the manufacturing sector has used metal for cutting tools and components
that has been hardened by heating it to high temperatures. This is not
only expensive, but also treats a much larger part of the surface than
necessary. CRAFT-funded research has resulted in a laser method of hardening,
which can be focused accurately on the part of the tool or component that
needs it. Large-scale testing of fully operational tools and products
in industrial settings has perfected the technique, which is now being
offered as a service world-wide by the participating firms and two newly
tools by heating
tools which are used to carve out intricate metal parts for manufacturing
industry suffer rough punishment. The materials they cut are themselves
durable and tough, and tools of this sort must withstand repeated
abrasion without wearing out. It is common practice to harden cutting
tools by heating the metal that is used to make them to temperatures
of up to 1000°C. This changes a normally ductile metal, making
it much harder but more brittle. The process is called transformation
hardening and has been used reasonably successfully for several
hardening the whole tool is expensive - heating a complete sheet
of metal uses a significant amount of energy. It also makes the
metal difficult to work with, as a tool made entirely of hardened
metal can become stressed, and can break.
alternatives, fine flames and plasma arcs have been used to try
to heat only the cutting part of the tool, but it has proved difficult
to direct the heat onto cutting edge with enough precision to obtain
a consistent level of hardening. If a more accurate technique could
be developed, the result would not just be better tools: there is
a whole range of high-performance metal components which need hard,
the mid-1990s, the USA and Japan were developing hardening techniques
using lasers, but European expertise lagged behind. Metallurgy research
organisations found they were being approached simultaneously by
many SMEs, desperate to use parts hardened using the latest laser
SMEs, however, did not have the research facilities or financial
resources to develop the process themselves. The University
of Twente and TNO
Industry, both in the Netherlands, and the Laserzentrum
of the Fachhochschule Münster in Germany, which already had
good working relationships with companies specialising in laser
technology, realised that a European project could be the way forward.
three laboratories worked with Demar
Laser and LaserProdukt to develop a CRAFT
project proposal, which included seven SME and three large company
component producers, from Belgium, Germany and the Netherlands.
WG Essers, a Dutch scientific research consultant, co-ordinated
the consortium's efforts. "The first step was to guide the
partners towards the right sort of research and to plan the proposal
for CRAFT funding," he explains. "Each company had its
own priorities and the decision making process was quite lengthy.
We had to choose the research route that seemed most likely to lead
to a commercially exploitable process."
test pieces to finished parts
proposal was selected and the CRAFT project began. Initially, individual
component producers made small test pieces and delivered them to
Demar Laser, LaserProdukt and the research organisations for various
laser treatments. They used two main techniques.
1. Laser heat only was used to achieve consistent transformation
along the cutting edge of the tool.
2. The surface of a component was coated, or clad, with a layer
of hardening material.
had previously been carried out by plasma spraying with a hot gas
flame - an imprecise technique, which coats more of the surface
than necessary. By contrast, the new technique uses a powder coating,
which is laser heated. The powder melts on the surface of the metal,
but only where the laser beam is focused. The molten coating formulation
clads the surface evenly and precisely.
Some techniques worked better than others, but there were some outstanding
successes. These were rapidly scaled up for further testing. Real
components were made, treated and then tested in simulated and then
genuine industrial conditions.
all the techniques worked, but we produced some very good results.
Some of the partners were able to develop tools that were far superior
to any that they had produced before," comments Dr Essers.
The laser technique is also able to harden other parts, such as
tools for producing complex gear rims used within moving machinery.
The precision of the lasers can easily cope with intricate shapes.
a hardening service worldwide
Laser felt that the results were so good that they, together with
another SME, have recently formed two separate companies. These
are dedicated to applying the technology tested in this project
and providing a hardening service to industry world-wide. NedClad
Technology BV and NedClad Production BV opened in early 2000. The
two companies are up and running, and although it is too early to
predict sales figures, the owners are confident of commercial success.
The other partners are either already exploiting the results, or
plan to do so.
technology moves very fast, and the team are ready to test their
methods using a new generation of diode lasers. "These will
be much more powerful than the lasers we have been using. In the
next couple of years we could develop state-of-the art laser technology
that will produce even better quality tools and machine parts,"
predicts Dr Essers.