Casting Mold Surface Processing for Coating Stability
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Solution Overview
Problem
The existing technologies for improving the liquidity of molten metal in casting molds, which involve forming microscopic grooves and coating with a carbon film, face issues with coating exfoliation due to high penetration rates, leading to increased contact area and friction, potentially reducing the heat insulation property and liquidity.
Innovation Solution
A casting mold with surface processing that includes grid-shaped groove parts coated with a carbon film, where the groove width is 35 μm or narrower, the skewness of three-dimensional surface roughness is between −0.8 and −0.2, and the indentation hardness of the carbon film is 1000 N/mm2 or higher, formed using a pulsed laser with a pulse width of 10 psec or narrower, to control coating exfoliation and maintain molten metal liquidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a carbon film is coated on groove parts formed in the mold surface, then heat insulation property is improved and liquidity of molten metal is enhanced, but the coating may exfoliate when molten metal penetrates into the groove part at high rate
Solution Approach 1:
The invention changes the geometric parameters of the groove parts (width ≤35 μm, depth 5-20 μm) and surface roughness parameters (skewness −0.8 to −0.2, Rz 1.5-3.0 μm) to control the penetration rate of molten metal. By optimizing these parameters, the penetration rate is reduced to 10% or less, preventing coating exfoliation while maintaining the heat insulation effect of the carbon film coating.
2Reliability
If the groove part width is reduced to control penetration rate, then coating exfoliation is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The invention replaces conventional mechanical groove formation methods with laser processing technology. The laser processing method can precisely control groove width (35 μm or narrower) and surface roughness parameters (skewness −0.8 to −0.2) without the limitations of mechanical tooling, achieving the required precision through optical field control rather than mechanical contact.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach optimizes the surface processing of the casting mold to prevent coating exfoliation, maintaining the liquidity of the molten metal by controlling the penetration rate to 10% or lower, thus ensuring improved heat insulation and efficient filling of the mold cavity.
Implementation Method 1
forming the groove part by emitting a pulsed laser beam onto a surface of the mold material with a pulsed laser device that emits the pulsed laser beam with a pulse width of 10 psec or narrower
Implementation Method 2
coating the inside of the groove parts with a carbon film in order to prevent the mold surface from cooling and the liquidity from decreasing
Data Source
AI summary
A casting mold and a production method thereof with which exfoliation of coating is controlled and liquidity of molten metal can be maintained are provided. This casting mold 1 includes a surface processing part 3 in which a plurality of groove parts 5 of a grid groove 4 formed in a surface of a molten metal contact part of a mold material 2 is coated with a carbon film 6. In this surface processing part 3, a width W1 of the groove parts 5 is 35 μm or narrower, skewness Ssk of three-dimensional surface roughness is in a range of −0.8 to −0.2, and indentation hardness of the carbon film 6 tested by a nanoindenter is 1000 N/mm2 or higher. With this arrangement, it is possible to optimize the surface processing part 3 in such a manner that a penetration rate of the molten metal (aluminum 10) is controlled to be low and the coating (carbon film 6) is unlikely to exfoliate from the groove parts 5.