mould & die
Training session maximises potential of new cutting tool
developments and adds productivity to toolmaker’s skill
capability.
Look and learn
A major strength of Investment Tooling
International (ITI), based in Kirkby-in-Ashfield,
is the quality of its die finishing. However this
part of the toolmaking process can be very time
consuming - not ideal when trying to maintain
promised deliveries. ITI serves the food industry,
packaging, gas, medical and automotive
customers (for which ITI has produced dies
weighing up to 12 tonnes). The company
employs 34 people, all very skilled in die and
mould work, and has a similarly sized sister
company in Manchester.
After winning a very competitively-priced
contract for a five-tonne twin impression tool
steel die for the automotive industry, works
manager John Dobinson invited leading tooling
companies to advise how machining costs could
be minimised. ‘We had very successfully used
milling tooling from LMT, who proposed to
stage a three-day seminar and workshop on our
machines to bring us up-to-date on techniques
using some of the latest tooling developments’ he
says. ‘As a result, we found we could reduce our
roughing times by at least 30%; that also led to
finishing times being reduced by almost half
with improved tool life and shorter bench time.’
He outlines the pressure that UK toolmakers
are under from Asia and recalls that a similar die
machined five years ago at the works would have
cost the customer at least 20% more. The 18 weeks
lead time from order to delivery had to be met;
Dobinson was concerned over the time taken to
machine the very deep cavities and create the
multitude of sharp corners without extensive
finishing. When margins are being squeezed,
New methods and
applications are being
implemented from the
programmers right
through the machine
shop.
investment in new machine tools and equipment
is more difficult to justify, so ITI aims to improve
productivity from the installed base of seven
CNC machining centres.
LMT (UK) suggested a seminar and workshop,
so Dobinson called together the CNC machinists
from the day and nightshifts as well as CNC
programmers. Milling applications specialist of
LMT Juergen Meyer ran the three day course.
‘The idea was to create a milling strategy course
that included discussions, tooling developments
and a workshop covering the various machines
and workpieces that also included the various
components that made up the automotive die’ he
explains. ‘An important focus was the deep cavity
and corner machining of the die plus a trouble
shooting session both as a group and more
personally in one to one situations.’
Adds Dobinson: ‘Not only did we develop new
strategies and save considerable time on the die
and its various components, but we also gained
an immediate payback in obtaining a massive
reduction in finishing and benchwork. When
the tool was assembled, it was very easy to put
together due to the more consistent machining
we had achieved.’
The initial part of the course focused on
roughing cycles. Meyer spent three hours
discussing the importance of the machine tool
specification and particularly how to take best
advantage of the spindle torque curve. He
followed this up by physically checking out each
machine. One thing that became very clear - very
common with many milling applications - was
that the cutters used were too large and therefore
62 MWP january 2009
could not fully exploit the metal removal rate
due to the level of torque available from the
spindle. Says Meyer: ‘As an example, ITI was
using 52mm diameter cutters at 500mm/min
feed rate on P20 DZ tool steel, and you could
clearly hear the machine was registering its
resentment. The inserts were not cutting
efficiently because the feed per tooth was smaller
than the edge preparation radius.’
The milling cutter was changed for the latest
LMT Fette 35mm diameter 4Feed HSC endmill
with four cutting edges that is specifically
designed for roughing cycles. The tool has a very
shallow approach angle with cutting geometry
that reduces radial cutting forces enabling high
feed rates - often double the normal rates on high
strength and hard materials. This tool enabled
ITI’s setter operators to run the spindle on the
Huron machine being used at 2,000revs/min and
8,000mm/min feed rate with a 1mm depth of
cut. By reducing the step over to suit the 35mm
diameter cutter this demonstration reduced the
roughing time by half.
Trials and discussions then followed on semifinish
cycles and especially corner milling on
various machines including a 4 1/2 axis Deckel
Maho 100T with manual tilting head. The
adjustable angle of the head gives better access to
a cavity and enables the length of cutter to be
reduced giving a more rigid set up. Here, LMT
(UK) set up a 3mm diameter 2Feed HSC solid
carbide cutter that has two shaped cutting edges
to reduce the radial cutting force, again helping
to increase the rates of feed.
Says John Dobinson: ‘Not only did this
method of working provide us with an improved
milling strategy but it also made the high
precision of our finishing cycles far easier to
maintain with a corresponding leap in tool life.
He says that the course opened everyone’s eyes to
how tooling had developed: ‘Our setter operators
are very skilled at their jobs but you can easily get
set in a way of working that is comfortable and
you understand, when all the time the world is
changing. The session with LMT has certainly
given us a new approach and to prove it the
methods and applications we discussed are being
implemented from the programmers right
through the machine shop. But it is the finishing
operations that are the real benefactors.’
www.LMT-tools.com www.iti-kirkby.co.uk
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