Reusable castings molds
View Patent ↗The invention is directed to a reusable mold for making a contact lens and the reusable mold has at least one of the mold halves is made from an oxide glass having a Knoop Hardness less than HK 350. The invention is also directed to a method for making an optical part by single point diamond turning an oxide glass having a Knoop Hardness HK less than 350.
1. A method for making a reusable mold for making a contact lens comprising the steps of:
(a) selecting an oxide glass material having a Knoop Hardness less than 350 for the reusable mold for making a contact lens,
(b) single point diamond turning the oxide glass with a neutral or negative rake angle to achieve the reusable mold having an optical quality surface.
2. The method of claim 1 ; wherein the Knoop Hardness is less than 340.
3. The method of claim 2 , wherein the Knoop Hardness is less than 320.
4. The method of claim 1 , wherein the rake angle is from 0° to −25°.
5. The method of claim 1 , wherein the reusable mold has a surface roughness (Ra) less than 30 nm.
6. The method of claim 5 , wherein the reusable mold has a surface roughness (Ra) less than 20 nm.
7. The method of claim 6 , wherein the reusable mold has a surface roughness (Ra) less than 10 nm.