Metal Threading and Hole Machining Techniques

Metal Threading and Hole Machining

The screw is created through a metal removal operation.

Tools for Threading

Taps

Taps are cutting tools in the form of screws with longitudinal edges that allow for cutting. The main parts include:

• Active or entry: serves as the starting point.
• Guide or body: draws up the thread.
• Handle: the extreme end for handling.

Taps and Dies

Dies are employed for external threads. The interior carries a thread with 3 or more slots that form the cutting edge and allow for swarf removal. One face has a countersunk area (60 to 120 degrees) to facilitate thread initiation.

Giramachos and Portaterrajas

These are handles used for turning taps and dies, available in fixed or adjustable designs.

Technical Manual Threading: Steps

1. Draw the center and mark with a punch.
2. Drill with the appropriate drill size.
3. Countersink the entry.
4. Place the number 1 tap.
5. Revolve the tap in a forward direction.
6. Constantly lubricate.
7. Repeat the operation with taps 2 and 3.

Threaded Screws with Sweep

• Select the diameter.
• Make a countersunk at 45 degrees on the dipstick.
• Place perpendicular to sweep the rod.
• Conduct the threads with sweep in a single pass.

Reaming

Reaming is used to smooth, remove burrs, and enlarge previously made holes. Benefits include:

• Improving surface quality.
• Improving fit.
• Achieving more accurate screw diameters.

The Reamer

The reamer is a tool steel implement with sharp edges used to enlarge and smooth holes. Its parts are:

• Handle: Subject area.
• Body: Central part with cutting edges.
• Admission: Lower tapered section.
• Cutting Edges: The edged cutting elements.

Countersinking

Countersinking involves creating a conical-shaped stop in previously drilled holes to accommodate screw heads and rivets.

Drilling: Basic Rules of Cutting Speed

Factors influencing cutting speed include:

• Diameter of the drill.
• Workpiece material.
• Material hardness of the drill.

Cutting Speed

• Excessive speed: Results in very fast wear, poor quality, and plastic deformation of the material.
• Low speed: Leads to low productivity and potentially higher costs.

Drill Advance

Drill advance refers to the space described in the progress of the bit about the piece drilled.

Cutting Capacity

Cutting capacity is the power consumed during the drilling process.

Lubrication

Lubrication improves the outcome of the drilling operation and its durability.

Safety

Safety glasses are recommended for protection from chips, and gloves for protection from cuts.

Load of the Holes

Formulas for hole load calculations:

• Outdoor rock: d = D - (0.2 * step)
• Machining of nut: D = d - (1.3 * step)
• Whitworth thread: d = D - (1.28 * step)