Knowledge

To reduce the porosity of ductile iron through mold design, the following aspects can be considered and optimized:

 

I. Mold Structure Design

Cavity Design:

Design a reasonable cavity structure to avoid overly complex and weak parts, thereby reducing the possibility of gas retention and the formation of gas holes. Ensure the cavity surface is smooth to minimize the adhesion and accumulation of gas within the cavity.

Parting surface design:

The design of the parting surface should be reasonable to ensure that the casting does not develop gas holes when demolded due to an uneven or misaligned parting surface. Exhaust grooves or holes can be set on the parting surface to facilitate the timely removal of gases from the mold cavity.

Draft angle:

Design an appropriate draft angle to ensure that the casting can be smoothly removed from the mold during demolding and to prevent porosity caused by difficult demolding.

 

II. Design of the gating system

Gate Design:

The location and size of the gate should be reasonably designed to ensure that the molten metal can enter the mold cavity smoothly and quickly, and to avoid the generation of vortices and the entrainment of gases during the pouring process. Bottom-gate or side-gate pouring systems can be adopted to reduce the splashing of the molten metal during its descent and the entrainment of gases.

Flow channel design:

The design of the runner should be smooth, avoiding sharp turns and dead corners to reduce the resistance of the molten metal during flow and the retention of gases. ​​​​​​​

 

III. Cooling System Design

 

Cooling channel layout:

Rationally arranging the cooling channels within the mold can control the solidification process of the casting, preventing local overheating and gas evolution. The quantity and position of the cooling channels should be precisely calculated and designed based on the structure and size of the casting.

 

Cooling rate control:

By adjusting the flow rate and temperature of the cooling water, the cooling speed of the casting can be controlled, enabling the casting to cool uniformly and stably during the solidification process and reducing the formation of pores due to uneven cooling.

IV. Design of Exhaust System

 

Exhaust slots and exhaust holes:

Exhaust grooves and holes should be set at appropriate positions on the mold to timely discharge the gas inside the mold cavity. The size and location of the exhaust grooves and holes should be designed based on the structure of the casting and the characteristics of the gating system.

 

Exhaust effect verification:

After the mold design is completed, the exhaust effect should be verified and tested to ensure that the exhaust system can effectively remove the gas in the mold cavity.

 

V. Other Matters to Note

 

Mold material selection:

Select mold materials that are resistant to high temperatures, wear and have good thermal conductivity to increase the service life of the mold and reduce the formation of pores.

 

Mold maintenance and care:

Regularly maintain and service the molds to keep them clean and in good condition, avoiding the formation of pores due to mold damage or wear.

 

Vigorhas more than 18 years experience on castings, we know how to avoid defects when production.If you have any question and demand of products development or improve your supply chain, please feel free to contact us atinfo@castings-forging.com