Sustainability has found its way to machining, increasing productivity and reducing cost at the same time. By Liu Peiling, principal research engineer, SIMTech.

1. www.equipment-news.com
metalworking equipment news Jan-Feb 201034
FIRSTCUT
A
sia n meta lwork ing
industr y is u nder
increasing pressure from
more stringent environ-
mental legislation, depletion of
raw materials, high energy cost,
and falling machinist skill levels.
The metal cutting companies
have generally been reluctant
to implement new sustainable
machining technologies – largely
due to a common belief that high
cost in implementation will reduce
their competitiveness. This is not
true for machining.
Profiting from sustainable
machining technology is not only
technologically possible with the
pervasive application of low cost
computing,butalsomakebusiness
sense in high mix and low volume
production, when the machining
profit margin is much smaller due
to international competition.
The increased profits come
from reduced operating costs,
reduced material purchase and
wastedisposalcosts,reducedwater
andenergyconsumption.Adopting
sustainable manufacturing
practices offer metal machining
companies of all sizes a cost-
effective route to improve their
economic, environmental and
social performance.
The competitive sustainable
machining technology, which is a
subset of sustainable machining
With Competitive Sustainable
Machining
Technology
Profiting
Sustainability has found its way to machining,
increasing productivity and reducing cost at the same time.
By Liu Peiling, principal research engineer, SIMTech.
technologies, focuses on replacing
trial cut and manual training by
virtual machining simulation,
increasing productivity by high
efficiency cutting, and reuse
material by re-machining of used
component.
Getting It Right
Many manufactured components
involvemachining.Forcomponents,
machining systems play an
important role in the product
life cycle as the connection
between design and the finished
components. The time and cost
of transition from specification to
commercial birth may significantly
affect the remaining phases of the
product life cycle.
Furthermore, the productivity
and the responsiveness of
machining systems as well as the
machined surface integrity are
importantfactorsaffectingproduct
quality. All these characteristics
are critical outcomes of machining
systems used in production.
There has been a continuous
improvement in machine tools and
machiningsystemstorespondtothe
needsforbetterqualityproductsat
lowercosts.Evolutionfrommanual
machinetoolstoNumericalControl
(NC) and Computer Numerical
Control (CNC) machine tools and
introduction of various sensing
and control improvements have
enabled machine tools to be more
capable, effective, and productive
over the last several decades.
Evenaftertheseimprovements,
machining systems still require
long periods of trial and error to
optimally produce a given new
productdesignorcomponent.They
still require cryptic NC language to
operate with limited knowledge of
what they are producing or how
well they are producing.
NC errors could destroy work
pieces and even damage machine
tools. One NC error could make
the workpiece a waste and take
days to rework and eat into
profits. In small batch production,
there is no time for trial and
errors. Especially for High Speed
Machining (HSM), the fast
Rigor789, Hungary
Competitive
Sustainable
Machining
Technology
@ A Glance

2. Jan-Feb 2010 metalworking equipment news
www.equipment-news.com
35
FIRSTCUT
moving and expensive cutter can
be easily broken. The dynamic
machining load will greatly affect
cutter life, geometry accuracy and
surface finishing.
Cutting Down Time Wastage
The ‘First Part Correct’ idea
embodiesmuchoftheleanconcept
that we are attempting to achieve.
Tremendous waste in time, cost
and resources have historically
occurred in the transition from
design to successful machining of
the first detail part. In the time of
high-mix low-volume production,
there is no time for trial cut.
Virtual machining is a modelling
process that realistically simulates
the setting up and running of an
actual machining operation. First,
the user specifies the raw material
shapefromwhichthepartwillbecut.
Then, after selecting the cutter, the
NCprogramautomaticallysimulates
the motion of the machine tool.
Theprogrammercanwatchthe
material removal process and see
detailsofhoweachcutchangesthe
in-process shape of the part. The
NC simulation program is smart
enough to detect problems such
as fast move error and collision
thatcouldscrapthepart,breakthe
cutter, or crash the machine.
Any error discovered by
simulating software allows the
NC programmer to immediately
identify the offending NC code.
Theproblemcanthereforebefixed
during the NC programming phase
so as to ensure an error-free code
when it reaches the shop floor.
High Efficiency Machining
Saves Energy
The ‘energy efficient export
initiative’,ledbytheGermanFederal
Ministry of Economics, underlines
the commercial importance for
the efficient use of energy. Metal
cuttingcompanieshaveintroduced
measures to increase their energy
efficiency, and energy cost is now
a focal point. Significant savings
have been gained through the use
Virtual machining is a modelling process that realistically simulates
the setting up and running of an actual machining operation
of intelligent controlling toolkits.
Improving energy efficiency
can be achieved in two steps,
the monitoring of energy flows
in factories and the analysis of
energyuseinindividualproduction
processes and systems. The
optimisation of energy usage in
production must go above the
energy management if the goals of
doubling total commercial energy
productivity by the year 2020
compared with that recorded in
the year 1990, are to be reached.
These optimisations include
energy management and the
controlling of energy coefficients,
ie: tailored machining process
planning and process implement-
ation with consideration for the
energy coefficients.
The current generation of tool
condition monitors work from
pre-set limits on various sensor
values, including power levels. But
spindle power, for example, can
have normal excursions such as
when the tool enters a corner cut.
Without any information about
the cutting process, these tool
condition monitors must act blind,
leadingtofalseerrorreportsand/or
missing true alarm conditions. The
available tool condition monitors
focusmainlyoncatastrophicevents
such as tool or tooth breakage.
Simulating Machining Operations
The simulation of chip formation
using the Finite-Element-Method
(FEM) predicates the cutting
force and chip thickness. In real
machining processes however,
these parameters are inter-
dependent and influence one
another heavily. Integrated
si mu lat ion, whereby t he
process-machine interaction is
simulated, is therefore a further
key technology for sustainable
production in the future.
Tool chatter is the barrier for
higher material removal rate and
can damage machine tool spindle.
A certain combination of depth
of cut and speed can incur self-
excited vibration of tooling system
and generate cutter marks on
the machined surface. Dynamic
machining model and simulation
can predicate best cutting speed
anddepthcombinationthatwillcut
faster without chattering.
The simulation of machining
operations offers the potential
to fulfil the ecological, social
and economic requirements of
sustainability.
For example, the adjustment
of the suitable feed rate in the
milling of complex geometries
from difficult to machine materials
may be optimised through
simulation and so reduce the
machining time by up to 40
percent. The resultant reduction
in consumed resources allows
savings in both costs and energy.
T he machining model,
simulation, and verification
processes ensure that the NC
programs sent to the shop are

3. www.equipment-news.com
metalworking equipment news Jan-Feb 201036
Getting Your Bearings
Machining ‘Blind’
Enquiry No. 1003
Re-Machining By Welding
Why discard damaged components when you can re-machine them?
FIRSTCUT
both accurate and efficient. To
createthe mostefficientmachining
processes possible, optimisation
software can determine the best
feed rates to use for each cutting
operation. Achieving the best feed
ratesforeachcutinanNCprogram
Tool chatter is the barrier for
higher material removal rate and
can damage machine tool spindle
has always been a goal for NC
programmers but has traditionally
been a very difficult task plagued
by a number of problems.
First,tryingtoimaginethecutter
contact and cutting conditions or
each cut in a large NC program
is virtually impossible. Manually
insertingdifferentfeedratesforeach
changing condition is not practical.
An incorrect feed rate estimate can
break the cutting tool, damage the
fixture, or scrap the part.
Typically either a single
conservative feed rate is used for
an entire machining sequence, or
a higher feed rate is used but with
a very conservative machining
strategy.
Bothmethodsattempttoensure
thatthecutterisnotoverloaded,but
at the expense of very inefficient
machining. Both of these strategies
result in overly slow cutting
speeds or light removal rates that
waste time, increase costs, and
prematurely wear cutters.

4. The minimum machining stock could be achieved through near net shape forming of the raw
material, such as casting, forging, and welding
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metalworking equipment news Jan-Feb 201038
MEN
Enquiry No. 1005
Strength In Numbers
In Taiwan, proximity to auxiliary services, coupled with the ‘cluster effect’ is a winning formula.
Submitted by PMC
To address this issue, a
knowledge-based machining
package essentially adds
intelligencetothecutter.Duringthe
simulation, in-process geometrical
model knows the exact depth,
width, and angle of each cut
because the software also knows
the exact shape of the in-process
material at every instant of the
machining sequence.
It knows exactly how much
material is removed by each cut
segment, and the exact shape of
thecuttercontactwiththematerial.
With this unique knowledge
set, it determines the best feed
rate for each cutting condition
encountered, taking into account
volume of material removed, chip
load,andmachineaccelerationand
deceleration requirements.
If desired, the software can also
divide cuts into smaller segments
andvarythefeedratesasneededin
order to maintain a consistent chip
loadorvolumeremovalrate.Itthen
createsanewNCprogram,withthe
same trajectory as the original, but
with improved feed rates.
Saving Material
Machining is a subtractive
manufacturingprocessthatacutter
removes chips from part surface
until it reaches a designed profile.
The chips are a major waste of raw
material. Innovative design of raw
material block can save a lot of
material. For example, a stepped
block can save almost one third of
raw material.
The machining stock is the
volume difference between the
designed part geometry and raw
material geometry, which may
be a bar or block. Reducing the
machining stock can save raw
material. The minimum machining
stock could be achieved through
near net shape forming of the raw
material, such as casting, forging,
and welding.
Generativemachiningprocesses
have experienced a significant
upsurge in recent years. In the field
of metallic materials, aluminium,
high-speed steel and stainless
steel can be first roughly formed
into 3D complicated components
using a direct laser sintering
process and then machined to a
precise profile.
Moulds with novel geometries
can,forexample,berealisedwithout
the need to use conventional
machining operations and small
batch production can already be
undertaken in a commercially
viable manner.
In the medium-term, generative
machining processes offer an
alternative to the time intensive
conventional processes with
both economical and ecological
advantages.
With respect to the protection
of resources the generative
technologies also offer potential
benefits, such as the production
of the necessary components on-
site, meaning transportation and
storage costs can be avoided.
Enquiry No. 1004
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