Turning Draft vs Milling Draft | Nx cad

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#Draft, refers to a slight taper or angle applied to vertical surfaces of a pattern or mold. This taper facilitates the removal of the pattern or casting from the mold without causing damage or distortion. Here's why draft is required on components:
1.Easier Removal: Draft ensures that the pattern or casting can be easily removed from the mold cavity without getting stuck. When the mold is opened, the tapered sides allow for smooth release, reducing the risk of damage to both the pattern and the mold.
2.Prevention of Damage: Without draft, sharp corners or vertical walls on the pattern or casting can get caught on the mold material, leading to chipping, cracking, or distortion of the casting. Draft helps prevent such damage by providing a gradual release.
3.Minimization of Friction: The taper provided by draft reduces the friction between the pattern or casting and the mold material. This makes it easier to extract the pattern or casting from the mold, especially in cases where the mold material may have a tendency to adhere to the pattern surface.
4.Improvement of Surface Finish: Draft can also help improve the surface finish of the casting by minimizing the likelihood of drag marks or sand inclusion during the removal process. A smoother release results in a cleaner surface on the final casting.
5.Consistency in Dimensional Accuracy: Applying draft consistently across all vertical surfaces of the pattern or casting helps ensure uniformity in dimensional accuracy and prevents distortion or warping during the casting process.
6.Reduction of Defects: Proper draft angles can help reduce defects such as shrinkage, cracking, and distortion in the final casting by promoting uniform solidification and cooling of the molten metal.
#Draft is typically categorized into three main types: positive draft, zero draft, and negative draft.
1.Positive Draft:
-Positive draft, also known as taper or draft angle, involves adding a slight angle to vertical surfaces of the pattern or mold. This angle is inclined outward from the vertical axis of the pattern or mold.
-Positive draft angles are commonly used in sand casting, investment casting, and other casting processes to ensure proper mold filling and easy pattern extraction.
2.Zero Draft:
-Zero draft, as the name suggests, refers to vertical surfaces that are perpendicular to the parting line or mold surface without any taper or angle.
-Zero draft is often used in situations where draft is not required or where the geometry of the component does not allow for the application of draft angles.
3.Negative Draft:
-Negative draft, also known as undercut or reverse draft, involves creating features on the pattern or casting that angle inward toward the core or mold cavity.
-Negative draft features can include undercuts, recesses, or protrusions that make it difficult or impossible to remove the pattern from the mold without causing damage.
-In foundry work, negative draft features must be avoided or minimized to prevent issues such as pattern breakage, mold locking, or casting defects.
"Turning draft" and "milling draft" are terms commonly used in machining processes, particularly in the context of CNC M/C, to refer to the angle or taper applied to vertical surfaces of a part to facilitate the M/C operation.
1. Turning Draft:
-Turning draft, also known as lathe draft or taper, refers to the slight angle or taper applied to vertical surfaces of a cylindrical workpiece during turning operations on a lathe.
-In turning, the cutting tool moves parallel to the rotational axis of the workpiece. If vertical surfaces on the workpiece do not have any draft, it may cause the cutting tool to drag against the workpiece, resulting in poor surface finish, chatter, or tool wear.
-Turning draft is typically specified in degrees and is applied to the side walls of the workpiece to facilitate smooth chip removal and reduce cutting forces during the turning process.
-The amount of turning draft required depends on factors such as the material being machined, the cutting tool geometry, and the desired surface finish of the final part.
2. Milling Draft:
-Milling draft, also known as draft angle or taper, refers to the angle or taper applied to vertical surfaces of a part during milling operations.
-In milling, the cutting tool rotates and moves across the surface of the workpiece to remove material. Without draft, vertical surfaces may be difficult to machine due to the side forces generated by the cutting tool.
-Milling draft is specified in degrees and is typically applied to the walls of pockets, slots, or other features to facilitate easy chip evacuation, improve surface finish, and prevent tool deflection or breakage.
-The amount of milling draft required depends on factors such as the material being machined, the cutting tool geometry, and the specific requirements of the part design.
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