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Jobisdone [24]
4 years ago
14

Explain the mechanical property issues that could be caused if pressure is not correctly controlled in Injection Molding process

.
Engineering
1 answer:
KiRa [710]4 years ago
6 0

Answer:

As soon as the material that is molded contacts the mold in the injection operation, it begins to cool and solidify. For this reason the injection must occur quickly, so that the cavity is filled while the material is molten. This is achieved with a high injection pressure since the compound is very viscous, despite the high temperatures. The molten material must overcome the resistance offered by friction, in the nozzle and cavity, which could not be done if the pressure is lower than required, preventing the proper filling of the mold.

If the injection pressure inside the mold is higher than the appropriate one, it exceeds its closing force, the partition line of the mold is forced to open; allowing the molded compound to escape from the cavity (resulting in burr and additional work is required in order to eliminate it).

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Thermosets burn upon heating. a)-True b)- false?
hram777 [196]

Answer:

true

Explanation:

True, there are several types of polymers, thermoplastics, thermosets and elastomers.

Thermosets are characterized by having a reticulated structure, so they have low elasticity and cannot be stretched when heated.

Because of the above, thermosetting polymers burn when heated.

5 0
3 years ago
g A steel water pipe has an inner diameter of 12 in. and a wall thickness of 0.25 in. Determine the longitudinal and hoop stress
zvonat [6]

Answer:

a) \mathbf{\sigma _ 1 = 4800 psi}

     \mathbf{ \sigma _2 = 0}

b)\mathbf{\sigma _ 1 = 6000 psi}

  \mathbf{ \sigma _2 = 3000 psi}

Explanation:

Given that:

diameter d = 12 in

thickness t = 0.25 in

the radius = d/2 = 12 / 2 = 6 in

r/t = 6/0.25 = 24

24 > 10

Using the  thin wall cylinder formula;

The valve A is opened and the flowing water has a pressure P of 200 psi.

So;

\sigma_{hoop} = \sigma _ 1 = \frac{Pd}{2t}

\sigma_{long} = \sigma _2 = 0

\sigma _ 1 = \frac{Pd}{2t} \\ \\ \sigma _ 1 = \frac{200(12)}{2(0.25)}

\mathbf{\sigma _ 1 = 4800 psi}

b)The valve A is closed and the water pressure P is 250 psi.

where P = 250 psi

\sigma_{hoop} = \sigma _ 1 = \frac{Pd}{2t}

\sigma_{long} = \sigma _2 = \frac{Pd}{4t}

\sigma _ 1 = \frac{Pd}{2t} \\ \\ \sigma _ 1 = \frac{250*(12)}{2(0.25)}

\mathbf{\sigma _ 1 = 6000 psi}

\sigma _2 = \frac{Pd}{4t} \\ \\  \sigma _2 = \frac{250(12)}{4(0.25)}

\mathbf{ \sigma _2 = 3000 psi}

The free flow body diagram showing the state of stress on a volume element located on the wall at point B is attached in the diagram below

8 0
4 years ago
Q2) An engineer borrowed $3000 from the bank, payable in six equal end-of-year payments at 8%. The bank agreed to reduce the int
tatyana61 [14]
Answer is: $637.28; just did the math but i really don’t want to type it all out.
6 0
3 years ago
A motor is mounted on a platform that is observed to vibrate excessively at an operating speed of 6000 rpm producing a 250-N for
vichka [17]

Answer:

The amplitude of the absorbed mass can be found

for ka:

X_{a} =0.002m=\frac{F_{0} }{K_{a} } =\frac{250}{K_{a} } =125000N/m

now

w^2=\frac{K_{a} }{m_{a} } \\m_{a} =\frac{K_{a} }{w^2} =\frac{125000}{[6000*2\pi /60]^2} =0.317kg

4 0
3 years ago
__________ affect(s) the amount of air conditioning required.
Grace [21]

Answer:

Option D

All the above

Explanation:

Depending with the number of occupants in a building, the number of air conditioners required can either be increased or reduced. For instance, if the building is to be a classroom of over 50 students, 1 air-conditioner can't serve effectively. Similarly, the activity of occupants also dictate the amount of air conditioners required since if it's a gym room where occupants exercise often then the air conditioners required is different from if the room was to serve as a  lounge. The appliances that also operate in a room require that air conditioners be installed as per the heat that may be generated by the appliances.

5 0
4 years ago
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