Halnn Bn-S20 CBN inserts used for hard turning Mill rolls Hard surface field

Halnn Bn-S20 CBN inserts used for hard turning Mill rolls Hard surface field

 

So-called hard surface process is collected surface build-up welding,spray welding,spraying,laser cladding technology,Surface heat treatment or nitriding process,etc.The surface of the work piece to obtain higher hardness, wear-resistance corrosion resistance,impact resistance, etc.Aiming at hard surface process,HALNN superhard developed a non-metal adhesive cubic boron nitride cutting tools BN-S20. Specific processing schemes are as follows. 1.Halnn superhard non-metallic adhesive CBN cutting tools BN-S20 rough turning surfacing rolls solution:     Processing Materials: Cobalt-based alloys；Processing parts: Surfacing Rolls(hardness HRC45-55);Cutting tools model: BN-S20；Processing procedure: External turning;Cutting parameters:ap=2.5mm，Fr=0.12mm/r,Vc=65m/min；Processing type: Wet cuttingProcessing effect: Compared to carbide cutting tools: The cutting speed of our cutting tools is 4.5 times higher than carbide cutting tools,cutting tool lifetime is 12 times of carbide cutting tools.  2.Halnn superhard non-metallic binder Hard Turning inserts BN-S20 rough machining Spray welding rolls solution: Processing parts: Spray welding parts；Processing materials: Nickel-based alloy powder spray welding parts;Hardness:HRC50Cutting tools model: BN-S20,Processing procedure: External turning,Wet cuttingCutting parameters: ap=1.5mm,Fr=0.15mm/r,Vc=145m/min；Processing effect: Compared Halnn BN-S20 model number with some European brand PCBN cutting tools:cutting speed in the same situation,HALNN BN-S20 cutting tool lifetime is 2 times of PCBN cutting tools life,and cutting tool flank is normal wear,rather than collapse damage,rupture. 3.Halnn superhard non-metallic binder CBN cutting tools BN-S20 rough machining spraying rolls solution: Processing Parts: Cobalt base spare parts, spraying thickness of 2 mm;Processing Materials: Cobalt-based alloy powder spraying roller;Hardness:HRC60Cutting tools model: BN-S20；Roughing cutting parameters: Vc=70m/min,Fr=0.7-0.8mm/r；ap=1.7mm；Finishing cutting parameters: Vc=120m/min,Fr=0.25mm/r;Processing effect: HALNN BN-S20 model number and carbide cutting tools compared: The cutting speed is carbide cutting tools 6 times,Cutting Depth is 3 times of carbide cutting tools,not only improved the processing efficiency,but also reduce processing costs. 4.Halnn superhard non-metallic adhesive CBN cutting tools BN-S20 finishing Laser cladding rolls solution:
Processing parts: Hydraulic prop；Processing Marterials: 27SiMn(The surface hardness after laser cladding is about HRC55);Processing procedure: Semi-finishing and finishing;Cutting tools model: BN-S20 CNMN120712;Cutting parameters: ap=1mm，Fr=0,15mm/r，Vc=145m/min；Processing type: Dry cuttingProcessing effect:Compared to carbide cutting tools: Not only improve processing efficiency,reduce production time,saving processing costs, and surface finish to Ra 0.4, long cutting tool life.

More information,Please check http://www.halnntools.com/jjfa/19.html ,Or E-mail to ushalnntools@gmail.com ,skype:cbn_inserts_angels

Halnn publish new type CBN inserts which can Hard Turning slewing ring bearings instead of grinding

Bearing Steel is one of the most demanding steels,it need high requirement on the materials:high hardness ,wear-resistance,contact fatigue strength,elastic limit,good impact toughness,fracture toughness, dimensional stability, rust resistance,hot and cold processing property,ect.So bearing steel must strictly require the uniformity of the chemical composition and carbide distribution.

Bearing Steel can be found almost everywhere,widely used in transportation ,wind power,Metallurgy and Petro-Chemical Machinery industry,such as slewing ring bearings ,Metallurgy bearings (called GCr15 bearings),ect.This article mainly introduce machining slewing ring bearings technology and inserts selection.

Part 1 Slewing ring bearings materials selection

(1)Slewing bearings definition:It is a kind large-scale bearings which can bear combined loads,large axial, radial load and overturning moment at the same time.It is called “Machine joints”.

(2)Slewing bearings materials selection:Slewing ring rolling elements usually use solid hardened carbon chromium bearing steel which is made of GCr15 or GCr15SiMn steel;Slewing bearings ring use surface hardened steel,we usually use 50Mn steel materials when users don’t have special requirement ,but sometimes we will choose other grade surface hardened steel like 42CrMo,5CrMnMo depending on user’s usage condition details.

Part 2 Process optimization of slewing ring bearings

For large-scale slewing ring bearings ,we need compile a reasonable machining technology before going into the workshop,it need get drawings measurement and precision and meanwhile can not affect the working efficiency .Following will introduce slewing ring bearings process routine:

Slewing ring bearing technology machining process :

Baiting---Forging---Annealing---Turning---Heat-treatment---Grinding---inspecting---Antirusting---Putting into warehouse.

The hardness of large-scale slewing ring bearings after heat-treatment  is above HRC45,and usually use grinding machining slewing ring bearings ,even though it can get high work piece precision ,but grinding efficiency is very low,which will affect working efficiency.

As the development of cutting technology ,casting cutting tools industry developed new cutting tools materials which can use turning instead of grinding ,turning instead of grinding process can not only improve work efficiency,but also satisfy drawing requirement.Currently Machinery factory usually use simple machining process:Rough machining---heat-treatment---finish turning and use turning instead of grinding.

In current times,there are 3 kinds cutting tools using turning slewing ring bearings instead of grinding:carbide tools, ceramic cutting tools, cubic boron nitride cutting tools. The followings will analyze three kinds of cutting tools advantages and whether suit for machining slewing ring bearings or not .

Part 3 Cutting tools materials used for machining slewing ring bearings  

The hardness of the slewing ring bearings after heat-treatment usually is above HRC45,channel part hardness usually is HRC55-62,so it will be difficult machining.We don’t advise use carbide and ceramic cutting tools ,but many factory use them to machining slewing ring bearings ,it will be found that the cutters has poor wear-resistance and often chipping ,the processing result can be unsatisfactory. Compared CBN inserts with Carbide and ceramic cutting tools ,CBN inserts not only has high hardness,but also has good wear-resistance and wear-heat,but large brittleness is undeniable, especially for machining discontinuous surface,CBN inserts still are unsatisfactory,also have same problems:poor wear-resistance and often chipping.China Halnn superhard materials research BN-S200 grade and BN-S20 grade CBN inserts through cutting tools industry’s continuous research and practice.The above materials both use non-metal (ceramic) as adhesive,which make sure high hardness ,wear heat-resistance and improved impact toughness ,BN-S200 used for finish turning  and BN-S20 used for both rough and finish turning .

Halnn superhard is the first one proposing concept on rough turning “Solid polycrystalline Cubic boron nitride cutting tools ”,  and accurately grasp the pulse of the times and research “high speed,finish machining”turning inserts ,milling cutters, CNC blade relying on long-term accumulation of technical strength and top technology development capability. Halnn Superhard materials has high reputation in Superhard tools academia .

The following will introduce the case of turning slewing ring bearings with Halnn CBN inserts  

Part 4 Halnn Superhard turning slewing ring bearings application Case

The work piece after heat-treatment will be deform,so we need choose different allowance depending on different work piece . The following we will choose cutting inserts grade and cutting parameters depending on the machining allowance.

(1)Finish turning slewing ring bearings allowance is less than 2mm: 

Choose Halnn Superhard BN-S200 CBN inserts (following figure),cutting depth will be less than 0.5mm. turning parameters:ap≤1mm，Fr=0.05-0.35mm/r,Vc=60-250m/min and the cutting parameters can range depending on machine rigidity.

Application Case 1:

Materials:42CrMo slewing ring bearings ;

Hardness : HRC47-55

Process:finish turning channel rolls,end surface

Cutting parameters:ap=0.5mm，Fr=0.45mm/r,Vc=110m/min

Efficiency:Compared to ceramic inserts(following figure):

On the basis of CBN inserts cutting speed is 22% higher than ceramic tool, the tool lifetime is 7 times than ceramic inserts, and roughness ensure less than Ra1.0.

Cutting Tools Materials	Cutting Speed	Cutting Tools lifetime	Roughness
Halnn BN-S200	110m/min	8pcs/cutter edge	Ra0.6-1.0
Some European brand ceramic inserts	90m/min	1pcs/cutter edge	Ra0.8-1.6

(2)Finish turning slewing ring bearings allowance is more than 2mm:

Choose Halnn superhard BN-S20 grade CBN inserts (following figure),machining circumcircle and groove parts of slewing ring bearings ,cutting depth can cut entire depth of the blade,cutting parameters:ap=1-10mm，Fr=0.15-0.7mm/r,Vc=50-150m/min and can range depending on machine rigidity.Efficiency: cutters has long lifetime ,and the roughness can arrive Ra0.4.

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

Three cutting factors and machining efficiency of CBN inserts

As we all know,Improve three cutting elements(linear speed,cutting depth,feed rate) is the most simple,direct method to enhance machining efficiency.But the method usually was limited by the lathe machine conditions,so the best way is to choose the suitable insert material.

Confirmed rules of the three cutting elements:cutting depth,feed rate and linear speed.The cutting depth was usually confirmed based on machining allowance,rough machining feed rate confirmed according to the lathe machine power,finish turning feed rate confirmed based on the surface roughness;linear speed confirmed by the insert material and lathe machines main shaft rotating speed.

Add cutting depth is a method which was worth to consider to improve the machining efficiency.The experiment shows that when cutting depth is 10 times of feed rate,the insert durability almost won’t change if increase the cutting depth continuous.While Change the cutting speed,the insert durability will also change with two times;the insert durability will also change with the feed rate change.So increase the cutting depth can not only realize a high production rate,but also won’t increase the insert cost.

People thought CBN(Cubic Boron Nitride) insert just can finish turning with high cutting speed.Actually CBN insert also can be used in roughing industry,such as following case:

1.Machining Gray cast iron

BN-S30 grade CBN inserts won’t crack when machining gray cast iron with sand,white.The cut depth is 2-3.5mm,its lifetime is 15 times longer than carbide insert of one Japan brand,efficiency improved 1 time.

2.High manganese steel,High-chromium cast iron,chilled cast iron and other difficult to machining castings.

Casting surface has some sand,pore.Chipping will happened easily with carbide insert ,caused insert serious loss,high machining cost and reduce the machining efficiency.

BN-S20 grade CBN inserts machining this type casting,cutting parameter:

Cutting depth ,ap=2-3.5mm ;feed rate=0.25mm/r;linear speed Vc=85m/min. Insert durability:3 hours per corner/cutting edge

With the research on CBN inserts,this cutting tools was used from the previous high-speed finish turning to interrupted turning,it also can rough machining,semi-finishing,also can used in the common lathe machine;has a more economical using cost.

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

Turning Hardened Steel and CBN inserts 

Introduction

We usually meet the following problems when hard turning quenched steel work piece,especially when rough machining quenched steel,interrupted turning,grooving machining,and the roughness of quenched steel after turning.Most people can’t choose the suitable cutting tools for turning quenched steel,kinds of machining problem appeared,such as:roughing,interrupted machining.Now we mainly discuss the common problems and introduce CBN insert.

The problems when hard turning quenched steel

1.Rough machining quenched steel

Turning Gears after heat-treatment,the hardness of gear and gear ring after quenching or cemented quenching was usually above HRC55,some even reach HRC60~HRC65.Common Gear materials are: 20Cr,20CrMnTi,40Cr,42CrMo,35CrMo. Some gear distorted serious,especially the big gear ring,big gear after cemented quenching,like high-speed rail gear, engineered machinery big gear ring,heavy industry big gear ring,etc,those big gears gear rings deformation was very big,this case involved rough machining quenched steel.At the same way,rough machining tool steel usually happened in manufacturing of die steel.

2.The interrupted machining of the quenched steel

Interrupted turning is a challenge,even for quenched steel hardness reach about HRC60.Especially when high speed turning quenched steel,if the work piece has interrupted turning,the cutting tools will stand more than 100 times impact per minute,it's a big challenge for the cutting tools.For example,Turning hardened gear instead of grinding,and the Vehicle gear occupy 62% in the whole gear industry,and auto gear occupy 62% in the Vehicle gear.It is said that the auto gear occupy about 40% in the whole gear market.Although turning quenched steel instead of grinding was wide spread,there are still some problem during machining the auto quenched gear,such as,there some oil hole in the auto gear,this will happen the interrupted turning trouble,many CBN inserts easily happen to chipping when machining the oil hole,its hard to guarantee the gears position tolerance.

3.Grooving machining quenched steel

Such as:hard turning the synchronizer sliding sleeve gate after quenched,the CBN inserts lifetime still not so satisfied though CBN inserts manufacturer research specialized CBN inserts used for synchronizer sliding sleeve.

4.The roughness of hard turning quenched steel

The bearing steel after quenching usually require a much good finish by turning,Gcr15 steel is a common bearing steel,the hardness after quenching is about HRC62,as the precision and finish of the bearing have a high requirement.Even if adjust the CBN insert edge well,it is still impossible to get a Ra 0.4 finish of the quenched steel after turning.

Choosing Cutting tools when machining the quenched steel

There are few aspect to choose CBN cutting tools for hard turning quenched steel in turning field:one is the choice of cutting tools material ,usually when cutting the quenched steel work piece which hardness less than HRC50 and with a small feed rate,a small cutting depth,ceramic cutting tools will be a better choice.CBN insert suit for the work piece which hardness is harder than HRC50,meanwhile ceramic insert need avoid semi-finishing and roughing,but CBN inserts can suit for interrupted turning,heavy rough machining.Another is the choice of CBN inserts manufacturer/grade and edges processing,a good CBN insert not only won’t chipping during rough machining process,but also can keep a longer working life and get a good surface finish when finishing efficiently.

When finish turning quenched steel,we can choose welding CBN insert.When rough machining or interrupted turning,we need choose the solid/overall CBN inserts,there just a few manufacturer produce this type CBN inserts,Halnn did best in China,BN-S10 CBN inserts from Halnn superhard material make it successful to rough machining and interrupted turning quenched steel industry,and Halnn superhard material company enjoy a highl reputation in world cutting tools industry.

More about our products,please click http://www.halnntools.com/pro/,or contact with us :halnntools@gmail.com,whatsapp:+8615036165377,skype:cbn_inserts_angels