Manufacturing Engineering & Technology
7th Edition
ISBN: 9780133128741
Author: Serope Kalpakjian, Steven Schmid
Publisher: Prentice Hall
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Textbook Question
Chapter 19, Problem 45QTP
In Fig. 19.2, what flight angle, θ, should be used so that one flight translates to a distance equal to the barrel diameter with each revolution?
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Question 3
The diameter of an extruder barrel is 65 mm and its length is 1.75 m. The screw rotates at 55
rev/min. The screw channel depth is 5.0 mm, and its flight (helix) angle is 18°. The head
pressure at the die end of the barrel is 5x10° Pa. The viscosity of the polymer melt is given as
100 Pa-s. Calculate the volume flow rate of polymer in the barrel.
The drag flow is given by the equation:
Qa = 0.5 n² D² N d̟ sinp cosp
The back pressure flow is given by the equation:
Pn D dễ sin²4
Qb
127L
The details of the extruder screw are given in figure 3.1
W.
channel
width
Perpendicular
Pitch
Helix
( p
angle
()
D
Channel depth de
|Axial
|light|
width
Axial
channel
width
Perpendicular
flight
-Direction of mass flow-
Figure 3.1. Schematic illustration of a typical "Archimedean" extruder screw.
width
Root
diameter
diameter
Review Problems
The extrusion die for a polyethylene parison used in blow
molding has a mean diameter of 18.0 mm. The size of the ring
opening in the die is 2.0 mm. The mean diameter of the parison is
observed to swell to a size of 21.5 mm after exiting the die
orifice. If the diameter of the blow molded container is to be 150
mm, determine (a) the corresponding wall thickness of the
container and (b) the wall thickness of the parison.
An extrusion operation is used to produce a parison whose mean diameter = 27 mm. The inside and outside diameters of the die that produced the parison are 18 mm and 22 mm, respectively. If the minimum wall thickness of the blow-molded container is to be 0.40 mm, what is the maximum possible diameter of the blow mold?
Chapter 19 Solutions
Manufacturing Engineering & Technology
Ch. 19 - What are the forms of raw materials for processing...Ch. 19 - What is extrusion? What products are produced by...Ch. 19 - Describe the features of an extruder screw and...Ch. 19 - How are injection-molding machines rated?Ch. 19 - What is (a) a parison, (b) a plastisol, and (c) a...Ch. 19 - How is thin plastic film produced?Ch. 19 - List several common products that can be made by...Ch. 19 - What similarities and differences are there...Ch. 19 - Explain the difference between potting and...Ch. 19 - What is thermoforming?
Ch. 19 - Describe runner, gate, sprue, and well.Ch. 19 - Describe the advantages of cold-forming plastics...Ch. 19 - What are the characteristics of filament-wound...Ch. 19 - Describe the methods that can be used to make...Ch. 19 - What is pultrusion? Pulforming?Ch. 19 - How are very thin plastic film produced?Ch. 19 - What process is used to make foam drinking cups?Ch. 19 - If a polymer is in the form of a thin sheet, is it...Ch. 19 - How are polymer fibers made? Why are they much...Ch. 19 - What are the advantages of coextrusion?Ch. 19 - Explain how latex rubber gloves are made.Ch. 19 - Describe the features of a screw extruder...Ch. 19 - Explain why injection molding is capable of...Ch. 19 - Prob. 24QLPCh. 19 - Explain the reasons that some plastic-forming...Ch. 19 - Describe the problems involved in recycling...Ch. 19 - Can thermosetting plastics be used in injection...Ch. 19 - Inspect some plastic containers, such as those...Ch. 19 - An injection-molded nylon gear is found to contain...Ch. 19 - Explain why operations such as blow molding and...Ch. 19 - Prob. 31QLPCh. 19 - Typical production rates are given in Table 19.2....Ch. 19 - What determines the cycle time for (a) injection...Ch. 19 - Does the pull-in defect (sink marks) shown in Fig....Ch. 19 - What determines the intervals at which the...Ch. 19 - Identify processes that would be suitable for...Ch. 19 - Identify processes that are capable of producing...Ch. 19 - Inspect several electrical components, such as...Ch. 19 - Inspect several similar products that are made of...Ch. 19 - What are the advantages of using whiskers a...Ch. 19 - Construct a table that lists the main...Ch. 19 - Estimate the die-clamping force required for...Ch. 19 - A 2-Iitcr plastic beverage bottle is made by blow...Ch. 19 - Consider a Styrofoam drinking cup. Measure the...Ch. 19 - In Fig. 19.2, what flight angle, , should be used...Ch. 19 - Make a survey of a variety of sports equipment,...Ch. 19 - Explain the design considerations involved in...Ch. 19 - Give examples of several parts suitable for insert...Ch. 19 - Give other examples of design modifications in...Ch. 19 - With specific examples, discuss the design issues...Ch. 19 - Die swell in extrusion is radially uniform for...Ch. 19 - Inspect various plastic components in a typical...Ch. 19 - It is well known that plastic forks, spoons, and...Ch. 19 - Prob. 55SDPCh. 19 - Make a survey of the technical literature, and...Ch. 19 - Prob. 57SDPCh. 19 - Prob. 58SDPCh. 19 - Prob. 59SDPCh. 19 - Examine some common and colorful plastic poker...Ch. 19 - Obtain different styles of toothpaste tubes,...Ch. 19 - By incorporating small amounts of blowing agent,...
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- 3. A dimension of 225.00 mm is specified for a particular injection moulded component manufactured in ABS. Calculate the corresponding dimension to which the mould cavity should be machined, using the value of shrinkage given in the table below. Typical values of shrinkage for moldings of selected thermoplastics. Shrinkage, mm/mm (in/in) Shrinkage, Plastic Plastic mm/mm (in/in) ABS Polyethylene Polystyrene 0.006 0.025 Nylon-6,6 Polycarbonate 0.020 0.004 0.007 PVC 0.005arrow_forwardConsider a single screw melt extruder with the following dimensions: D = 6.0 cm, L = 60.0 cm, H = 0.6 cm, W = 6.0 cm & helix angle of 17.4º. The capacity at open discharge is 10 kg/hour and the viscosity of the polymer melt is 500 Ns/m?. a. Determine the pressure when Q = 5 kg/hr. b. Determine the pressure when a round die of diameter 3.00 cm and length 10.0 cm is attached to the extruder.arrow_forwardAn extrusion operation produces continuous tubing with outside diameter = 5 cm and inside diameter = 4.25 cm. The extruder barrel has a diameter = 10 cm and length = 3 m. The screw rotates at 50 rev/min; it has a channel depth = 0.63 cm and flight angle = 16°. The head pressure has a value of 2.5 MPa and the viscosity of the polymer melt is 55 Pa-s. Under these conditions, what is the production rate in length of tube/min, assuming the extrudate is pulled at a rate that eliminates the effect of die swell (i.e., the tubing has the same OD and ID as the die profile)?arrow_forward
- 12) Assuming injection molding pressures of 10kpsi, estimate the die clamping force required for injection molding 10 identical 1.5-in.-diameter disks in one die. Assume runner area is 5.0 in?. Discuss the affects of reorienting the disks.arrow_forwardAn extruder barrel has a diameter of 4.0 in and an L/D ratio of 28. The screw channel depth = 0.25 in, and its pitch is 4.8 in. It rotates at 60 rev/min. The viscosity of the polymer melt is 100 x 10-4 lb-sec/in2. What head pressure at exit is required to obtain a net volume flow rate of 150 in3/min? Assume that you are extruding 1/2 in PVC pipe (schedule 40) using the conditions above. How long would it take to extrude a 30 foot section? Be sure to note in your solution where you got your dimensions for the PVC pipe.arrow_forwardWhat kind of system is compression molding machine? open, closed, or isolated? Explain.arrow_forward
- An extruder has barrel diameter and length of 150 mm and 3.1 m, respectively. The screw rotational speed = 55 rev/min, channel depth = 8 mm, and flight angle = 18°. The plastic melt has a shear viscosity = 175 Pa-s. Determine: (a) the extruder characteristic, (b) the shape factor Ks for a circular die opening with diameter = 4.0 mm and length = 15 mm, and (c) the operating point (Q and p).arrow_forwardWhich law of thermodynamics best apply to compression molding machine? Explain why.arrow_forward10) Die swell in extrusion is radially uniform for circular cross-sections, but is not uniform for other cross-sections. Recognizing this fact, make a qualitative sketch of a die profile that will produce each of the following extruded polymer: a. square b. triangular a) Describe the features of an extruder screw and comment on their specific functions. b) List the differences between the barrel section of an extruder and that on an injection-molding machine.arrow_forward
- I only need the answer to question 2. I provided the correct answer for question 1 1)An extruder barrel has a diameter of 4.0 in and an L/D ratio of 28. The screw channel depth = 0.25 in, and its pitch is 4.8 in. It rotates at 60 rev/min. The viscosity of the polymer melt is 100 x 10-4 lb-sec/in2. What head pressure at exit is required to obtain a net volume flow rate of 150 in3/min? Assume that you are extruding 1/2 in PVC pipe (schedule 40) using the conditions above. -2193 lb/in2 2) How long would it take to extrude a 30 foot section? Be sure to note in your solution where you got your dimensions for the PVC pipe.arrow_forwardIn a particular extruder screw the channel depth is 2.4 mm, the screw diameter is 50 mm, the screw speed is 100 rev/min, the flight angle is 17o and the pressure varies linearly over the screw length of 1000 mm from zero at entry to 20 MN/m2 at the die entry. The plastic viscosity was 200 Ns/m2. · Estimate the operating point for the extruder when it is combined with an oval die with dimension of 20x 3 mm.arrow_forwardAn injection molded polyethylene part has a dimension of 6.25 cm. A new material, polycarbonate, is used in the same mold. What is the expected corresponding dimension of the polycarbonate molding?arrow_forward
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