ASTM C485-16 pdf download.Standard Test Method for Measuring Warpage of Ceramic Tile.
6. Apparatus
6.1 General Apparatus—The size and arrangement of the apparatus for measuring the warpages vary, depending on the size and shape of the tile to be measured. In general, the apparatus consists of two stationary pins (reference pins) spaced apart 3 ⁄ 4 in. (19 mm) less than the length of the edge or diagonal being tested, and a dial indicator tip midway between the stationary pins and in line with them. The pins and the dial indicator are mounted firmly on the same rigid metal bar. The pins may have a hemispherical tip, as described in 6.2.2, or they may be conical to a point. A more versatile apparatus for standard sizes of tile consists of a metal plate having three movable reference pins, three movable registry stops, and the necessary number of dial indicators. See Fig. 1 and Fig. 2.
6.2 Apparatus for Square Tile: 3 6.2.1 Metal Plate—A flat metal plate, 6 by 6 in. (152 by 152 mm) square and 1 ⁄ 4 in. (6.4 mm) thick, with a 7 ⁄ 16 -in. (11-mm) wide slot starting at the midpoint of one side and running at right angles to that side for a distance of 2 5 ⁄ 8 in. (67 mm) toward the center of the plate. The plate also has a 7 ⁄ 16 -in. diameter hole in the exact center of the plate. One side of the plate has two 1 ⁄ 8 -in. (3.2-mm) thick, 1 ⁄ 2 -in. (13-mm) wide, and 1-in. (25-mm) high projections, located not more than 1 ⁄ 2 in. from the corners, and a similar projection located on an adjacent side and not more than 1 ⁄ 2 in. from one of the corners of the first side. These projections serve as permanent registry stops for 6- by 6-in. tile during measurement.
6.2.1.1 In addition, the plate has a series of tapped holes for insertion of removable reference pins and removable registry stops. The centers ofthe holes for the reference pins are located for each nominal size oftile near three ofits corners, 3 ⁄ 8 in. (9.5 mm) in from each side, when the tile is centered on the plate, except that for 2- by 2-in. (51- by 51-mm) tile the distance in from the edges is 1 ⁄ 4 in. (6.4 mm). To receive the three registry stops, the centers oftwo holes are located for each nominal size of tile 1 ⁄ 2 in. (13 mm) from the corners of one side and 1 ⁄ 8 in. (3.2 mm) from the edge of the tile, while the center of a third hole is located on an adjacent side, 1 ⁄ 2 in. from one of the corners of the first side and 1 ⁄ 8 in. from the edge of the tile.
6.2.2 Reference Pins—Three movable reference pins 5 ⁄ 8 in. (16 mm) high and 1 ⁄ 4 in. (6.4 mm) in diameter, with the free end ground to a hemispherical tip and the other end threaded for a distance of 1 ⁄ 4 in. The reference pins are inserted in the metal plate to support the tile during measurement.
6.2.3 Registry Stops—Three 1 ⁄ 4 -in. (6.4-mm) diameter and 1 1 ⁄ 4 -in. (32-mm) high, movable, flat top registry stops with a 1 ⁄ 16 -in. (1.6-mm) wide and 1 ⁄ 8 -in. (3.2-mm) deep slot on one end for the insertion ofa screwdriver and threaded on the other end for a distance of 1 ⁄ 4 in. The registry stops are inserted in the metal plate to fix the horizontal position of the tile during measurement. 6.2.4 Dial Indicators—Two adjustable dial indicators, read- ing in 0.001-in. (0.025-mm) increments and accurate to 60.001 in. One is inserted from the bottom through the 7 ⁄ 16 -in. (11-mm) hole in the center of the plate, permanently fastened to the underside of the metal plate, and used for measuring diagonal warpage. The other is inserted into the slot in the plate and fastened in any one of four positions which represent midpoints between reference pins on one side of each of the different nominal sizes of tile. This dial indicator is used for determining edge warpage.ASTM C485 pdf download.