What are common cast iron ground rails?
On a surface plate with an accuracy grade lower than "00," sand holes with a diameter less than 15mm are allowed to be plugged with the same material, and their hardness should be lower than that of the surrounding material. There should be no more than four plugged areas on the working surface, and the distance between them should be no less than 80mm.

Empirical formula for calculating the pouring time of gray cast iron: Casting mass pouring time coefficient. When the casting wall thickness is 3–5mm, S = 1.63; when the wall thickness is 6–8mm, S = 1.85; when the wall thickness is 9–15mm, S/=<450kg=2.2. Generally, S1 = 2; when the carbon content is less than 3.3%, the molten iron has a high sulfur content, poor fluidity, and a low pouring temperature, <10:t=s1, or when using a bottom-pouring gating system with risers at the top, or when internal chills require fast pouring, S1 = 1.7–1.9.
When the casting wall thickness is 08/thick and high quality is required, fast pouring is needed to avoid prolonged baking time causing the coating layer to fall off, S1 = 1.2–1.7. When the casting wall thickness is <10mm, S2 = 1.11; when the wall thickness is 11–20mm, S2 = 1.44; when the wall thickness is 21–40mm, >10tt=S2CS2 = 1.66; when the wall thickness is >40mm, S2 = 1.89. Note: 1 - Pouring time for cast iron ground rails; S, S1, S2 - coefficients; 8 - Main wall thickness of cast iron ground rails; G - Pouring mass (including the mass of the gating and riser systems).
During the installation of cast iron ground rails, they must be matched with the foundation embedded anchor bolts (ground anchors) in the foundation. If a vibration isolation system foundation is used, it is recommended to also use an air spring vibration isolation system; otherwise, the cast iron ground rails cannot be installed. Before the foundation is poured, the anchor frame should be placed in the required positions. Once all anchor bolts are installed in their designated positions, the foundation pouring can begin and should be completed in one go. After pouring, the foundation enters a curing period. Once the curing period is over, the installation of the cast iron ground rails can commence.

Gates should be set at the thin-walled parts of the casting, with a large number and dispersed layout, so that the molten metal can quickly and evenly fill the mold cavity, avoiding local overheating of the sand mold near the gates. For castings requiring directional solidification, gates should be set at the thick-walled parts.
Vertical slot gating system. The vertical slot gating system is a special form of the step gating system. Since the gates in the step gating system are difficult to remove during molding, the larger cross-section sprue and multi-layer gates are replaced with a vertical slot, which is a typical intermediate pouring gating system.
This setup ensures that the thick sections of the casting are fully fed without shrinkage cavities or porosity, while minimizing stress and deformation. It also helps improve the as-cast structure of the casting.
Layout of multiple gates. Practice has shown that when multiple gates of equal cross-section are on the same runner, the flow rates in each gate are uneven. Gates farther from the sprue have higher flow rates, while those closer to the sprue have lower flow rates. This phenomenon can cause local overheating of the casting, leading to uneven quality. To prevent missing material after cleaning. Connection structure between gates and the casting. Vertical slot gating system step gating system. For heavy castings, especially important ones, using a single type of cast iron ground rail gating system may not meet the requirements. In such cases, two or more types of gating systems can be used simultaneously, known as a composite gating system. An example is the simultaneous use of bottom-pouring and shower-type gating systems for pouring a high-horsepower diesel engine cylinder liner (mass approximately 3100kg).
After the positions of the anchor bolts for the cast iron ground rails are set, the adjustment of the cast iron ground rails using the anchor bolts can begin. Once the on-site inspectors complete their measurements, the rails can be used.
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