**5.4.1 Input the process parameters**

We set the melt temperature, cavity temperature and cooling pipe diameter to be 150 C, 40 C and 8mm respectively. The coolant is water ( 25 C) and Reynolds number is 10000. Finally, we use t software to calculate cooling time.

### **5.4.2 Simulation results of cooling time**

We obtain coolant temperature, coolant velocity, cooling pipe temperature and Reynolds number of coolant (Fig. 13, Fig. 14, Fig. 15) after analyzing cooling process.

According to Fig. 13, Fig. 14, Fig. 15, we find that pipe and coolant temperature distribution in the third cooling system is much more homogeneous than that in the former two. In order to compare the cooling efficiency of three different cooling systems, we can calculate the cooling time of three cooling system by software. The calculated cooling time is shown as Table. 12. According to Table. 12, the first cooling system has longest cooling system, next is the second cooling system and the third cooling system has shortest cooling time.

Therefore, the third cooling system has best heat balance and cooling efficiency.

MPI/Cool can simulate the cooling pipe (separator pipe, jet pipe and connecting hose), insert, various mould materials, cool runner and hot runner, parting surface and product

MPI/Cool can not only analyze the neutral plane and fusion mould but also analyze 3D mould. Also, the dynamic analysis of injection process could be obtained by combining

Product mould could be constructed by Pro/E and UG etc. which can be read into MPI by STL file format. Then, cooling system and gating system are built in MPI. Three different

Cooling system one Cooling system two Cooling system three

We set the melt temperature, cavity temperature and cooling pipe diameter to be 150 C, 40 C and 8mm respectively. The coolant is water ( 25 C) and Reynolds number is 10000.

We obtain coolant temperature, coolant velocity, cooling pipe temperature and Reynolds

According to Fig. 13, Fig. 14, Fig. 15, we find that pipe and coolant temperature distribution in the third cooling system is much more homogeneous than that in the former two. In order to compare the cooling efficiency of three different cooling systems, we can calculate the cooling time of three cooling system by software. The calculated cooling time is shown as Table. 12. According to Table. 12, the first cooling system has longest cooling system, next is the second cooling system and the third cooling system has

number of coolant (Fig. 13, Fig. 14, Fig. 15) after analyzing cooling process.

Therefore, the third cooling system has best heat balance and cooling efficiency.

temperature. This can provide information for optimizing the cooling system.

MPI/Cool and MPI/Flow.

**5.4 Cooling simulation** 

cooling systems are shown Table 11 (Liu et al., 2010).

Table 11. Arrangement of cooling systems.

**5.4.2 Simulation results of cooling time** 

shortest cooling time.

Finally, we use t software to calculate cooling time.

**5.4.1 Input the process parameters** 

Fig. 13. Simulation outcomes of first cooling system.

Fig. 14. Simulation outcomes of second cooling system.

Optimization and Simulation for Ceramic Injection Mould of ZrO2 Fiber Ferrule 167

(a) (b)

Table 13 demonstrates the general temperature difference of product in three cooling systems respectively when cycle period is 35s. According to Table 13, product temperature difference in the first cooling system is similar to that in the second cooling system. Also, temperature difference in the third cooling system is comparatively higher for it cools much faster, which causes local parts cool significantly. However, product temperature differences

temperature Minimal temperature Temperature

difference

difference

Fig. 16. Cavity labels; (a) Number of cavities; (b) Three locations in each cavity.

Maximum

Cooling system one 46.13 37.34 8.79 Cooling system two 45.93 37.15 8.78 Cooling system three 45.19 36.35 8.84 Table 13. General temperature difference of product when cycle period is 35s ( C).

Table 14 illustrates the temperature simulation of three different parts in the cavity axis in different cooling systems when the cycle period is 35s. According to Table 14, the given part temperature in certain cavity in the first cooling system is the highest. Next is the second cooling system. The given part temperature in certain cavity in the third cooling system is

Number of cavities 1 2 3 4 5 6 Maximal

Table 14. Temperature simulation of three different parts in the cavity axis in different

Top 41.90 41.94 41.97 41.98 41.96 41.92 0.09 Middle 46.10 46.19 46.21 46.26 46.25 46.15 0.16 Bottom 37.74 37.80 37.9 37.91 37.89 37.85 0.17

Top 41.68 41.68 41.75 41.70 41.72 41.76 0.08 Middle 45.53 45.55 45.66 45.60 45.59 45.58 0.13 Bottom 37.53 37.54 37.65 37.68 37.60 37.68 0.15

Top 40.99 41.01 41.05 41.03 41.03 41.04 0.06 Middle 44.69 44.71 44.79 44.75 44.80 44.74 0.11 Bottom 36.67 36.70 36.75 36.73 36.75 36.76 0.09

**5.5.1 Simulation outcomes with 35s cycle period** 

in these cooling systems all are acceptable.

the lowest.

Cooling system one

Cooling system two

Cooling System three

cooling systems when cycle period is 35s ( C).

Fig. 15. Simulation outcomes of third cooling system.


Table 12. Cycle time of different cooling system.

#### **5.5 Comparison between simulation results of these three cooling system**

There are two kinds of cooling analysis, namely manual and automatic cooling analysis. We need to set the cooling time when using manual cooling analysis. Cooling time is calculated by software in the automatic cooling analysis. We use the automatic approach to analyze the cooling efficiency of three different cooling systems in the former chapter. In order to compare their cooling efficiency with given cooling time, we use the manual cooling analysis and set the cycle period to be 35s, 30s, 25s respectively.

During cooling process, six cavities are cooled unevenly for the different arrangement of cooling pipes. We number the six cavities according to clockwise direction (Fig. 16 (a)) and select the top, middle and bottom parts of every cavity (Fig. 16(b)) to analyze the temperature distribution of each cavity with different cooling condition.

Fig. 16. Cavity labels; (a) Number of cavities; (b) Three locations in each cavity.

### **5.5.1 Simulation outcomes with 35s cycle period**

166 Some Critical Issues for Injection Molding

Circuit coolant temperature=26.67[C] Circuit flow rate=3.387[lit/min]

Circuit metal temperature=34.65[C] Circuit Reynolds number=10001

Cooling system one Cooling system second Cooling system three

Cycle time (S) 38.9850 37.9800 32.5205

There are two kinds of cooling analysis, namely manual and automatic cooling analysis. We need to set the cooling time when using manual cooling analysis. Cooling time is calculated by software in the automatic cooling analysis. We use the automatic approach to analyze the cooling efficiency of three different cooling systems in the former chapter. In order to compare their cooling efficiency with given cooling time, we use the manual cooling

During cooling process, six cavities are cooled unevenly for the different arrangement of cooling pipes. We number the six cavities according to clockwise direction (Fig. 16 (a)) and select the top, middle and bottom parts of every cavity (Fig. 16(b)) to analyze the

**5.5 Comparison between simulation results of these three cooling system** 

analysis and set the cycle period to be 35s, 30s, 25s respectively.

temperature distribution of each cavity with different cooling condition.

Fig. 15. Simulation outcomes of third cooling system.

Table 12. Cycle time of different cooling system.

Table 13 demonstrates the general temperature difference of product in three cooling systems respectively when cycle period is 35s. According to Table 13, product temperature difference in the first cooling system is similar to that in the second cooling system. Also, temperature difference in the third cooling system is comparatively higher for it cools much faster, which causes local parts cool significantly. However, product temperature differences in these cooling systems all are acceptable.


Table 13. General temperature difference of product when cycle period is 35s ( C).

Table 14 illustrates the temperature simulation of three different parts in the cavity axis in different cooling systems when the cycle period is 35s. According to Table 14, the given part temperature in certain cavity in the first cooling system is the highest. Next is the second cooling system. The given part temperature in certain cavity in the third cooling system is the lowest.


Table 14. Temperature simulation of three different parts in the cavity axis in different cooling systems when cycle period is 35s ( C).

Optimization and Simulation for Ceramic Injection Mould of ZrO2 Fiber Ferrule 169

cavity three and four have comparatively high temperature. Cavity three and four do not have ideal cooling efficiency. In the second cooling system, product temperature in the cavity one and six is much lower than that in the cavity three and five. In the third cooling system, cavity one and six have much lower temperature. However, temperature

Number of cavities 1 2 3 4 5 6 Maximal

Table 16. Temperature simulation outcomes of three different positions of six cavities in

Extreme values of temperature difference of various positions in each cavity when cycle period is 30s are shown as Fig. 18. The extreme values of temperature difference of top, middle and bottom part in each cavity in the third cooling system are smaller than that in

Fig. 18. Extreme values of temperature difference of various positions in each cavity when

Top Middle Bottom

Table 17 demonstrates the temperature difference of product with three cooling system when cycle period 25s. According to Table 17, temperature difference of product in the first cooling system is similar to that in the second cooling system. The general temperature difference of product in the third cooling system is the highest. Simulation results are

Top 44.10 44.11 44.23 44.25 44.19 44.15 0.15 Middle 48.15 48.19 48.37 48.36 48.28 18.20 0.22 Bottom 39.49 39.50 39.52 39.69 39.62 39.56 0.20

Top 43.95 43.98 44.09 44.03 44.05 44.08 0.14 Middle 48.99 45.00 49.15 49.09 49.09 49.18 0.19 Bottom 39.33 39.33 39.50 39.4 39.45 39.50 0.17

Top 43.12 43.15 43.20 43.19 43.18 43.23 0.11 Middle 47.32 47.34 47.49 47.41 47.43 47.45 0.17 Bottom 38.38 38.41 38.51 38.46 38.49 38.55 0.16

> Cooling system one Cooling system two Cooling system three

difference

distribution in six cavities is even.

three cooling system when cycle period is 30s ( C).

**5.5.3 Simulation outcomes when cycle period is 25s** 

similar to the outcomes obtained above.

Cooling system one

Cooling system two

Cooling system three

the former two.

cycle period is 30s ( C).

The cooling effect of given position varies in different cavities. In the first cooling system, Cavity one and two near the coolant inlet have better cooling effect compared with cavity three and four. In the second cooling system, cavity one and six have better cooling effect compared with cavity four and five. In the third cooling system, Cavity one has the lowest temperature. However, the general temperature of six cavities is approximately the same.

In these cooling systems, the extreme value of temperature difference of each cavity is shown as Fig. 17. It demonstrates that the extreme value of temperature difference of top, middle and bottom parts in the third cooling system is much lower than that in the former two, which means that the third cooling system has the best cooling efficiency.

Fig. 17. Extreme values of temperature difference of various positions in each cavity when cycle period is 35s ( C).

#### **5.5.2 Simulation result with 30s cycle period**

Table 15 demonstrates the general temperature difference of product in these three cooling systems when the cycle period is 30s.

According to Table 15, product temperature difference in the first cooling system is similar to that in the second cooling system. On the other hand, product temperature in the third cooling system is comparatively higher. Therefore, simulation results are similar to that in three cooling systems when the cycle period is 35s.


Table 15. General temperature difference of products when cycle period is 30s (°C).

Table 16 illustrates temperature simulation outcomes of three different positions in six cavities in three cooling system when the cycle period is 30s. In the first cooling system, cooling effect of given position in product varies in different cavities. Cavity one and six near the water inlet have better cooling efficiency. Next is cavity two and five. Positions in

The cooling effect of given position varies in different cavities. In the first cooling system, Cavity one and two near the coolant inlet have better cooling effect compared with cavity three and four. In the second cooling system, cavity one and six have better cooling effect compared with cavity four and five. In the third cooling system, Cavity one has the lowest temperature. However, the general temperature of six cavities is approximately the same.

In these cooling systems, the extreme value of temperature difference of each cavity is shown as Fig. 17. It demonstrates that the extreme value of temperature difference of top, middle and bottom parts in the third cooling system is much lower than that in the former

Fig. 17. Extreme values of temperature difference of various positions in each cavity when

Top Middle Bottom

Table 15 demonstrates the general temperature difference of product in these three cooling

According to Table 15, product temperature difference in the first cooling system is similar to that in the second cooling system. On the other hand, product temperature in the third cooling system is comparatively higher. Therefore, simulation results are similar to that in

Cooling system one 48.84 38.98 9.86 Cooling system two 48.62 38.76 9.86 Cooling system three 47.80 37.87 9.93 Table 15. General temperature difference of products when cycle period is 30s (°C).

Table 16 illustrates temperature simulation outcomes of three different positions in six cavities in three cooling system when the cycle period is 30s. In the first cooling system, cooling effect of given position in product varies in different cavities. Cavity one and six near the water inlet have better cooling efficiency. Next is cavity two and five. Positions in

temperature Minimal temperature Temperature

difference

Cooling system one Cooling system two Cooling system three

cycle period is 35s ( C).

**5.5.2 Simulation result with 30s cycle period** 

three cooling systems when the cycle period is 35s.

Maximum

systems when the cycle period is 30s.

two, which means that the third cooling system has the best cooling efficiency.

cavity three and four have comparatively high temperature. Cavity three and four do not have ideal cooling efficiency. In the second cooling system, product temperature in the cavity one and six is much lower than that in the cavity three and five. In the third cooling system, cavity one and six have much lower temperature. However, temperature distribution in six cavities is even.


Table 16. Temperature simulation outcomes of three different positions of six cavities in three cooling system when cycle period is 30s ( C).

Extreme values of temperature difference of various positions in each cavity when cycle period is 30s are shown as Fig. 18. The extreme values of temperature difference of top, middle and bottom part in each cavity in the third cooling system are smaller than that in the former two.

Fig. 18. Extreme values of temperature difference of various positions in each cavity when cycle period is 30s ( C).

#### **5.5.3 Simulation outcomes when cycle period is 25s**

Table 17 demonstrates the temperature difference of product with three cooling system when cycle period 25s. According to Table 17, temperature difference of product in the first cooling system is similar to that in the second cooling system. The general temperature difference of product in the third cooling system is the highest. Simulation results are similar to the outcomes obtained above.

Optimization and Simulation for Ceramic Injection Mould of ZrO2 Fiber Ferrule 171

Firstly, we used Moldflow to calculate pressure drop, filling time, temperature difference and clamp force of five different cross-section shapes. Outcomes demonstrate that U-shape runner has smallest pressure drop, shortest filling time, minimal temperature difference and highest efficiency. Therefore, U-shape runner is most suitable for cool-runner mould rather

Secondly, we investigated runner systems with rectangular and circular shunt respectively by orthogonal table. Also, we researched influence of mould temperature, injection temperature, screw velocity and gate dimension on products. Results show that runner system with circular shunt is most suitable for Ceramic Injection Molding. Furthermore, we considered the gravity influence on Ceramic Injection Molding and found that short shot tends to happen on the top cavity when runner diameter is 4mm. All six cavities are filled

Finally, we simulated cooling efficiency of three cooling systems and results show that the third cooling system has shortest cooling cycle and best cooling efficiency, which can cool product as fast as possible. Cooling efficiency in six cavities is not the same for the cooling system arrangement and for the inlet and outlet location. Temperature extreme values of top, middle and bottom positions in each cavity in the third cooling system are smaller than

Chen, J. B.; Shen, C. Y.; Wang, Z. F. (2002). Numerical simulation of the cooling process of

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Liu, F.; Lin, B.; Zhang, M. M.; Li, L. J. (2010). Redesign and optimization for ceramic injection

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**6. Conclusion** 

than circular or other kinds of runners.

that in former two cooling system.

ISSN 1000-7555

ISSN: 1662-9795

pp.838~846, ISSN 0032-3888

**7. References** 

well after increasing runner diameter to 4.17 mm.


Table 17. General temperature difference of product when cycle period is 25s (°C).

Table 18 shows the temperature simulation of three different positions in different cooling system when the cycle period is 25s. Apparently, cooling efficiency of third cooling system is the best and temperature distribution of each cavity is even in the third cooling system.


Table 18. Temperature simulation of three different positions with different cooling system when cycle period is 25s ( C).

Extreme values of temperature difference of various positions in each cavity are shown as Fig. 19 when cycle period is 25s. The extreme values of temperature difference of top, middle and bottom parts in each cavity in the third cooling system are smaller than that in the former two.

Fig. 19. Extreme values of temperature difference of various positions in each cavity when cycle period is 25s ( C).
