Milling Cycle Research Articles

Influence of High-Energy Milling and Sintering Cycle on Obtaining TiAl from Elemental Ti and Al Powders

The present work studies the influence of high-energy milling (HEM) and sintering cycle of Ti and Al powders on the obtainment of TiAl. This study shows that HEM modifies the diffusion processes during the sintering stage. The ignition temperature of the exothermic reaction (SHS) that occurs between Ti and Al, was considered as the key parameter of the sintering process, leading to the study of sintering cycles that avoid uncontrolled processes caused by the SHS reaction. The samples were obtained by cold uniaxial and isostatic pressing, pre-sintered at different temperatures, and then heated up to the sintering temperature. This study also shows the effect of powder additions processed by HEM on the sintering behavior of blended elemental Ti and Al powder compacts.

Automatics for Flotation Machines, in the Case of IF-19S

Abstract This work presents control systems developed and manufactured by the Institute of Non-Ferrous Metals in Gliwice. designed for IF-type flotation machines offered by the Institute for the processes of mineral material flotation enrichment. The measurement and executive equipment and automatics systems based on PLC controllers have been considered for different machinery types. The example of flotation in the milling cycle has been used to demonstrate the control system structure and engineering as well operation assessment.

On the Monitoring of Cutting Forces in End Milling Processes (2nd Report)

Control strategies of cutting forces in end milling process have been long studied as a methodology to autonomously optimize cutting conditions. In particular, a model-based feedforward control approach has been recognized as a simple, and yet practical way to regulate the cutting force. This paper proposes an identification scheme of a prediction model of cutting force, and a feedrate control scheme based on it. Model identification cycles are included within a canned milling cycle, where the cutting force is estimated from servo motor current and spindle motor current in order to identify the cutting force prediction model. By performing cutting force control in subsequent processes based on the identified model, it is experimentally validated that the machining efficiency is significantly improved, while avoiding an excessive tool load.

Nitriding of Transition Metal Powders by Ball Milling in Nitrogen Gas

Ti, Zr, Nb, Ta, Cr and Mo powders have been mechanically nitrided by ball milling in nitrogen gas. The structures of nitrided powders were examined by means of X-ray analysis and transmission electron microscopy. A kinetic analysis for the nitriding rate was also carried out. About 50 at.% of nitrogen is absorbed in the milled powders, resulting in the formation of stable or metastable NaCl-type nitrides. The nitriding rate increases with an increase in the enthalpy of nitride formation. The nitriding rate is proportional to the cube of milling cycle. This fact means that the nitrogen absorption in the milled powders occurs at the instance of ball collision and the quantity of nitrogen absorbed at one collision event is proportional to the energy supplied to the powder from colliding balls

Rheology in dispersion testing and mill base formulation optimization

Rheology offers only slight advantages in terms of mill base formulation, because of the comparatively low shear rates available on existing viscometers and the considerable changes in mill base rheology which occur during the milling cycle. These changes can however be utilised as a means of dispersion testing and satisfactory and reproducible “milling isotherms” can be obtained for a wide variety of dispersion and size reduction operations. It would seem possible to characterise grinding and dispersion by changes in mill base rheology in that grinding shows an increase in non-Newtonian characteristics whereas dispersion shows a decrease in these characteristics. Care must be taken to ensure that controlled pretreatment of the samples is adopted be ore satisfactory results can be ensured, but extensive storage periods tend to magnify differences between samples.