Dormer’s Shark Line HSS-E-PM taps
Thomas Lundqvist and Gunnar
Wistrand from Larssons
Customer case study
An example of a real-world
application comes with Dormer’s
A553 high speed cobalt (HSS-E)
drill, which has become a key
component for a Swedish manufacturer.
Larssons Mechanical Workshop,
founded in 1951, manufacture
subcontracted metal products,
as well as processing and
assembly support for a wide
range of industries. One particular
job involved the machining of
thousands of holes in its packaging
machine rollers made from 2346
and 2333 stainless steel.
A 12mm diameter A553 drill –
which features a TiAlN Top coating
and internal coolant – is used to
drill thousands of holes to depths
of up to 70mm, which equates
to 70-75 meters of drilling. For
Larssons, HSS is the preferred
option as Gunnar Wistrand, CNC
operator, says: “It is flexible drill
that, unlike a carbide drill, is more
forgiving if something happens.
Another safety advantage of the
A553 is that we can leave the
machine without risk of failure.”
In this respect, the advantages
far outweigh the disadvantages
as Gunnar confirms, “Utilising the
A553 it takes an extra 30 seconds
for each reel to be produced.
However, the process is more
predictable and changeover time is
greatly reduced. The extra time it
would take to change tools would
cost us far more. Not changing the
tool as frequently also eliminates
any safety concerns with tool
hardness and slightly improves heat conductivity, while
carbon, increases wear resistance and is responsible
for the basic hardness (approximately 62-65 Rc). The
addition of 5-8% more cobalt to HSS improves strength
and wear resistance.
Typically, drills made with the addition of more cobalt are
used in application specific operations.
HSS tools can resist vibrations, whatever the type of
machine tool, even if rigidity has been lost over time
and regardless of work-piece clamping conditions. It
can prevent mechanical shocks at tooth level in milling
operations and cope with varying lubrication conditions
which may result in thermal changes.
Also, thanks to the unique strength of high speed steels,
tool manufacturers can produce extremely sharp cutting
edges. This make it easier to machine difficult materials,
offers less work hardening of austenitic stainless steels
and nickel alloys, gives a better surface quality and
tolerances of machined parts.
As the metal is cut and not torn, it provides longer tool
life with lower cutting edge temperatures. It also requires
lower cutting forces, which ultimately means less power
consumption from the machine tools.
From a tool life point of view, HSS performs very well with
intermittent cutting applications. However, it has limited
cutting speed range which is far lower when compared to
Coatings and substrates
HSS may be an established cutting tool material, but
it does not mean it has not been subject to constant
development and improvements since it was first used
back in the late 19th century.
Dormer Pramet’s range of HSS substrates, for example,
is anything but outdated. The company has have invested
in powder technology to develop a material that provides
HSS-E with powder metallurgy offers a higher content of
alloy elements and a combination of unique properties to
improve toughness, wear resistance and hardness. Using
HSS-E-PM prolongs tool life, makes it more predictable,
improves feed and speed performance, as well as helps
reduce chipping problems.
The most recent application of this powdered metallurgy
technology is in Dormer’s Shark Line taps. They are
manufactured from a HSS-E-PM substrate, specifically
developed for taps to give the additional toughness
required, consistently stable properties and superior
grind-ability compared to conventional high-speed steels.
These improved characteristics mean the taps have a
more predictable and assured life.
Also, HSS-E and HSS-E-PM are excellent substrates
for a variety of coatings, such as titanium nitride
(TiN),titanium aluminum nitride (TiAlN), titanium carbon-nitride
(TiCN), as well as multilayer coatings.
Coatings considerably improve tool life and further boost
the performance of HSS tools in environments where productivity
and speed and feed rates are high, as well as in
dry operations and for machining of difficult materials.
They offer increased surface hardness for higher wear
resistance, reduced friction for better chip creation,
reduce cutting forces and less heat generation, crater
wear resistance and improved surface quality of finished
parts. TiAlN-coated HSS-E cutting tools, for example, are
highly suited to dry machining of cast iron as this helps
resist high temperatures, while TiAlN coated HSS-E-PM
tools are suitable for the machining of titanium and nickel
Summary - choice
In an age where users require reliable, consistent,
versatile tools at a cost-effective price, high speed steel is
still the ideal choice for many applications. As such, it can
still hold its own in the market place against younger and
more technically advanced materials.
If anything, HSS has over the many years become
stronger, by adapting itself with new coatings, adjusting
its composition and adding new technology, all helping
to retain its position as a vital material in the metal
cutting industry. The cutting tool industry has always
been a competitive landscape and HSS remains a key
component to offering customers what has always been
an essential requirement: choice.