Halnn is a professional manufacturer of cbn insert .This article will show you the characteristic of hard turning ,the technology of hard turning and 3 kinds of cutting tools can be used for hard turning insert .The most suitable cutting tools for hard turning hardened steel is CBN insert .

1. CBN insert
BN-S20,BN-S200,BN-H11,BN-H20,BN-H21
The advantages of CBN insert hard turning parts
With the continuous development of modern technology, more and more manufacturers
are looking for the way to reduce the cost of mechanical parts and products to improve
their company strength. Although the current quality of the products have been sufficient
to meet the needs of the market, but its quality is constantly improving, and the cost of
parts has a increasing pressure under the market pressure and the buyer's markets
pressure. In order to cope with high-quality, high-cost challenges, machinery
manufacturing only should seek new technology solutions to enhance the
competitiveness of the enterprises.
Before 1990s,the turning insert just applied for roughing before quenching process,
finishing process after quenching still use the grinding way.
The traditional process is Roughing-Heat-treatment (quenching)-Milling.
With the continuous development of machinery manufacturing industry, more and more
materials comes which is difficult to machine , so as the complex materials. It is difficult to
process with the traditional turning tools, or even can not process the high strength, high
hardness material. However the modern hard turning tools make it possible, and achieved
very good results in production.
Part 1:The characteristics of hard turning
Hard turning is to turning hardened steel as the final processing or finishing process, like
some parts instead of to grinding the work piece, also known as the "turning instead of
grinding."
The characteristics of the hard turning:
(1) high production efficiency: reducing the processing time compared with grinding way;
(2) belong to clean hard turning process, in most cases, do not need to add coolant,
reducing cooling equipment, reduce processing costs, and turning is convenient for
recycling the chips;
(3)hard cut didn’t need the special tools, special machinery and fixtures, but the grinding
requires there is a grinder, hard turning can be run on the ordinary lathe or CNC lathe;
(4) hard turning can make the parts get a good overall precision: most of the heat
produced by hard turning can be take away with the chips, will not produce a burns and
cracks surface like grinding , has excellent processing Surface Quality.
Part 2: The Technical requirements of the Hard turning
(1) The work pieces of processing

2. CBN insert
BN-S20,BN-S200,BN-H11,BN-H20,BN-H21
The Hardness of the cutting hard work pieces was generally more than HRC45, if the
hardness of the work piece is higher, it is more valuable , commonly the material of the
hard turning have hardened steel (tool steel mold steel , carburizing steel, gear steel,
bearing steel, etc.), high-alloy cast iron (such as high-chrome cast iron, high
nickel-chromium cast iron, high manganese steel, etc.), powder metallurgy superalloy or
other special materials .
(2)How to choose machine when processing
Machines rigidity also determines the precision of the work piece which need hard turning,
if common lathes or CNC lathes have a enough rigid and can keep the soft surface
roughness when machining the soft material work piece, it can process the hardened
steel.
(3) Blade of the turning tools
Currently, the tools blade include: coated carbide tools, ceramic cutting tools and cubic
boron nitride cutting tools (CBN tools) when using hard turning lathe. Choose the right tool
is the only way for hard turning and high-speed cutting.
a. coated carbide tools: one or more layers which wear good are coated on carbide
cutting tool like: TiN, TiCN, TiAlN and Al2O3, etc., coating thickness is 2 ~ 18mm. Its
advantage compared with the carbide cutting tools: ① has high hardness and wear
resistance, and high temperature, compared with uncoated tools (blades), coated tools
allow the cutting in a higher speed; or increase tool life at the same cutting speed, ; ② as
the friction coefficient was lower which between the coating material and the material
processed, so the cutting force of the coated tools (blades) less than the uncoated tool
(blade); ③The surface of the parts have a better quality after process with a coating knife
(blade) processing.
b. Ceramic insert: ceramic tool is harder than carbide cutting tools that can stand high
temperatures reach 2000 degrees, has a high hardness, high strength, heat resistance,
stability of high-temperature chemical, and there are abundant raw materials of ceramic
cutting tools, it is said cant run out. but the biggest obvious disadvantage is that the
ceramic tool was too brittle to interrupted cutting, it mainly used for the finishing process.
c. CBN insert: the hardness of cbn cutting tools is higher than the carbide insert and
ceramic insert, the hardness is just like diamond cutting tools, the two were known as
super-hard tool. CBN tools has a high hardness, wear
resistance, anti-crushing performance, but the biggest
disadvantage of common CBN is brittle like ceramic
insert. With continuous research and experiments,
China developed a non-metallic binder super-hard
cubic boron nitride insert(CBN insert), using ceramic as
a binder, increasing the toughness of CBN tools.
BN-K1,BN-S20,BN-S30 CBN insert which is widely
used in hard turning hardened steel (hardened steel),
pearlite gray iron, ductile iron high-grade, high hardness

3. CBN insert
BN-S20,BN-S200,BN-H11,BN-H20,BN-H21
cast iron and high temperature alloy parts, etc.
Summarize
CBN insert is most suitable cutting tools materials for machining black metal, Halnn is the
representative of the non-metallic binder super-hard cubic boron nitride cutting tools,
leading the world-class level, and enjoying a highly reputation.
Part 3 CBN insert Hard turning work piece
CBN insert can hard turning the hardened steel: such as the processing gear steel,
bearing steel, tool steel, tool steel and other parts, the hardness after heat treatment are
generally more than HRC50, you can choose different corresponding grade and cutting
parameters of BN-S20 CBN insert to solve the above parts, the following table is the
parameters of how to choose different tools grade for processing different parts.
Parameters of how to choose CBN insert grade for processing different parts.
BN-H10, BN-H11, BN-H20 CBN insert all belong to welded cubic boron nitride insert,
which can be used in the finishing process.
BN-S200 CBN insert belong to the Solid CBN insert, also only for finishing.
BN-S20 grades not only has high hardness but also has wear resistance and impact
resistance, which already caused a great sensation in the tool field .
Quenched steel
parts
CBN insert for
finishing
Optimal cutting parameters
Depth of
cut(mm)
Feed Rate (mm/r)
Cutting
speed(m/min)
Gear BN-H10 0.2 0.1 180
Bearing BN-11 2.5 0.12 140
Ball screw BN-S20 4.5 0.10 90
Synchronizer BN-H20 0.15 0.1 170
Universal
coupling
BN-H10 0.15 0.15 190
Mould BN-S200 0.5 0.12 130