Manufacturing Engineering & Technology
7th Edition
ISBN: 9780133128741
Author: Serope Kalpakjian, Steven Schmid
Publisher: Prentice Hall
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Chapter 11, Problem 52SDP
The optimum shape of a riser is spherical to ensure that it cools more slowly than the casting it feeds; however, spherically shaped risers are difficult to cast, (a) Sketch the shape of a blind riser that is easy to mold, but also has the smallest possible surface-area-to-volume ratio. (b) Compare the solidification time of the riser in part (a) with that of a riser shaped like a right circular cylinder. Assume that the volume of each riser is the same and the height of each is equal to the diameter. (See Example 10.1.)
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Parvinbhai
A cylinder with a diameter of 40 mm and height of 80 mm solidifies in 3 minutes in a sand casting operation. What is the solidification time if the cylinder height is doubled? What is the time if the diameter is doubled?
/The total solidification times of three casting shapes are to be compared: (1) a
sphere with diameter= 10 cm, (2) a cylinder with diameter and length both = 10 cm,
and (3) a cube with each side = 10 cm. The same casting alloy is used in the three
cases. (a) Determine the relative solidification timesfor each geometry. (b) Based on
the results of part (a), which geometric element would make the
best riser? (c) If the mold constant = 3.5 min/cm2 in Chvorinov's rule, compute the
total solidification time for each casting.
Chapter 11 Solutions
Manufacturing Engineering & Technology
Ch. 11 - Describe the differences between expendable and...Ch. 11 - Name the important factors in selecting sand for...Ch. 11 - What are the major types of sand molds? What are...Ch. 11 - List important considerations when selecting...Ch. 11 - What is the function of a core?Ch. 11 - What is the difference between sand-mold and...Ch. 11 - What are composite molds? Why are they used?Ch. 11 - Describe the features of plaster-mold casting.Ch. 11 - Name the type of materials typically used for...Ch. 11 - What are the advantages of pressure casting over...
Ch. 11 - List the advantages and limitations of die...Ch. 11 - What is the purpose of a riser? What is a blind...Ch. 11 - Explain the purpose of a vent and a runner in a...Ch. 11 - How are shell molds produced?Ch. 11 - What keeps the mold together in vacuum casting?Ch. 11 - What is squeeze casting? What are its advantages?Ch. 11 - What are the advantages of the lost-foam casting...Ch. 11 - Prob. 18RQCh. 11 - What are the reasons for the large variety of...Ch. 11 - Why are risers not as useful in die casting as...Ch. 11 - Describe the drawbacks to having a riser that is...Ch. 11 - Why can blind risers be smaller than open-top...Ch. 11 - Why does die casting produce the smallest cast...Ch. 11 - Why is the investment-casting process capable of...Ch. 11 - What differences, if any, would you expect in the...Ch. 11 - Recently, cores for sand casting have been...Ch. 11 - Would you recommend preheating the molds used in...Ch. 11 - Give reasons for, and examples of, using die...Ch. 11 - Referring to Fig. 11.3, do you think it is...Ch. 11 - Explain why squeeze casting produces parts with...Ch. 11 - How are the individual wax patterns attached on a...Ch. 11 - Describe the measures that you would take to...Ch. 11 - You have seen that, even though die casting...Ch. 11 - How are hollow parts with various cavities made by...Ch. 11 - It was stated that the strength-to-weight ratio of...Ch. 11 - How are risers and sprues placed in sand molds?...Ch. 11 - In shell-mold casting, the curing process is...Ch. 11 - Why does the die-casting machine shown in Fig....Ch. 11 - Prob. 39QLPCh. 11 - What are the benefits to heating the mold in...Ch. 11 - The slushy state of alloys refers to that state...Ch. 11 - Can a chaplet also act as a chill? Explain.Ch. 11 - Rank the casting processes described in this...Ch. 11 - Estimate the clamping force for a die-casting...Ch. 11 - In sand casting, it is important that the...Ch. 11 - If an acceleration of 100 g is necessary to...Ch. 11 - A jeweler wishes to produce 24 gold rings in one...Ch. 11 - Describe the procedures that would be involved in...Ch. 11 - The optimum shape of a riser is spherical to...Ch. 11 - Sketch and describe a casting line consisting of...Ch. 11 - Outline the casting processes that would be most...Ch. 11 - Make a list of the mold and die materials used in...Ch. 11 - Write a brief paper on the permeability of molds...Ch. 11 - Light metals commonly are cast in vulcanized...Ch. 11 - It sometimes is desirable to cool metals more...Ch. 11 - The part shown in Fig. P11.59 is a hemispherical...Ch. 11 - Porosity that has developed in the boss of a...Ch. 11 - In Fig. II.1b the gemstones have been cast in...
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- EX.3//A cylindrical riser must be designed for a sand-casting mold. The casting itself is a steel rectangular plate with dimensions 7.5 cm x 12.5 cm x 2.0 cm. Previous observations have indicated that the total solidification time (TTs) for this casting =1.6 min. The cylinder for the riser will have a diameter-to-height ratio=1.0. Determine the dimensions of the riser so that its TTS = 2.0 min.arrow_forwardI am in a hurry, I need the answer as soon as possible, please help.arrow_forwardAsaparrow_forward
- With a solidification factor of 0.97 x 106 s/m², the solidification time (in seconds) for a spherical casting of 200 mm diameter is...arrow_forward. A round casting is 0.2 m in diameter and 1 m in length. Another casting of the same metal iselliptical in cross section, with a major-to-minor axis ratio of 2, and has the same length andcross sectional area as the round casting. Both pieces are cast under the same conditions.What is the difference in the solidification times of the two castings?arrow_forwardA riser in the shape of a sphere is to be designed for a sand casting mould at Simon Castings. The casting is a rectangular plate, with length = 400 mm, width = 250 mm, and thickness = 15 mm. If the total solidification time of the casting itself is known to be 7 min, determine the diameter of the riser so that it will take 30% longer for the riser to solidify.arrow_forward
- Manufacturing Processesarrow_forwardAnswer this broadly.arrow_forwardProblem 1 Suppose we want to cast a magnesium bar 20x20x45 mm³. We are to use a mid gating (exactly at the parting line) system with two runners and multiple ingates (no bends in runner), a top riser of 1:1.2 (D:H) ratio, and the bar lying down. The pouring cup to be used has a height of 10 mm. What would be the riser dimensions for this casting? Use the JB Caine Method (a, b, c = 0.10, 0.06, 1.08). If the choke area is 20 mm?, how long would the pouring time be?arrow_forward
- Which of these factors causes more porosity to form toward the interior of a casting rather than toward the outside? (a) Gasses are less soluble in the solid metal than the liquid, so solidified areas push dissolved gasses toward the interior. (b) Casting under a vacuum causes gasses near the liquid metal surface to be drawn out of the liquid during solidification. (c) The feeding structures of the mold are designed to force entrapped air into the center of the casting. (d) Draft on the mold wall forces air bubbles toward the interior of the solidifying metal. (e) None of the above Non-eutectic alloys (most commercial alloys) solidify over a temperature range. Which of the following statements explains how this affects the casting process. (a) Solidified non-eutectic alloys are especially difficult to remove from metal dies (b) Non-eutectic alloys have significantly less fluidity than pure metals or eutectic alloys. (c) Non-eutectic alloys solidify starting from the outside of the…arrow_forwardWhat is a pattern? What are the consideration necessary while designing pattern in casting?arrow_forward4. Riser (a) What is the purpose of a riser in sand casting? (b) What are the design parameters for a riser, and what are the design constraints that you need to satisfy given your answer in (a)? (c). Assuming you are using a sand casting process, use an example to show the appropriate relationships between the design parameters for your riser that result in the longest solidification time.arrow_forward
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