To know the service life of IMZ drills, repeated drilling tests were done for spiral and cannon drills using pig thighbone under 450 gf static load,
As a result, the following conclusion were obtained.
1. On the spiral drill, drilling time was extended after every drilling and drilling became impractical after the twenty seventh time drilling.
2. And the edge of the spiral drill was worn out after twenty seven times' repeated drilling.
3. Difference in drilling time with cannon drill was not recognized up to fifty times' repeated drilling.
4. And the edge of cannon drill did not wear out.