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Halnn superhard CBN inserts Machining rolls after repaired

With the increased demands of the steel materials, Roll Factory emerge constantly, it required more on the performance of the important part of the roll machine - rolls. The roller belongs to consumables, and long time machining will lead to the roller failure (such as Crack, Fracture, ect) If scrap directly, that is wasteful, if re-produce the roll, it will waste time, so people adopt restoration method, repair the roll to original dimension, and finishing again, then it can be used again, thus not only save the time, but also avoid source wasted.

The repaired rolls has high hardness and is difficult to machine. But for inserts materials, it must has high hardness, well-resistance and good impact resistance. In current times, the most suitable material for machining repaired rolls are non-metal adhesive BN-K1 and BN-S20  Solid CBN inserts researched by Halnn.
Now we will introduce that Why Halnn CBN inserts mostly suit for machining repaired roller?

Part 1 Rolls classification and different kinds rolls processing
1. Rolls Classification
Rolls have so many types, and the common rolls materials include cast steel rolls, cast iron rolls and Forged roll three kinds. Cast steel rolls and cast iron rolls belong to cast rolls, both of them are cast molding, just the cast materials are different.
Cast roll: A kind of roll which used smelting steel or smelting iron-casting Direct-casting.
Forging roll: A technology which used forging machine put pressure on the metal blank, and make it get plastic deformation so that forged roll with certain mechanical properties, shape and dimensions.
2. Different Kinds of materials rollers machining technology
(1) Iron Roll Processing Technology: Smelting - Casting - Softening Treatment - Roughing - Heat treatment (improve the hardness) - Finishing - flaw detection - Final product.
(2) Cast steel roll Processing Technology: For example, Alloy steel roll: Smelting - Casting - Roughing - Heat treatment - Finishing - Performance, Flaw detection Testing - Final product.
(3) Forged steel roll Processing Technology: For example, Cold-rolled work roll: Selection raw materials → EBT refining → LF Finishing → Vacuum degassing → Casting molding → ESR → forging → spheroidization annealing → roughing → Modulation (quenching and tempering) → semi-finishing → flaw detection → preheating → dual quenching →  cold treatment →  low Tempering → finishing → hardness, ultrasonic and metallographic → packaging.
Part 2 Rolls Failure modes
The rolls quality affect directly on the rolls machine processing efficiency, product quality, production and Rolls consumption, ect. And rolls, as one of the most important Consumable parts in the processing will be destructed because of so many reasons.
Especially for hot rolls, its working environment will be even worse. The main failure mode include crack (photo 1), Flaking and fracture (photo 2),and any one failure mode will affect the rolls lifetime.

Part 3 How to restore roller and how to machining repaired roller
There are many ways to restore the workpiece, such as surfacing, spraying, laser cladding, thermal spray, the following will introduce how to machining the repaired surfacing roll.
Repaired roll hardness usually is above HRC45, and the roll surface after surfacing is Irregular. In current times, there are 2 kinds processing methods: one is grinding, the other is turning.

For high precision on surface (Less Ra0.8) we choose grinding method; for less precision on surface (Above Ra0.8),we choose Ra0.8.

In current times, inserts which used for turning repaired rolls include Carbide alloy tools, Ceramic cutting tools and CBN inserts. Because the roller irregular surface ,we don’t recommend to use ceramic cutting tools, and carbide alloy tools hardness is low, which is suit for workpiece hardness below HRC45, so we recommend to choose CBN inserts to machining workpiece which hardness is above HRC45.

CBN Inserts is the best cutting tools material to machining repaired roller in current times, especially Halnn researched BN-K1 and BN-S20 non-metal adhesive Solid CBN inserts, the processing effect is best when machining repaired roller. It not only can be used for large allowance turning, but also can be used for interrupt turning.

Halnn always commit to researching new cutting tools materials and solutions on high speed cutting and high hardness turning field, is a company which collected scientific research, manufacturing and sales. Halnn offer customers professional, high efficiency inserts and cutting tools solutions, and has so many inserts grade which has trusted by many customers .cubic boron nitride cutting tools provide quality tools  and services for mechanical industries.

Part 4 Halnn Superhard BN-K1 and BN-S20 grade non-metal adhesive CBN inserts machining repaired roller
Machining Materials Recommend cutting parameters and CBN inserts grade

Machining Materials
Recommend cutting parameters and CBN inserts grade
Linear Speed Vc(m/min)
Cutting Depth ap(mm)
Feed Rate Fr(mm/r)
Common used CBN inerts grade
Cast iron rolls
Cast steel roll(≥ 45HRC)
Above table shows: Non-metal adhesive BN-K1 Solid CBN inserts suit for machining high hardness cast iron roll, Non-metal adhesive BN-K1 grade CBN cutting tools suit for machining high hardness cast steel/forged steel roll.CBN inserts not only has high hardness, well wear-resistance, and also solved the problems of not wear and chipping appeared when carbide alloy cutting tools and ceramic inserts machining high hardness roller. Halnn CBN inserts can machine normally and will not appear severe wear or chipping when encountered casting defects.

Part 5 Conclusion
With the development of the modern technology, more and more workpiece use surfacing technology or other repaired technology to improve workpiece hardness and restore the dimension, the Machinery Manufacturers always look for the best cutting tools materials which can high efficiency machining repaired workpiece. For cutting tools industry, only continue to develop high quality, efficient tool material, it can better promote the development of machinery manufacturing.

More information on machining rolls, please click http://www.halnncbn.com/Solution/Mill_Rolls.html, Or contact with us info@halnntools.com, Whatsapp:+8615617635382

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