16
YOUR GLOBAL CRAFTSMAN STUDIO
Q:
Tell us how the BC81 Series came to be
developed.
Yumoto:
In recent years, the automotive and
machine industries have entered a growth
trend and there has been an increase in
demand for CBN (cubic boronnitride) tools that
could be used for machining high-hardened
steel parts. Mitsubishi Materials launched
BC8020, a coated CBN material for general
cutting of high-hardened steel in 2010, but in
some cases it lagged behind the products of
our competitors. Taking this disappointment to
heart, we drew fully upon the strengths of new
technologies and developed the BC81 Series
coated CBN material for machining high-
hardened steel.
Q:
TellusaboutthedevelopmentofBC8110.
Yumoto:
BC8110 was developed as a coated
CBN material for continuous cutting of high-
hardened steel. In our development process,
we committed ourselves particularly to
pursuing “what customers seek.” By having
our entire teamfocus onuser-orientedproduct
development rather than on technology-driven
development, wewere able to proceed towards
the same goal without going off track.
Maekawa:
When starting our development
we exhaustively investigated “what needs to
be improved” in comparison with competitors’
products.Theresultpointedtoanimprovement
of wear and chipping resistance, so we set our
eyes on developing as our main concept “a
CBN base material with excellent chipping
resistance and a coating with superior wear
resistance.”
Q:
How was the development actually
carried out?
Yumoto:
First of all, to develop “a CBN base
material with excellent chipping resistance,”
we single-mindedly worked to improve the
toughness of the CBN basematerial. However,
all sintered CBN materials, including those
of our competitors, had the same type of
composition, so it was evident that CBN base
material produced in the ordinary way would
only provide the same level of performance
in the final analysis. Therefore, to achieve a
toughness that outstrips our competitors, we
invented the new “ultrafine binder” technology.
Owing to this technology, we were able to
make the BC8110 binder much finer than
our previous and competitors’ products and
succeeded in developing a ceramic binder with
improved toughness. We were thus able to
achieve extremely good resistance to chipping.
Maekawa:
Following the development of
the base material, we embarked on the
development of “a coating with superior wear
resistance.” Generally speaking, coatings
do not adhere as easily to CBN tool material
compared to other carbide tool materials.
So what needed to be done to achieve both
adhesive strength and wear resistance? As a
result of examining the issue in various ways,
we decided to modify our company’s unique
Miracle coating technology so that it could be
applied to CBN. This involved what seemed to
be an endless series of trials and errors to find
the appropriate conditions, this was because
carbide tools and CBN tools differ completely
in the way a coating adheres to them. We also
introduced new facilities to the manufacturing
stage and added a new process after coating.
There were bound to be disadvantages to
increasing the number of work processes,
but a comprehensive review needed to be
performed, beginning with the manufacturing
stage in order to achieve the performance we
desired.
Okada:
Frankly, as a member in charge of
manufacturing, I doubted whether increasing
the number of work processes would make
any difference. However, seeing one of our
members passionately explain the need to
increase the number of processes to achieve
the goal, I had to believe in him. In the end it
led to good results, although there is still more
room for improvement.
Yasuda:
In the product testing stage, we
performed repeated field tests with the
cooperation of our customers. By proposing a
new perspective to the customer at this stage,
they came to value our product more than
our competitors, especially as we ultimately
succeeded in extending tool life.
Maekawa:
Customers who cooperated in the
testing requested to buy the product before
its release, even if it was a special-purpose
product. Receiving such high commendation
before a product’s release has left a very strong
impression on us.
Q:
TellusaboutthedevelopmentofBC8120.
Yumoto:
BC8120 is a successor of the BC8020
coated CBN grade for general cutting of
high-hardened steel, which was released in
2010. Some application problems arose with
BC8020, such as degradation in dimensional
precision due to delamination of the coating
and also when chipping occurred during
continuous cutting. When developing BC8120,
we therefore aimed to resolve these problems
and to develop a material that delivers greater
intermittent performance compared to
competitors’ products.
Yasuda:
BC8020 lagged behind our
competitors’ products in some areas, so we
knew that we would fall further behind if we
were to spend four to five years developing
something new. For this reason, it was
essential to develop our next product in a short
period of time. As a matter of fact, it took us
only a year or so to further improve our CBN
basematerials and coatings.
Yumoto:
It was necessary to increase the
chipping resistance of the CBN base material.
We initially thought we could enhance
toughness to a certain degree by applying the
ultrafine binder technology to BC8120 that had
been developed for the CBN base material,
but this was no easy task. Due to limited time,
we even worked over the weekends making
sample after sample and ultimately succeeded
in applying the ultrafine binder to develop a
dedicated CBN basematerial for BC8120.
Maekawa:
For the coating our main objective
was to control delamination. We began by
considering film compositions and applied a
new technology that would control residual
stress in order to enhance adherence strength.
As a result, we achieved greater adherence
strength than ever before.
Q:
Were any special efforts made in
manufacturing the BC81 series?
Kodera:
Because the BC81 series is a new
type of material, we began searching for
processing methods only after gaining a
thorough understanding of the material. It was
a tremendous challenge to produce samples in
a short time without any disruption to regular
production.
Yumoto:
Mr. Kodera is a specialist, so he
would make a sample three times faster than
other people. That is why we always ended up
asking him to make a sample (laughs). Having
someone likeMr. Kodera on themanufacturing
staff is an enormous support to production
development.
Kodera:
Theresultwasachievednotonlybyme,
but by the cooperation of the manufacturing
staff. The members of the CBN/PCD team are
extremely cohesive and tend to want to help
whenever someone needs it (laughs).
Kubota:
On the production floor, we hear our
customers’ appreciation and words that they
are awaiting our product and this motivates
us to make greater efforts. In hindsight, I think
that our wish to “make outstanding CBN/
PCD products” created a solidarity beyond
the bounds of departments and roles. This is
because we had a relationship of mutual trust
that we were able to realize our product goals.
Q:
Please say a few words to your
customers.
Yumoto:
We have absolute confidence in the
BC81 series, particularly considering all the
struggles we have gone through. We will
actively engage incutting testsandPRactivities
and hope customers will try our products.
Maekawa:
This fiscal year, BC8105 coated
CBN material for finishing high-hardened
steel and the BC8130 coated CBN material for
continuous cutting of high-hardened steel are
scheduled to be released. However, we will
also focus our efforts on further developments,
so please look forward to our future lineup of
products.
CRAFTSMAN STORY
Fracture resistance
Cutting Speedm/min
