**Figure 2.**

*Product with shrinkage defect and linked simulation*

the existing design and the caveats can be ironed out by proper methoding. Final simulation results show that there is hardly any detrimental defect in the cast part and thus a huge cost for trial and error is saved. To demonstrate the role of methoding and solidification criterion on casting defects, one crucial industrial case study is discussed here.

The foundry is producing three major components of CBC i.e. coupler body, knuckle and yoke in a single mould. Cast Steel (ASTM M-211 GRADE-E) was used as the casting material and green sand under high pressure moulding system was

**61**

filling.

**Table 1.**

needed to be taken care of.

Quality of the casting

*Techno-Economy Analysis of Wedge Casting/Ton*

Rejection

*Simulation and Validation of Castings in Shop Floor DOI: http://dx.doi.org/10.5772/intechopen.94596*

**Figure 5(a)** shows the level of entrapped air at a level of 20% filled mould cavity while **Figure 5(b)** shows when the metal pouring has been completed. The final picture depicts that no air particles have been entrapped observed in cavity during

Aesthetic Look Standard World class Processing time 1 Unit 1/3 Unit Consistency Not up to the mark Very Consistent

Good 30%

Very Good (ASTM 2) 5%

**Factors Considered Conventional Stack Moulding** Bunch Weight 42.96 kg 75.19 kg Weight/piece 5.80 kg 5.80 kg No. of pieces/bunch 4 nos 7 nos Net Casting weight/bunch 23.20 kg 40.60 kg Bunch Yield % 54% 54% Metal Cost 22644.93.(INR) 22644.93 (INR) Ferro Alloy Cost 2485.40 (INR) 2336.27 (INR) Electricity Cost 15395.74 (INR) 14472.00 (INR) Core cost/Molding cost 1640.24 + 6481.00 (INR) 16223.82 (INR) Store Cost 7408.04 (INR) 6768.32 (INR) Heat Treatment Cost 3500.00 (INR) 3500.00 (INR) Shot Blasting Cost 227.00 (INR) 227.00 (INR) Labor Cost (Production) 4887.45 (INR) 2625.26 (INR) Labor Cost (Fettling) 2930.00 (INR) 2758.00(INR) Maintenance Cost 1300.00 (INR) 1300.00 (INR) Total Variable Cost 68899.80 (INR) 72855.60 (INR) Fixed Cost 4200.00 (INR) 4200.00 (INR) Rework 7000.00 (INR) 500.00 (INR) Total Cost 80,099.80 (INR) 77,555.60 (INR) Cost per piece 570.57 (INR) 561.55 (INR)

Solidification temperature pattern shows rate of solidification and time taken to solidify. It is evident from left top corner of **Figure 6(a)** shows after elapse of 123 seconds the solidification is 1%. Similarly **Figure 6(b)** indicates that it takes 2910.558 seconds to solidify 100%. The temperature scale shows that some portion of the product has been delinked with the riser and contains higher heat. This will cause shrinkage defect in those locations. The yellow arrows of **Figure 7** indicates the major shrinkage cavities produced after solid simulation and these hot spots are

Now, the detail component wise defect analyses of the knuckle, coupler body and yoke have been shown in **Figures 8**, **9** and **10** respectively. **Figure 8** shows that the knuckle is free from shrinkage, blow holes and air entrapment issues. As per Research Designs and Standards Organization (RDSO) standard, there is no porosity

#### **Figure 3.** *Scheme to indicate the modification done*

used. The 3D CAD model is created in solid modeling software and converted to .STL format. The .STL file imported into the Z-CAST simulation software. Here, pouring temperature is taken as 1610 °C, and pouring time is 30 seconds. Exothermic sleeves are used in this case and the mould temperature is considered as 30°C before the pouring of molten metal. The shrinkage allowance of the material is also considered as 3.5%.

The flow simulation of the product shows filling percentage with respective temperature scales as shown in **Figure 4**. The flow temperature analysis can test fluidity of the molten material and assist to locate the un-filling regions by analyzing temperature plots in thin sections of the cavity. The white colour in the temperature scale corresponds to the highest temperature of the melt i.e. the pouring temperature. Yellow, red, dark blue and finally light blue are indicating temperatures of gradual decreasing order. Filling condition of this product at different filled position (2, 10, 40, 60, 80 and 100%) is shown in the figure. **Figure 4a** shows that the molten metal is entering in the mould cavity through sprue. Mould filling is an essential matter since the melt temperature will commence decreasing when it comes in contact with the cooler mould surface. **Figure 4a** shows that molten metal will flow according the slope of mould cavity. **Figure 4b** shows that 10% volume of the mould cavity is filled by the molten metal. **Figure 4(c-e)** indicate that 40, 60 and 80% space of the mould cavity is filled by the melt and the liquid metal has started solidification process. **Figure 4f** shows that at 100% filled condition the components at the farthest point from the sprue have blue colour which indicate that the temperature at those points are sufficient lower than the pouring temperature. At the end of 30 seconds i.e. the complete pouring of metal, temperature drops from 1610°C to 1490°C

The air entrapment simulation is shown in **Figure 5**. This flow un-filling simulation shows when molten material enters into the mould cavity, how the entrapped air escapes and thus this simulation can predict the unfilled locations of the cavity. Here, the red colour indicates cavity yet to be filled and transparent area shows metal is filled. Small dots indicate the amount of entrapped air in the cavity.

#### *Simulation and Validation of Castings in Shop Floor DOI: http://dx.doi.org/10.5772/intechopen.94596*

*Casting Processes and Modelling of Metallic Materials*

used. The 3D CAD model is created in solid modeling software and converted to .STL format. The .STL file imported into the Z-CAST simulation software. Here, pouring temperature is taken as 1610 °C, and pouring time is 30 seconds. Exothermic sleeves are used in this case and the mould temperature is considered as 30°C before the pouring of molten metal. The shrinkage allowance of the material is

The flow simulation of the product shows filling percentage with respective temperature scales as shown in **Figure 4**. The flow temperature analysis can test fluidity of the molten material and assist to locate the un-filling regions by analyzing temperature plots in thin sections of the cavity. The white colour in the temperature scale corresponds to the highest temperature of the melt i.e. the pouring temperature. Yellow, red, dark blue and finally light blue are indicating temperatures of gradual decreasing order. Filling condition of this product at different filled position (2, 10, 40, 60, 80 and 100%) is shown in the figure. **Figure 4a** shows that the molten metal is entering in the mould cavity through sprue. Mould filling is an essential matter since the melt temperature will commence decreasing when it comes in contact with the cooler mould surface. **Figure 4a** shows that molten metal will flow according the slope of mould cavity. **Figure 4b** shows that 10% volume of the mould cavity is filled by the molten metal. **Figure 4(c-e)** indicate that 40, 60 and 80% space of the mould cavity is filled by the melt and the liquid metal has started solidification process. **Figure 4f** shows that at 100% filled condition the components at the farthest point from the sprue have blue colour which indicate that the temperature at those points are sufficient lower than the pouring temperature. At the end of 30 seconds i.e. the complete pouring of metal, temperature drops

The air entrapment simulation is shown in **Figure 5**. This flow un-filling simulation shows when molten material enters into the mould cavity, how the entrapped air escapes and thus this simulation can predict the unfilled locations of the cavity. Here, the red colour indicates cavity yet to be filled and transparent area shows metal is filled. Small dots indicate the amount of entrapped air in the cavity.

**60**

also considered as 3.5%.

*Scheme to indicate the modification done*

**Figure 3.**

from 1610°C to 1490°C


**Table 1.**

*Techno-Economy Analysis of Wedge Casting/Ton*

**Figure 5(a)** shows the level of entrapped air at a level of 20% filled mould cavity while **Figure 5(b)** shows when the metal pouring has been completed. The final picture depicts that no air particles have been entrapped observed in cavity during filling.

Solidification temperature pattern shows rate of solidification and time taken to solidify. It is evident from left top corner of **Figure 6(a)** shows after elapse of 123 seconds the solidification is 1%. Similarly **Figure 6(b)** indicates that it takes 2910.558 seconds to solidify 100%. The temperature scale shows that some portion of the product has been delinked with the riser and contains higher heat. This will cause shrinkage defect in those locations. The yellow arrows of **Figure 7** indicates the major shrinkage cavities produced after solid simulation and these hot spots are needed to be taken care of.

Now, the detail component wise defect analyses of the knuckle, coupler body and yoke have been shown in **Figures 8**, **9** and **10** respectively. **Figure 8** shows that the knuckle is free from shrinkage, blow holes and air entrapment issues. As per Research Designs and Standards Organization (RDSO) standard, there is no porosity

**Figure 4.** *Simulated filling conditions at different filled positions*

**63**

**Figure 8.**

**Figure 6.**

**Figure 7.**

*Solid simulation of product*

*Indicating shrinkage cavities after solid simulation*

these are under level 2.

from the cavity. In some non-critical locations, some minor porosity has formed but

*Defect analysis of the knuckle and real cross section of critical location indicating zero defect*

While analyzing **Figure 10**, it is found that the yoke is free from major shrinkage defect but some minor shrinkage defects have been observed (indicated by yellow

*Simulation and Validation of Castings in Shop Floor DOI: http://dx.doi.org/10.5772/intechopen.94596*

**Figure 5.** *Air entrapment simulation*

in critical location of the knuckle component. But in other non-critical locations some porosity can be observed but those would be passed through the radiography NDT testing of level 2.

**Figure 9** indicates that major shrinkage defects have formed in the coupler body and these are to be removed by adopting proper casting methodology. The figure also indicates some major porosity formation which are crossing the level 2 of radiography testing, therefore, these porosities are also needed to be eliminated *Simulation and Validation of Castings in Shop Floor DOI: http://dx.doi.org/10.5772/intechopen.94596*

**Figure 6.** *Solid simulation of product*

*Casting Processes and Modelling of Metallic Materials*

**62**

**Figure 5.**

**Figure 4.**

*Simulated filling conditions at different filled positions*

NDT testing of level 2.

*Air entrapment simulation*

in critical location of the knuckle component. But in other non-critical locations some porosity can be observed but those would be passed through the radiography

**Figure 9** indicates that major shrinkage defects have formed in the coupler body and these are to be removed by adopting proper casting methodology. The figure also indicates some major porosity formation which are crossing the level 2 of radiography testing, therefore, these porosities are also needed to be eliminated

**Figure 7.** *Indicating shrinkage cavities after solid simulation*

#### **Figure 8.**

*Defect analysis of the knuckle and real cross section of critical location indicating zero defect*

from the cavity. In some non-critical locations, some minor porosity has formed but these are under level 2.

While analyzing **Figure 10**, it is found that the yoke is free from major shrinkage defect but some minor shrinkage defects have been observed (indicated by yellow

**Figure 9.** *Defect analysis of the coupler body*

arrows) along with some minor porosity below the riser, which needs to be eliminated from casting. The porosities crosses the radiography level 2 and therefore, needs to be eliminated from the cavity.

**65**

**Figure 11.**

*Simulation and Validation of Castings in Shop Floor DOI: http://dx.doi.org/10.5772/intechopen.94596*

system is used with following minor modifications.

By analyzing **Figures 4**–**10**, it can be concluded that knuckle has no major issues to be solved but the coupler body mouth and one end of yoke are prone to shrinkage defect and porosity respectively. Cross-section of critical section before modified methoding is shown in **Figure 11**. To solve the issues, two sprue with existing gating

**Figure 6(a)** and **Figure 12(a)**, it can be found that the dimensions of the risers are different. It is needless to mention that the authors are unable to share such

b.In mouth area of coupler body, chromite sand core (shown as the red arrow in **Figure 13(a)** and the schematic of the core shape is shown in detail in **Figure 13(b)**) is to be used to have effect of chill in order to minimize the major hot spot in the critical location. **Figure 9** indicates that the mouth of the coupler body is most prone to shrinkage defect and to eliminate that use of chromite sand core is necessary since it has high thermal conductivity and

c.The yoke is also prone to shrinkage and porosity defect as discussed in **Figure 10**. To eliminate this defect, a riser should be used as shown by a

d.Additional three more chills are required and suggested to be placed in the mouth core of the coupler body else a small riser should be incorporated. The use of chills or a riser is technically equivalent but both chill and riser have certain pros and cons. The use of extra riser is associated with some extra cost related to material, energy to melt, cutting, re-melting etc. Whereas use of chills does not have such extra cost, they are to be purchased or fabricated once. But in practical shop floor, it is seen that after several production runs, the labours forgot to collect all the chills while breaking the sand mould and eventually the chills are misplaced. Therefore, it becomes a decision of the proprietor of the company, whether he will go for chill or a riser. In this case a

riser is used which is marked as a deep blue arrow in **Figure 13(a)**.

a.Minor modification in riser sizes: If a close comparison is done between

**7.1 Iteration**

data in detail.

good chilling effect.

brown arrow in **Figure 13(a)**.

*Cross-section of Critical Section before modified methoding*
