**3.2 Taguchi results**

#### *3.2.1 Analysis of mean*

The S/N ratios were calculated for each of the nine conditions of the test. All the details: the values, the average of each parameter at different levels, and the standard deviation of each test were depicted in **Table 4**.

The responses studied are the tensile strength and the elasticity module. **Tables 5** and **6** represented the average values of mean response relative to the four control parameters (factors) studied. **Figures 4** and **5** illustrated these values.

The optimum conditions corresponded to the maximum tensile strength and the elasticity module. These conditions illustrated the levels of the highest mean responses values chosen for each IM process parameter.

The averages values of the tensile strength (σ) and the elasticity module (E) were depicted in **Figures 4** and **5**. Hence, the optimum condition levels corresponding to the maximum tensile strength of the injection molding process of the PC/ABS blend was A3, B3, C2, and D3. That is to say, in the third level, at the material temperature of 260°C, represented by parameter A; an injection pressure of 50 bar, represented by parameter B; a mold temperature of 60°C represented by parameter D; and in


σ*: Overall mean of tensile strength = 49.31 MPa.*

*E: Overall mean of elasticity module = 1921 MPa.*

#### **Table 4.**

*Experimental results of mechanical properties for T45PG.*


**157**

**Figure 5.**

parameters for the tensile strength.

*Average values of elasticity module (E) for each parameter at levels 1–3.*

*Influence of Injection Molding Parameters on the Mechanical Properties of Injected PC/ABS Parts*

**Parameter Level 1 Level 2 Level 3 Max-Min Rank** A 1878 1920 1966 88 1 B 1898 1946 1919 48 4 C 1890 1940 1933 50 3 D 1928 1884 1951 67 2

*Average values of the elasticity module (E) at the different levels and their main effects.*

*Average values of tensile strength (*σ*) for each parameter at levels 1–3.*

the second level at a holding time of 8 sec, represented by parameter C. In parallel, the injection pressure was considered the more prominent than the other IM process

*DOI: http://dx.doi.org/10.5772/intechopen.95089*

**Table 6.**

**Figure 4.**

#### **Table 5.**

*Average values of the tensile strength (*σ*) at the different levels and their main effects.*

*Influence of Injection Molding Parameters on the Mechanical Properties of Injected PC/ABS Parts DOI: http://dx.doi.org/10.5772/intechopen.95089*


**Table 6.**

*Quality Control - Intelligent Manufacturing, Robust Design and Charts*

dard deviation of each test were depicted in **Table 4**.

responses values chosen for each IM process parameter.

tion parameters.

**3.2 Taguchi results**

*3.2.1 Analysis of mean*

these values.

properties measured of each test performed were extracted. These values were introduced in the MINITAB 18 statistical software in order to optimize the injec-

The S/N ratios were calculated for each of the nine conditions of the test. All the details: the values, the average of each parameter at different levels, and the stan-

The responses studied are the tensile strength and the elasticity module. **Tables 5** and **6** represented the average values of mean response relative to the four control parameters (factors) studied. **Figures 4** and **5** illustrated

The optimum conditions corresponded to the maximum tensile strength and the elasticity module. These conditions illustrated the levels of the highest mean

The averages values of the tensile strength (σ) and the elasticity module (E) were depicted in **Figures 4** and **5**. Hence, the optimum condition levels corresponding to the maximum tensile strength of the injection molding process of the PC/ABS blend was A3, B3, C2, and D3. That is to say, in the third level, at the material temperature of 260°C, represented by parameter A; an injection pressure of 50 bar, represented by parameter B; a mold temperature of 60°C represented by parameter D; and in

**Test Number A B C D** σ**(MPa) S/N E(MPa) S/N** 1 1 1 1 46.46 33.34 1830 65.24 1 2 2 2 48.3 33.67 1885 65.5 1 3 3 3 51.38 34.21 1918 65.65 2 1 2 3 49.33 33.86 1946 65.78 2 2 3 1 47.66 33.56 1962.67 65.85 2 3 1 2 46.66 33.37 1850 65.34 3 1 3 2 47.53 33.53 1917.67 65.65 3 2 1 3 57.5 34.23 1989.67 65.97 3 3 2 1 55 34.81 1990 65.97

**Parameter Level 1 Level 2 Level 3 Max-Min Rank** A 48.72 47.89 51.36 3.47 1 B 47.78 49.16 51 3.25 2 C 48.21 50.89 48.86 2.68 4 D 49.72 47.5 50.74 3.24 3

*Average values of the tensile strength (*σ*) at the different levels and their main effects.*

**156**

**Table 5.**

σ

**Table 4.**

*: Overall mean of tensile strength = 49.31 MPa. E: Overall mean of elasticity module = 1921 MPa.*

*Experimental results of mechanical properties for T45PG.*

*Average values of the elasticity module (E) at the different levels and their main effects.*

#### **Figure 4.** *Average values of tensile strength (*σ*) for each parameter at levels 1–3.*

#### **Figure 5.** *Average values of elasticity module (E) for each parameter at levels 1–3.*

the second level at a holding time of 8 sec, represented by parameter C. In parallel, the injection pressure was considered the more prominent than the other IM process parameters for the tensile strength.

**Figure 5** shows that the material temperature represented by parameter A was more prominent than the other IM process parameters for the elasticity module. Moreover, the maximum elasticity module was recorded in the third level, at the material temperature of 260°C, represented by parameter A; a mold temperature of 60°C, represented by parameter D; and in the second level at; an injection pressure of 40 bar, represented by parameter B; a holding time of 8 sec, represented by parameter C.

The average values of S/N ratios of various parameters at different levels are shown in **Tables 7** and **8**. These values are plotted in **Figures 6** and **7**.

The S/N ratio analysis of the tensile strength plotted in **Figure 6** provides in to the same levels of the parameters as depicted in **Figure 4**. Therefore, A3, B3, C2, and D3 were the best levels for reducing the variability of the injection molding process of the PC/ABS blend.


**Table 7.**

*Average values (*σ*) of S/N ratios at the different levels and their main effects.*


#### **Table 8.**

*Average values (E) of S/N ratios at the different levels and their main effects.*

**159**

*Influence of Injection Molding Parameters on the Mechanical Properties of Injected PC/ABS Parts*

The S/N ratio analysis of the elasticity module depicted in **Figure 7** offers in to the same levels of the parameters as shown in **Figure 5**. So, A3, B2, C2, and D3 were the best levels for reducing the variability of the injection molding process of

**Table 3** shows the combinations of factor levels (3, 3, 2, 3) and (3, 2, 2, 3) were not among the obtained combinations within the tested experiment. Thus, it was necessary to verify the optimum injection molding conditions via confirmation

The optimum levels of the control parameters of the tensile strength (μ1) and the elasticity module (μ2) are determined as A3, B3, C2, D3 and A3, B2, C2, D3

( ) ( ) ( ) ( )

51.36 51 50.89 50.74 – 3 x 49.31 56.06 .

 σ

is the average tensile strength at the third level of material tempera-

is the average tensile strength at the third level of holding time, 8 sec, *D*<sup>3</sup>

is the average elasticity module at the third level of material tempera-

is the average elasticity module at the second level of holding

is the average elasticity module at the second level of injection

is the average tensile strength at the third level of injection pressure,

*MPa*

*MPa*

(1)

σis

(2)

 σ

( ) 13 3 2 3

 σ

the mean of tensile strength obtained from **Table 4**.

=+ − + − + − + − = ++ + = *ABCD*

 σ

is the average tensile strength at the third level of mold temperature, 60°C and

( ) 23 2 2 3

=+ − + − + − + − =+++− = *E AE BE CE DE*

( ) ( ) ( ) ( )

1966 1946 1940 1951 3 x 1921 2040 .

*DOI: http://dx.doi.org/10.5772/intechopen.95089*

the PC/ABS blend.

**Figure 7.**

respectively [18, 19]:

Where A3

Where A3

pressure, 40 MPa, C2

ture, 260°C; *B*<sup>2</sup>

ture, 260°C, *B*<sup>3</sup>

50 MPa, C2

tests of the experimental design.

*Average values (E) of S/N ratio for each parameter at levels 1–3.*

*3.2.2 Estimation of predicted mean*

µσ

µ

#### **Figure 6.**

*Average values (*σ*) of S/N ratio for each parameter at levels 1–3.*

*Influence of Injection Molding Parameters on the Mechanical Properties of Injected PC/ABS Parts DOI: http://dx.doi.org/10.5772/intechopen.95089*

**Figure 7.** *Average values (E) of S/N ratio for each parameter at levels 1–3.*

*Quality Control - Intelligent Manufacturing, Robust Design and Charts*

parameter C.

process of the PC/ABS blend.

**Figure 5** shows that the material temperature represented by parameter A was more prominent than the other IM process parameters for the elasticity module. Moreover, the maximum elasticity module was recorded in the third level, at the material temperature of 260°C, represented by parameter A; a mold temperature of 60°C, represented by parameter D; and in the second level at; an injection pressure of 40 bar, represented by parameter B; a holding time of 8 sec, represented by

The average values of S/N ratios of various parameters at different levels are

The S/N ratio analysis of the tensile strength plotted in **Figure 6** provides in to the same levels of the parameters as depicted in **Figure 4**. Therefore, A3, B3, C2, and D3 were the best levels for reducing the variability of the injection molding

**Parameter Level 1 Level 2 Level 3 Max-Min Rang** A 33.74 33.6 34.2 0.59 1 B 33.58 33.82 34.13 0.55 3 C 33.65 34.12 33.77 0.46 4 D 33.91 33.53 34.1 0.57 2

**Parameter Level 1 Level 2 Level 3 Max-Min Rang** A 65.47 65.66 65.87 0.4 1 B 65.56 65.78 65.66 0.22 4 C 65.52 65.75 65.72 0.23 3 D 65.69 65.5 65.8 0.3 2

*Average values (E) of S/N ratios at the different levels and their main effects.*

*Average values (*σ*) of S/N ratio for each parameter at levels 1–3.*

*Average values (*σ*) of S/N ratios at the different levels and their main effects.*

shown in **Tables 7** and **8**. These values are plotted in **Figures 6** and **7**.

**158**

**Figure 6.**

**Table 8.**

**Table 7.**

The S/N ratio analysis of the elasticity module depicted in **Figure 7** offers in to the same levels of the parameters as shown in **Figure 5**. So, A3, B2, C2, and D3 were the best levels for reducing the variability of the injection molding process of the PC/ABS blend.

**Table 3** shows the combinations of factor levels (3, 3, 2, 3) and (3, 2, 2, 3) were not among the obtained combinations within the tested experiment. Thus, it was necessary to verify the optimum injection molding conditions via confirmation tests of the experimental design.

### *3.2.2 Estimation of predicted mean*

The optimum levels of the control parameters of the tensile strength (μ1) and the elasticity module (μ2) are determined as A3, B3, C2, D3 and A3, B2, C2, D3 respectively [18, 19]:

$$\begin{split} \mu\_1 &= \overline{\sigma} + \left(\overline{A}\_3 - \overline{\sigma}\right) + \left(\overline{B}\_3 - \overline{\sigma}\right) + \left(\overline{C}\_2 - \overline{\sigma}\right) + \left(\overline{D}\_3 - \overline{\sigma}\right) \\ &= 51.3\,6 + 51 + 50.89 + 50.74 - \left(3 \ge 49.31\right) = 56.06 \, MPa. \end{split} \tag{1}$$

Where A3 is the average tensile strength at the third level of material temperature, 260°C, *B*<sup>3</sup> is the average tensile strength at the third level of injection pressure, 50 MPa, C2 is the average tensile strength at the third level of holding time, 8 sec, *D*<sup>3</sup> is the average tensile strength at the third level of mold temperature, 60°C and σ is the mean of tensile strength obtained from **Table 4**.

$$\begin{aligned} \mu\_z &= \overline{E} + \left(\overline{A}\_3 - \overline{E}\right) + \left(\overline{B}\_2 - \overline{E}\right) + \left(\overline{C}\_2 - \overline{E}\right) + \left(\overline{D}\_3 - \overline{E}\right) \\ &= 1966 + 1946 + 1940 + 1951 - \left(3 \ge 1921\right) = 2040 \text{ MPa}. \end{aligned} \tag{2}$$

Where A3 is the average elasticity module at the third level of material temperature, 260°C; *B*<sup>2</sup> is the average elasticity module at the second level of injection pressure, 40 MPa, C2 is the average elasticity module at the second level of holding time, 8 sec, *D*<sup>3</sup> is the average elasticity module at the third level of mold temperature, 60°C and *E* is the mean of elasticity module obtained from **Table 4**.

#### *3.2.3 Confirmation tests*

Three confirmation experiments were conducted at the optimum settings of the process parameters recommended by the investigation. The average tensile strength and the elasticity module obtained at the optimal level of the process parameters were 56.28 MPa and 1983 MPa.

Obviously, there was a difference between the computed and the experimental results. However, this difference can be considered not significant. Therefore, the confirmation tests indicate that the optimal conditions obtained above produced the best mechanical properties (σ, E) of the PC/ABS blend (**Table 9**).


**Table 9.** *Confirmation test results.*

### **4. Conclusion**

This work focused on Taguchi experimental method for investigating the influence of the injection parameters on the mechanical properties of PC/ABS during injection molding. Taguchi's results proposed two sets of optimal injection parameters conditions to achieve the best mechanical characteristics (σ, E). A first series: a material temperature of 260°C, an injection pressure of 50 bars, a holding time of 8 sec and a mold temperature of 60°C. A second series: a material temperature of 260°C, an injection pressure of 40 bar, a holding time of 8 seconds and a mold temperature of 60°C. All mechanical properties measurements matched very well with the experimental data. The most important parameter affecting the maximum tensile strength was the injection pressure. However, the material temperature was considered the most important parameter affecting the elasticity module. Consequently, it is shown clearly the above performance characteristics in the injection molding process are greatly significant through this study. So, we recommend that future works involve the impact of injection processing on the surface quality of the PC/ABS parts.
