Automation of machining operations, being result of mass volume production of components, imposes more restrictive requirements
concerning mechanical properties of starting materials, inclusive of machinability mainly. In stage of preparation of material, the
machinability is influenced by such factors as chemical composition, structure, mechanical properties, plastic working and heat treatment,
as well as a factors present during machining operations, as machining type, cutting parameters, material and geometry of cutting tools,
stiffness of the system: workpiece – machine tool – fixture and cutting tool.
In the paper are presented investigations concerning machinability of the EN AC-AlSi9Cu3(Fe) silumin put to refining, modification and
heat treatment. As the parameter to describe starting condition of the alloy was used its tensile strength Rm. Measurement of the machining
properties of the investigated alloy was performed using a reboring method with measurement of cutting force, cutting torque and cutting
power. It has been determined an effect of the starting condition of the alloy on its machining properties in terms of the cutting power,
being indication of machinability of the investigated alloy. The best machining properties (minimal cutting power - Pc=48,3W) were
obtained for the refined alloy, without heat treatment, for which the tensile strength Rm=250 MPa. The worst machinability (maximal
cutting power Pc=89,0W) was obtained for the alloy after refining, solutioning at temperature 510 o
C for 1,5 hour and aged for 5 hours at
temperature 175 o
C. A further investigations should be connected with selection of optimal parameters of solutioning and ageing
treatments, and with their effect on the starting condition of the alloy in terms of improvement of both mechanical properties of the alloy
and its machining properties, taking into consideration obtained surface roughness.
The machinability and the process parameter optimization of turning operation for 15-5 Precipitation Hardening (PH) stainless steel have been investigated based on the Taguchi based grey approach and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). An L27 orthogonal array was selected for planning the experiment. Cutting speed, depth of cut and feed rate were considered as input process parameters. Cutting force (Fz) and surface roughness (Ra) were considered as the performance measures. These performance measures were optimized for the improvement of machinability quality of product. A comparison is made between the multi-criteria decision making tools. Grey Relational Analysis (GRA) and TOPSIS are used to confirm and prove the similarity. To determine the influence of process parameters, Analysis of Variance (ANOVA) is employed. The end results of experimental investigation proved that the machining performance can be enhanced effectively with the assistance of the proposed approaches.
This paper presents the results of experimental testing of parameters of the flow of an agitated liquid in a stirred tank with an eccentrically positioned shaft and with a Rushton turbine. The investigations were focused on the impact of the stirrer shaft shift in relation to the stirred tank vertical axis on the agitated liquid mean velocities and the liquid turbulent velocity fluctuations, as well as on the turbulence intensity in the tank. All the experiments were carried out in a stirred tank with the inner diameter of 286 mm and a flat bottom. The adopted values of the shaft eccentricity were zero (central position) and half the tank radius. The liquid flow instantaneous velocities were measured using laser Doppler anemometry.