Material removal depth measurement by scribing
AssigneeApple Inc.
InventorsSimon R. Lancaster-Larocque, Lucas Allen Whipple
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Abstract
The described embodiment relates generally to the polishing of a device housing. The device housing can be formed of a thermoplastic, or a metal such as aluminum or stainless steel. More particularly, a method and an apparatus are described for accurately measuring the amount of material removed during a polishing process. Accurate measurement of such a polishing process can be especially helpful in measuring material removal on curved surfaces and edges where material removal rates tend to be less predictable.
Claims19
a method for refining polishing accuracy across a curved surface of a housing, comprising:
- polishing at least a portion of the curved surface of the housing that includes a plurality of clustered scribe marks etched across at least a portion of the curved surface of the housing, the plurality of clustered scribe marks comprising:
- a first plurality of indicia at a first location, each indicia having a different predetermined depth dimension, a deepest one of the indicia having a depth no greater than a maximum material removal depth, and a second plurality of indicia at a second location different than the first location;
- optically checking a material removal amount around the portion of the curved surface of the housing that includes the plurality of clustered scribe marks by observing how many of the indicia remain visible;
- and
- adjusting the polishing to cause an amount of material removed during the polishing at the first and second locations to be about the same.
An apparatus, comprising:
- a laser having a wavelength small enough to etch scribe marks narrower than a minimum abrasive particle diameter of a polishing pad used to polish the housing;
- and
- a computer numerical control (CNC) system for orienting the laser along a desired scribe mark path as it cuts scribe marks across a curved surface of the housing,
- wherein the laser is configured to scribe a plurality of clustered scribe marks into the curved surface of the housing, the clustered scribe marks comprising:
- a first plurality of indicia at a first location, each indicia having a different depth dimension, the deepest of the indicia having a depth no greater than a maximum material removal depth, and a second plurality of indicia at a second location different than the first location,
- wherein a polishing operation is adjusted to cause a material removal amount to be about the same at both the first location and the second location.
A non-transient computer readable medium for storing computer code executable by a processor in a computer aided manufacturing system for polishing a surface of a housing, comprising:
- computer code for obtaining the housing, the housing including a plurality of clustered scribe marks disposed across the surface of the housing, the clustered scribe marks comprising:
- a first plurality of indicia at a first location, each indicia having a different depth dimension, and a second plurality of indicia at a second location different than the first location
- wherein a relative position of each of the indicia in relation to other indicia makes it optically discernible from the other indicia;
- computer code for polishing the surface of the housing including the plurality of clustered scribe marks;
- computer code for optically checking a material removal amount proximate the plurality of clustered scribe marks by observing which ones of the plurality of indicia remain visible
- computer code for adjusting the polishing to cause an amount of material removed during the polishing at the first and second locations to be about the same.
Dependencies are inferred from the claim text.