Журнал інженерних наук (Dec 2016)
Measuring of roundness after turning of composite material with natural fibers
Abstract
The article is based on practical requirements from the reason of unequally removed material during the turning of the wood plastic composite (WPC). This results in geometrical deviations of the WPC bar diameter. WPC represents a relatively new group of materials that has been at the market for almost 30 years. In 1983 Lear Corporation in Wisconsine, USA made for the first time the interior panels of cars from composite materials – PP matrix with organic filler – 50 % wood flour. WPCs displace traditional materials such as wood, steel and cement materials in the marina industry. Designers are not limited technology of production from construction aspect, because different shapes and profiles can be produced by injection (resp. process of extrusion), but in the process of machining were monitored problems with tolerances. Mixed colors can be achieved by using of different pigments and one feels that this is real wood. Technologists begin to use convention technologies – drilling, milling and turning, as tendency of application of WPC increased. Knowledges about machining of WPC are not elaborate as deep as machining of metals or plastics. And this is a reason for orientation in this direction too. Commercial wood plastic composite MEGAWOOD (70 % wood flour, 30 % HDPE) was a sample material in current investigation of roundness after turning of WPC. HSS EN ISO HS6-5-2 cutting tool was used. The geometry of the cutting tool was γ0 = 20°, α0 = 8°, κr = 45°, rε = 0,5 mm, εr = 90°. Cutting conditions during turning were as follows: cutting speed n = 900 m/min (constant), feed f = 0,1 to 0,61 mm), depth of cut ap = 0,5 mm for turning of final diameter d = 36 mm. It was dry turning. Roundness/cylindricity measuring system RA – 120 was used for measuring of roundness deviation. It was found that the roundness deviation increases with feed increasing. Popped heat was not used during the turning to final diameter – 36 mm. Using of popped heat results in decreasing of roundness deviation. Waviness was not possible to measure within the range of ±1 000 µm on the sample No. 4 (f = 0,41 mm) and sample No. 5 (f = 0,6 mm). Tip of the measuring systems could not filtrate parameter of roughness (surface after turning – low value of tool nose radius rε = 0,5 mm and high feed caused distinctive toolmark). Inaccuracy of macrogeometry (including roundness) could have caused state of machine, tool and fixture too.
