Appunti completi del corso "Advanced Manufacturing Processes"

Manufacturing processes

Tornitura = Turning

Alesatura = Boring

Foratura = Drilling

Fresatura = Milling

Rettifica = Grinding

Planing

Shaping

Brocciatura = Broaching

Finitura = Polishing/Buffing

Imbutitura = Deep Drawing

Piegatura = Bending

Punzonatura = Punching

Trafilatura = Wire drawing

Tranciatura = Blanking

General issues

• Classification of unconventional manufacturing processes
• General modeling of processes and systems

Thermal processes

• Thermal modeling
• Laser beam processing
• Electro discharge machining
• Plasma arc processing
• Additive manufacturing processes

Mechanical processes

• Waterjet processing
• Hydroforming
• Ultrasonic processing
• Micromachining

Manufacturing Processes

Tornitura = Turning

Alesatura = Boring

Foratura = Drilling

Fresatura = Milling

Rettifica = Grinding

Planing

Shaping

Brocciatura = Broaching

Finitura = Polishing/Buffing

Imbutitura = Deep Drawing

Piegatura = Bending

Punzonatura = Punching

Trafilatura = Wire drawing

Tranciatura = Blanking

General issues

• Classification of unconventional manufacturing processes
• General modeling of processes and systems

Thermal processes

• Thermal modeling
• Laser beam processing
• Electro discharge machining
• Plasma arc processing
• Additive manufacturing processes

Mechanical processes

• Waterjet processing
• Hydroforming
• Ultrasonic processing
• Micromachining

Terms and abbreviations

USM, WJM, Abrasion (MA), Jet, Abrasives, Fluid, Slurry

Workpiece

EDM, PAC, LBM

Discharges, Plasma beam, Laser beam, Plasma, Photons, Dielectric, Gas, Air

EBM, IBM, Electron beam, Ion beam, Electrons, Ions, Vacuum

Thermal modeling

Modelling of temperature field

Analytic solutions are:

• Fast to resolve, faster than experiment
• Easy to manipulate
• Intuitive for engineers

However they suffer from:

• Unmodeled physics: phase transformation, material flow, gas pressure
• Homogeneous and fixed material properties (complete isotropy), temperature dependence not considered
• Beam shape neglected, everything is uniform
• Highly reliant on efficiency/optical absorption parameters

Common solutions

• Planar source: the temperature changes only in one direction
• Line source: the temperature is the same along the vertical direction
• Point source: the temperature is different in every direction

Heat transfer

• Conduction: through direct molecular communication without a flow of the material medium
• Convection: combination of conduction and the transfer of thermal energy by fluid circulation or movement of the hot particles in bulk to cooler areas in a material medium
• Radiation: transfer of heat through radiation, transfer of heat through things glowing.

Conduction

Fourier Law

Along x direction: \( \vec{q}_x" = -k \frac{dT}{dx} \) [W/m²]

Along all directions: \( \vec{q}_n" = -k \frac{\partial T}{\partial n} \hat{n} = -k \nabla T \)

There might be some symmetries, so it's useful to rewrite the equation in other coordinates:

Rectangular (cartesian) coordinates:

\( \vec{q}" = -k \nabla T = \left( k \frac{\partial T}{\partial x} \hat{i} + k \frac{\partial T}{\partial y} \hat{j} + k \frac{\partial T}{\partial z} \hat{k} \right) \)

Cylindrical coordinates (r, z, φ):

\( \vec{q}" = -k \nabla T = \left( k \frac{\partial T}{\partial r} \hat{r} + k \frac{1}{r} \frac{\partial T}{\partial φ} \hat{φ} + k \frac{\partial T}{\partial z} \hat{k} \right) \)

Spherical coordinates (r, θ, φ):

\( \vec{q}" = -k \nabla T = \left( -k \frac{\partial T}{\partial r} \hat{r} + k \frac{1}{r} \frac{\partial T}{\partial θ} \hat{θ} + \frac{1}{r \sin θ} \frac{\partial T}{\partial φ} \hat{φ} \right) \)

Thermal conductivity

We'll consider that the thermal conductivity is isotropic in every direction

\( k = - \left( \frac{q_x"}{\left( \frac{\partial T}{\partial x} \right)} \right) \) \([ \frac{W}{m \cdot K}] \)