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 New 1PC Hole Saw Tool Iron Cutting HSS Twist Drill Bit Select from 12mm To 35mm $5.61 |
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 30 PCS HSS COBALT COATED DRILL BIT SET 1 4 SHANK BITS $59.99 |
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 8 PC INDUSTRIAL SILVER DEMING DRILL BIT HSS 3 4 13 16 7 8 15 161 $45.95 |
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 8 PCS HSS METAL DRILL BIT SET metric Brand new $115.30 |
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Hss Drill Bit
Metabo Power Tools: Comparison of cobalt alloyed vs HSS-R drill bits by corded and cordless tools.
FYI on Hss Drill Bit
Cobalt Alloy Bits - Currently The Hardest Drill Bits
As you probably already realize, there are many different drill bits each with a specific usage. Some bits are designed for relatively soft materials, such as wood. Most bits you use are twist bits, a cylinder that has been cast or machined with grooves called flutes. Bits can also be coated with specialized materials such as carbon or ceramics. Other special drill bits are designed to penetrate the hardest materials known to mankind. Cobalt steel drill bits make holes possible in metals a bullet wouldn't penetrate. As a matter of fact, cobalt drill bits can be used to make a gun barrel.
Cobalt drill bits are made from a steel alloy, and are a little different from standard high speed drill bits in that they contain more cobalt, hence the name - head over to hss drill bits for additional details about this theme. They are designed to hold their sharpness even at high temperatures. Most steel drill bits, while drilling through metals such as stainless steel, will lose their hardness and thus, the sharpness of the bit will be diminished. They can literally start to melt due to the friction. The superior strength of these drill bits does have a counterbalancing weakness: they are more brittle or breakable. However there are ways of working around this. Even with these bits it's a good idea to use lubricating fluid to reduce temperature build up - see osha training for extra details pertaining to this issue.
The advantage of being able to drill through heavy metals is obvious, but be aware that not all cobalt drill bits are alike. The percentage of cobalt in the alloys varies depending on the manufacturers specifications. The grades of cobalt bits are the M35, which has 5% cobalt, and the M42 with 8% cobalt. The M35 is preferred for uses where the bit will be heated beyond the norm, and the M42 used for longevity as it is less likely to be damaged.
Cobalt is used in steel alloys for its resistance to wear and corrosion. It does not reduce the magnetic properties of steel, which is very useful should you drop a cobalt drill bit, as you can find it with a magnet like you would ordinary drill bits. To give you an idea of the durability and usefulness of the alloyed metal, it is also used in jet engines and prosthetic hip replacements. The cobalt in the steel alloy sets these bits apart from their high-speed steel brethren.
In industry cobalt drill bits are used to drill through hardened steel and other hard alloys like titanium. They will withstand temperatures are higher than thousand degrees Celsius without reducing effectiveness. The casting of the bits is done with a web design to increase the rigidity of the tool and to prevent snapping when going through abrasive materials.