مقدمة في التفريز والتدوير

Introduction to Turning and Milling

• Turning and milling are fundamental machining processes for shaping parts from various materials.
• Both use cutting tools to remove material from workpiece blanks.
• Turning creates cylindrical shapes, while milling produces flat surfaces and intricate profiles.

Turning

• Definition: Turning uses a single-point cutting tool to remove material from a rotating workpiece.
• Purpose: Creates cylindrical surfaces (shafts, rods, parts with rotational symmetry).
• Methods:
  • Facing: producing a flat surface on the end of a workpiece.
  • External turning: creating external cylindrical surfaces.
  • Internal turning: creating internal cylindrical surfaces.
  • Threading: creating threads on a workpiece.
• Tool Geometry: Tool shape and angles (rake angle, clearance angle, nose radius) affect chip formation, surface finish, and tool lifespan.
• Material Removal: Material is progressively removed by the rotating cutting tool.
• Workpiece Considerations: Workpiece material, diameter, and length impact process choice.
• Machining Parameters: Feed rate, cutting speed, and depth of cut influence process quality and efficiency.
• Cutting Fluids: Lubricate and cool the cutting zone, enhancing surface finish and tool life.

Milling

• Definition: Milling uses a multi-point cutting tool (milling cutter) to remove material from a stationary or rotating workpiece.
• Purpose: Creates flat surfaces, slots, grooves, and complex 3D shapes.
• Methods:
  • Face milling: producing flat surfaces.
  • End milling: creating grooves and slots.
  • Peripheral milling: machining large surfaces.
  • Profile milling: machining complex shapes.
• Tool Geometry: Milling cutters have multiple cutting edges and specific geometries (e.g., end mill, face mill).
• Material Removal: Multiple cutting edges of the cutter remove material.
• Workpiece Considerations: Workpiece material, size, and shape impact cutter and machine selection.
• Machining Parameters: Feed rate, cutting speed, and depth of cut influence process efficiency and quality.
• Workpiece Support: Crucial for preventing workpiece deflection and distortion during milling.
• Cutting Fluids: Utilised for lubrication and cooling during milling, improving surface finish and tool life.

Commonalties

• Both turning and milling require careful consideration of cutting parameters (speed, feed, depth of cut) for optimal material removal and tool life.
• Proper selection of cutting tools (geometry, material) is crucial for efficient machining.
• Appropriate workpiece support is vital to minimise vibrations and ensure dimensional accuracy.
• Safety precautions are essential to prevent workplace injuries.

Differences

• Turning uses a single-point cutting tool; milling uses a multi-point tool.
• Turning creates predominantly cylindrical surfaces; milling creates a wider variety of 2D and 3D shapes.
• Turning typically involves a rotating workpiece; milling can involve a rotating cutter or a moving workpiece.