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Brocas, tipos de

Types de forets

Twist drill bit (DIN 1412)

Twist drill bit with straight shank

Twist drill bit with tapered shank

A wide variety of spiral (twist) types are used for different materials:

Standard twist type N made of HSS (High Speed Steel)
for steel of 500?1300 N/mm²,

alloyed and heat-resistant steels, stainless steels,

cast iron and malleable cast iron,

nonferrous metals like zinc, light alloys,

brass Ms 60?Ms 63, copper.

RN = clockwise-cutting, type N

Long-spiralled twist type H made of HSS for brittle and hard materials:
for steel of 1300 N/mm² and higher,

plastics, resin bonded fabric, paper base laminate, bakelite, novotex,

pertinax and compressed laminated materials,

short-chipping light alloys,

magnesium alloys, electron,

brittle brass Ms 58,

eternite, fulgurite, marble, slate, coal, mica,

hard rubber, plexiglass, ebonite

Application: short-chipping brass and bronze types, plastics (moulded parts)

Short-spiralled twist drill bit type W made of HSS for soft materials:

aluminium alloys,

tough and tempered light alloys,

plastics, nylon, perlon, polyamide, polystyrene,

Trolitul, Styroflex, Igelit,

cast resins, phenolic resins, celluloid, cellon, vulcanised fibre,

hard wood and high-density wood

Application: aluminium and soft aluminium alloys, copper, phosphor bronze,

soft plastics.

Step drill bit

Step drill bits are tiered or graded drill bits used to prepare holes for hexagon screws, countersunk screws or pan-head screws. They are used for simultaneous drilling and countersinking of holes.

Subland twist drill bit

Subland twist drill bits are multi-step drill bits used, among others, for countersunk screws.

Micro drill bits in accordance with DIN 1899 A?C

Micro twist drill bits are bits with a reinforced shank. Drill bits up to 0.79 mm are equipped with a 1.0 mm shank.

Bits from 0.8 to 1.45 mm have a 1.5 mm shank.

Bits over 1.45 mm have a 2.0 mm shank.

Collets are used as tool fittings for these drill bits. Used with reinforced fibre-glass, copper-sheathed epoxy resinboards for printed circuits.

Flat micro drill bits are round-shank bits without spiral. They are used for drilling in the precision mechanical and optical industry in cases where drilling depth and diameter are roughly the same.

Centring bit in accordance with DIN 333

Centering bits are used to drill central holes in rotating shafts. They are rarely used with hand-held power tools.

Masonry or stone drill bits

Twist drill bits which have a tungsten-carbide chip soldered or sintered into their cutting edge were developed for drilling into rock, masonry or concrete with impact drills. The drill point of a masonry drill bit is shaped like a chisel to crush the stone with the hammer blows from the machine. Exception: ?Karat? drill bits. Here the front surface of the tungsten-carbide chip remains intact producing a sharp cutting edge. These bits must only be used with rotation as the chip may break off. ?Karat? drill bits are recommended for all types of soft stone and glazed tiles in which you cannot or must not use a impact drill. They are equipped with cylindrical straight shanks and a spiral helix to remove masonry debris.

Carbide-tipped twist drill bits for rotary hammers

These are special drill bits for use with light and medium rotary hammers to drill dowel holes and other types of fastening holes in masonry.

The SDS-plus tool fitting has been very successful in light rotary hammers. BOSCH has introduced the small splined shank as tool fitting for medium rotary hammers, and the large splined shank for heavy rotary hammers, however in the meantime the medium and heavy hammers have changed to SDS-max. The advantage of SDS-max is easy and dust-free operation and that it can also hold chisels. SDS-plus bits are also available as TC multi-purpose bits (?Karat?).

Carbide-tipped dustless drill bits for rotary hammers

One or several bores in the drill bit shank allow the removal of stone dust from the drilled hole by using an optional dust extraction fixture and a vacuum cleaner. Dust extraction drill bits with straight shanks are available for drill diameters of 8 to 14 mm. Dustless drill bits with center bore for drill diameters from 16 to 26 mm are equipped with a spiral single flute for the efficient removal of drilling dust.

Carbide-tipped spiral or twist drill bits for rotary hammers

They are used to drill holes of a wide range of diameters from 12 to 52 mm and have effective lengths of 150 to 550 mm. Spiral bits are recommended for through-drilling and for holes for fastening elements. The special spiral single flute facilitates fast and safe removal of drilling dust. The special chrome-nickel-molybdenum alloy ensures very high drill bit quality. Spiral hammer bits are available with standard double-cutter head or multi-cutter x-head. The multi-cutter x-head has the following features:

- good centring and pin-point accuracy,

- high drilling capacity and therefore faster drilling,

- exact straight hole guidance without hooking,

- quieter operation with less vibration,

- long service life even if you hit reinforcement bars,

- high precision drilling holes for fixtures.

The head shape of the multi-cutter x-head allows double fluting and therefore fast removal of drilling dust.

Carbide-tipped through drill bits for rotary hammers

Short-spiralled carbide-tipped twist drill bits with long usable lengths for through-holes for cable installations with drill diameters from 45 to 80 mm and usable lengths of 500 and 850 mm.

Carbide-tipped core bits for rotary hammers

are used to drill core holes for tapping and feeder boxes. The remaining core can be easily removed with a chisel. Drill diameter from 40 to 125 mm and effective length of 100 mm.