Machining of glass fiber reinforced polyamide（玻璃纤维增强聚酰胺的加工）.pdf

eXPRESS Polymer Letters Vol.1, No.12 (2007) 810–816 Available online at DOI: 10.3144/expresspolymlett.2007.112 Machining of glass fiber reinforced polyamide * F. Quadrini, E. A. Squeo , V. Tagliaferri Department of Mechanical Engineering, University of Rome Tor Vergata, Via del Politecnico n°1, 00133 Rome, Italy Received 27July 2007; accepted in revised form 24 October 2007 Abstract. The machinability of a 30 wt% glass fiber reinforced polyamide (PA) was investigated by means of drilling tests. A disk was cut from an extruded rod and drilled on the flat surface: thrust was acquired during drilling at different drilling speed, feed rate and drill diameter. Differential scanning calorimetry (DSC) and indentation were used to characterize PA so as to evaluate the intrinsic lack of homogeneity of the extruded material. In conclusion, it was observed that the chip for- mation mechanism affects the thrust dependence on the machining parameters. A traditional modeling approach is able to predict thrust only in presence of a continuous chip. In some conditions, thrust increases as drilling speed increases and feed rate decreases; this evidence suggests not to consider the general scientific approach which deals the machining of plastics in analogy with metals. Moreover, the thrust can be significantly affected by the workpiece fabrication effect, as well as by the machining parameters; therefore, the fabrication effect is not negligible in the definition of an optimum for the machin- ing process. Keywords: polymer composites, machining, drilling, cutting forces 1. Introduction cutting forces on process parameters. For example, Machining of polymers is employed when the in 1977, Roy and Basu defined generalized equa- quantity of items does not justify the cost for molds, tions for evaluating the main cutting force and the or when a pro