Minor Cutting Edge Wear in Finish Turning Operations

In finish turning operation, it has already shown, that for the sake of control the dimensional accuracy and the micro-geometry of the worked surface, the wear parameters employed in rough turning operations are not suitable. In the present work the study of wear in fmish turning operations, is carried out, employing a particular groove survey methodology, already proposed in a previous paper, that is based on the techniques of acquirement and processing of images. In order to verify the applicability of the proposed technique two kind of alumina-based inserts and two kind of sintered carbide inserts have been tested. The experimental tests have confirmed the validity of the technique in th…

Effect of Chemical Etching on Adhesively Bonded Aluminum AA6082

The efforts of new automotive industry are mainly directed towards the substitution of aluminum for steel in the body structure because the aluminum structures are lighter than traditional steel ones and meet the requirements, in terms of both vehicle design and manufacture. However, this substitution is not so automatic, but it is important to study the material properties and the structure design, focusing the attention on the methods of joining. Welding, typical technique to joint steel parts, is particularly difficult when applied on aluminum ones and then, in many cases, the adhesive bonding is preferred. To optimise the joint performances it is necessary to pre-treat the metal surface…

Study of new joining technique: flat clinching

In this paper a development of clinching, called flat clinching, is presented. After a press clinching process, the joined sheets have been deformed by a punch with a lower diameter against a flat die. In this way a new configuration is created with a geometry that has no discontinuity on the external surface (bottom). A new procedure has also been tested: the second step is perfomed by pressing the joint between two flat dies. This second case has revealed itself to be very effective.Tensile tests have been done to compare the joints strength among the various joining techniques. Moreover some joints have been cut to analyse the changing of the contact line shape and how its characteristic…

Adhesive joining of Aluminum AA6082: the effect of resin and surface treatment

Abstract In this work the effects of both the substrate surface condition and the adhesive properties on single-lap aluminium joint resistance were analysed. The aluminium sheets were mechanically treated with two abrasive surfaces evaluating the induced roughness; four different resins were used in adhesion tests. Moreover, wettability tests were performed in order to evaluate the effect of the above-mentioned parameters on the substrate/adhesive interaction. A design of experiments was defined in order to quantify the effect of the considered factors and their correlation.

Metal Matrix Composites - Mmc - Turning: Comparison of Tool Materials

The main properties required to the modem cutting tools to be employed in production, are both high wear resistance and chemical stability. In this last years, in the machining of MMCs several kinds of coated tools have been developed; they are characterized by high hardness to resist to the relevant strength and abrasive action of the reinforce fibers or particles, arranged inside the matrix. In turning of MMC the employ of Tungsten Carbide tools coated with Polycrystalline Diamond (PCD) have shown to be very effective, whereas they are very expensive thus increasing the production costs.

Wiper Tools in Turning Finishing of Quenched Steel

In the last years, the research on metal machining has been focused on the development of tools that can support an increment of the cutting parameters instead of the increment of tool life; this strategy is focused to obtain a relevant productivity increment without getting worse the final product quality. The new design of the tool corner radius has allowed preserving the same product quality due to the “wiper effect” generated during the cut. The employ of such re-designed tools can allow substantial productivity improvements and, by employing the same feedrate, it is possible to achieve excellent surface finish and eliminate the grinding operation. With the aim to verify the possibility…

Failure Map of Composite Laminate Mechanical Joint

The aim of this research is to investigate the pin/hole contact stress of a composite laminate and failure modes when submitted to tensile bearing tests. The limit loads and failure modes are evaluated as a function of pin diameter and hole position. Analyzing the joint geometry effect on the fracture mechanisms, a failure map is obtained, identifying three regions of typical failure modes of mechanically fastened joints. A theoretical approach is proposed to identify the field of each fracture mode to obtain a simple experimental methodology to support the design of a particular joint laminate. In addition, a simplified numerical model is proposed to evaluate near the hole the stress/stra…

Bearing failure prediction: an experimental versus numerical approach

Validation of Predictive Approaches for Ductile Fracture in Cold Extrusion

Cold extrusion is sometimes accompanied by some typical internal defects, known in the technical literature as “central bursts”, which dramatically could affect the component behaviour during its service life. Several researchers, following both analytical and numerical approaches have attempted central bursting prediction in extrusion. Among the latter several approaches have been proposed in the literature, namely the ones based on the use of ductile fracture criteria and the ones founded on the damage mechanics analysis. Each one of these approaches presents some advantages and drawbacks. In the paper the authors analyze a set of cold extrusion processes on AISI 1040 specimens at varying…

Effects of powder concentration and type of resin on the performance of marble composite structures

In this work, we will expose the behaviour of a composite structure reinforced with marble powder. The attention was focused on the effects produced on the physical and mechanical properties due to different kinds of matrix (epoxy and polyester resins) and filler amounts (60%, 70%, 80%). Rheological, static flexural and Izod impact tests have been carried out. An experiment designed was defined for the mechanical tests, in order to quantify the effects of both the resin and the marble percentage on the material properties, as well as to identify a possible correlation between these factors. Moreover, water absorption and stain resistance have been evaluated to study the surface properties o…

Paper-reinforced biomimetic cellular structures for automotive applications

The aim of this work was to make and test some sandwich structures, made of biomimetic cellular cores of recycled paper. In a preliminary study some paper laminates were investigated. Then two different kinds of cores were made by simple processes, according to two natural structures (i.e. feather and honeycomb). To evaluate the mechanical properties of these new sandwiches, static flexural, flatwise and edgewise compression tests were performed.

Experimental and numerical evaluation of sandwich composite structures

The main problem working with sandwich composite structures is their intrinsic anisotropy and non-homogeneity that does not allow their correct modelling. Nowadays the available data on mechanical properties of complex structures, necessary to allow a correct and reliable design, are not sufficient. The aim of the present work is to extend the knowledge of mechanical properties both on single components and on complete structures, focusing on the effects induced by different kind of skin arrangements (Kevlar, glass and carbon fibres). Compressive, shear and flexural tests were performed for a complete static mechanical characterisation of the sandwich structure both on each single component…

Effects of natural fibres reinforcement in lime plasters (kenaf and sisal vs. Polypropylene)

Nowadays the tendency to realize environment-friendly products is becoming more widespread to ensure sustainable and smart development. The synthetic fibres, frequently used, are harmful to the environment because they are non-degradable and non-renewable. Their use has resulted in an increase of oil consumption. Therefore, the possibility of replacing them with natural fibres becomes increasingly concrete confirmed by the researches and investigations carried out. In this work three lime based plasters were prepared and analysed to evaluate the influence on their performance of different fibres used as reinforcement. In particular each plaster was realised by adding to the mortar the same …

A New On-Line Roughness Control in Finish Turning Operation

A new on-line control method for the wear state of sintered carbide tools for finish turning operations is proposed.

An Automated System for Dimensional Control Based on Computer Vision

A totally automated control method for the dimensional control of pieces has been developed by Computer Vision techniques, combined with a movement equipment managed by the control system. By employing this technique it’s possible to perform the dimensional control on manufactured articles having geometric characteristics that don’t allow a trouble-free image acquisition maintaining a good resolution. By employing the same equipment an automated three-dimensional control system, based on stereoscopic vision has been developed.

Load-deflection characteristics of superelastic and thermal nickel-titanium wires

SUMMARY The aim of this study was to investigate the mechanical properties of superelastic and thermal nickel–titanium (NiTi) archwires for correct selection of orthodontic wires. Seven different NiTi wires of two different sizes (0.014 and 0.016 inches), commonly used during the alignment phase, were tested. A three-point bending test was carried out to evaluate the load–deflection characteristics. The archwires were subjected to bending at a constant temperature of 37°C and deflections of 2 and 4 mm. Analysis of variance showed that thermal NiTi wires exerted significantly lower working forces than superelastic wires of the same size in all experimental tests (P < 0.05). Wire size had a s…

A Study on the Correlations between Machining Parameters and Specimen Quality in WEDM

Wire electrical discharge machining (WEDM) is widely used in manufacturing, medical, aircraft applications and, virtually, all areas of conductive material machining. The process involves a series of very complex electrical, thermodynamical and electromagnetical phenomena that are still partially unknown. Due to the large amount of parameters involved in the process, a suitable set-up of the variables aimed to obtain the best performance is often very difficult. In the paper the results of a wide experimental analysis are presented: the tests were carried out on high-speed steel and tempered steel specimens utilising brass wires. The influence of the most important process parameters on the…

Comparisons of processing and strength properties of two adhesive systems for composite joints

Abstract In the present study rheological, static and impact tests are carried out on two adhesive resins usually employed in marine applications; then single lap joint tests are conducted on composites joints evidencing the effect of the curing time of both resins on the mechanical properties of the joint. The applicability and workability conditions of the adhesive resins are determined evaluating the curing evolution by a preliminary rheological analysis; then the relation of curing properties with the mechanical performances of the resins themselves and with ones of the composite joints is estimated. Static flexural and Izod impact tests are performed on the resins at increasing time af…

An XML interface to Step-NC Systems For Remote Collaborative Concurrent Engineering

Effect of curing time on the performances of hybrid/mixed joints

Abstract The aim of this work is the study of a mixed method used for the joining of aluminum alloys with glass reinforced polymer’s substrates (in the next GFRP). In particular, the technique of self-piercing riveting (in the next SPR) was applied on a co-cured joint in order to evaluate the influence of the time of inserting the rivet on the mechanical behavior of the mixed joints. Three different joints were realized: adhesive by co-curing technique, mechanical by self piercing riveting (in the next SPR) and a mixed one in which the joining techniques (i.e. adhesive and mechanical) were combined. In particular, to determine the optimum time to insert the rivet, three different times from…

Geometry and stacking sequence effect on composite spinnaker pole’s stiffness: experimental and numerical analysis

Composite materials are widely employed in sailing sports, a possible application is for the mast pole or other sail poles. In the paper the attention is focused on the spinnaker poles mechanical performances; in particular the focus is on axial and ring compressive properties of three different carbon fibre/epoxy resin spinnaker poles, to investigate both the diameter and stacking sequence effect on the mechanical performance of the structure. Starting from the stacking sequence used in the production of a particular spinnaker pole, the effect of a lamina at 0- in the middle of wall thickness is investigated with the purpose to obtain a more stiff structure. Moreover to test the proposed s…

Experimental and numerical study of composite T-joints for marine application

Abstract The aim of this work was to study the behaviour of composite T-joints used in marine applications. The effect of several parameters was investigated. In particular, three configurations were studied; i.e. with adhesive and with two different over-laminations. Moreover, the joined sections were made of different materials. These joints were subjected to a tensile load in the plane of the sheet. To quantify the effect of different designs on the strength, a variance analysis was performed. Finally, a numerical model was developed using a commercial finite element code (Ansys).

Effetti della temperatura sul ritorno elastico nella piegatura di strisce d’alluminio

Rivettatura autoperforante e clinching: due tecniche innovative

Study of Snowboard Sandwich Structures

The aim of the present research is to extend the knowledge of mechanical properties both on single components and on complete structure employed for snowboard. Flexural and torsion tests are performed to acquire important comparison parameters between snowboard sandwich structures that differ for the core material employed (wood, PVC foam core). A simplified FEM model is proposed to simulate the flexural tests of the sandwich structure showing good predictive capability.