Appunti di tutte le lezioni del corso Advanced Manufacturing Processes

Introduction:

Growth/productivity decline in last 50 years:

• Big growth from 1st manufacturing revolution
• I 1850 ➔ steam engine (replace energy)
• II 1900 ➔ mass production models (Ford)
• III 1970 ➔ automation

1. Manufacturing revolution ➔ advanced robots
2. AM ➔ more parts in one
3. Change location, role and mode of work (service-based)
4. Technology ↑ displace productivity
5. Cons ↑ energy consumption
6. Adaptability (res) flexibility ↑ automation
7. Models ➔ advanced = specification, precise, non-traditional size, not always new (restat)
8. Different form of energy: manual, mechanical, chemical/reactive

• Chemal, ACL, EDM, WJT, FDM & bound setting PBF, DED
• New and advanced materials (ceramic, carbon fibre...)
• New or difficult products ➔ new parts, minimization size tolerance, easier assembly
• Tools fixed at step ➔ reduce tool setup cost and times (new technology and technique)
• Better ➔ it's an intersection (3 skills) to finish products and process

• Phenomenon ➔ Reality
• Model ➔ dimension
• Formula
• A tooth psi a coin, tooth fairy

Introduction

Growth/productivity decline in the last 50 years:

• 3 big growth from big manufacturing innovations:
• I 1850 = steam engine (create energy) → huge productivity ↑
• II 1900 = mass production model (Ford) → ↑ mpr
• III 1970 = automation

• IV manufacturing revolution → advanced robots
• AM → more parts in one → huge optimization ↑
• op ktop → multiple factors eos → flexibility, more personal
• ts convert market, ts re-based → permanent

• technology ↑ different
• productivity (factor?) flexibility
• cons (cheap?) automation
• different/lll (leis) models

Advanced = innovation, higher, non-traditional, not always new (exist)

• different form of energy, human mechanics, chemical/reactive
• casting, AL, EDM, GWT, FDM → 6 bound setting PBF, DED

• → new and advanced materials (ceramic, carbon fiber...)
• → new on difficult products → few parts, minimization, higher tolerance, easier
• → iocaa fixed at xtep tolerance
• → cost and times new technology and skills better

it's an integration (is still) to finish production and process

phenomenon reality → model = ambition → we need theoretical knowledge → unique reference model or and part of process

• → mathematical model → physical model
• → formal → "black box" → empirical model

unique specific moase original or rational to code

THERMAL MODEL

heat transfer = temperature difference

Fourier Law

conduction

q''_x = -k dT/dx

k - thermal conductivity [W/mK]

Newton Law

convection

q'' = h (T_s - T_∞)

h - convection coeff [W/m²K]

assumptions:

• k constant - k = k(T) NO
• isotropic and homogeneous material
• control volume, temporal element

Energy Balance / Thermodynamic Law

E_in + E_p - E_out = E_st

G_x is flow of energy

d²T/dx² + d²T/dy² + dT/dt = 1/α dT/dc

α - thermal diffusivity [m²/s] = k/(ρc_p)

T(x,t) - 1D unsteady heat flow - 1D unsteady ∂(T/∂t)

Material Heat Source Weak Internal Heat

Type:

• 1D constant
• isotropic and homogeneous material
• same thermal and chemical property of material
• No internal heat source
• 1D semi infinite geometry - D x
• pure conduction - no convection or radiation

T(x,t) = θ - solution: heat flow ρ⁰ across finite t

τ(x, t) = q⁰ √(4αt) erfc(x/√(4αt)) + T_i

erf - integral of normalized Gaussian function

erfc - complementary error function

ierfc - integral of complementary error function

D = √(4αt) thermal distance experiment material differentiated by heat source

LASER

• 6 basic laser manufacturing companies are the top 10 revenue Co. in Europe and 5 in the top 10 machine tool companies in Italy
• 50% market occupied by fiber laser
• Laser systems revenue is about 5-10 times laser source revenue

1960 first laser public demonstration in 004 range but there are 2 variables laser invisible and modern RCL#[?]

• cutting, welding, marking, heat treatment