Pin based method of precision diamond turning to make prismatic mold and sheeting

Abstract

A system, and corresponding method for use, for providing a mass-producible retroreflective material, or sheeting, featuring full cube corner pins is presented. The full cube corner shaping may be provided with the use of a diamond turning tool. The diamond turning tool may be used to simultaneously manufacture a number of pins. The pins may be used to form a mold featuring a triangular or full cube corner surface formation.

What is claimed is: 
     
         1 . A method for making a mold for forming a retroreflective sheeting, the method comprising:
 forming a pin bundle from a plurality of pins;   leveling a top and a bottom surface of the pin bundle;   machining the top surface of the pin bundle with a diamond turning tool to provide predefined shapes for each pin on the top surface;   selecting a sub-set of pins from the pin bundle to form a sub-set bundle, each pin in the sub-set bundle having a same predetermined shape, wherein the predetermined shape comprises a single full cube corner; and   electroforming the sub-set bundle to provide the mold.   
     
     
         2 . The method of  claim 1  wherein machining the top surface further comprises:
 making cuts along three axes with the diamond turning tool along the top surface of the pin bundle, each of the three axes comprising a different direction and an associated tool tilt angle. 
 
     
     
         3 . The method of  claim 1  wherein the predetermined shape has three smooth and retroreflective surfaces. 
     
     
         4 . The method of  claim 1  wherein the three tool tilt angles comprise an equal value. 
     
     
         5 . The method of  claim 4  wherein the pins have a hexagonal cross section. 
     
     
         6 . The method of  claim 5  wherein the full cube corner includes a hexagonal aperture and the cube corner has three facets, each facet including a polygon boundary of equal value. 
     
     
         7 . The method of  claim 6  wherein the polygon is a rectangle, square, or pentagon. 
     
     
         8 . The method of  claim 4  wherein the pins have a rectangular cross section. 
     
     
         9 . The method of  claim 8  wherein the full cube corner includes a rectangular aperture, and the full cube corner also includes first and second facets including a trapezoid boundary of equal value and a third facet having a symmetrical polygon boundary. 
     
     
         10 . The method of  claim 4  wherein the pins have a circular cross section. 
     
     
         11 . The method of  claim 10  wherein the full cube corner includes a circular aperture and, the full cube corner also includes three facets with a same circle sector boundary including a 90° center angle. 
     
     
         12 . The method of  claim 1  wherein the pins have a diameter on the order of 10 to 5000 microns. 
     
     
         13 . The method of  claim 1  wherein the pins are formed a material selected from the group consisting of polyethylene, teraphthalate, polymethyl methacrylate, polycarbonate, brass, nickel, copper, and aluminum. 
     
     
         14 . The method of  claim 1  further comprising:
 specifying diamond turning tool configurations selected from the group consisting of pitch, tilt angle, cutting angle, and depth. 
 
     
     
         15 . The method of  claim 1  wherein the machining further comprises:
 cutting three sets of parallel lines, each set being in a different axial direction, with a pitch of at least two of the sets being of equal value, and the pitch of the three sets being larger than the dimensional cross section of each pin in the pin bundle.