Biomedical Engineering Reference
In-Depth Information
FIGURE 15.18
Dental bur drilling machine.
drilled. The drilling unit ( Figure 15.18 ) was constructed. It was constructed with a water-cooling
system so that maximum spindle speeds of 250,000 revolutions per minute (rpm) feed rates of
between 5 and 20 μm per revolution and cutting speeds in the range 100-200 m min 1 for drilling
with dental burs could be achieved.
After the dental burs were coated and examined for adhesion, the coated burs were used to
machine a number of dental materials. The coated burs were compared with uncoated burs to distin-
guish them in terms of their drilling behavior. The machine shown in Figure 15.18 was constructed
using three principal axes each controlled using a DC motor connected to a Motionmaster™ con-
troller. A laser light source was focused on the rotating spindle in order to measure the speed of the
dental bur during drilling.
The flank wear of the burs was analyzed by SEM at selected machining time intervals of between
1 and 3 min. Prior to SEM analysis, the diamond-coated burs were ultrasonically washed with 6M
H 2 SO 4 solutions to remove any unwanted machining material, which eroded the surface of the CVD
diamond-coated bur. For comparison, conventional diamond sintered burs with different geometry
were also tested on the same substrate materials.
15.4.4 Dental Bur Machining: Machining Experiments on Human Teeth
To examine the machining characteristics of coated and uncoated dental burs, a specially constructed
clamp was developed to locate over the tooth to prepare it for the location of a crown. Figure 15.19
shows the construction of the clamping device.
 
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