Jet variable speed drill press - 20" - j-2221vs Guia Do Utilizador
14
Drilling Recommendations
Speeds for Drilling
The speed of a drill is usually measured in terms of
the rate at which the outer periphery of the tool
moves in relation to the work being drilled. The
common term for this is Surface Feet per Minute
(SFM). The relationship of SFM is expressed in the
following formulas:
the rate at which the outer periphery of the tool
moves in relation to the work being drilled. The
common term for this is Surface Feet per Minute
(SFM). The relationship of SFM is expressed in the
following formulas:
SFM = 0.26 X rpm X Drill Diameter (in inches)
RPM = 3.8 x ________SFM__________
Drill diameter (in inches)
In general, the higher the speed the shorter the drill
life. Operating at the low end of the speed range
for a particular material will result in longer life. The
most efficient speed for operating a drill depends
on many variables:
life. Operating at the low end of the speed range
for a particular material will result in longer life. The
most efficient speed for operating a drill depends
on many variables:
1.
Composition and hardness of material.
2.
Depth of the hole.
3.
Efficiency of the cutting fluid.
4.
Type and condition of the drilling machine.
5.
Desired quality of the hole.
6.
Difficulty of set-up.
Feeds for Drilling
The feed of a drill is governed by the size of the
tool and the material drilled. Because the feed rate
partially determines the rate of production and also
is a factor in tool life, it should be chosen carefully
for each job. In general, the most effective feeds
will be found in the following ranges:
tool and the material drilled. Because the feed rate
partially determines the rate of production and also
is a factor in tool life, it should be chosen carefully
for each job. In general, the most effective feeds
will be found in the following ranges:
Diameter of Drill
Feed per Revolution
(inches)
(inches)
Under
1/8
.................... 0.001 to 0.002
1/8 to 1/4 ..................... 0.002 to 0.004
1/4 to 1/2 ..................... 0.004 to 0.007
1/2 to 5/8 ..................... 0.007 to 0.015
Indication of Extreme Speeds and
Feeds
Feeds
A drill that splits up the web is evidence of too
much feed or insufficient tip clearance at the center
as a result of improper grinding. The rapid wearing
away of the extreme outer corners of the cutting
edges indicates that the speed is too high. A drill
chipping or braking out at the cutting edges
indicates that either the feed is too heavy or the
drill has been ground with too much tip clearance.
much feed or insufficient tip clearance at the center
as a result of improper grinding. The rapid wearing
away of the extreme outer corners of the cutting
edges indicates that the speed is too high. A drill
chipping or braking out at the cutting edges
indicates that either the feed is too heavy or the
drill has been ground with too much tip clearance.
Speeds for High Speed Steel Drills
Speed
Material In
Material In
SFPM
Alloy Steel — 300 to 400 Brinell ................ 20 - 30
Stainless Steel .......................................... 30 - 40
Automotive Steel Forgings ........................ 40 - 50
Tool Steel, 1.2C ........................................ 50 - 60
Steel, .4C to .5C........................................ 70 - 80
Mild Machinery Steel, .2C to .3C ............. 80 - 110
Hard Chilled Cast Iron ............................... 30 - 40
Medium Hard Cast Iron ........................... 70 - 100
Soft Cast Iron ........................................ 100 - 150
Malleable Iron ........................................... 80 - 90
High Nickel Steel or Monel ........................ 40 - 50
High Tensile Bronze ................................. 70 -150
Ordinary Brass and Bronze ................... 200 - 300
Aluminum and its Alloys ........................ 200 - 300
Magnesium and its Alloys ...................... 250 - 400
Slate, Marble, and Stone ............................ 15 -25
Plastics and similar material (Bakelite) .. 100 - 150
Wood ..................................................... 300 -400
Titanium Alloys.......................................... 10 - 25
Titanium Alloy Sheet ................................. 50 - 60
In cases where carbon steel drills are applicable,
the drill should be run at speeds of from 40 to 50
percent of those given above.
the drill should be run at speeds of from 40 to 50
percent of those given above.