When designing a sow mold, it is necessary to combine the thermodynamic properties of metal casting, the service life of the mold, and the quality requirements of the ingot, and focus on the following process parameters:
一. Cavity size and structural parameters
•Cavity volume and size: It is necessary to match the weight (usually hundreds to several tons) and shape (such as rectangle, trapezoid) of the target ingot to ensure that the depth and width of the cavity match the volume of the molten metal to avoid incomplete or wasteful ingot molding due to dimensional deviation.
•Cavity slope (draft slope): To facilitate demolding, the side wall of the cavity needs to be designed with a certain slope (usually 0.5°-2°). Too small a slope is prone to mold sticking, and too large a slope may affect the dimensional accuracy of the ingot.
•Fillet and edge processing: The bottom and corners of the cavity need to be rounded (R angle) to reduce stress concentration and avoid cracks in the mold due to thermal shock; at the same time, prevent shrinkage or cold shut at the corners of the ingot.
二. Thermal and cooling parameters
•Wall thickness design: The mold wall thickness needs to be calculated based on the melting point of the casting metal (such as aluminum about 660℃, copper about 1083℃) and heat capacity to ensure that it can withstand the thermal shock of high-temperature molten metal and control the heat dissipation rate through reasonable wall thickness (too thick will cool too slowly, too thin will be easy to deform).
•Cooling system layout: If forced cooling (such as water cooling) is used, the position, diameter and spacing of the cooling channel need to be designed. The channel needs to avoid the stress concentration area of the cavity and keep a reasonable distance from the cavity surface (usually ≥50mm) to ensure uniform cooling of the ingot and reduce defects such as shrinkage cavities and cracks.
•Thermal expansion compensation: Considering the solidification shrinkage rate of the molten metal (such as the shrinkage rate of aluminum is about 1.3%-2%) and the thermal expansion coefficient of the mold itself, reserve compensation in the cavity size design to avoid ingot size deviation or mold locking.
三. Metal liquid flow and filling parameters
•Gate and runner design: The gate position should avoid the metal liquid directly impacting the bottom of the cavity (to prevent splashing and oxidation), and the runner cross section should match the metal liquid flow rate to ensure uniform filling speed (generally controlled at 0.5-1.5m/s) and reduce slag rolls and pores.
•Vent structure: Design venting grooves (width 0.1-0.3mm, depth 0.5-1mm) at the top or corner of the cavity to avoid air encapsulation and pores when the metal liquid is filled, and prevent incomplete filling due to gas back pressure.
四. Mechanical performance parameters
•Mold strength and rigidity: According to the weight of the ingot (such as 500kg-5 tons) and the static pressure of the molten metal (calculation formula: pressure = molten metal density × height × gravity acceleration), select the appropriate material (such as cast steel, ductile iron) and design the reinforcing rib structure to prevent the mold from deformation or cracking.
•Mold release mechanism matching: If mechanical or hydraulic mold release is used, it is necessary to reserve the installation space of the mold release device (such as the ejector hole, the position of the hydraulic cylinder) to ensure that the mold release force (usually 1.5-2 times the weight of the ingot) acts evenly on the bottom of the ingot to avoid damage to the ingot or mold.
五. Material and surface treatment parameters
•Material thermal fatigue resistance: For the cyclic process of repeated heating (such as aluminum liquid 660℃) and cooling of molten metal, select materials with moderate thermal conductivity (such as cast steel thermal conductivity of about 40-50W/(m・K)) and high thermal fatigue strength to reduce thermal cracking.
•Surface treatment process: Improve surface wear resistance and anti-adhesive aluminum performance through nitriding (hardness up to 50-60HRC), shot peening or coating (such as ceramic coating), reduce demoulding resistance, and reduce erosion and wear of the mold surface by molten metal.
These parameters need to be comprehensively optimized in combination with the characteristics of specific casting metals (aluminum, copper, zinc, etc.), production efficiency (such as the number of castings per hour) and quality standards (such as internal flaw detection requirements for ingots), and ultimately achieve the goal of long mold life and high ingot quality.
Email: cast@ebcastings.com
When designing a sow mold, it is necessary to combine the thermodynamic properties of metal casting, the service life of the mold, and the quality requirements of the ingot, and focus on the following process parameters:
一. Cavity size and structural parameters
•Cavity volume and size: It is necessary to match the weight (usually hundreds to several tons) and shape (such as rectangle, trapezoid) of the target ingot to ensure that the depth and width of the cavity match the volume of the molten metal to avoid incomplete or wasteful ingot molding due to dimensional deviation.
•Cavity slope (draft slope): To facilitate demolding, the side wall of the cavity needs to be designed with a certain slope (usually 0.5°-2°). Too small a slope is prone to mold sticking, and too large a slope may affect the dimensional accuracy of the ingot.
•Fillet and edge processing: The bottom and corners of the cavity need to be rounded (R angle) to reduce stress concentration and avoid cracks in the mold due to thermal shock; at the same time, prevent shrinkage or cold shut at the corners of the ingot.
二. Thermal and cooling parameters
•Wall thickness design: The mold wall thickness needs to be calculated based on the melting point of the casting metal (such as aluminum about 660℃, copper about 1083℃) and heat capacity to ensure that it can withstand the thermal shock of high-temperature molten metal and control the heat dissipation rate through reasonable wall thickness (too thick will cool too slowly, too thin will be easy to deform).
•Cooling system layout: If forced cooling (such as water cooling) is used, the position, diameter and spacing of the cooling channel need to be designed. The channel needs to avoid the stress concentration area of the cavity and keep a reasonable distance from the cavity surface (usually ≥50mm) to ensure uniform cooling of the ingot and reduce defects such as shrinkage cavities and cracks.
•Thermal expansion compensation: Considering the solidification shrinkage rate of the molten metal (such as the shrinkage rate of aluminum is about 1.3%-2%) and the thermal expansion coefficient of the mold itself, reserve compensation in the cavity size design to avoid ingot size deviation or mold locking.
三. Metal liquid flow and filling parameters
•Gate and runner design: The gate position should avoid the metal liquid directly impacting the bottom of the cavity (to prevent splashing and oxidation), and the runner cross section should match the metal liquid flow rate to ensure uniform filling speed (generally controlled at 0.5-1.5m/s) and reduce slag rolls and pores.
•Vent structure: Design venting grooves (width 0.1-0.3mm, depth 0.5-1mm) at the top or corner of the cavity to avoid air encapsulation and pores when the metal liquid is filled, and prevent incomplete filling due to gas back pressure.
四. Mechanical performance parameters
•Mold strength and rigidity: According to the weight of the ingot (such as 500kg-5 tons) and the static pressure of the molten metal (calculation formula: pressure = molten metal density × height × gravity acceleration), select the appropriate material (such as cast steel, ductile iron) and design the reinforcing rib structure to prevent the mold from deformation or cracking.
•Mold release mechanism matching: If mechanical or hydraulic mold release is used, it is necessary to reserve the installation space of the mold release device (such as the ejector hole, the position of the hydraulic cylinder) to ensure that the mold release force (usually 1.5-2 times the weight of the ingot) acts evenly on the bottom of the ingot to avoid damage to the ingot or mold.
五. Material and surface treatment parameters
•Material thermal fatigue resistance: For the cyclic process of repeated heating (such as aluminum liquid 660℃) and cooling of molten metal, select materials with moderate thermal conductivity (such as cast steel thermal conductivity of about 40-50W/(m・K)) and high thermal fatigue strength to reduce thermal cracking.
•Surface treatment process: Improve surface wear resistance and anti-adhesive aluminum performance through nitriding (hardness up to 50-60HRC), shot peening or coating (such as ceramic coating), reduce demoulding resistance, and reduce erosion and wear of the mold surface by molten metal.
These parameters need to be comprehensively optimized in combination with the characteristics of specific casting metals (aluminum, copper, zinc, etc.), production efficiency (such as the number of castings per hour) and quality standards (such as internal flaw detection requirements for ingots), and ultimately achieve the goal of long mold life and high ingot quality.
Email: cast@ebcastings.com
