Geometric modelling and validation of twist drills
with a generic point profile.
After the twist drills
are grinded out with the designated different angles, the main drill point angles are measured for each twist drill
as proposed by Kim and Zou ; the measurement values of the drill point angles are shown in Table 1.
HSS twist drill
registers a high value of thrust force.
Scott Allison, president of MTD Acquisitions, says his group intends to operate Minnesota Twist Drill
and continue to serve its customers.
One of the first points to be made regarding the annular tool is the fact that it is a cutter, where twist drills
are part cutting tool and part chisel.
Step drill: Two or more diameters may be ground on a twist drill
to produce a hole with stepped diameters.
For example, manufacturing a twist drill
from a hardened blank requires five basic operations: 1) centerless grinding, 2) flute grinding, 3) OD clearance grinding, 4) point grinding and 5) split point grinding.
A unique secondary process utilizes a twist drill
to drill a 90 degree lubrication hole in four parts simultaneously, intersecting with the 23.74" deep hole; a post-drilling inspection provides continuous gaging to assure that the two holes intersect.
The twist drills
used for most types of drilling were the first adapted to the task.
Now able to cover the 61- to 81- mm diameter range, ISCAR's (www.iscar.com) DR indexable twist drills
are optimized for use on all steels, alloys and cast iron.
It stores dozens of special drill point geometries in memory, and sharpens HSS, cobalt, and carbide 2 flute twist drills
with diameters from 1/8" to 5/8".