Lancing in Press Working

Definition

Lancing is a specialized press working operation where a cut is made across a portion of a metal strip or sheet without removing any material. Unlike shearing or blanking, lancing does not produce scrap; instead, it cuts and simultaneously bends the metal to create features such as tabs, louvers, or ventilation slots.

Main Content

1. The Nature of the Cut

• Lancing is a "parting" operation that does not result in the separation of a piece of scrap metal.
• The action involves a single-line cut followed by a deformation or bending process that moves the cut edge away from the plane of the sheet.

2. Geometric Requirements

• The tool geometry is designed to pierce and push the material in a single stroke of the press.
• Common geometric features created include "louvers," which are often used in electronic enclosures for airflow, and "tabs" used for cable management or mounting components.

3. Material Characteristics

• Ductility is essential for lancing because the material must withstand a bending stress immediately after the shearing process.
• If the material is too brittle, the edge of the lanced feature may crack during the forming stage of the process.

       Side view of Lancing
      ____________________
     |                    |
     |    Direction of    |
     |      Punch         |
     |        |           |
     |        V           |
     |  ____/  \____      |
     | |            |     |
     | |   Sheet    |     |
     |_|____________|_____|
       ^          ^
     (Cut)      (Bent)

Working / Process

1. Positioning and Alignment

• The sheet metal strip is fed into the press and aligned against a gauge or stop to ensure the lancing occurs at the precise location.
• The punch and die assembly must be perfectly synchronized to ensure the cut is clean and the bending happens simultaneously.

2. Penetration Phase

• The press descends, and the sharp edge of the lancing punch contacts the sheet metal.
• The punch shears through the metal along the predefined line, while the die profile forces the resulting flap of metal to deform at an angle.

3. Forming and Clearance

• As the punch continues its stroke, the cut edge is pushed into the die cavity, which is shaped to achieve the desired bend angle (often 45 to 90 degrees).
• The punch then retracts, and the strip is moved forward to the next station or ejected if the process is complete.

Advantages / Applications

• Cost-Efficiency: Since no metal is removed, there is zero material waste during the lancing operation.
• Improved Airflow: It is widely used in the manufacturing of electrical cabinets, computer cases, and HVAC panels to create vents (louvers).
• Structural Features: Lancing is ideal for creating internal tabs used to guide wires or lock parts into place without needing additional fasteners like screws or rivets.

Summary

Lancing is a press working process where a sheet is simultaneously cut and bent to form features like louvers or tabs without creating scrap metal. It is highly valued in manufacturing for its speed, material efficiency, and ability to add functional, non-detachable features to sheet metal components. Key terms to remember include louver, punch, die, shearing, and deformation.