Palram PALSU - Manual (Page 28)

28
Drilling
General Indications
Drill bits: Regular, new high-speed steel twist drills, or new carbide-tipped drills are suitable for drilling holes in PALSUN sheets of
various thicknesses, as long as they are sharpened well. They are used mainly for bores up to 12 mm(1/2 “) diameter.
Larger holes may be drilled by flat, chisel edged drill blades with a triangular cutting tip, similar to those used in woodworking, kept
always very sharp. Rake angle should be about 5° to avoid side friction. They are used mainly for bores from 12 to 20mm (1/2 “ to 13/16 “).
Commercially available cutting cups or circle cutters of several types can be used for performing large round apertures.
Speed: Decrease the drill’s speed as hole diameter and / or sheet thickness gets larger. Drilling speed may vary due to actual conditions.
Feed rate: May vary due to actual conditions.
Drilling Speed and Feed Rate Change in Accordance with Bore Diameter
Hole Diameter Drill Speed Feed Rate
mm Inch 1 Inch 2 rpm mm/rev inch/rev
3 1/8 0.12 1500 - 1800 0.03 - 0.07 0.012 - 0.028
6 1/4 0.24 800 - 1500 0.03 - 0.07 0.012 - 0.028
10 13/32 0.4 500 - 1000 0.01 - 0.07 0.004 - 0.028
15 19/32 0.6 350 - 700 0.07 0.028
20 25/32 0.8 250 - 350 0.07 0.028
Recommended Drill Bit Configurations
Property Sign Units Value
Clearance angle 10 – 20°
Rake angle γ° 0 – 10°
Drill tip angle β° 110 – 150°
Helix angle α° 30°
Cutting velocity m/min. (ft./min.) 15 - 30 (49 - 98)
Notes: For small gauge sheets (1 - 2 mm or 0.04 - 0.08 in.) we recommend using flatter tip drill bits (β = 140 - 150°) for achieving a cleaner bore with less risk of chipping.
Figure 14a: Regular Drill Bit Figure 14b: Flat Chisel Edged Drill Blade