Casting Flashcards

In the manufacturing process, what stage immediately follows Conceptual Design?

Design for Manufacture

What are the three categories of unit manufacturing processes listed for transforming raw materials into shaped parts?

Injection molding, thermoforming, and machining

Name four methods used for the assembly and joining of product parts.

Fastening, adhesive bonding, soldering/brazing, and diffusion bonding

According to the source, approximately when did the practice of metal casting begin?

Between 5000 and 3000 BC

What is the approximate melting temperature of Aluminum?

660 degree C

What is the approximate melting temperature for Iron and Steels?

1500 degree C

List the 5 general process steps for all casting methods

Pattern/mold making, melt preparation, mold filling, solidification/cooling, and removal/breakout

What is a primary advantage of casting regarding part complexity?

It allows for the creation of complex parts as a single integral unit.

Cope

The top half of a sand casting mold

Drag

The bottom half of a sand casting mold

In sand casting, what is the purpose of the Sprue?

It acts as the vertical channel through which molten metal enters the mold.

What is the function of a Riser in a casting mold?

It serves as a reservoir of liquid metal to compensate for shrinkage during solidification

What component is used in a mold to create internal surfaces or hollow features in a casting?

A core (usually made of sand).

In sand casting pattern making, what is the purpose of a ‘shrinkage allowance’?

To account for the contraction of the metal as it cool and solidifies.

Why is a ‘draft angle’ included in the design of a casting pattern?

To allow the pattern to be removed from the sand mold without damaging the cavity.

How does the cooling rate generally affect the microstructure of a cast part?

The cooling rate directly determines the resulting grain structure and properties.

Between thick and thin cast parts, which are typically stronger?

Thinner cast parts

Viscosity

A fluid's resistance to shear forces.

Reynolds Number (Re)

Re=vDρ/η​ (where v is velocity, D is diameter, ρ is density, and η is viscosity).

In casting gating systems, at what Reynolds Number (Re) value does turbulence typically become severe?

Values in excess of 20,000

What defect is caused by the reaction of liquid metal with air, forming a scum on the surface?

Dross (or slag)

During the flow stage of sand casting, how is the runner velocity (vrun​) estimated using Bernoulli’s Principle?

vrun = sqrt(2gh1)

In sand casting, where does the clamping force (Fclamp​) primarily come from to keep the mold halves together?

The weight of the cope (mcope*g)

What is the Heat Energy (Eheat​) required for a mass formula

Eheat = ρVcΔT

What is the Melt Energy (Emelt​) required for phase change formula

Emelt​=ρVH (where H is latent heat).

Chvorinov’s Rule Formula

tsolidify​=C(A/V​)^2 (where V is volume and A is surface area).

In sand casting, what factor typically limits the rate of solidification?

The rate of heat transfer through the sand mold.

In die casting, what factor typically limits the rate of solidification?

The rate of heat transfer at the die-part interface.

Thermal Diffusivity (α) formula

α = ​k/ρcp​ (where k is conductivity, ρ is density, and cp​ is specific heat capacity).

Compare the thermal diffusivity (α) of the tool versus the part in injection molding.

The thermal diffusivity of the tool is much greater than that of the polymer part (αtool​>αpolymer​).

What is the typical range of pressures used in Die Casting?

1 to 1000 MPa (150 psi to 150 kpsi).

Why do die casting dies require tool-grade steel or special materials?

To withstand high temperatures and prevent heat-induced cracking or corrosion.

What is the main procedural difference between hot-chamber and cold-chamber die casting?

In cold-chamber, the metal is poured into the shot sleeve from an external source, whereas in hot-chamber, the injection mechanism is submerged in the molten metal.

Misrun

Solidification of the metal occurs before the mold cavity is completely filled.

Cold Shut

A lack of fusion between two streams of metal due to premature freezing.

Cold Shot

Small globules of metal splatter that become entrapped in the final casting.

What causes a 'shrinkage cavity' in a cast part?

A surface depression caused by the internal contraction of the metal during solidification.

What are the two primary goals when designing sprue, runner, and gate systems?

To ensure rapid mold filling while minimizing turbulence and erosion

Name the casting process that uses a ceramic mold and a wax pattern to achieve excellent surface finishes.

Investment Casting

What is a significant advantage of Lost Foam Casting regarding design complexity?

It requires no cores and allows for greater design freedom.

In terms of manufacturing attributes, how does the tooling cost of Sand Casting compare to Die Casting?

Sand casting has low initial investment in tooling, while die casting has high tooling costs.

What is the typical tolerance range for Sand Casting?

0.7 mm to 2.0 mm

What is the typical tolerance range for Die Casting?

0.08 mm to 0.2 mm

Mushy Zone

The temperature region in binary alloy solidification where both liquid and solid phases coexist.

Dendrites

Tree-like branched structures that form during the solidification of alloys.

In the context of cast microstructure, what is the 'chill zone'?

The outer layer of fine, randomly oriented grains formed due to rapid cooling at the mold wall.

How does increasing the melt temperature affect the fluidity of the molten metal and the overall process cost?

It improves fluidity but increases costs due to higher energy use and longer cooling times.

What is the typical labor intensity and cycle time for Sand Casting?

It is labor-intensive with a long cycle time.

Why is Investment Casting often used for jewelry and jet engine parts?

Because it provides excellent surface finish and can handle high-melting-point metals.

What is the 'parting line' in a sand mold?

The interface where the cope (top) and drag (bottom) sections of the mold meet.

In the cooling process of a casting, what causes the temperature to remain constant at the melting point for a period of time?

The release of latent heat during the phase change from liquid to solid.

What is a 'distortion allowance' in pattern design?

An adjustment to the pattern shape to compensate for warping caused by non-uniform cooling.

Which casting process is most suitable for production quantities of 2,500 units and up with high surface detail?

Die Casting

According to Chvorinov's Rule, if the volume-to-surface area ratio (V/A) of a part doubles, how does the solidification time change?

It increases by a factor of four.

What is the Fourier’s Law for heat conduction formula

q=-kdT/dx (where q is heat flux and k is thermal conductivity)