Rough machining
Drum Brake used CBN insert
Drum brake is one of the main parts of
the automotive, and belong to consumables, the surface roughness require about
Ra1.6.We can choose a suitable insert to get better surface roughness while not
affect the manufacture benefit.
Part 1 Machining drum brake process
In current times, the brake drum brake
main materials are gray cast iron. Gray cast iron has good shock absorption and
wear resistant, and low noisy, it need simple process.
General process as follows:
Casting-Roughing-Semi-Finishing-Finishing-Drilling-Test.
(1) Casting: when machining the drum brake,
need control the charge mass, also the chemical composition of the molten iron,
the pouring temperature, proper ingredients, avoiding casting defects, such as
clip sand, porosity, white and so on.
(2) Roughing: Manufacturers usually use
CNC lathe machining the drum brake. Advantages(1.reduce the rejection rate of
the work piece, 2.improve the processing efficiency. )
Roughing brake drums need about 0.5mm working
allowance for subsequent semi-finishing and finishing guarantee finish
requirements.
Part 2 The insert selection of rough machining drum brake
Process the drum brake need three steps,rough
machining allowance within 3mm, and the brake drum need a high demand. In the
process, it is important to ensure dimension, but improve processing
efficiency,
Insert selection required:
1.High-speed cutting
2.Reducing processing time and improving
processing efficiency.
First, manufacturers will use carbide insert,
but its linear speed is low ,can not satisfy the requirements. So when meet machining
gray cast iron with high speed, manufacturer will choose cbn insert which will
not only improving the working efficiency, but also save the processing cost.
Especially Halnn BN-S30 and BN-K20 CBN
insert, will be more effective for machining drum brake.
Part 3 Select the most suitable cbn insert for different process
(1) Roughing:When the working allowance
within 3mm, select BN-S30 CBN insert, which not only has high hardness and high
strength, but also has better wear-resistance and impact-resistance. Following
show the figure on BN-S30 CBN insert machining brake drum:
Cutting parameters: ap=1-10mm,Fr=0.2-1mm/r,Vc
= 200-800m/min. Processing effect: BN-S30 CBN insert lifetime with one cutting
edge will be15 times than the coated carbide insert.
(2)Semi-finishing: Working allowance
within0.5mm, BN-S30 CBN insert Cutting parameters: ap≤1mm, Fr = 0.05-0.3mm / r,
Vc = 300-1500m / min.
(3)Finishing: within margin of 0.3mm,
select BN-K20 CBN insert ,which will be more economical, can make sure the
braking surface finish and mouth stop finish and dimension tolerances.
Following is the figure of BN-K20 CBN
insert machining surface and mouth stopper .
Cutting parameters: ap≤1mm, Fr =
0.05-0.3mm / r, Vc = 300-1500m / min. Processing effect: BN-K20 CBN insert finish
turning to ensure roughness Ra1.0, the single cutting edge lifetime is about 2
times than other PCBN insert.
Halnn is the most famous cbn insert
brand in China, and always devote to researching new cbn insert to satisfy
customers’ requirements.
More
information http://www.halnntools.com/pro/,or contact
with us halnntools@gmail.com,skype:cbn_inserts_angels
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