This year’s MACH show could justifiably boast the attendance of a diverse cross-section
of the world’s most influential software developers – all under one roof. It was therefore
the ideal venue for those, like myself, wishing to catch up on the industry developments,
and the future of computer integrated manufacturing generally. By Martin Oakham
Software – the magic key
Delcam’s FeatureCAM
range of knowledge-based
CAM software products
has been certified by the
Autodesk Inventor
Certified Application
Program for Autodesk
Inventor 2008.
july 2008
SOFTWARE developments at MACH08 showed a
clear progression towards Computer Integrated
Manufacturing (CIM) where the increasing emergence of
manufacturing tools such as automatic feature
recognition, advanced multi axis verification and global
data management are signalling a shift in the route to
increased productivity. Now that developments in high
speed machining, 5-axis kinematics, one-hit machining
solutions and automated machining cells are plateauing
out, CNC programming is becoming the new bottleneck,
tying up resources and holding up workflow. Already
most of the details of 5-axis movement are out of the
hands of the CAM programmer. The software determines
which axes need to be moved, and when they need to be
moved, and keeps an eye on collision potential and makes
the necessary moves to avoid mishap. The CAM
programmer is concerned only with the most suitable
strategy on offer to give the best overall finish/time ratio.
AI/Feature Recognition
The vast majority of CAM developers exhibiting at
MACH08 are moving away from operations-based
interfaces, where the user is required to go through
multiple steps to machine each part, in favour of processbased
systems and feature recognition. Process based
systems attempt to reduce the arduous task of selecting
software & controls
the operation to use, the machining boundary, the
toolpath strategy, tools and feeds and speeds etc. by
grouping operations in standard processes that can be
called up in the form of a knowledge database (expert
system).
In short, the program remembers the processes used
for many operations such as drilling a sequence of holes,
and repeats them for future operations. However, this
method only really pays dividends when the machine
shop is using the same processes again and again for the
same type of components. When a process is applied to
different types of components, or parts made of different
materials, the CNC programmer must still verify that
the correct operations were used and that the correct
tools, stepovers, speeds and feeds were selected. This is the
reason why more and more CAM developers are now
developing Feature-based CAM systems, which
automatically adapt to every part based on the
‘intelligence’ incorporated within the CAD model.
Such systems identify features that can be machined
based on the CAD geometry; for example, two opposite
flats with radiused ends would suggest the possibility of a
slot feature. This would then be further interrogated to
support or reject the findings. Each identified shape has a
preferred set of associative machining rules associated
with it. These ‘rules’ outline preferences such as how and
where material removal should occur, cutting depths,
whether to use conventional cutting techniques or climb
techniques, whether to use a spot drill or to use a centre
drill, and the preferred machining strategies for
roughing and finishing, based on expert systems
databases within the CAM system.
Armed with this information, the CAM system is able
to evaluate the component geometry and material, select
the most appropriate tools and operations, and
recommend machining strategies, feeds and speeds and
ultimately to generate useable NC code which can be
post-processed for 3 to 5-axis continuous machine tools.
In order to maximise cutting efficiency on 5-axis
machine tools, strategies are emerging that use
predominately continuous 3 or 4 axis motion, but which
switch to continuous 5-axis motion if and only if a
feature can be machined more efficiently by using
additional rotary axes.
Integration
Because feature-based CAM systems must retain the
design intelligence inherent in a CAD model, the direct
communication between CAD and CAM vendors has
MWP
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