5-2. GRINDING AND POLISHING
The propeller will be completed after ground and polished in the finishing procedure to be conducted after the blade surface milling duly made. The grinding and polishing are mainly carried out by experienced/skilled workers manually. The blade surface with chipped-off marks made in the milling procedure is carefully ground off and polished for being finished with smoothly curved helicoidal Surface. Since the propeller blade's surface roughness offers a notable influence on the propeller efficiency, the surface is usually finished within the fine allowance of 6μ Ra. The blade tip and the round edge shapes, which are very important positions for the propeller efficiency, are accurately finished using edge gauges to be manufactured in good accordance with the dimensions in the drawing by means of the laser beamed processing machine of NC.
5-3. INSPECTION
Upon the completion of propeller manufacture, measurement is made by means of the automatic measuring equipment to check whether the machining has been carried out within the stipulated allowances. The principal measuring items are diameter, pitch, blade width, relative position of blades etc. Material test, appearance check, non-destructive inspection are also conducted in line with the inspection procedure.
Photograph 9 shows the automatic measuring equipment intended for smaller-sized propellers. The equipment is for automatic 3-dimensional measuring utilizing laser beam, and the measurement is completed within a very short time after the propeller for measurement is set on the equipment. The measured results are instantly printed out, and simultaneously stored in personal computer as measured data.
