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1. Injection Molding The gate and runner system that you use to move plastic into an injection molding cavity are critical design parameters. Suppose the polymer material that you are using has a viscosity μ of 950Ns/m² under your processing conditions. Suppose your initial gate and round runner system is 3.5 mm in diameter and approximately 25 mm long. Your part has a volume of approximately 20000 mm³ and a projected area of approximately 1800 mm². Your Engel machine claims that it can melt and deliver material at a rate of 165 cm³/sec. Assume that there is no pressure loss between the mold cavity and the runner system, and none of the clamping force is lost in deforming the molds when they come together. (a) What is shortest injection time for the part? (b) Recall that the equation for Newtonian flow through a round channel is: Prª Q 8μL where Q is the flow (m³/s), P is the pressure change (Pa), r is the radius of the channel (m), u is viscosity (Ns/m²), and L is the length of the channel (m). What is the pressure required to inject your part if you use the smallest injection time? (c) What happens if you change the injection time to 1 second instead? What is the pressure required? What is the required clamping force? What happens to the clamping force if you make your channel radius 10 percent larger? (d) Why is it ok to increase the injection time to 1 second? What prevents you from using a 10 second injection time? What are the disadvantages of making a 10mm radius runner channel?

1. Injection Molding The gate and runner system that you use to move plastic into an injection molding cavity are critical design parameters. Suppose the polymer material that you are using has a viscosity μ of 950Ns/m² under your processing conditions. Suppose your initial gate and round runner system is 3.5 mm in diameter and approximately 25 mm long. Your part has a volume of approximately 20000 mm³ and a projected area of approximately 1800 mm². Your Engel machine claims that it can melt and deliver material at a rate of 165 cm³/sec. Assume that there is no pressure loss between the mold cavity and the runner system, and none of the clamping force is lost in deforming the molds when they come together. (a) What is shortest injection time for the part? (b) Recall that the equation for Newtonian flow through a round channel is: Prª Q 8μL where Q is the flow (m³/s), P is the pressure change (Pa), r is the radius of the channel (m), u is viscosity (Ns/m²), and L is the length of the channel (m). What is the pressure required to inject your part if you use the smallest injection time? (c) What happens if you change the injection time to 1 second instead? What is the pressure required? What is the required clamping force? What happens to the clamping force if you make your channel radius 10 percent larger? (d) Why is it ok to increase the injection time to 1 second? What prevents you from using a 10 second injection time? What are the disadvantages of making a 10mm radius runner channel?

Elements Of Electromagnetics
Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
Section: Chapter Questions
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1. Injection Molding The gate and runner system that you use to move plastic into an injection molding cavity are critical design parameters. Suppose the polymer material that you are using has a viscosity μ of 950Ns/m² under your processing conditions. Suppose your initial gate and round runner system is 3.5 mm in diameter and approximately 25 mm long. Your part has a volume of approximately 20000 mm³ and a projected area of approximately 1800 mm². Your Engel machine claims that it can melt and deliver material at a rate of 165 cm³/sec. Assume that there is no pressure loss between the mold cavity and the runner system, and none of the clamping force is lost in deforming the molds when they come together. (a) What is shortest injection time for the part? (b) Recall that the equation for Newtonian flow through a round channel is: Pr4 8μL where Q is the flow (m³/s), P is the pressure change (Pa), r is the radius of the channel (m), u is viscosity (Ns/m²), and L is the length of the channel (m). What is the pressure required to inject your part if you use the smallest injection time? (c) What happens if you change the injection time to 1 second instead? What is the pressure required? What is the required clamping force? What happens to the clamping force if you make your channel radius 10 percent larger? (d) Why is it ok to increase the injection time to 1 second? What prevents you from using a 10 second injection time? What are the disadvantages of making a 10mm radius runner channel?
Transcribed Image Text:1. Injection Molding The gate and runner system that you use to move plastic into an injection molding cavity are critical design parameters. Suppose the polymer material that you are using has a viscosity μ of 950Ns/m² under your processing conditions. Suppose your initial gate and round runner system is 3.5 mm in diameter and approximately 25 mm long. Your part has a volume of approximately 20000 mm³ and a projected area of approximately 1800 mm². Your Engel machine claims that it can melt and deliver material at a rate of 165 cm³/sec. Assume that there is no pressure loss between the mold cavity and the runner system, and none of the clamping force is lost in deforming the molds when they come together. (a) What is shortest injection time for the part? (b) Recall that the equation for Newtonian flow through a round channel is: Pr4 8μL where Q is the flow (m³/s), P is the pressure change (Pa), r is the radius of the channel (m), u is viscosity (Ns/m²), and L is the length of the channel (m). What is the pressure required to inject your part if you use the smallest injection time? (c) What happens if you change the injection time to 1 second instead? What is the pressure required? What is the required clamping force? What happens to the clamping force if you make your channel radius 10 percent larger? (d) Why is it ok to increase the injection time to 1 second? What prevents you from using a 10 second injection time? What are the disadvantages of making a 10mm radius runner channel?
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