From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Directions for the study and chipping test of hard composite dielectrics.
| Identifier | ExFiles\Box 24\2\ Scan216 | |
| Date | 21th February 1922 guessed | |
| 574 DIRECTIONS FOR THE STUDY OF HARD COMPOSITE DIELECTRICS. (b) Tool. The taper cut shall be made with the following tool :— Form of tool . . . . See Fig. 18. Material . . . . . . Silver steel. Diameter . . . . . . ¼ inch. Tool angle . . . . . . 70°. Front clearance . . . 20°. Top rake . . . . . . 0°. Temper . . . . . . Glass-hard in clean cold water and left with a good cutting edge. FIG. 18.—Form of Tool for Chipping Test. The tool shall be finished on a fine oilstone, using a jig to ensure obtaining the specified angle and accurate shape. The tool shall be set at an angle of 75° to the axis of the specimen.* The tool shall be set accurately centrally, so that the plane of its upper face contains the axis of rotation of the specimen. A newly sharpened tool shall be used for each specimen. Shoulder chipping shall be taken as the criterion (see Fig. 19); and the taper cut shall be continued until chipping is visible to the naked eye. * A suitable form of tool holder is shown in Fig. 17. FIG. 19.—Setting of Tool for Chipping Test. (c) Conditions. The taper cut shall be made under the conditions given below, the specimen being kept under observation for chipping :— Revolutions per minute . . . = 100 ± 2. Revolutions per inch of feed . . = 48. Taper . . . . . . . . = 1 in 50. Temperature of the specimen . . = 20° C. ± 2·5° C. All materials should be tested dry. If, however, it be desired to obtain results with lubricant, the same test shall be employed, and a definite lubricant shall be specified by the manufacturer of the material for the purpose of the test. When reporting on a material tested with lubricant, full particulars of its composition, and the rate of flow of the lubricant during the test, shall be stated. | ||