**3. SCUBA system utilizing VC\_RHCS**

The underwater environment imposes many physical and mental stressors on those working in the modern SCUBA (Self-Contained Underwater Breathing Apparatus) diving equipment. A scuba system consists of a high pressure compressed air tank and a pressure regulator. The development of SCUBA diving is based on the invention of the regulator. The high pressure air carried by diver must be reduced to the pressure in the ambient environment by the regulator before the diver can breathe it. The life of the diver thus depends on the performance and stability of the regulator. The SCUBA is based on the

Condition Max. stress (Kgf / cm2) Strength (%)

Cavity temp. = 75°C 165 88.9

Cavity temp. = 75°C 178 95.7

Cavity temp. = 110°C 184 98.9

Cavity temp. = 75°C 186 100.0

Two gates with vapour chamber heating system appears light welding line and its tensile strength of testing part is higher 6.8% than the part of two gates without vapour chamber system. If increasing the preheating temperature from 75°C to 110°C with two gates vapour

Another test part is the multi-holes products tested to evaluate the effectiveness of the system with vapour chamber in different situation of cavity and core temperatures. These multi-holes products have eight holes with four 10mm and 5mm diameter holes, respectively. The dimensions of eight holes products are 110 x 53 x 3.175mm3. Three temperature combinations were tested in the experiments. Case 1 is the conditions of cavity temperature 60°C and core temperature 60°C. Case 2 is the conditions of cavity temperature 60°C and core temperature 130°C. Case 3 is the conditions of cavity temperature 80°C and

Figs. 5 show the specification of the eight holes test part and SEM images of V-notch. The means is that there are many welding lines on the surface of the transparent parts. The depth of the V-notch is deeper the welding line is more obvious for transparent. From the Figs. 5, the depths of the V-notch found on each case are 12μm, 2μm, and 0.5μm respectively. The product of the case 1 shows a V-notch 24 times deeper than the product of case 3. The effects of cavity and core temperatures are also important for welding line. Finally, utilizing VC\_RHCS shows that the temperature differences of cavity employing vapour chamber are smaller than that without vapour chamber and increasing preheating temperature can add the tensile strength for two opposite gates resulting from extending enough fluid flow. And the new VC\_RHCS

The underwater environment imposes many physical and mental stressors on those working in the modern SCUBA (Self-Contained Underwater Breathing Apparatus) diving equipment. A scuba system consists of a high pressure compressed air tank and a pressure regulator. The development of SCUBA diving is based on the invention of the regulator. The high pressure air carried by diver must be reduced to the pressure in the ambient environment by the regulator before the diver can breathe it. The life of the diver thus depends on the performance and stability of the regulator. The SCUBA is based on the

Two gate without vapour chamber

Two gate with vapour chamber

Two gates with vapour chamber

One gate without vapour chamber

chamber system, the tensile strength can again add 3.2%.

**2.3 Employing VC\_RHCS in eight holes test part** 

can reduce the depth of v-notch as much as 24 times.

**3. SCUBA system utilizing VC\_RHCS** 

Table 1. The results of the tensile test.

core temperature 130°C.

Fig. 5. SEM picture of the eight holes plate.

invention of breathing regulators. Basically, a regulator can be divided into the first and second stages. The first stage regulates air output pressure at a stable value of 14atm, reducing from the compressed air cylinder pressure of 200atm to 20atm, and then supplies that air to the second stage. The second stage is connected to the divers' mask and supplies air at ambient pressure based on the diver's respiration.

Underwater movement requires a higher expenditure of energy and an increased rate of respiration than the same movement on land. This is caused by the higher density of water, and the need to overcome water resistance or drag. The second stage supplies air at a pressure equivalent to water pressure, which in turn depends on the depth, in order to lessen the diver's lung burden. A structural representation of the second stage is shown in Fig.6, while Fig. 7 gives a schematic of the second stage. The second stage of the regulator thus affects the smoothness of diver breathing, a key factor in the divers' ability to function underwater. During this experiment, the relationship between characteristic factors and performance of breathing regulators will be explored through numerical methods, to enable designers to create more efficient breathing regulators.

Breathing resistance is directly related to the diver's ability to receive sufficient air to safely perform in the underwater environment and must be considered a primary factor in the design of breathing apparatuses. An ideal breathing regulator allows divers to breathe without consuming additional energy when breathing under water. In other words, in the ideal regulator, respiratory work rate and respiratory impedance are zero. Many patents (Belloni 2001; Brown & Brown 2000 & 2002; Christianson 1987; Ferguson 1997; Garraffa 1997; Garraffe 1996; Hansen & Lingenfelter 1987; Houston 1981; Toth1985) involve optimum designs for breathing regulator. These patents discussed above provide researchers with a

Insert Molding Process Employing Vapour Chamber 215

negative pressure must be produced to open the valves. These pressures are cumulatively known as respiratory impedance. Respiratory impedance values are widely used to evaluate various breathing mask products, such as filter-type dust masks and gas masks. A picture of the regulators under this study is shown in Fig. 9. A deflecting plate is located at the front end of the air inlets, whose angle can be adjusted by the user. There are two spray holes, one in the upper part and the other in the lower part, directing air flow towards the diaphragm, inside the housing. The factors under consideration in this research are the deflecting plate

For the numerical analysis, the entire analytical model is established by utilizing file conversion skill between CAD/CFD. The overall dimension of simulation analytical model is about 30 x 30 x 25 cm3. Schematic process of numerical simulation analysis adopted in the article can be divided into pre-processing, numerical solving and post-processing. With regard to pre-processing, first of all, a geometrical model is established for 3D CFD module. Generally, in order to reduce computation grid elements and time taken for simulation and solving, some minor characteristics without influence or with a little influence will be ignored when establishing 3D geometrical model. And input the boundary conditions and thermo-physical properties, which the ambient temperature is set to 27 °C, the input pressure is set to 9 atm and initial pressure is set to be the surrounding conditions, turbulent model is the k-ε two-equations, the grid pattern is structural one and the entire simulation analysis type is transient time state. For the entire module, about 1,500 thousands grid

and the spray holes.

Fig. 9. A picture of the test regulator.

Fig. 8. The regulator testers made by ANSTI Co.

Fig. 6. The structural representation of the second stage.

Fig. 7. The schematic diagram of the second stage.

reference for developing new breathing regulators. However, in previous studies, the parameters affecting the breathing regulator's performance have not been identified. This research identifies the design parameters affecting regulator performance through experimental and numerical methods.

The analysis is divided into two steps in this section. In the first step, the mechanical characteristics of samples are varied and the relevant performance parameters of the breathing regulators are tested using demand regulator testers made by ANSTI Co., as shown in Fig. 8. In the second step, we modify the characteristic internal shapes of the regulators and explore how these changes influence regulator functions using commercial numerical simulation software, FLOW-3D® from Flow Science Inc. Company. There are several important considerations to design of breathing regulators for diving apparatus. A regulator must meet the requirements for easy breathing and a stable air supply at normal conditions. Easy breathing is the most key index of a regulator. However, to a great extent, the above factors are shaped by the subjective feeling of the user. In order to accurately describe breathing smoothness, designers have defined two parameters, namely respiratory work rate and respiratory impedance.

The unit of respiratory work rate is Joule/Liter and its value represents the average energy consumed by breathing in and out one liter of air. Respiratory impedance can be regarded as the pressure supplied by a diver when breathing underwater. For example, in order to smoothly discharge gas through a regulator when diving, a diver must apply a pressure using the thoracic cavity and mouth to force the valves to open. To breathe in, additional

reference for developing new breathing regulators. However, in previous studies, the parameters affecting the breathing regulator's performance have not been identified. This research identifies the design parameters affecting regulator performance through

The analysis is divided into two steps in this section. In the first step, the mechanical characteristics of samples are varied and the relevant performance parameters of the breathing regulators are tested using demand regulator testers made by ANSTI Co., as shown in Fig. 8. In the second step, we modify the characteristic internal shapes of the regulators and explore how these changes influence regulator functions using commercial numerical simulation software, FLOW-3D® from Flow Science Inc. Company. There are several important considerations to design of breathing regulators for diving apparatus. A regulator must meet the requirements for easy breathing and a stable air supply at normal conditions. Easy breathing is the most key index of a regulator. However, to a great extent, the above factors are shaped by the subjective feeling of the user. In order to accurately describe breathing smoothness, designers have defined two parameters, namely respiratory

The unit of respiratory work rate is Joule/Liter and its value represents the average energy consumed by breathing in and out one liter of air. Respiratory impedance can be regarded as the pressure supplied by a diver when breathing underwater. For example, in order to smoothly discharge gas through a regulator when diving, a diver must apply a pressure using the thoracic cavity and mouth to force the valves to open. To breathe in, additional

Fig. 6. The structural representation of the second stage.

Fig. 7. The schematic diagram of the second stage.

experimental and numerical methods.

Normal

work rate and respiratory impedance.

Fig. 8. The regulator testers made by ANSTI Co.

negative pressure must be produced to open the valves. These pressures are cumulatively known as respiratory impedance. Respiratory impedance values are widely used to evaluate various breathing mask products, such as filter-type dust masks and gas masks. A picture of the regulators under this study is shown in Fig. 9. A deflecting plate is located at the front end of the air inlets, whose angle can be adjusted by the user. There are two spray holes, one in the upper part and the other in the lower part, directing air flow towards the diaphragm, inside the housing. The factors under consideration in this research are the deflecting plate and the spray holes.

Fig. 9. A picture of the test regulator.

For the numerical analysis, the entire analytical model is established by utilizing file conversion skill between CAD/CFD. The overall dimension of simulation analytical model is about 30 x 30 x 25 cm3. Schematic process of numerical simulation analysis adopted in the article can be divided into pre-processing, numerical solving and post-processing. With regard to pre-processing, first of all, a geometrical model is established for 3D CFD module. Generally, in order to reduce computation grid elements and time taken for simulation and solving, some minor characteristics without influence or with a little influence will be ignored when establishing 3D geometrical model. And input the boundary conditions and thermo-physical properties, which the ambient temperature is set to 27 °C, the input pressure is set to 9 atm and initial pressure is set to be the surrounding conditions, turbulent model is the k-ε two-equations, the grid pattern is structural one and the entire simulation analysis type is transient time state. For the entire module, about 1,500 thousands grid

Insert Molding Process Employing Vapour Chamber 217

B1 6.899 6.931 -4 B2 6.883 6.9065 -12.5 B3 7.0272 7.047 -16.2

channel will cause the gas inside the flow channels to flow into the housing, creating a pressure drop at the suction end. The offset have to be close zero pressure drop. Our numerical results showed that the original design "B1" obtains the best inhale pressure.

After entering the second stage from the spray holes, high-speed gas strikes the diaphragm, which results in a pressure rise inside the diaphragm. A change in the angle of the spray holes will affect the spray whole's pressure shock against the diaphragm. The authors modified the characteristics of actual samples and tested these modified samples on a tester bench. A comparison was made between experimental data and simulation values obtained by FLOW-3D® to confirm that the mode for setting boundary conditions, in which air is vented out at a constant flow rate, is consistent with actual conditions. These modifications mainly aim at the characteristics of the dimensions of period, line and depth. After confirming that the data

Table 3 shows the characteristics of the five groups of samples were varied across experiments (A1 to A5) in order to verify that numerical simulation data and experimental data reliable. These modifications are mainly aimed at the characteristics of deflector holes

As we have seen, a comparison of the experimental data and numerical simulation results is given in Table 4. And the comparison of the experimental data and the simulated data of inhale pressure are shown in Fig. 12. The results show that the simulated data are acceptably

pressure in the mouthpiece (bar)

Offset (mbar)

Model pressure inside the housing

Table 2. Comparison of different length of flow channel.

**3.2 Angle of the spray holes** 

and spray holes.

(bar)

obtained from numerical model is consistent with experimental data.

Table 3. The test parameters of the regulator.

elements are used, time step is about 10-9, iterations is about 50 per time-step and it will take about 14 days to simulate every scenario.

The following paragraphs will describe the functions of the three parts.

### **3.1 Flow channel**

A flow channel functions to direct gas from the valves into the diver's mouth. Flow channel design is thus closely related to respiratory impedance, respiratory work rate, and gas flow velocity. Fig. 10 shows three types of flow channel design for the simulation models. Model B1 represents the original design; Model B2 is a lengthened flow channel which completely covers the entire suction port, while Model B3 is short flow channel design.

Fig. 10. The design of Model B1~B3 modified the length of the flow channel.

The analytical data is given in Table 2 and pressures obtained from the three designs are compared in Fig. 11. The offset is the difference between maximum pressure inside the housing and mouthpiece, which obtained from simulated data of FLOW-3D®. Our simulations show that when an excessively long flow channel covers the upper part of the suction port, the gas inside the housing will be blocked, unable to enter the suction end, resulting in a pressure rise inside the housing. By the same token, an excessively short flow

Fig. 11. Inhale pressure of different length of flow channel.


Table 2. Comparison of different length of flow channel.

channel will cause the gas inside the flow channels to flow into the housing, creating a pressure drop at the suction end. The offset have to be close zero pressure drop. Our numerical results showed that the original design "B1" obtains the best inhale pressure.

### **3.2 Angle of the spray holes**

216 Some Critical Issues for Injection Molding

elements are used, time step is about 10-9, iterations is about 50 per time-step and it will take

A flow channel functions to direct gas from the valves into the diver's mouth. Flow channel design is thus closely related to respiratory impedance, respiratory work rate, and gas flow velocity. Fig. 10 shows three types of flow channel design for the simulation models. Model B1 represents the original design; Model B2 is a lengthened flow channel which completely

The following paragraphs will describe the functions of the three parts.

covers the entire suction port, while Model B3 is short flow channel design.

Fig. 10. The design of Model B1~B3 modified the length of the flow channel.

Fig. 11. Inhale pressure of different length of flow channel.

The analytical data is given in Table 2 and pressures obtained from the three designs are compared in Fig. 11. The offset is the difference between maximum pressure inside the housing and mouthpiece, which obtained from simulated data of FLOW-3D®. Our simulations show that when an excessively long flow channel covers the upper part of the suction port, the gas inside the housing will be blocked, unable to enter the suction end, resulting in a pressure rise inside the housing. By the same token, an excessively short flow

about 14 days to simulate every scenario.

**3.1 Flow channel** 

After entering the second stage from the spray holes, high-speed gas strikes the diaphragm, which results in a pressure rise inside the diaphragm. A change in the angle of the spray holes will affect the spray whole's pressure shock against the diaphragm. The authors modified the characteristics of actual samples and tested these modified samples on a tester bench. A comparison was made between experimental data and simulation values obtained by FLOW-3D® to confirm that the mode for setting boundary conditions, in which air is vented out at a constant flow rate, is consistent with actual conditions. These modifications mainly aim at the characteristics of the dimensions of period, line and depth. After confirming that the data obtained from numerical model is consistent with experimental data.

Table 3 shows the characteristics of the five groups of samples were varied across experiments (A1 to A5) in order to verify that numerical simulation data and experimental data reliable. These modifications are mainly aimed at the characteristics of deflector holes and spray holes.


Table 3. The test parameters of the regulator.

As we have seen, a comparison of the experimental data and numerical simulation results is given in Table 4. And the comparison of the experimental data and the simulated data of inhale pressure are shown in Fig. 12. The results show that the simulated data are acceptably

Insert Molding Process Employing Vapour Chamber 219

Model pressure inside the housing (bar) pressure in the mouthpiece (bar) Offset

A2 6.4685 6.5025 -2 C1 6.6745 6.7095 -1 C2 6.623 6.665 6 C3 6.7395 6.775 -0.5

Table 5. Comparison of different angle of spray hole.

Fig. 13. Model C1 and C2 modified the direction of the spray hole.

Fig. 14. Model C3 modified the direction of the spray hole.

(mbar)

close to the experimental data. After confirming that the data obtained from numerical model is consistent with the experimental data, the authors changed the characteristics of the second stage mechanisms and then determined how the shape characteristics affect regulator performance, using numerical simulation.


Table 4. The experimental results VS. The results of simulation.

Fig. 12. Simulation VS experimental results in inhale pressure.

In our model design, Model A2 is used as a control, and the angle of its lower spray hole B is varied. Three designs are adopted, designated C1, C2 (Fig.13) and C3 (Fig.14). The key point in the C3 design is to prevent the gas from directly striking the housing and instead allow it to pass along the housing edge when gas enters the housing. The analytical data is summarized in Table 5 and a comparison is given in Fig.15. Our results are also confirmed in the stream line diagram as shown in Fig.16. At this condition, the internal pressure value can be reduced to about one-third of the pressure of the original design of Model A2. However, if the gas is not applied to the diaphragm at all after entering the housing, as in C2, the inhale pressure will become a positive value, which increases respiratory impedance. This must be avoided by the designer. Fig. 17 depicts a stream line diagram of C2.

close to the experimental data. After confirming that the data obtained from numerical model is consistent with the experimental data, the authors changed the characteristics of the second stage mechanisms and then determined how the shape characteristics affect

> Offset (mbar) (Simulated Data)

Inhale pressure measured from ANSTI test machine (mbar) (Experimental Data)

regulator performance, using numerical simulation.

pressure in the mouth piece (bar)

Table 4. The experimental results VS. The results of simulation.

Fig. 12. Simulation VS experimental results in inhale pressure.

designer. Fig. 17 depicts a stream line diagram of C2.

In our model design, Model A2 is used as a control, and the angle of its lower spray hole B is varied. Three designs are adopted, designated C1, C2 (Fig.13) and C3 (Fig.14). The key point in the C3 design is to prevent the gas from directly striking the housing and instead allow it to pass along the housing edge when gas enters the housing. The analytical data is summarized in Table 5 and a comparison is given in Fig.15. Our results are also confirmed in the stream line diagram as shown in Fig.16. At this condition, the internal pressure value can be reduced to about one-third of the pressure of the original design of Model A2. However, if the gas is not applied to the diaphragm at all after entering the housing, as in C2, the inhale pressure will become a positive value, which increases respiratory impedance. This must be avoided by the

A1 7.0905 7.111 -16.4 -15.5 A2 6.899 6.931 -5 -4 A3 8.468 8.515 8.43 11 A4 6.655 6.696 5.56 5 A5 6.654 6.683 -6.89 -7

pressure inside the housing (bar)

Model


Table 5. Comparison of different angle of spray hole.

Fig. 13. Model C1 and C2 modified the direction of the spray hole.

Fig. 14. Model C3 modified the direction of the spray hole.

Insert Molding Process Employing Vapour Chamber 221

The size of the spray holes will affect the flow velocity of the gas into the second stage, resulting in a change in internal pressure. The spray hole affects the pressure inside the diaphragm and housing to a great extent. When high-speed gas from the spray holes directly strikes the diaphragm, the pressure inside the diaphragm will rise. The size of the spray holes affects the gas velocity inside the housing. In this research, three groups of models, namely D1, D2 and D3, are used for testing. The position and diameters of the spray

The analytical data in Table 6 and Fig.19 shows that the pressure inside the housing is proportional to the hole diameter. The larger the hole diameter is, the higher the pressure inside the housing, which in turn reduces the differential pressure between the internal pressure and pressure at the suction end. However, when the hole diameter is too small (D3), the increasing differential pressure will cause the inhale pressure to change from a negative value to a positive value, thus reducing respiratory impedance. After several tests by simulation, when the spray hole diameter decreases from 2mm to 1.8mm, the inhale pressure will be reduced to one-third of the inhale pressure of the original design. In last, these experimental results can be simulated by numerical analysis software FLOW-3D®.

D1 6.899 6.931 -4 D2 6.4685 6.5025 -2 D3 6.3835 6.3435 +4

pressure in the mouthpiece (bar)

Offset (mbar)

**3.3 Size of spray holes** 

holes are shown in Fig. 18.

Model pressure inside the housing

Table 6. Comparison of different size of spray hole.

(bar)

Fig. 18. Modify the size of spray hole (Model D1, D2, and D3).

Fig. 15. The inhale pressure of different angle of spray hole.

Fig. 16. The stream lines of Model C3.

Fig. 17. The stream lines of Model C2.

#### **3.3 Size of spray holes**

220 Some Critical Issues for Injection Molding

Fig. 15. The inhale pressure of different angle of spray hole.

Fig. 16. The stream lines of Model C3.

Fig. 17. The stream lines of Model C2.

The size of the spray holes will affect the flow velocity of the gas into the second stage, resulting in a change in internal pressure. The spray hole affects the pressure inside the diaphragm and housing to a great extent. When high-speed gas from the spray holes directly strikes the diaphragm, the pressure inside the diaphragm will rise. The size of the spray holes affects the gas velocity inside the housing. In this research, three groups of models, namely D1, D2 and D3, are used for testing. The position and diameters of the spray holes are shown in Fig. 18.

Fig. 18. Modify the size of spray hole (Model D1, D2, and D3).

The analytical data in Table 6 and Fig.19 shows that the pressure inside the housing is proportional to the hole diameter. The larger the hole diameter is, the higher the pressure inside the housing, which in turn reduces the differential pressure between the internal pressure and pressure at the suction end. However, when the hole diameter is too small (D3), the increasing differential pressure will cause the inhale pressure to change from a negative value to a positive value, thus reducing respiratory impedance. After several tests by simulation, when the spray hole diameter decreases from 2mm to 1.8mm, the inhale pressure will be reduced to one-third of the inhale pressure of the original design. In last, these experimental results can be simulated by numerical analysis software FLOW-3D®.


Table 6. Comparison of different size of spray hole.

Insert Molding Process Employing Vapour Chamber 223

Brown, R.I. ; Brown, D.S. (2000). System and method to prevent the transmission of

Brown, R.I. ; Brown, D.S. (2002). Diving regulator with valved mouthpiece, US Patent

Ferguson A.R. (1997). Adjustment mechanism for a scuba second stage airflow regulator, US

Garraffa D.R. (1997). Breathing regulator apparatus having automatic flow control, US

Hansen H.R. ; Lingenfelter T.A. (1987). Breathing regulator mouthpiece, US Patent 4,683,881.

Wang, J.-C. & Chen, T.-C. (2009). Vapour chamber in high performance server. *Microsystems* 

*Conference (IMPACT), 2010 5th International,* Taipei, October, 2010, pp.1-4. Wang, J.-C. & Tsai,Y.-P. (2011). Analysis for Diving Regulator of Manufacturing Process.

Wang, J.-C. & Wang R.-T. (2011). A Novel Formula for Effective Thermal Conductivity of

Wang, J.-C. (2010). Development of Vapour Chamber-based VGA Thermal Module.

Wang, J.-C. (2011a). Applied Vapour Chambers on Non-uniform Thermo Physical

Wang, J.-C. (2011b). Investigations on Non-Condensation Gas of a Heat Pipe. *Engineering,*

Wang, J.-C. (2011c). L-type Heat Pipes Application in Electronic Cooling System. *International Journal of Thermal Sciences,* Vol. 50, No. 1, January, 2011, pp.97-105. Wang, J.-C. (2011d). Thermal Investigations on LEDs Vapour Chamber-Based Plates.

Wang, J.-C. ; Wang, R.-T. ; Chang, C.-C. & Huang, C.-L. (2010b). Program for Rapid

*Advanced Materials Research,* Vol. 213, February, 2011, pp.68-72.

Conditions. *Applied Physics,* Vol. 1, April, 2011, pp.20-26.

Molding Process on Part Tensile Strength. *EXPERIMENTAL TECHNIQUES,* Vol.

*IEEE 2010 Print ISBN: 978-1-4244-4341-3, Packaging Assembly and Circuits Technology Conference (IMPACT), 2009 4th International,* Taipei, October, 2009, pp.364-367. Wang, J.-C. & Huang, C.-L. (2010). Vapour chamber in high power LEDs. *IEEE 2011 Print* 

*ISBN: 978-1-4244-9783-6, Microsystems Packaging Assembly and Circuits Technology* 

Vapour Chamber, *EXPERIMENTAL TECHNIQUES,* Vol. 35, No 5, September/

*International Journal of Numerical Methods for Heat & Fluid Flow,* Vol. 20, No. 4, June,

*International Communication in Heat and Mass Transfer,* Vol.38, No. 9, November,

Computation of the Thermal Performance of a Heat Sink with Embedded Heat Pipes. *Journal of the Chinese Society of Mechanical Engineers,* Vol. 31, No. 1,

Toth D.J. (1985). Diaphragm assembly for scuba diving regulator, US Patent 4,508,118. Tsai, Y.-P. ; Wang, J.-C. & Hsu, R.-Q. (2011). The Effect of Vapour Chamber in an Injection

pathogenic entities between the multiple users of second stage regulators, US

Belloni A. (2001). Regulator with bypass tube, US Patent 6,279,575.

Christianson T. (1989). Regulator second stage for scuba, US Patent 4,862,884.

Garraffe, D.R. (1996). Second stage scuba diving regulator, US Patent 5,549,107.

Houston, C.E. (1981). Underwater breathing apparatus, US Patent 4,245,632.

35, No 1, January/February, 2011, pp.60-64.

**6. References** 

Patent 6,089,225.

Patent 5,660,502.

Patent 5,678,541.

October, 2011, pp.35-40.

Vol. 3, April, 2011, pp.376-383.

January/February, 2010, pp.21-28.

2010, pp.416-428.

2011, pp. 1206-1212.

6,354,291.

Fig. 19. The inhale pressure of different size of spray hole.

#### **4. Conclusions**

This study proved that, among existing insert molding process, the temperature of inserts has impact on the final assembly strength of product. In this chapter, the local heating mechanism of vapour chamber can control the molding temperature of inserts; and the assembly strength can be improved significantly if the temperature of inserts prior to filling can be increased over the mold temperature, thus allowing the local heating mechanism to improve the weld line in the insert molding process. A VC\_RHCS for injection molding can effectively reduce the welding lines of the transparent plastic products. The heating and cooling injection molding system associated with vapour chamber can raise the tensile strength and reduce the defect of the welding lines of a plastic product because of VC\_RHCS rapid-uniform heating and cooling cycle. The results show that the plastic products with two opposite gates was found increasing by 6.8% and 10% of tensile strength compared with the conventional one, and the other plastic product with eight holes plate is decreased from 12μm to 0.5μm of the depth of the welding line. And the performance of the breathing regulator can be accurately confirmed using numerical simulation software. The angle and diameter of the spray holes are key parameters affecting the performance of breathing regulators. Further, the diameter of the internal spray holes is inversely proportional to inhale pressure. These results indicate that the product formed by the VC\_RHCS can effectively achieve high material strength and reduce weld line.

#### **5. Acknowledgments**

This chapter originally appeared in these References and is a minor revised version. Some of the materials presented in this chapter were first published in these References. The authors gratefully acknowledge Prof. R.-Q. Hsu and his MPDB Lab. and Dr. Y.-P. Tsai for guidance their writings to publish and permission to reprint the materials here. The work and finance were supported by National Science Council (NSC), National Taiwan Ocean University (NTOU), National Taiwan Normal University (NTNU) and National Defense University (NDU). Finally, the authors would like to thank all colleagues and students who contributed to this study in the Chapter.

#### **6. References**

222 Some Critical Issues for Injection Molding

This study proved that, among existing insert molding process, the temperature of inserts has impact on the final assembly strength of product. In this chapter, the local heating mechanism of vapour chamber can control the molding temperature of inserts; and the assembly strength can be improved significantly if the temperature of inserts prior to filling can be increased over the mold temperature, thus allowing the local heating mechanism to improve the weld line in the insert molding process. A VC\_RHCS for injection molding can effectively reduce the welding lines of the transparent plastic products. The heating and cooling injection molding system associated with vapour chamber can raise the tensile strength and reduce the defect of the welding lines of a plastic product because of VC\_RHCS rapid-uniform heating and cooling cycle. The results show that the plastic products with two opposite gates was found increasing by 6.8% and 10% of tensile strength compared with the conventional one, and the other plastic product with eight holes plate is decreased from 12μm to 0.5μm of the depth of the welding line. And the performance of the breathing regulator can be accurately confirmed using numerical simulation software. The angle and diameter of the spray holes are key parameters affecting the performance of breathing regulators. Further, the diameter of the internal spray holes is inversely proportional to inhale pressure. These results indicate that the product formed by the

VC\_RHCS can effectively achieve high material strength and reduce weld line.

This chapter originally appeared in these References and is a minor revised version. Some of the materials presented in this chapter were first published in these References. The authors gratefully acknowledge Prof. R.-Q. Hsu and his MPDB Lab. and Dr. Y.-P. Tsai for guidance their writings to publish and permission to reprint the materials here. The work and finance were supported by National Science Council (NSC), National Taiwan Ocean University (NTOU), National Taiwan Normal University (NTNU) and National Defense University (NDU). Finally, the authors would like to thank all colleagues and students who contributed

Fig. 19. The inhale pressure of different size of spray hole.

**4. Conclusions** 

**5. Acknowledgments** 

to this study in the Chapter.

Belloni A. (2001). Regulator with bypass tube, US Patent 6,279,575.


**10** 

*Iran* 

Mohammad Farsi

**Thermoplastic Matrix Reinforced with Natural** 

**Fibers: A Study on Interfacial Behavior** 

*Department of Wood and Paper Science, Sari Branch, Islamic Azad University,* 

The composites and their constituent components and structures have to meet increasingly development during recent decades. Some important concerns such as increasing price of petroleum and the impending depletion of fossil fuels and the interest in reducing the environmental impact of polymers is leading to the development of newer materials that can reduce stress on environment. Current developments and likely future trends are covered across key areas of the natural fibers reinforced polymer industry, together with existing and potential opportunities for the innovative use of plastic and bio-based fibers products. The challenges facing the world, such as environmental requirements and the need for recycling of plastic materials, are also included. Hence, the attention is increasingly being given to the use of natural fibers as reinforcement filler in low melting thermoplastic matrix manufactured by conventional plastic process such as extrusion and injection molding process. Injection molding is one of the most widely used processes for manufacturing molded parts from reinforced thermoplastic materials. Short natural fiber reinforced composites can be processed into complex shaped components using standard

Although the use of bio-based fillers is not as popular as the use of mineral or inorganic fillers, natural fiber-derived fillers have several advantages over traditional fillers and reinforcing materials such as low density, flexibility during the processing with no harm to the equipment, acceptable specific strength properties and low cost per volume basis.

The worldwide markets show the increased demands for natural and bio-based fibers. In 1967, the USA demand for fillers by the plastic industry was 525,000 tons; filler use had grown to 1,925,000 tons by 1998 (Eckert, 1999) and the projected use of fillers by the USA plastic industry in 2010 is to 8.5 billion pounds, of which 0.7 billion pounds (8%) was estimated to be bio-based fibers. It has been also summarized major markets for natural fibers in plastic composites as fig. 1a, on a weight basis (Eckert, 2000). Based on Fig. 1a, the main application areas of bio-based fibers filled composites are the building products in which they are used in structural applications as fencing, decking, roofing, railing, cladding

Most bio-fiber plastic additives are derived from wood that incorporated in Wood-plastic composites (WPCs). WPCs contain wood (fiber or flour) and polymer as matrix. The

**1. Introduction** 

thermoplastic injection molding equipment.

and siding, park benches and etc. as shown in Fig. 2.

