Hardness is always to point out reach a particular degeneration necessary force.

2012-08-21 14:29

  Hardness is usually a way of measuring the product quality and grade of spectacle oakley sunglasses cheap   is one of the important factors, different hardness of the lens material have different processing methods and Oakleyonsale requirements.


(3) elastic modulus


Coefficient of elasticity is remarked that now pressure and eliminate pressure restore their original shape following deformation produced in the event the ratio between, usually refers to the ratio of height or volume.


(4) impact resistance


Impact resistance is spectacle lens material must requirements of mechanical properties. Impact resistance test method often utilised by the usa fda institution (FDA) dangerous a falling ball test to said. Falling ball test on the specific strategy is: make use of a 16 grams of steel ball, from 1.27 meters height alignment lens center fall, if the lens will not occur damage, the impact resistance performance is great, otherwise the impact resistance performance difference.


(5) resistance to breaking Stephanie blog  point


Potential to deal with disconnect point is also spectacle lens material must requirements of mechanical properties.


Breaking point of resistance test method employed by the eu committee for standardization formulated "CEN static deformation test" method. Quality of the specific method: within a constant speed, to be measured lens gradually increasing pressure, until it reaches 100 Newton, if your lens does not occur damage, the resistance to disconnect point performance is a great one; If material deformation a lot more than 4.5 mm, the capacity disconnect point performance deviation; If the lens happened is damaged, its effectiveness disconnect point performance difference.


Five, thermal properties


Thermal property refers back to the temperature ingesting the lens material changes state. Thermal properties including heat conductivity and specific heat capacity, linear expansion coefficient, freezing point, boiling point, lens stress temperature, etc.


Six, electrical properties


Electrical properties said material nonparticulate radiation and electric effect characteristics, sometimes need Cheap oakley sunglasses sale , optical properties and electrical properties relate to consider. Usually the lens material in manufacturing should take into account the following two parameters, dielectric strength and scheduled frequency on the dielectric loss factor.


Seven, chemical properties


Chemical property refers to the spectacle lens manufacturing and daily use, lens material for chemical reflect characteristic, maybe in some extreme conditions lens material reflect characteristic. For example, the accelerated aging test would be to test the reliability of material, the test often use cold water, warm water, acids and various organic solvent.Cheap Oakley sunglasses