Industrial Engineering Chapter 5 There Are Several Drosstrap Designs Use Infoundries Good Discussion Trap Design Prg

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

0.50 in.

0.45 in.

4.00 in.

The sketch for a typical green-sand casting pat-

tern for the spool is shown below. A cross-

sectional view is also provided to clearly in-

(b) Locating pins will be needed in the pattern

plate to ensure that these features align

properly.

(c) Shrinkage allowance = 5/32 in./ft.

(d) Machining allowance = 1/16 in.

5.71 Repeat Problem 5.70, but assume that the alu-

minum spool is to be cast using expendable-

pattern casting. Explain the important differ-

some variations in the patterns produced by

students depending on which dimensions are as-

signed a machining allowance. The important

elements of this pattern are as follows (dimen-

sions in inches):

0.56 in.

0.52 in.

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

Section A-A

3.00

2.00

2.50

1.00

0.50

2.00 1.00

1.00

2.50

4.00

5.00

R = 0.75

Material: Low-carbon steel

Density: 0.26 lb/in3

All dimensions in inches

3.00

F=pA

5.73 The optimum shape of a riser is spherical to

are difficult to cast. (1) Sketch the shape of a

5.2).

A sketch of a blind riser that is easy to cast is

Hemisphere

h=r

r

Note that the height of the cylindrical portion

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

5.74 The part shown in the accompanying figure

is a hemispherical shell used as an acetabular

(mushroom shaped) cup in a total hip replace-

ment. Select a casting process for this part

=C“πd2h/4

(πd2/2 + πdh)#

=Cdh

2d+ 4h= 4 min

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

5.77 A sprue is 12 in. long and has a diameter of 5

in. at the top, where the metal is poured. The

molten metal level in the pouring basin is taken

as 3 in. from the top of the sprue for design pur-

poses. If a ﬂow rate of 40 in3/s is to be achieved,

what should be the diameter of the bottom of

the sprue? Will the sprue aspirate? Explain.

It designed on the principle that a trap at the

end of a runner will take the metal through the

runner and keep it away from the gates. The

design shown is a wedge-type trap. Metal en-

tering the runner contacts the wedge, and the

leading front of the metal wave is chilled and

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

5.79 Pure aluminum is being poured into a sand

mold. The metal level in the pouring basin is

10 in. above the metal level in the mold, and

the runner is circular with a 0.4 in. diameter.

What is the velocity and rate of the ﬂow of the

metal into the mold? Is the ﬂow turbulent or

laminar?

would occur with the normal case of a pouring

basin on top of the sprue with a large cross-

sectional area), then v1= 0. The velocity at

Pure aluminum has a density of 2700 kg/m3

m),

ameter should be decreased to bring Re below

20,000 or so.

5.80 For the sprue described in Problem 5.79, what

runner diameter is needed to ensure a Reynolds

number of 2000? How long will a 20 in3casting

take to fill with such a runner?

= 0.0266 in3/sec

This means that a 20 in3casting would take 753

5.81 How long would it take for the sprue in Problem

5.79 to feed a casting with a square cross-section

of 6 in. per side and a height of 4 in.? Assume

in2. The velocity will change as the mold fills,

because the pouring basin height above the

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

A= 36 in2,tis found to be 14.7 s. As a compar-

5.79, the mold would require approximately 13

200 mm ×400 mm is filled with aluminum with

no superheat. Determine the final dimensions

5.1 on p. 206, the volumetric contraction for

aluminum is 6.6%. Therefore, the box volume

will be

V= (1 −0.066)(0.008 m3) = 0.007472 m3

5.83 The constant Cin Chvorinov’s rule is given as

of 125 mm. Estimate the time for the cast-

Assuming the cylinder cools evenly, how much

time must transpire after pouring the molten

= 2 hπ

4(75)2i+π(75)(125)

= 38,290 mm2

V=π

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

that 0.533(624)=333 s is needed. However, this

would not be sufficient because an annular sec-

tion at an outside radius has more material than

has to wait 602 s before the mold can be broken.

5.84 If an acceleration of 100 g is necessary to pro-

duce a part in true centrifugal casting and the

part has an inner diameter of 10 in., a mean

outer diameter of 14 in., and a length of 25 ft.,

what rotational speed is needed?

a 0.5 in. diameter. The rings are located in

and 0.5-in. long runner to the sprue. Estimate

rings, runners, and sprues. The specific gravity

of gold is 19.3.

then 0.18 in3, and a total volume for 20 rings of

so this volume component is

V= 20 π

4d2L= 20 π

4(0.125 in.)2(0.5 in.)

ended question that requires considerable focus

work problem.

Design

p. 203). Make appropriate sketches and explain

the important features of each design.

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

Fluidity index

fects and discontinuities in cast products. Re-

view each one and offer design solutions to avoid

them.

Riser

(c)

(d)

Cold tearing

5.90 Design a test method to measure the perme-

ability of sand for sand casting.

5.91 Describe the procedures that would be involved

in making a bronze statue. Which casting pro-

cess or processes would be suitable? Why?

5.92 Porosity developed in the boss of a casting is

illustrated in the accompanying figure. Show

that by simply repositioning the parting line of

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

5.93 For the wheel illustrated in the accompanying

figure, show how (a) riser placement, (b) core

1 in.

(25 mm)

1.5 in.

(38 mm)

1 in.

(25 mm)

1 in.

Ribs or brackets

(a)

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

5.96 Three sets of designs for die casting are shown

in the accompanying figure. Note the changes

(1)

(2)

(1) (2)

(3)

(1) (2)

•Heated molds will maintain temperatures

higher than room temperature, but will

heat from the molten metal will then warm

is higher (permanent-mold processes).

the rate of heat loss by conduction.

5.98 Design an experiment to measure the constants

Cand nin the Chvorinov’s Rule [Eq. (5.11)].

•The most straightforward tests involve

lidified. This inevitably results in spilled

molten metal and may therefore a difficult

test procedure to use.

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

1.0 in.

10 in.

0.45±0.05 in.

Ra=125 in.

Process Note Cost rationale

Sand casting This is probably

best.

Shell-mold casting (a)

Lost Foam Need tooling to

blanks. Too low of

production rate to

justify, unless rapid

tooling is used.

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.

This material is protected by Copyright and written permission should be obtained from the publisher prior to any prohibited

reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or

likewise. For information regarding permission(s), write to:

Rights and Permissions Department, Pearson Education, Inc., Upper Saddle River, NJ 07458.