| Summary: | Milling is used to manufacture a wide variety of metal parts, from simple to complex geometries,
in small or large volumes. The requirements for these parts usually necessitate that the milling operation is accurate, but also the production rate must be as high as possible. These two
requirements, which appear conflicting as first, are met if the milling operation is well planned.
While NC programming is still based in many industries on past experience and practical knowledge,
research in the areas of cutting mechanics, modelling and simulation are gradually changing
the manufacturing practices.
This thesis investigates Virtual Milling, which is the integration of milling simulation and
CAD/CAM capabilities. Available milling simulation systems can simulate the process for one
set of cutting conditions. The objective with Virtual Milling is to not only simulate the milling
operation for the whole NC program, but also to integrate features such as feedrate scheduling.
A milling simulation for the whole part was developed based on the analytical closed-loop
milling model presented by Spence[36]. The input to the simulation is the cutter-workpiece intersections
along the tool path. The simulation results include force, torque and power, and deflection
along the tool path.
The second part of this thesis is the implementation of a Virtual Milling framework. The first
step is the selection of cutting conditions which is done during the NC programming. CAD/CAM
software do not provide tools to select appropriate cutting conditions, therefore we established the
requirements for such a tool using stability lobe theory. An interface was implemented in a commercial
CAD/CAM software to demonstrate this. The milling simulation is then used to identify
critical locations along the tool path, and it is also used to perform feedrate scheduling. Two offline
approaches for feedrate scheduling were implemented, constraint-based feedrate scheduling
and off-line adaptive force control, and evaluated to see if their use would lead to improved machining accuracy, better control of cutting forces, and improved machining time. Cutting tests
were conducted and these approaches were also compared to an existing online adaptive force
control. === Applied Science, Faculty of === Mechanical Engineering, Department of === Graduate
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