robotics, automation & assembly
Improved automated grinding and finishing of
castings, with lower manufacturing costs and
higher surface quality, is now possible with
the launch of a new software function
Breaking down barriers
RobotWare Machining FC
raises productivity and
boost consistency of robotassisted
finishing cells
TRADITIONALLY, foundry finishing has been very
labour-intensive, delivering inconsistent quality from
manual grinding, deburring and polishing. Robots used
have been position-controlled, moving according to
defined positions and speeds; and if a robot is struggling to
trace the programmed path, its servo will increase power to
maximum torque, causing a collision with the excess
material. The robot stops, the tool breaks, or the work piece
gets damaged. Consequently, conventional cast cleaning
robots run slow - limiting productivity. This approach also
needs complex and time-consuming programming to
make the robot path as exact as possible. The expectation is
for consistent grinding or polishing; in reality the cast
products are all individual with different tolerances and
this generates inconsistent process results.
But now a major obstacle to productivity improvement
has been lifted, according to Andreas Eriksson, Product
Manager Foundry ABB Robotics, with the new RobotWare
Machining FC function. ‘It removes the bottleneck and
greatly increases process efficiency, saving time, raising
overall consistency and boosting product quality. It
incorporates two advanced software features. FC Pressure
lets robots grind, polish or buff castings while maintaining
a constant pressure between the tool and the work surface;
FC SpeedChange enables a robot to debur or deflash part
line and surfaces of castings at a controlled speed, slowing
down when encountering excessive burr. Benefits include:
■ Improved process results/product quality: secure
controlled contact force in grinding applications gives an
improved and consistent product quality
■ Reduced programming time: 80% faster programming
for grinding by allowing the robot to ‘feel’ the surface
■ Shorter cycle time: 20% faster deburring applications as
the robot adapts to surface defects
■ Longer tool life: up to 20% longer tool
life as there is consistent wear and no
tool and work piece collisions
FC Pressure addresses processes which
demand high quality surface finish. It
allows the robot to effectively ‘feel’ its
surroundings and follow the casting
surface, changing position in order to
apply constant pressure, even if the
exact position of the surface is not
known. Consistent contact means
debris, such as a burr, is removed to the
same depth. This improved force
control accuracy is critical for
surface finish, where even a 5
Newton force difference can
have a huge impact.
The result is improved
24 MWP january 2008
surface finish; ability to handle variations in castings;
minimum risk of damage to the casting surface; and
predictable tool wear. The function is suitable for
polishing, grinding and cleaning, where a surface needs to
be even and smooth. Typical applications include:
■ Grinding water taps, turbine/propeller blades and other
types of castings
■ Polishing lap tops, mobile phones, electronic parts, water
sinks, etc
■ Buffing bumpers, speakers, chromate engine covers, etc.
Where path accuracy is important and where the finished
result must comply with specific dimensions, FC
SpeedChange is recommended. The robot is position
controlled and follows a programmed path that maintains
a constant material removal rate. It operates at maximum
process speed but if machining forces exceed a certain
value, then the path speed is automatically reduced,
decreasing forces, minimising changed dimensions due to
deflections of the robot arm and subsequently avoiding
damaging the part or tool due to stress and heat. This
results in shorter cycle times; ability to handle variations in
castings; minimum risk of damage to the castings; and
predictable tool wear.
FC SpeedChange can be used for:
■ Grinding unevenly distributed material on cast surfaces
■ Milling along the edge of a work piece
■ Deburring along the contours of a work piece
■ Deflashing unevenly distributed burr along a part line
on castings
RobotWare Machining FC provides, for the first time,
force control in different machining applications where
the robot needs to be sensitive to process forces. It comprises
advanced software instructions for machining applications
and a computer adapted for force control For full
functionality the system requires standard ABB robots
fitted with a force sensor; ABB IRC5 controller housing an
interface card linking the sensor to the controller's
computer; and cabling between the sensor and the
controller. The force sensor measures the process forces
used to adjust the robot's behaviour. For FC Pressure, either
a six degree of freedom (6DOF) - that is full force and full
torque - or a one degree of freedom (1DOF) force sensor can
be used.
For FC SpeedChange, either a 6 DOF sensor or an
analogue signal representing the machining forces, such as
spindle voltage output, can be used. The choice of sensor
input depends on the required flexibility of the application.
The sensor can be mounted on the robot or on a stationary
fixture in any combination with the robot holding the
work piece or the tool. www.abb.com
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