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US 2010/0058588 A1Published application
Machining of Ceramic Materials
AssigneeIvoclar Vivadent AG
InventorsMarkus Heinz, Klaus Rinner, Georg Gorfer, Marius Aster, Marcel Schweiger, Dmitri Brodkin
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Abstract
Milling strategies for machining dental ceramic materials are provided that reduce milling time while maintaining strength, accuracy and marginal integrity.
Claims41
A method of reducing the time for machining a dental ceramic blank, wherein the fracture toughness (Klc) and the flexural strength (σf) of the dental ceramic material are known, comprising:
- calculating an estimate of the maximal surface critical flaw size and an estimate of the maximal volume critical flaw size of the dental ceramic using the following formula:
- c=(Klc/σf)2
- wherein:
- c is the maximal surface critical flaw size and
- 2c is the maximal volume critical flaw size;
- implementing a machining strategy using a series of diamond tools, wherein the diamond tools comprise embedded diamonds;
- wherein the machining strategy comprises rough, intermediate and fine machining steps;
- wherein each step comprises a tool path and machining parameters,
- wherein the tool path and machining parameters are carried out by at least one of the series of diamond tools;
- wherein the grain size of the embedded diamonds is larger than approximately the estimated maximal size of the surface critical flaw and smaller than approximately the estimated maximal size of the volume critical flaw.
7 more elements
A machining strategy for machining a dental ceramic blank into a dental article, wherein the fracture toughness (Klc) and the flexural strength (σf) of the dental ceramic material are known, comprising:
- calculating an estimate of the maximal surface critical flaw size and an estimate of the maximal volume critical flaw size of the dental ceramic using the following formula:
- c=(Klc/σf)2
- wherein c is the maximal surface critical flaw size and
- 2c is the maximal volume critical flaw size;
- determining the number of machining steps needed to mill the dental ceramic blank into the dental article, wherein each machining step comprises rough, intermediate and/or fine machining, at least one tool path and machining parameters;
- using at least one of a series of diamond tools for each machining step, wherein the diamond tools comprise embedded diamonds;
- wherein the grain size of the embedded diamonds is larger than approximately the estimated maximal size of the surface critical flaw and smaller than approximately the estimated maximal size of the volume critical flaw.
4 more elements
Dependencies are inferred from the claim text.