As the critical channels for molten metal filling and feeding, the layout, dimensions, flow direction and process adaptability of ingates directly determine the forming quality, dimensional accuracy and service performance of castings. The design criteria sorted out in this paper cover all dimensions including solidification matching, liquid flow control, structural optimization, production operation and defect prevention and control, featuring strong universality and easy implementation. They can provide standardized technical guidance for process design, production optimization and quality control of various castings, facilitating the refined and high-quality production development of the foundry industry.

I. Determine the Position and Quantity of Ingates Based on Solidification Modes

1. Simultaneous Solidification Castings (Thin-Wall Parts Prone to Stress Cracking)

   Set ingates at thin-wall sections with scattered multi-ingate layout; avoid local overheating of sand molds to reduce casting stress and deformation.

2. Progressive Solidification Castings (Heavy-Section Parts Prone to Shrinkage Cavities)

   Arrange ingates at thick hot spots; where risers are equipped, lead molten metal into the casting through risers to extend the heat preservation time of molten metal in risers and strengthen feeding effect.

3. Castings with Complex Composite Structures

   Combine zoned sequential feeding and overall balanced filling via multiple ingates: each hot spot relies on sequential solidification feeding to prevent shrinkage cavities, while scattered liquid inlet overall reduces stress and deformation.

4. Working Conditions with Great Wall Thickness Disparity Where Liquid Can Only Be Fed Through Thin Walls

   Open ingates on thin walls, place chills on thick walls to accelerate cooling, and match with risers for feeding to balance solidification temperature difference.

II. Control Molten Metal Flow Direction to Prevent Sand Erosion, Slag Inclusion and Other Defects

1. Forbid liquid flow to directly impact delicate sand cores, mold walls, chills and core supports, so as to avoid sand erosion, sand holes, core offset and fracture.

2. For circular castings with ordinary surface appearance requirements, tangential feeding is acceptable to utilize swirling flow for impurity floating upward.

3. Tangential feeding is prohibited for cylindrical castings and those requiring high precision on inner surfaces, to prevent molten slag and oxide scale from accumulating cyclically on inner walls and resulting in slag inclusion and leakage defects.

III. Prioritize Thin Ingates for Slag Retention, Easy Cleaning and Improved Casting Compactness

1. Thin ingates narrow the slag absorption area and boost slag retaining effect together with runner systems.

2. Ingates shall be thinner than casting wall thickness to prevent damage to casting bodies during cutting and cleaning.

3. Thin ingates for iron castings can improve casting compactness by virtue of graphitization expansion.

4. Specification for ductile iron: both the width and length of ingates shall be 4 times their thickness.

IV. Utilize Multiple Ingates as Auxiliary Feeding Channels for Thin-Wall Castings

When independent large risers are unavailable for thin-wall castings, multiple ingates serve dual functions of filling and feeding. The cross-sectional dimensions of ingates shall be designed in accordance with riser neck standards to guarantee unobstructed feeding channels.

V. Avoid Critical Working Surfaces of Castings and Prioritize Secondary/Machining Surfaces for Ingates

1. Do not arrange ingates on areas requiring high compactness and metallographic properties, otherwise coarse grains and degraded mechanical properties will occur at such positions.

2. For pressure-resistant and leakage-proof pipeline castings, set ingates on flanges to avoid shrinkage porosity and leakage on pipe walls.

3. Prioritize machining surfaces for ingate layout; after machining and grinding, no ingate marks will remain for smoother surface finish.

VI. Unify Molten Metal Flow Direction for Stable Filling and Reduced Turbulence, Gas Entrapment and Slag Inclusion

Maintain the same flow direction of molten metal through all ingates to avoid collision and turbulent rolling of two streams of liquid. This reduces gas entrapment, oxide inclusions and blowhole defects caused by turbulence, and facilitates rapid mold cavity venting and slag floating.

VII. Prioritize Ingate Layout on Mold Parting Lines to Simplify Molding and Pattern Making

Ingates arranged on parting lines simplify pattern drawing, mold repairing and mold closing operations, cutting molding man-hours and reject rates. If layout on parting lines is infeasible, stepped, top-pouring or bottom-pouring hidden ingates can be adopted alternatively.

VIII. Anti-Cracking Design for High-Shrinkage Alloys (Cast Steel, Ductile Iron, Cast Aluminum, etc.)

Alloys with large shrinkage and high hot cracking tendency shall not be restrained rigidly by ingates, which would generate tensile stress and trigger hot cracking during solidification shrinkage.

Optimization solutions: narrow, thin and short ingates, scattered multi-ingate layout and arc-transition gates to lower restraint on casting shrinkage.

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