Metalworking Processes and Essential Tools

What is a Collet and How is it Used?

A collet is a tightly fitting sleeve that fits over the base of a workpiece or tool. When placed in a chuck, it provides a more secure grip. This is particularly useful for pieces with a short base or where high precision is required.

EDM: Operation and Advantages

Electronic Discharge Machining (EDM) "burns" away material by electrical discharge. It provides accurate cuts on internal surfaces that are difficult or impossible to reach by conventional machining.

Common Machining Tools

• Drill Bit: Cuts holes by moving axially; cylindrical, fluted steel or carbide shaft with a conic cutting head on the end.
• End Mill Cutter: Cuts slots and along surfaces by moving perpendicular to its axis; cylindrical, fluted steel or carbide shaft with a flat cutting head on the end.
• Tap: Cuts internal threads; cylindrical, steel with discontinuous thread cutters on the outside.
• Die: Cuts external threads; donut-like with discontinuous thread cutters on the inside of the annulus.

Types of Chucks and Saws

• Three-Jaw Chuck: Three self-centering jaws, for holding cylindrical workpieces.
• Vertical Band Saw: For roughing out large, thick sheets and cutting contours; workpiece guided.
• Horizontal Band Saw: For slicing off sections of rods and bars; blade guided.

Qualities of Engineering Designers

• Imaginative: Engineering designers require a high level of conceptual thinking.
• Realistic: When designing outside the envelope, the experiments must be cheap.
• Optimistic: You can make it better! (Edison, Wright Brothers, etc.)

Metal Forming Processes

• Forging: A process in which metal is pressed, pounded, or squeezed under great pressure into a high-strength part of a desired shape, usually at elevated temperatures.
• Broaching: A progressively expanding tooth-cutting tool is dragged past the workpiece, shaving off more and more material as it passes.
• Extruding: The workpiece is forced through a die opening to produce a desired cross-sectional shape.
• Flat Rolling: The thickness of the workpiece is reduced by compressive forces exerted by two opposing rollers.
• Drawing: The cross-section of a bar is reduced by pulling it through a die opening.