Manufacture Of Blanks Research Articles

Electric discharge milling of polycrystalline diamond

Polycrystalline diamond (PCD) has been used widely in modern industry. However, the manufacture of PCD blanks is not an economical and efficient process. The shaping of PCD blanks with conventional machining methods (such as grinding), is a long, labour-intensive and costly process. Electromachining processes promise to be effective and economical techniques for the production of tools and parts from PCD blanks. Wire electric discharge machining is able to effectively slice PCD. Electrical discharge machining (EDM) and electrical discharge grinding (EDG) shape PCD blanks at a lower cost. However, EDM and EDG of a large surface area on PCD show lower efficiency. This paper presents a new process of machining PCD using electrical discharge (ED) milling. ED milling employs a DC source instead of the pulse generator used in EDM, and uses a water-based emulsion as the machining fluid. This process is able to effectively machine a large surface area on PCD, and effectively machine other advanced conducting materials such as cubic born nitride (CBN), and ceramics. The effect of pulse on-time, peak current, and polarity on the process performance has been investigated.

Material Removal in WEDM of PCD Blanks

Polycrystalline diamond (PCD) tools are now widely used in machining a large variety of advanced materials. However, the manufacture of PCD tool blanks is not an economical and efficient process. The shaping of PCD blanks with conventional machining methods (such as grinding), is a long, labor-intensive and costly process. Wire electric discharge machining (WEDM) promises to be an effective and economical technique for the production of tools from PCD blanks. However, a knowledge base for wire electrical discharge machining of PCD blanks needs comprehensive investigations into the proper parameter setting, metal removal mechanisms, and surface integrity of machined blanks. This paper presents the results of experimental and theoretical investigations of the influence of discharge frequency and discharge energy on the material removal rate of WEDM of PCD blanks. The mechanism of removing diamond grains from the matrix during electrical erosion is also discussed on the basis of thermal stresses between the diamond grain and cobalt phase.

The Use of technological and metric data in the study of four Levantine Aurignacian sites in the Mount Carmel region. A preliminary study.

Dans cet article nous cherchons à démontrer que l'utilisation d'informations technologiques et métriques peut être vue comme un moyen de faire la corrélation entre certains complexes culturels d'une part et comportements humains d'autre part dans la fabrication d'outils, et en particulier celle du silex. Cette étude préliminaire démontre que les informations métriques semblent être plus significatives que les informations technologiques, ces dernières étant plus largement utilisées à travers toutes les époques de la pierre taillée. Le but final de l'étude est de démontrer qu'il existe certaines habitudes dans la fabrication du silex qui se rattachent à plusieurs relations inter-culturelles dans la région étudiée.

BUNTING ALLOY 907

Abstract BUNTING Alloy 907 is a cast copper-tin alloy (tin bronze) recommended for severe service requirements. It is used widely for bearings and gears. It is a standard alloy for the manufacture of cast gear blanks and has long been known as Phosphor Gear Bronze. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive strength as well as fracture toughness. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Cu-328. Producer or source: NL Industries Inc., Bearing Division.

Design of tapered gears

In this paper the conjugate tooth profile of a tapered gear in mesh with involute helicoid cylindrical pinion is found for both on-center and off-set gear meshings. The phenomenon of undercutting and that of pointing are analysed and on this basis the gear blank dimensions to utilise the maximum area of the surface of contact are found. Finally a procedure to design the optimal shape and size of the gear blank is recommended from the point of view of ease of manufacture and inspection of the gear blanks.