for hardened steel processing
IB50 : Uncoated grade, sintered from 50% fine-grained CBN particles combined with a special binder. It is used for finishing medium-high speed hardened steel under continuous turning processing conditions. Its excellent wear resistance allows for very high surface quality to be machined.
IB10H : Uncoated grade, sintered from a 53.5% content of ultrafine grained CBN particles combined with a special binder. For medium-high speed finishing of hardened steel under continuous turning to slightly intermittent turning. Its excellent wear resistance allows for very high surface quality to be machined.
IB20H : Uncoated grade, sintered from 65% fine grain and medium grain size CBN particles combined with a special binder. As a general-purpose grade, it is used to finish hardened steel at medium speed under the conditions of continuous turning to medium intermittent turning. Highly balanced between wear resistance and impact toughness properties.
IB55 : Uncoated grade, sintered from a 60% fine grained CBN particle combined with a special binder. For finishing of hardened steel at medium speed under processing conditions from continuous turning to medium intermittent turning. Suitable for medium speed feed and medium depth of cut processing conditions with very high toughness.
IB10HC : PVD coated grade, sintered from a 53.5% content of ultrafine grained CBN particles combined with a special binder. For high-speed finishing of hardened steel under continuous turning to slightly intermittent turning. Excellent wear resistance makes it highly resistant to crater wear and achieves high standards of machined surface quality.
IB25HC : PVD coated grade, sintered from 75% coarse-grained CBN particles combined with a special binder. For high-speed finishing of hardened steel under medium to heavy duty interrupted machining conditions. Has a very high toughness and impact toughness.
IB25HA : PVD coated grade, sintered from 65% fine grain and medium grain size CBN particles combined with a special binder, is a general grade for finishing hardened steel. It is used to finish hardened steel at medium speed under the processing conditions of continuous cutting to medium-sized intermittent turning. Highly balanced between wear resistance and impact toughness properties. Both HF and HM chipbreakers are available.
2.2. PCBN grades for cast iron and hardened steel processing
IB90 : Uncoated grade, sintered from a 90% content of medium-grained grain CBN particles in combination with a special binder. It is used for finishing cast iron at high speeds, and is also suitable for finishing medium hardened steels under heavy-duty interrupted turning conditions. Has a very high toughness and impact toughness.
IB90A : Uncoated integral CBN grade, sintered from a 90% coarse-grained CBN particle combined with a special binder. Used for semi-finishing and roughing of cast iron at high speeds. Excellent performance in heavy-duty interrupted cutting, also suitable for machining hardened steel under interrupted turning conditions. Has a very high toughness and excellent impact toughness.
2.3. PCBN grades for high temperature alloys and sintered metal processing
IB05S : Uncoated grade, sintered from a 95% content of ultrafine grained CBN particles combined with a special binder. It is used to finish the sintered metal at high speed under the processing conditions of continuous turning. The high hardness properties give it a good wear resistance and therefore a very high surface quality.
IB10S : Uncoated grade, sintered from a 95% content of ultrafine grained CBN particles combined with a special binder. For high-speed finishing of sintered metals, it is also used to machine valve seats and titanium alloys under continuous cutting to slightly interrupted cutting. Has high hardness and high wear resistance.
3. Blade edge processing
In the hardening hardware turning process, the PCBN blade edge processing form is very important. The main way is to grind a narrow T-land negative chamfer to the cutting edge and add a passivation process to make the blade rounded slightly to make the blade stronger.
3.1. PCBN grade cutting edge treatment for hardened steel processing
3.1.1. After 10°-15°T-land negative chamfering of the cutting edge of the insert, the sharp edge generated by the chamfer is passivated to make the cutting edge stronger, ensuring that the insert can be used for continuous turning of the quenching hardware ( HPT).
3.1.2. After 15°-25°T-land negative chamfering of the cutting edge of the insert, the sharp edge of the chamfer is passivated to make the cutting edge stronger, ensuring that the insert can be used for continuous turning of the quenching hardware. To slight intermittent turning. This is also the preferred form of edge processing when trying to make PCBN blades more versatile.
3.1.3. After the 25°-35°T-land negative chamfering of the cutting edge of the insert, the sharp edge generated by the chamfer is passivated to make the cutting edge very strong, ensuring that the insert can be subjected to harsh processing conditions. Medium to heavy duty interrupted turning for hardened hardware.
3.1.4. Only passivation treatment is required as needed. Passivation of the PCBN insert helps to make the cutting edge stronger and protects the cutting edge from premature chipping or breakage. This type of edge treatment is a good choice when the surface quality of the workpiece is very high and a narrow tolerance band is required. Only the passivated PCBN inserts are mainly used in the machining of continuous turning. In order to make the cutting process more efficient, it is recommended that the feed rate be larger than the passivation process size.
3.2. PCBN grade cutting edge treatment for cast iron processing
Only 15°-25°T-land negative chamfering of the PCBN insert cutting edge without passivation is the first choice for the cutting edge of the cast iron machining insert, ensuring that the cutting edge is strong and sharp, such cutting edge is processed cast iron Ideal for materials.
3.3. Isca PCBN grade cutting edge treatment for high temperature alloy and sintered metal processing
It is recommended to passivate the sharp edge of the chamfer after 15°-25°T-land negative chamfering on the cutting edge of the blade. The passivation R value is 0.01-0.02.
In the processing of sintered metal and high-temperature alloy, it is recommended to passivate the sharp edge of the chamfer after 15°-25°T-land negative chamfering of the cutting edge of the insert. The use of two processing steps on the cutting edge ensures that the cutting edge is more suitable for the machining of such difficult-to-machine materials, and the blade performs better when the cutting edge is prone to breakage.
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