Definition of Forging Process Parameters: The primary parameters of the forging process include machining allowances, draft angles, forging radii, core prints, core seats, shrinkage allowances, and similar factors.

Machining Allowance: In carbon steel casting, this refers to the additional material added to the dimensions specifically for subsequent machining (grinding) operations.

The machining allowance should be determined based on the production batch size of the carbon steel castings, the alloy type, the molding method, processing requirements, and the shape, dimensions, and gating location of the casting.

Machine molding is utilized, offering high precision and allowing for smaller machining allowances.

These typically have rougher surface finishes, requiring larger machining allowances compared to cast iron.

These are generally high-cost materials with smooth surface finishes, allowing for smaller machining allowances.

Refer to the specific machining allowance grades/standards.

Regarding whether holes or slots in carbon steel castings should be "cast-in" (formed during the casting process), the decision depends not only on technical feasibility but also on practical considerations. Larger holes and slots should generally be cast-in, as this reduces subsequent machining time and helps minimize "hot spots" (areas prone to shrinkage defects) during production. Smaller holes and slots need not be cast-in; it is often more economical to create them entirely during the subsequent machining stage. Furthermore, complex-shaped holes and holes in expensive non-ferrous metal castings should—whenever possible—be cast-in to minimize machining costs.

Note: ① If a hole is intended for subsequent machining, the specified hole diameter must include the additional thickness required for the machining allowance. ② Castings with special or unique requirements are exempt from these general guidelines.

To facilitate the easy removal of the pattern (or core) from the sand mold (or core box), a specific taper—known as the draft angle—must be applied in the direction of withdrawal. For surfaces that are intended for subsequent machining, the draft angle should be directly incorporated into the dimensions alongside the machining allowance. For surfaces that are not intended for machining (non-machined surfaces), the draft angle (often referred to as a "structural draft") need only be indicated via textual notation or a general note. Draft Angles for Cores

Magnitude of Draft Angles: Determined by the relative height of the vertical wall, the molding method, and the pattern material. The taller the vertical wall, the smaller the draft angle; external surface angles are smaller than internal cavity angles; patterns used for machine molding generally have smaller angles than those used for hand molding; and patterns for metal mold casting have smaller angles than those for wooden patterns. Specific values ​​can be found in relevant reference manuals. Generally, external surfaces feature angles of 1.5° to 3°, while internal cavities range from 3° to 10°.

Used to prevent sand wash and cracking at intersecting corners; the fillet radius is typically approximately ⅓ to ½ of the average thickness of the two intersecting walls.

After cooling, the dimensions of a casting are slightly smaller than those of the mold cavity. To ensure the casting achieves its required dimensions, the pattern dimensions must be made larger than the casting dimensions by an amount corresponding to the specific shrinkage rate of the alloy being cast.

Gray Cast Iron: 0.7% – 1.0%

Cast Carbon Steel: 1.3% – 2.0%

Alloys: 0.8% – 1.2%

Tin Bronze: 1.2% – 1.4%

Core prints can be classified into two categories: vertical core prints and horizontal core prints.