# Simulation of Jetting in Injection Molding Using a Finite Volume Method

^{*}

## Abstract

**:**

## 1 Introduction

## 2. Melt Flow Theory

#### 2.1. Governing Equations

#### 2.2. Boundary Conditions

_{a}and T

_{w}represent the heat exchange coefficient and mold wall temperature, respectively.

#### 2.3. Trace of Melt Front

#### 2.4. Viscous Model

## 3. Numerical Method

#### 3.1. Discrete Momentum Equation

_{p}is the volume of P, the symbol with subscript f represents the corresponding value convected through face f.

#### 3.2. Discrete Continuity Equation

#### 3.3. Discrete Energy Equation

#### 3.4. Time Step Determination

## 4. Results and Analysis

#### 4.1. Jetting Evolution and the Induced Mechanism

#### 4.2. Injection Speed

#### 4.3. Melt Temperature

#### 4.4. Gate Location

#### 4.5. Experimental Verification

^{2}∙K) (Moldflow suggested) which may be larger than the actual value. Thus, the simulated the melt front temperature may be lower than the real melt temperature, which increases the viscous resistance for buckling swinging. Since the times of the melt contacting the air in the middle and rear jet are shorter than that of the front jet, the decreased temperatures in these two sections are less than that of the front and the simulated difference does not induce significant influence on the buckling flow.

## 5. Conclusions

## Acknowledgements

## Author Contributions

## Conflicts of Interest

## References

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**Figure 1.**The simulated jetting evolution and buckling flows at (

**a**) 0.2 s; (

**b**) 0.4 s; (

**c**) 0.6 s; (

**d**) 1.0 s; (

**e**) 1.3 s; and (

**f**) 1.6 s.

**Figure 3.**The buckling flow evolution varies with injection speeds of (

**a**) 100 mm/s (t = 1.85 s); (

**b**) 200 mm/s (t = 1.35 s); and (

**c**) 300 mm/s (t = 0.95 s).

**Figure 5.**Buckling flow shapes at the end of jetting at melt temperatures (

**a**) 235 °C (1.55 s); (

**b**) 245 °C (1.45 s); (

**c**) 255 °C (1.35 s); (

**d**) 265 °C (1.2 s); (

**e**) 275 °C (1.1 s); and (

**f**) 285 °C (0.95 s).

**Figure 6.**Melt shapes near the gate in the initial filling stage for gate locations at (

**a**) 1 mm; and (

**b**) 0 mm away to mold wall.

**Figure 7.**Comparison between simulated jetting (

**a**) and experimental jetting (

**b**) for the plate part molding.

Seven-constant viscosity | Other |
---|---|

$n=0.3263$ | $\rho =1024.7\text{\hspace{0.17em}}\text{kg}/{\mathrm{m}}^{3}$ |

${\tau}^{*}=19274.6\text{\hspace{0.17em}Pa}$ | ${C}_{p}=2143\text{\hspace{0.17em}}\mathrm{J}/\left(\text{kg}\cdot \mathbb{C}\right)$ |

${A}_{1}=33.685$ | $k=0.25\text{\hspace{0.17em}}\mathrm{W}/\left(\mathrm{m}\cdot \mathbb{C}\right)$ |

${\tilde{A}}_{2}=51.6\text{\hspace{0.17em}}\mathrm{K}$ | |

${D}_{1}=1.01748e+15\text{\hspace{0.17em}Pa}\cdot \mathrm{s}$ | |

${D}_{2}=263.15\text{\hspace{0.17em}}\mathrm{K}$ | |

${D}_{3}=0\text{\hspace{0.17em}}\mathrm{K}/\text{Pa}$ |

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**MDPI and ACS Style**

Hua, S.; Zhang, S.; Cao, W.; Wang, Y.; Shao, C.; Liu, C.; Dong, B.; Shen, C.
Simulation of Jetting in Injection Molding Using a Finite Volume Method. *Polymers* **2016**, *8*, 172.
https://doi.org/10.3390/polym8050172

**AMA Style**

Hua S, Zhang S, Cao W, Wang Y, Shao C, Liu C, Dong B, Shen C.
Simulation of Jetting in Injection Molding Using a Finite Volume Method. *Polymers*. 2016; 8(5):172.
https://doi.org/10.3390/polym8050172

**Chicago/Turabian Style**

Hua, Shaozhen, Shixun Zhang, Wei Cao, Yaming Wang, Chunguang Shao, Chuntai Liu, Binbin Dong, and Changyu Shen.
2016. "Simulation of Jetting in Injection Molding Using a Finite Volume Method" *Polymers* 8, no. 5: 172.
https://doi.org/10.3390/polym8050172