Hybrid Ceramic Sand Core for Small Engine Passages
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Solution Overview
Problem
Conventional sand core casting methods are limited in creating small internal passages and holes due to thermal shock and binder evaporation, restricting the size of features that can be cast, which necessitates additional machining and reduces design flexibility in engine components like cylinder blocks and cylinder heads.
Innovation Solution
The use of hybrid ceramic/sand cores, where ceramic sections are integrated to form small passages and holes, allowing for the creation of features with cross sections as small as 1 mm, which cannot be achieved with traditional sand cores, and can be economically produced using injection molding and caustic solution cleaning for extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sand core casting methods are used to create internal passages, then the manufacturing process is simple and cost-effective, but the cross section size of passages is limited to above certain minimum dimensions due to thermal shock and binder evaporation
Solution Approach 1:
The patent applies composite materials by combining ceramic and sand in a single core structure. The ceramic portion (made via injection molding) provides thermal stability and structural integrity for small passages, while the sand portion provides ease of manufacture and cost-effectiveness. This composite approach allows the core to maintain stability at smaller passage dimensions while remaining manufacturable.
Solution Approach 2:
The patent applies local quality by using different materials in different regions of the core. The ceramic material is used specifically in the portion forming the small passage (where thermal stability is critical), while sand is used in other regions where ease of manufacture is more important. This localized material selection optimizes both passage precision and overall core reliability.
2Manufacturing precision
If conventional sand core casting is used, then large passages can be cast easily, but small passages (cross section below limiting dimensions) cannot be formed without core disintegration
Solution Approach 1:
The hybrid ceramic/sand core uses composite materials to enable small passage formation. The injection-molded ceramic portion can be produced with high precision for small dimensions, while the sand portion maintains ease of manufacture. The combination allows small passages to be formed without the core disintegrating, as the ceramic provides the necessary structural support.
Solution Approach 2:
The patent applies segmentation by dividing the core into distinct ceramic and sand portions. The ceramic segment is injection-molded to precise dimensions for small passages, while the sand segment is formed using conventional methods. This segmentation allows each material to be optimized for its specific function, enabling small passage formation while maintaining manufacturability.
3Manufacturing precision
If machining is used to create small passages after casting, then precise small features can be produced, but design flexibility is reduced due to line-of-sight access requirements and additional parts count
Solution Approach 1:
The patent applies preliminary action by forming the small passages during the casting process itself using the hybrid core, rather than requiring subsequent machining operations. The injection-molded ceramic portion of the core precisely defines the small passages in three dimensions, eliminating the need for post-casting machining and thereby maintaining full design flexibility for complex passage geometries.
Solution Approach 2:
The patent extracts the passage-forming function from the machining process and integrates it into the casting process. By using the hybrid core with injection-molded ceramic, the small passages are created directly during casting, removing the need for separate machining operations and enabling greater design freedom for complex fluid networks.
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 method reduces machining requirements, enhances design flexibility, and improves cooling efficiency by allowing more intricate fluid passage networks within engine components, leading to cost savings and improved engine performance.
Implementation Method 1
caustic solution cleaning for extraction
Data Source
AI summary
A hybrid ceramic/sand casting method of manufacturing a metal part. The method is especially suitable for manufacturing engine cylinder blocks or cylinder head, which have very small internal passages or other very small internal features. These parts are formed using a hybrid core having at least one ceramic section and at least one sand section, with the ceramic section being used to create the internal feature. A mold cavity is created for the part, and the hybrid core is positioned in the mold. Molten metal is introduced into the mold, and after the metal cools, the core is removed, thereby forming the part with the internal feature.