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There are a number of ways to measure the flatness of a surface. The most common method within the Flat Lapping sector is by using a Monochromatic Sodium light unit and an Optical Flat. This gives extremely precise measurements, more accurate than most CMM measurements, in an economical way.
Articles for Precision Lapping. Reading Light Bands. What Are Light bands? Light bands formed by using an optical flat and a monochromatic light source represent an inexpensive yet accurate method of checking surface flatness.
15 lut 2018 · A method of measuring seal face flatness. One helium light band equals 0.0000116 inches or 0,3 microns. Seal faces are lapped to less than one helium light band by most seal manufacturers, but after lapping the part relaxes and can go out of flat as much as three helium light bands.
To accurately measure the level of flatness, count the number of dark lines and multiply this by the width of the light band. This will give the height difference between the component's surface and the optical flat. This height difference will be represented in units of length, such as millimeters.
An optical flat is a contact optical measurement device used in conjunction with a monochromatic light source to measure precision flat surfaces. Lapmaster optical flats are manufactured from high quality fused quartz.
Light band readings are a very valuable way to check for improper lapping techniques, incorrect vehicle and abrasive ratios, or faulty equipment. The two examples below show the most typical light band patterns
Introduction. The easiest and best way to test the flatness of a flat lapped or polished surface is with an optical flat. Such surfaces are found on micrometers, measuring machines, gage blocks, snap gages, ring seals, valve seats and precision flat lapped parts.
