What is stack drilling?
Stack drilling is a method used for drilling a large number of holes through thin plates. Typical applications include the drilling of baffle plates for heat exchangers and components for bridges.
Minimizing the gap between the stacked plates is crucial for successful stack drilling. This can be done by clamping or welding the plates together. A good common practice is to insert industrial paper (thickness of approx. 0.5–1 mm (0.020–0.039 inch)) between the plates to level out any irregularities and dampen vibrations. As the axial force will be several thousand newtons during the drilling process, the clamping supports are an important consideration.
If the gap is not minimized:
- Exit discs can move along the plates, be re-cut and thereby damage the drill
- The plates tend to deflect more and can spring back when the drill exits cut, damaging both the hole and the tool
Solid carbide drills and exchangeable-tip drills
Feed reduction is not usually needed.