1. Aperture size: directly lock the drill bit type
φ <10mm: Priority should be given to gun drills (for external chip removal), suitable for deep processing of small holes.
φ 10-30mm: Choose BTA or spray suction drill (internal chip removal) to balance efficiency and chip removal.
φ 30mm: Optional rotary blade deep hole drill or DF system to reduce costs and improve rigidity.
2. Depth to diameter ratio (L/D): Determine whether a system is needed
5-20 times: ordinary extended Fried Dough Twists drill or worm shaped Fried Dough Twists drill can be used.
>20 times: Deep hole drills (gun drills/BTA drills/spray drills) must be used, as ordinary drill bits are prone to deviation and breakage.
3. Workpiece material: matching drill bit material
Ordinary steel/cast iron: High speed steel (HSS) drill bits with low cost and sufficient toughness.
Difficult to process materials (stainless steel, high-temperature alloys): cobalt containing high-speed steel or solid hard alloy drill bits, heat-resistant and wear-resistant.
High hardness material: coated hard alloy drill bit, reducing friction and extending service life.