The Application of turning steel iron rolls with Halnn superhard CBN inserts

The Application of turning steel iron rolls with Halnn superhard CBN inserts

Part 1 The grade options of common clamp machine cutting tools which is used for turning steel iron rolls

Machining large scale steel iron rolls usually use heavy rolls milling, the common clamp insert holder which is used for large scale steel iron roller is 40*40 mm;common inserts holder angle is 45°clamp turning inserts or Arc turning inserts.Some small scale steel iron rolls use 25*25 and 32*32 mm clamp turning inserts holder.The option of the clamp turning insert holder main angle depend on the roller“ length-diameter ratio”, The slender rolls usually use 90°or 75°angle clamp turning inserts,Turning “Sturdy roller”usually use 45°clamp turning inserts or Arc turning inserts.

Part 2 The options of CBN inserts size and grade depending on turning cutting allowance and processing situations

When turning cast iron rolls with BN-K1 grade CBN cutting tools,we usually use RNMN200800,RNUN200800,RNMN150700,RNUN160800,RNUN150716,RNMN150716 

grade CBN cutting tools .

When turning forged steel cold roll with BN-S20 grade CBN inserts,we usually use SNMN120712, SNMN120412,SNMN120408,RNMN120400 grade CBN cutting tools .

Clamp turning inserts and CBN inserts

Part 3 The options and the Cutting parameters guidance of CBN inserts which used for turning mill rolls

The option principle:

1.the mill rolls materials

2.The mill rolls hardness

3.The mill rolls cutting allowance and Heat-treatment method

Depending on the milling rolls materials which is corresponding with the cutting inserts grade used for turning steel iron rolls ,it can be divided into 3 sorts :

a.Turning the low-hardness rolls

Ductile Cast Iron rolls,High alloy cast iron rolls usually used for heat-rolls,support-rolls,intermediate-rolls,the feature is that hardness is lower comparing to working-rolls.It can turning common alloy cutting tools and the common cutting tools grade is YG 6 or YG 6X.

b.Turning high hardness cast iron rolls

When turning chilled cast iron rolls (include unlimited chilled cast iron rolls),High nickel chrome rolls,high chrome rolls,boron high speed steel rolls, semi-steel rolls (including casting semi-steel rolls and high-carbon steel semi-rolls);nickel-chromium-molybdenum centrifugal composite rolls,Rolls rough usually have Porosity, trachoma,sand bag defects because of the rolls high hardness.So the tools need well impact resistance, heat resistance and wear resistance. In the past ,this kind rolls usually use ceramic cutting tools,the cutting tools will easily chipping.

In current times,People usually use BN-K1 grade CBN inserts machining this kind rolls. BN-K1 grade CBN inserts not only insist the excellent property of high hardness and well impact resistance ,but also have well impact roughness ,can not easily chipping ,and can pull shortage roughing rolls. BN-K1 grade CBN inserts is the best impact resistance high hardness CBN inserts in the current times.This grade CBN inserts can obey large cutting depth,high metal cutting ratio,the common cutting parameters as follows :

For BN-K1 grade Halnn CBN inserts turning HSD82 hardness high nickel-chromium cast iron rolls：Unilateral cutting depth can arrive 12 mm;Feed rate is 1.5 mm/r.

The cutting parameters of turning high hardness cast iron rolls with Halnn BN-K1 grade CBN inserts

No.	Rolls Materials	Mill Rolls working layer hardness	Recommend Cutting Parameters
1	Casting High nickel-chromium	HSD72-82	Rough finishing	Vc=15-30m/min,ap=3-7mm,f=1-2.5mm/r
			Semi-finishing	Vc=20-40m/min,ap=4mm,f=1.5-2.5mm/r
2	Cast high chromium iron	HSD72-78	Rough finishing	Vc=10-20m/min,ap=3-7mm,f=0.5-1.2mm/r
			Semi-finishing	Vc=15-30m/min,ap=4mm,f=1.5-2.5mm/r
3	Cast High Speed Steel	HSD82-90	Vc=5-15m/min,ap=3-8mm,f=1-2.5mm/r
4	Casting Semi-steel	HSD55-65	Vc=30-60m/min,ap=4mm,f=1.5-2.5mm/r
5	High carbon Semi-steel	HSD65-72	Vc=25-50m/min,ap=4mm,f=1.5-2.5mm/r
6	Chilled cast iron	HSD50-70	Vc=25-50m/min,ap=4mm,f=1.5-2.5mm/r
7	Casting high-chromium steel	HSD68-75	Vc=20-45m/min,ap=4mm,f=1.5-2.5mm/r
8	Tungsten carbide roll ring	HRA88	Vc=10-15m/min,ap=1mm,f=0.3-0.7mm/r
9	Forging 9Cr2Mo	HSD92-105	Vc=10-25m/min,ap=4mm,f=0.5-1.2mm/r

c.Turning high hardness forged steel cold rolls:

For example,turning GCr15 Rolling bearing steel roll ,Cr3,Cr5 roller ;86CrMoV7,9Cr2Mo rolls.This kind roll rough is forge work piece, usually use as cold roll after heat-treatment ,the common inserts grade is BN-S20 grade CBN cutting inserts.

BN-S20 grade CBN insert is the research result of National key scientific project,it is made of non-metal adhesives and CBN refined powder ,and it not only follow BN-K1 grade inserts’ toughness ,but also especially researched for long iron material forged steel cold roll.When machining forged steel cold rolls,BN-S20 grade CBN cutting insert Wear-resistance will be about 3 times of common CBN cutting inserts .

The cutting parameters of BN-S20 CBN inserts turning forged steel cold roll

(1)For example ,turning Sweden cold working rolls (HRC67):cutting depth4-7mm,line speed 90m/min ,life time is 2.5 times than some foreign brand CBN cutting inserts .

(2)When turning repairing 9Cr2Mo cold working roll,it will have good effect with BN-S20 cutting insert,the cutting insert lifetime is 4 times than other domestic CBN cutting inserts. And when turning cold working rolls , Chapped parts not chipping can guarantee the safety use and economy of CBN cutting insert .

Part 4 Rolls materials and common questions

BN-K1 and BN-S20 grade CBN cutting insert Turning rolls hardness and materials Fluctuation range (Remark:when rolls hardness is less than HSD70,it can choose cemented carbide grade cutting inserts,such as YG6,YG6X ect .When rolls hardness is more than HSD75 or above HSD110,it can choose BN-K1 and BN-S20 grade cutting inserts (Choose cutting inserts grade according to the rolls materials )

Roll Materials and Roll hardness range Comparison chart

Remark: Halnn Superhard cutting tools research department remind you:when choose CBN inserts turning rolls,the rolls hardness is not the only  factor,the most important factor is rolls materials.

Halnn CBN Cutting inserts materials grade:

Grade	Type	Applications
BN-K10	Welded	Fit for continuous finish turning gray cast iron and wear-resistance cast iron material,such as finish turning brake drums, brake discs, flywheels, cylinder workpiece.
BN-K20		Fit for finish turning gray cast iron,powder metallurgy materials and high-speed finish turning boring
BN-H10		Fit for continuous finish turning and high-speed finish turning hardened steel materials ,like “turning instead of grinding” wheel gear and bearing .
BN-H20		Fit for medium/strong finish turning and high-speed finish turning harden materials,such as machining contoured shaft and high-precision gears, bearings and small bore
BN-S20	Solid	Perfect Impact resistance and wear-resistance,good choice for rough and semi-finish turning workpiece; widely used for machining gray cast iron ,wear-resistance cast iron  sand inclusion,white cast iron, and various  steel, hardened steel materials
BN-S30		Best wear-resistance and well impact resistance,fit for high-speed finish turning cast iron,and fit for high speed and efficiency boring, milling

Halnn CBN inserts application range:

1.High hardness cast iron/cast steel,like rough and finish turning high chromium cast iron,white cast iron,Ni-hard cast iron and Heat-resistant and wear resistant steel material,usually use for turning rolls,Impurities pump impeller and other high hardness wear part.

2.Turning high hardness work piece after heat-treatment ,such as hard turning hardened bearing steel,Carburizing steel,tool steel,mold steel after heat-treatment.

3.Other difficult cutting materials:Turning high temperature alloys, powder metallurgy ect.

4.High speed turning cast iron high-grade ductile iron,

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