The lifetime and wear resistance of CBN inserts

Part 1 Summary

The common failure mode of cutting tools is wear,the inserts lifetime has a lot to do with the wear resistance,after testing,the CBN(Cubic Boron Nitride) inserts lifetime is usually several longer times or even more than carbide inserts and ceramic inserts.CBN inserts lifetime is not only relate the tools quality,but also related to the workpieces materials, machining speed etc.So it is necessary to know more about the relationship between CBN inserts lifetime and performance,use the suitable CBN inserts,increase machining efficiency,reduce the the unnecessary machining waste.

1.The comparison between CBN inserts lifetime and other materials inserts

(1)The round CBN inserts from Halnn super hard,with cutting parameters Vc=40m/min,f=0.16mm/r to machining chilled cast iron with HRC55.CBN inserts durability is 500 min ,but the ceramic inserts is just 5 min.CBN inserts durability is 100 times longer than ceramic inserts.The solid Polycrystalline Cubic Boron Nitride(PCBN) inserts developed by Halnn superhard was widely used in roughing application,CBN inserts begin used in roughing process with big feed rate and cutting depth.It has a higher cutting efficiency than carbide inserts.For example,CBN inserts turning chilled cast iron roll,getting a high cutting efficiency.The cutting parameters:Vc=61m/min,ap=/mm,f=0.94mm/r,the metal cutting efficiency can reach 400cm3/min,the inserts almost has no wear.

(2) Halnn superhard CBN inserts machining the gray iron,cutting parameter:linear speed 600m/min,was 2 higher times efficiency than carbide inserts,the lifetime can be improved about 6-12 times longer when roughing,has 15-20 times longer lifetime than carbide inserts when finishing.

Part 2 The relation between CBN inserts grade and its performance

The CBN inserts performance is closely to the CBN inserts grade.The CBN granularity, contect, and the different kind of binder directly decide CBN inserts performance,each manufacturer define them own grade according to the performance and element,the grade cant used universally although they are similar.

CBN inserts can be divided into two categories according to its organization:one is made by CBN grain sintered directly without binder,has a high CBN content(more than 70%),has a high hardness,used for turning machining the heat-resisting alloy,cast iron and iron series sintered metal;another category is base the CBN grain as the main body,according to the ceramic binder(main contain TiN,TiC,TiCN,AIN,Al2O3,etc)sintered,this kind CBN inserts has a low content CBN(less than 70%),has a lower hardness,just suir for machining the hardened steel.

The classification of CBN inserts grade:Halnn superhard CBN inserts can be divide into rough machining and finish turning according to CBN inserts granularity size;The detail classification is based on the CBN grain crystal.

1.The CBN grain crystal classification of CBN inserts

The size of CBN grain crystal can be divide into three categories: coarse grain (the average size is 20-50μm),medium size grain crystal(10-20μm), fine grain(2-10μm).the larger size of the grain,the better wear resistant and longer lifetime the CBN inserts will have.but the blade of the inserts will be worse,its hard to make a high precision inserts. On the contrary,the the fine grain CBN inserts has a good quality blade,the work piece will have a good surface after machining.There are 1μm,less than 0.5μm grain now,we can choose the different size grain according to the different machining process require of roughing and finishing.

2.The corresponding work piece of the different CBN inserts grade

Currently CBN inserts don't have a uniform classification just like carbide inserts,each manufacturer has themselves type and grade,we need choose base on them catalogue during using.The famous CBN inserts grade was BK-K1 and BN-H1 which were developed by Halnn super hard material company,those two grade inserts was used for machining cast iron and hardened steel separately.Later,BN-S20 and BN-S30 grade inserts were the solid PCBN inserts,can machining:High-chromium cast iron,white cast iron, austempered ductile iron,high-temperature alloy, powder metallurgy,gray cast iron,hardened steel and so on,connect the machining condition(roughing , semi-finishing,finishing)require to the CBN grain size to form the CBN inserts grade.

The different CBN inserts grade has a different cutting performance as the different composition,so we need pay more attention when choose the CBN inserts.

Part 3 How to judge the CBN inserts quality

Judge the CBN inserts from the using point of view,the good quality CBN inserts has two characteristic:

1.Has a good impact resistance,especially in the roughing field,the inserts will not crack,this is most basic guarantee use security of CBN inserts.

2.Has a good wear resistance,in the same time for ensure the efficient machining also can reduce the cost and can instead of carbide inserts and ceramic inserts,this is the economical guarantee of CBN inserts.

Part 4 Discriminate the inserts wear resistance and toughness

It is not difficult to improve the cutting tools hardness and toughness,but with increase of the cutting tools materials hardness,the toughness will reduced,so we need consider the work piece material,the CNC lathe,machining condition comprehensive in use,avoid the contradiction between the hardness and toughness.Aim at the CBN inserts character,Halnn seperhard company research one grade CBN inserts which suit for cutting with low speed and roughing,it has a excellent impact resistance,Halnn superhard material company enjoy a high reputation in cutting tools industry.

Part 5 High efficiency machining is not mean machining with high speed

Cubic boron nitirde is the highest hardness cutting tools material for machining the ferrous metals,so most people thought ‘high hardness,low toughness,just suit for high speed cutting or high precision machine tool’ by mistake,but its not.High efficient machining is not mean high-speed machining,the cutting tools lifetime also will reduce with the increased linear speed even the CBN inserts has a very high hardness.

It is more suitable to machining the difficult processing materials with increasing the cut depth and feed rate for improving the machining efficiency.This is the Halnn superhard company purpose to the reason why research the cubic boron nitride inserts,and facts proved that this case solved the customers practical machining problem,The CBN inserts from Halnn superhard company will not crack when machining with high efficient,expeciall in the industry which interrupted cutting the difficult cut material,this is also the biggest success in the hard cutting tools field.

More information ,http://www.halnntools.com/prohttp://www.halnntools.com/pro,Or contact with us halnntools@gmail.com,whatsapp:+8615036165377,skype:cbn_inserts_angels