Final exam review
This presentation is the property of its rightful owner.
Sponsored Links
1 / 29

Final Exam Review PowerPoint PPT Presentation


  • 103 Views
  • Uploaded on
  • Presentation posted in: General

Final Exam Review. Material-Process-Geometry Relationships. Function. Role of Prod Engr. Material. Geometry. Role of Mfg Engr. Process. Materials in Manufacturing . Most engineering materials can be classified into one of four basic categories: Metals Ceramics Polymers Composites.

Download Presentation

Final Exam Review

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Final exam review

Final Exam Review


Material process geometry relationships

Material-Process-Geometry Relationships

Function

Role of Prod Engr

Material

Geometry

Role of Mfg Engr

Process


Materials in manufacturing

Materials in Manufacturing

  • Most engineering materials can be classified into one of four basic categories:

    • Metals

    • Ceramics

    • Polymers

    • Composites


Processing operations

Processing Operations

  • Three categories of processing operations:

    • Shaping operations - alter the geometry of the starting work material

    • Property‑enhancing operations - improve physical properties of the material without changing its shape

    • Surface processing operations - clean, treat, coat, or deposit material onto the exterior surface of the work


Shaping four main categories

Shaping – Four Main Categories

  • Solidification Processes - starting material is a heated liquid that solidifies to form part geometry

  • Deformation Processes - starting material is a ductile solid that is deformed

  • Material Removal Processes - starting material is a ductile/brittle solid, from which material is removed

  • Assembly Processes - two or more separate parts are joined to form a new entity


Comparing processes

Comparing Processes


Stress strain relationships

Stress-Strain Relationships

  • Figure 3.3 Typical engineering stress‑strain plot in a tensile test of a metal.


True stress strain curve

True Stress-Strain Curve

Figure 3.4 ‑ True stress‑strain curve for the previous engineering stress‑strain plot in Figure 3.3.


Strain hardening

Strain Hardening

Figure 3.5 True stress‑strain curve plotted on log‑log scale.


Recrystallization and grain growth

Recrystallization and Grain Growth

Scanning electron micrograph taken using backscattered electrons, of a partly recrystallized Al-Zr alloy. The large defect-free recrystallized grains can be seen consuming the deformed cellular microstructure.

--------50µm-------


Phase dispersion speed of quenching

Phase Dispersion – speed of quenching


Allotropic transformation and tempering

Figure 6.4 Phase diagram for iron‑carbon system, up to about 6% carbon.

Allotropic Transformation and Tempering

Austenizing

Quenching

Tempered Martensite

12


Final exam review 1206483

Precipitation Hardening - Al 6022 (Mg-Si)

Figure 27.5 Precipitation hardening: (a) phase diagram of an alloy system consisting of metals A and B that can be precipitation hardened; and (b) heat treatment: (1) solution treatment, (2) quenching, and (3) precipitation treatment.

13


Machining relationships

Machining Relationships

Machine Tool

Workholding Tool

Cutting Tool

Workpiece


Final exam review 1206483

Effect of Higher Shear Plane Angle

  • Higher shear plane angle means smaller shear plane which means lower shear force, cutting forces, power, and temperature

Figure 21.12 Effect of shear plane angle  : (a) higher  with a resulting lower shear plane area; (b) smaller  with a corresponding larger shear plane area. Note that the rake angle is larger in (a), which tends to increase shear angle according to the Merchant equation

15


Turning parameters illustrated

Turning Parameters Illustrated


Machining calculations turning

Machining Calculations: Turning

  • Spindle Speed - N(rpm)

    • v = cutting speed

    • Do = outer diameter

  • Feed Rate - fr(mm/min -or- in/min)

    • f = feed per rev

  • Depth of Cut - d(mm -or- in)

    • Do = outer diameter

    • Df = final diameter

  • Machining Time - Tm(min)

    • L = length of cut

  • Mat’l Removal Rate - MRR(mm3/min -or- in3/min)


  • Unit power in machining

    Unit Power in Machining

    • Useful to convert power into power per unit volume rate of metal cut

    • Called the unit power, Pu or unit horsepower, HPu

      or

      • Tool sharpness is taken into account multiply by 1.00 – 1.25

      • Feed is taken into account by multiplying by factor in Figure 21.14

    where MRR = material removal rate


    What if feed changes

    What if feed changes?


    Unit horsepower

    Unit Horsepower

    The significance of HPu is that it can be used: 1) to determine the size of the machine tool required to perform a particular cutting operation; and 2) the size of the cutting force on the workholding and cutting tools.

    HPu ~ hp/in3/min

    Cf ~ correction factor

    MRR ~ in3/min

    Fc~ lb

    V ~ ft/min

    E ~ machine tool efficiency

    33,000 ~ conversion between ft-lb & hp


    Example

    Example

    • In a turning operation on stainless steel with hardness = 200 HB, the cutting speed = 200 m/min, feed = 0.25 mm/rev, and depth of cut = 7.5 mm. How much power will the lathe draw in performing this operation if its mechanical efficiency = 90%.

    • From Table 21.2, U = 2.8 N-m/mm3 = 2.8 J/mm3

    • Since feed is 0.25 mm/rev, the correction factor is 1


    Example solution

    Example: Solution

    • MRR = vfd

      = (200 m/min)(103 mm/m)(0.25 mm)(7.5 mm)

      = 375,000 mm3/min = 6250 mm3/s

    • Pc = (6250 mm3/s)(2.8 J/mm3)(1.0) = 17,500 J/s

      = 17,500 W = 17.5 kW

    • Accounting for mechanical efficiency, Pg

      = 17.5/0.90 = 19.44 kW


    Final exam review 1206483

    Casting

    Common process attributes:

    • Flow of Molten Liquid Requires Heating

    • Heat Transfer of Liquid in Mold Cavity During and After Pouring

    • Solidification into Component


    Gating system

    Gating System

    Channel through which molten metal flows into cavity from outside of mold

    • Consists of a downsprue, through which metal enters a runner leading to the main cavity

    • At top of downsprue, a pouring cup is often used to minimize splash and turbulence as the metal flows into downsprue


    Pouring calculations

    Pouring Calculations

    Minimum mold filling time, MFT

    MFT =V/Q

    Q: volumetric flow rate, cm3/s

    V: mold cavity volume, cm3


    Chvorinov s rule

    Chvorinov's Rule

    where TST = total solidification time;

    V = volume of the casting;

    A = surface area of casting;

    n = exponent usually taken to have a value = 2; and

    Cm is moldconstant


    Amount and composition

    Amount and Composition

    Figure 6.2 Phase diagram for the copper‑nickel alloy system.


    Shrinkage in solidification and cooling

    Shrinkage in Solidification and Cooling

    Figure 10.8 Shrinkage of a cylindrical casting during solidification and cooling: (0) starting level of molten metal immediately after pouring; (1) reduction in level caused by liquid contraction during cooling (dimensional reductions are exaggerated for clarity).


    Shrinkage in solidification and cooling1

    Shrinkage in Solidification and Cooling

    Figure 10.8 (2) reduction in height and formation of shrinkage cavity caused by solidification shrinkage; (3) further reduction in height and diameter due to thermal contraction during cooling of solid metal (dimensional reductions are exaggerated for clarity).


  • Login