What should be noted in gray iron casting?

What should be noted in gray iron casting?

Gray cast iron contains flaky graphite, resulting in a relatively small effective load-bearing area and making stress concentrations prone to occur at the top. As a result, gray iron has lower strength, ductility, and toughness compared to other types of cast iron—but it boasts excellent vibration damping, low notch sensitivity, and high wear resistance. So, what are the key considerations when casting gray iron? Here are the important precautions for gray iron casting:

1. Process details of gray iron parts that can be clearly depicted in a particular view or sectional view do not need to be shown with all process symbols on every single view, as this could lead to an overabundance of symbols on the drawing, causing them to overlap and obscure one another.

2. If the machining allowance dimensions for gray iron are the same as those for the top surface, inner holes, bottom surface, and side surfaces—but are not explicitly marked on the drawing—they may be noted in the drawing’s process card on the reverse side or specified in the technical requirements.

3. For gray iron castings, the casting fillets and draft angles of equal magnitude are specified in the technical requirements, though they are not explicitly marked on the drawings.

4. If the sand core boundary line for gray iron parts coincides with the part line, machining allowance line, and chills line, the sand core boundary line can be omitted.

5. The relationship between the mold surface sand core line and the machining allowance line in gray iron molds varies depending on the specific practices of different factories.

6. For single-piece gray iron parts, small-batch products, and even some mass-production factories, casting process diagrams are drawn directly on the product drawings to guide production.

7. Various process dimensions or data marked on gray iron parts should not overlap the data shown on the product drawings; instead, they should be easy for workers to follow and align with the actual conditions of the factory.

What maintenance measures are there for gray iron castings?

1. When not in use, gray iron should be cleaned promptly and thoroughly, then coated with a layer of rust-preventive oil, covered with rust-proof paper, and finally sealed with the outer packaging of the gray iron stand to prevent damage to the working surface.

2. To prevent overall deformation of the gray iron, remove the workpiece from the gray iron, gray iron plate, and cast iron platform after use, as prolonged pressure from the workpiece on the cast iron plate could cause the gray iron to warp.

3. Gray iron parts should be inspected weekly according to national standards, with the inspection interval adjustable to 6–12 months depending on specific circumstances.

What are the cleaning methods for gray iron castings?

1. First, the cleaning personnel should follow the principle of addressing urgent tasks before less critical ones when clearing the castings from each furnace.

2. Secondly, when cleaning the castings, inspect the surface for any serious defects. If serious defects are found but it’s impossible to determine whether the casting should be scrapped after cleaning, promptly report the issue to your supervisor.

3. Additionally, care should be taken not to damage the castings during cleaning. If the edges or corners of the castings are chipped, thin-walled castings must not be struck with a large hammer.

4. Afterward, when cleaning large and medium-sized castings, ensure they are securely placed and thoroughly rinsed. When turning them over, make sure the lifting hooks are firmly fastened to prevent the castings from falling or colliding.

We are a manufacturer of gray iron. If you'd like to learn more about this, feel free to contact us—we’re happy to provide insights from various perspectives.