This paper deals with analyzes of the influence of the perpendicularity of the spindle of the milling machine on the machined surface. This is part of the geometric errors of machine tools and in a direct manner constitutes a defect on the quality of the workpiece. Therefore, the surface roughness is particularly sensitive to the cutting speed, the feed rate, round of teeth default, the tool tip radius and the cutter teeth number. This article examines the characteristics of the surface topography of steel parts, in finishing machining using milling cutters. The study is conducted by computer simulation tests and experimental part using surface condition monitoring instruments, taking into consideration the round teeth default. The variation of the inclination of the spindle of the milling machine in three positions (90°+ 30#, 90°, and 90°-30#) shows a good agreement between the simulation and the experimental results for sharp and moderately worn tools. Similarly, this study showed that the presented model could thus be integrated into systems computer-aided design and computer-aided manufacturing. Finally, the physical and statistical parameters of roughness during milling at position 90°confirmed that, when the defect of the perpendicularity is eliminated to the maximum, the best surface conditions are obtained.

This paper presents and describes the design, manufacturing, calibration and performance of a universal cutting dynamometer based on the principle of extensometer strain gage techniques. The device developed in this paper was designed and calibrated for measuring separately components forces developed during turning, drilling and milling operations. Its design is carried out according to the two principal criteria which are in contradictory matters such as sensitivity and rigidity. It consists principally of two circular rings, one allowing its fixation on the tables of the three type of machine tools, and the other one is machined so that the complete dynamometer can be attached to machines tables. The strain gages are then cemented on the parts of the dynamometer where the deformations (traction, compression and torsion) are maximum. The gages are connected in the form of a full wheatstone bridge, any unbalance in which would indicate the thrust force ant the torque providing maximum sensitivity and complete temperature compensation. The disposition and the connection of the strain gages in complete Wheastone bridge are carried out according to the force component to measure while taking account of the interactions between the three directions and the compensation of the effect of the temperature. The reading is indicated on standard indicator of constraints B & K 1526. Some experimental measurements of components forces and torque in the drilling process obtained with the described dynamometer are presented and compared with available data given by other research worker.

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In this study, we use the finite element method to analyse the behaviour of cracks emanating from microcavities in the bone cement, binding the cup to the bone, according to their size and position around the cavity, the position of the patient, the cavity's location and the inter-defects distance (cavity-crack, crack-crack). We show that the most unstable stress intensity factor, in mode I, when the crack located in the cement's centre and propagating along this thickness. This instability is all the more important that its size increases, tends towards the cavity, the cracks are located in a vicinity one to other and that the patient is in a squatting position. The predominant fracture mode, in mode I and II, depends on the crack's position priming site around the microcavities. This work allows the better understanding of the interconnection phenomena of the microcavities experimentally observed.