En españa lo que he descrito no se conoce, y menos en una tienda física o ferretería. Nunca las han visto.
Sólo han visto las de hormigón o como mucho las de perforar cristal.
Pero se venden :
http://cgi.ebay.com/Kemmer-2-10mm-Tungsten-Carbide-Drill-NEW-Lot-8-YB51_W0QQitemZ380192843369QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item5885426669ALgo de opiniones por ahi en un minuto de busqueda :
I have never seen a chart comparing tool life of HSS vs. carbide using constant parameters. In fact I would be very surprised to see a chart of this nature, for several reasons.
Carbide and HSS have very different properties and therefore are design to be applied at vastly different operating parameters. If the two are applied using the same speed and feed, performance of one of the tools will being compromised, resulting in poor tool life, poor work piece finish, or inadequate chip removal.
To compare HSS and carbide let?s look at the three main properties important to cutting tool materials; the ability to stand up to wear (wear resistance), the strength to not break (toughness), and the ability to attain hardness and chemical stability at high temperatures (hot hardness). HSS is tough, carbide is brittle. Carbide is more expensive than HSS, but it can withstand higher temperatures and run at higher speeds, given the stable conditions of today?s CNC machines, all due to carbide?s superior hardness and hot hardness.
To give a quantitive comparison, carbides have a hardness of roughly 90-95 Rockwell A, whereas HSS?s have ratings between 84-85 Rockwell A. If you are not familiar with the Rockwell A Scale, the hardness of HSS is about 65-68 Rc. Note this is the hardness at room temperature. In addition, the values provided may vary, but it is important to note the relativity of the hardness of the two materials. The increased hardness of carbide makes it more wear resistant, resulting in higher speed capability or longer tool life.
During machining temperatures rise to very high levels. Carbides have the ability to maintain their hardness at temperatures around 1400 degrees F, compared to HSS at 1000 ? 1100 degrees F (not considering the effects of coatings). Therefore carbides have excellent high-hardness or red-hardness qualities.
With the increased hardness and ability to withstand temperature carbide is able to run at speeds roughly 3-4 times greater than high speed steel.
Finally, HSS is twice as tough as carbide. Therefore, if the application is un-rigid, the part has cross holes, uneven exit or entry surfaces, or hole depths over 7 times diameter, HSS may be required.
In addition, consider the following situation to note the performance differences between the two materials. The example is based on free machining, plain carbon steel with a machinability rating of 1.0, using a 킽? diameter drill and a constant of 20 minutes tool life. Notice the difference below in linear inches of drilling. Naturally, the carbide drill produces 3 times as many linear inches of drilling, because of the reduced time in cut resulting from 3 times faster speed.
HSS:
125 sfm, 955 rpm, .007 ipr, 7 ipm, at 20 minutes tool life
Produces 134 linear inches of drilling
Carbide:
375 sfm, 2865 rpm, .007 ipr, 20 ipm, 20 min life,
Produces 401 linear inches of drilling
In summary, I would choose carbide for your drilling applications, unless the application presents unstable or demanding conditions.