# ms Term paper

Topics: Fluid dynamics, Casting, Volume Pages: 17 (882 words) Published: October 18, 2014
Casting Processes
Sand Casting
Investment Casting

Die Casting
Continous Casting
Centrifugal Casting

Process Physics

1
A1
V1

2
V2

A2

1

h1

2

Flow characteristics

rD

Reynold’s number
Re 

r : density (kg/m3)
v : velocity of the fluid (m/s)
D : diameter of the channel (m)
Viscosity (η) is a measure of a fluid’s resistance to flow :

• If Re < 2000:
laminar flow
If 2000< Re < 20000:
laminar+turbulent (mixed)
If 20000 < Re:
turbulent flow (cavitation)

Laminar Flow

Turbulent Flow

 Ns 
 m2 
 

• What is the casting yield of process described below?

10 Kg

5 Kg

Exercise-1
A certain mold is used to cast a cylindrical part. The cylinder diameter and height is 10 mm and 30 mm respectively. 3000
mm3 liquid is poured into the mold in 10 sec. The horizontal runner has a square cross-section with dimension of 2 mm.
Determine;
a) The casting yield
b) The volumetric flow rate of molten metal
c) The velocity of the liquid at the runner

Exercise-2
In a die casting application the molten metal is fed to a
vacuumed die cavity at the same height, i.e. the inlet gate to the cavity and the molten metal outside are at the same
height. The outside supply is open to the atmosphere. The
density is 8000 kg/m3 and the supply velocity can be assumed

to be negligible. (Atmospheric pressure is 100 kPa.) What is the inlet velocity of the metal into the cavity (m/s)?

Exercise-3
A sphere with radius 300mm will be cast in a die with a vacuum casting process as shown below. The molten metal (ρ=7800kg/m3) passes through the pouring hole. The vacuum in the die is applied after the pouring channel is fully filled. The diameter of the pouring channel is 60mm (Both the pouring channel and the runner are cylindrical). During solidification the casting shrinks by 15%. Assume that the pouring time is 1/10 of the solidification time. Calculate the followings: a) The required volume of the molten metal to be poured and the filling time of the die. b) The maximum runner diameter and the velocity in the runner channel in order to have laminar flow (Re≤2000).

c) The velocity of the liquid in the pouring channel
d) The pressure in the pouring channel .
C= 0.02s/mm2 ; η=2.23 Pa.s

Runner area

Pouring hole

Pouring hole
D60mm
vchannel

Vrunner

R300mm

P=0 (Vacuum)

Pouring channel

Exercise-4
A sprue is 30.48 cm long and has a diameter of 12.7 cm at the top. If a flow rate of 655.48 cm^3/s is to be achieved, what should be the diameter at the bottom of the sprue? Will the sprue aspirate? Explain.

Exercise-5
Pure aluminum is being poured into a sand mold. The metal level

in the pouring basin is 25.4 cm above the metal level in the mold, and the runner is circular with a 1.016 cm diameter. What is the

velocity and rate of the flow of the metal into the mold? Is the flow turbulent or laminar?

Exercise-6
For the sprue described in Exercise 5, what runner diameter is needed to ensure a Reynolds number of 2000? How long will a

327.74 cm^3 casting take to fill with such a runner?

Exercise-7
In the casting of steel under certain mold conditions, the mold constant in Chvorinov’s Rule is known to be 4.0 min/cm2, based on previous experience. The casting is a flat plate whose length 30 cm, width 10 cm and thickness 20 mm. Determine how long it will take to solidify.

Exercise-8
A disc shaped part is to be cast out of aluminum. The diameter of disc is 500 mm and its thickness is 20 mm. If the mold
constant, C, is 2 sec/mm2 in Chvorinov’s Rule, how long will it take the...