www.engineeringnews.co.nz 19
Specially designed trains,
operating at a constant
speed of 700 meters
per hour, machine the
existing track profile. By
removing millimetres of metal from
the damaged surface, the track is
restored to its original condition.
With each application, the first cutter
roughens the surface, the second
one finishes it, and the two units act
on both rails simultaneously.
The operation provides a high-quality
surface finish, while metal chips
produced during the milling stage
are transferred to a nearby container,
ensuring no debris is left on the
track.
This ‘on the-move’ application
requires specialised equipment to
achieve optimum results, such as
‘train machine tools’ designed to
carry dynamic rail milling cutters
and inserts. An increasing number
of these are being produced by
leading global manufacturers as
demand from railway organisations
and government bodies for track
maintenance increases.
Global cutting tool manufacturer
Dormer Pramet works in partnership
with several high-speed milling
machine manufacturers to delivery
key projects around the world. One
of these projects included the milling
of three different rail profiles for a
customer in the Netherlands.
Dormer Pramet’s 600mm diameter
dynamic rail milling cutter was able
to machine the combined profile
(60E1, 54E1, 46E3 1:40) and
another profile 54E5 1:40, without
having to change the inserts. Using
the same cutting tools across
several profiles is hugely beneficial
as it saves both time and costs,
reducing the number of tool changeovers.
Tomas Hantek, application manager
for railway at Dormer Pramet, says:
“As with all railway projects, each
application is different from the next,
so we regularly tailor our products to
meet the need of the customer.
“It is very important we work closely
with the machine tool manufacturer
and rail organisation to identify
where adaptions need to be made
to achieve the desired results.”
The development of new rail
technology is constantly taking place
and modifications are needed on
both sides to optimise the match
between the machine and cutting
tool. Dormer Pramet has adapted
its popular dynamic milling cutter
in various sizes, from 300mm to
900mm, with plans to develop a
1,400mm diameter version in the
future.
Tomas says, “We recently delivered
a 300mm diameter dynamic rail
milling cutter to a customer for
testing. This has been custom made
to specifically fit their new machine.
In the first trial, they discovered
that the cutter profile was as they
required. However, they realised their
new machine was not strong or rigid
enough to cope with the demands
of the application. We are now
working with them to make some
changes and help move the project
forward.”
At present, Dormer Pramet has more
than 50 dynamic rail milling cutters
out in the market, including in the
Netherlands, Germany and Poland.
This is an indication of the international
nature of the railway segment,
with tool suppliers, machine tool
builders and customers from
different parts of the world, working
together on applications which often
take place in different countries.
This not only requires precise
logistical management, but an
understanding of different standards
and accreditations between
countries. Many projects involve
large international organizations, as
well as support from government
agencies and administrations, along
with affiliated transport associations.
Wheel returning
Another example where Dormer
Pramet provides support to
the railway segment is in wheel
returning. This too can see standard
tools being modified to become
custom-made specials, unique to
the requirement of the application.
Its assortment of rectangular
LNMT and round ROEX inserts, for
example, have proven a big hit with
customers in North America, with
the range available from its distribution
centre in Hebron, Kentucky.
A customer in Philadelphia was
having issues with its previous
LNMT inserts as they were not
able to break chips during a wheel
turning operation. The resultant
long, continuous swarf congested
the area around the workpiece.
The process to clear the chips is
not only time consuming but can
also be hazardous.
Dormer Pramet put forward
its standard LNMT inserts, but
during tests, found these too did
not break the chips as required.
Following further feedback and
discussions with the customer, the
company was able to make two
key changes to its insert. First it
added a corner radius chip breaker
to relieve some of the pressure
on the tool. It then tailored the
geometry and design of the insert
to prevent nesting at high depths
of cut.
The end user wanted to make one
pass, so the LNMT insert needed
to be able to achieve a staggering
.700” (18mm) depth of cut at
the first attempt. Following the
changes, the insert was put in for
further testing.
Not only did this new design fix the
chip control problem, but it consistently
outperformed all other inserts
tested. The customer now orders
from Dormer Pramet.
In addition, the company has
started to use their RCMX, RCMT
and TNMG inserts on a variety of
operations, such as the turning
down of axles. This has allowed
them to reduce cycle time by an
average of 30 per cent, saving more
than $30,000 USD in the first year,
with greater operational efficiency
and improved performance.
Railway wheel turning is an area
Dormer Pramet is looking to expand
its assortment further. Where the
LNMT can support large depths of
cut, the company is now working
on a new insert for delivering small
depths of cut, around 1mm.
A popular trend with customers
when machining railway wheels is
to perform the operation with a low
depth of cut. This is still completed
in one pass, but the reconditioning
will be required more often between
uses. This new product will support
those applications. It is currently in
the testing phase, with the aim to
launch the insert in 2020.
When renovating railway lines there are generally
two preferred options; grinding or dynamic milling.
Compared to grinding, the high-speed re-profiling of a
line represents significant time and financial savings.
A wheel profiling application with no chip control
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