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Direct Molding Process (DMP)
An outstanding casting method that would realize a complex shaped casting.
Hybrid Full Mold Casting process is a unique casting process of Kimura
utilizing DMP technology where polystyrene pattern together
with a sand core is combined to form a casting.
Hybrid Full Mold Casting process is a unique casting process of Kimura utilizing DMP technology where polystyrene pattern together with a sand core is combined to form a casting.
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A Hybrid of Full Mold Casting process and Direct Molding Process
We have developed a brand new casting technology by combining Full Mold Casting process and Direct Molding Process technology. (Patent application 2010-291172)
This technology has enabled us to produce complex large scale castings of max. 30t with a min. wall thickness of 3mm. Mainly, the technology could be applied to the manufacturing of casting parts for large diesel engine application. This technology has taken away some of the design limitations (such as undercut, wall thickness etc.) and providing wider options for designer prioritizing the efficiency of products.
Features of the technology
One of the main features of the technology is that for example, the outer part of a product where its geometry is simple could be covered by the Full Mold Casting process whilst the inner complex geometry could be formed by the Direct Molding Process technique. Unlike conventional casting method, neither wood patterns nor molds are necessary and therefore requires less lead time for transition from prototyping to mass-production. This way, it realizes us to support our customers' vertical take off and design changes. Moreover, since DMP has higher flexibility to designing, cores used for a part could be made as a single body attached to main mold. Assembling is not needed and therefore an unexpected gap between cores could be minimized and therefore, made possible the accuracy to assure 3mm wall thickness.
A typical casting defect called veining is often caused by using the cores made by DMP. This issue needed to be solved in order to apply the technology in producing cast iron parts, since it is difficult a task to remove the veining appeared inside a complex geometry. Nonetheless, we achieved to clear out the problem by establishing a DMP molding technique using artificial sand. (Patent application 2012-113632)
Other related patent application no.: Patent application 2012-013109
The phase transition point of silica sand is around 570 deg C and at that time, a mold would crack from the volume expansion which would cause burrs to appear on castings. Using artificial sand which does not have phase transition would prevent veining defects to occur.
Figure 1 The phase transition point of silica sand is around 570 deg C and at that time, a mold would crack from the volume expansion which would cause burrs to appear on castings. Using artificial sand which does not have phase transition would prevent veining defects to occur.
Sectioned surface of a cylinder head produced as test parts.
Figure 2 Sectioned surface of a cylinder head produced as test parts.
Surface with veining defects when produced by natural silica sand (Left)
Surface free of veining defects by adopting artificial sand (Right)
Sectioned surface of a cylinder head produced as test parts.
Figure 3 Laminating molding device used to produce a sand core by artificial sand.
Background and details of the development
In the era where exhaust gas regulation is everywhere, combustion efficiency improvement is a must for an internal-combustion engine. In tandem to this, the customer needs for complex, thick wall and lighter iron casting parts have always existed. In conventional casting method, the accuracy of wall thickness especially for large scale castings was hard to guarantee which was an obstacle to challenge thinner wall castings. In addition, the traditional casting process had various limitations in its producible casting geometry such as undercut shape and drafts. For our latest development, we successfully combined these two casting processes, which each provide high dimensional accuracy, to establish a brand new casting technology.
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