International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

It is possible to do laser marking on plastic surfaces by using lasers. Coding of information is very popular in last years because of its ability to convert information in one symbol. But there are lot of small sized parts where it is hard to do laser marking or physical impact on material is so big, that this code would be readable. On the other side contrast of marked area must be good enough so camera used in experiment would be capable read it. Goal of research is to find laser parameters that would be good enough to do laser marking on plastic surfaces so that physical impact would be made on that surface. There is used two-dimensional code- QR code. Target is to find parameters which would allow to do 3.5mm big square.

Electrochemical machining (ECM) is prevalent and competitive manufacturing process which uses for machining of hard and tough materials in high tech industries. Hence, experimental investigations on ECM of different materials play essential role to effectively utilize this process. This paper demonstrates a systematic approach for achieving comprehensive mathematical models in order to investigate the effect of machining parameters on the process responses of 321-Stainless-Steel and analysis of machining performance based on the response surface methodology (RSM). Machining voltage, tool feed rate, electrolyte flow rate and concentration of NaNO3 solution were considered as the machining parameters while material removal rate (MRR) and surface roughness (Ra) were considered as the process responses. Experimental plan was performed by a central composite design (CCD), and the proposed mathematical models statistically have been evaluated by analysis of variance (ANOVA). Analysis shows that the RSM method has been appointed properly as the design of experiments (DOE) method for resolving curvature in ECM process responses. Also, the results show that the machining performance is greatly influenced by machining parameters. Especially the voltage and electrolyte concentration are the most important parameters.

The minimum quantity lubrication (MQL) and dry machining operations are two types of environmentally friendly processes that have potentials to replace with conventional cooling methods. In recent years, the studies have been performed on the environmentfriendly lubrication methods such as MQL method in machining operations. These studies have also focused on the usage of vegetable cutting fluids instead of mineral based oils due to increasing awareness to the environment and human health. In this experimental study, Aluminum 6061 was machined under dry and MQL conditions and the cutting force components and surface roughness values were measured. The experiments were carried out by CNC milling machine tool at three different cutting speeds and constant depth of cut and feed. The vegetable cutting fluid was pulverized to the rake face by using single nozzle and double nozzles at two flow rates during MQL milling. Cutting force components and surface roughness values were compared for minimum quantity lubrication and dry milling operations of Aluminum 6061.

The purpose of the present paper is to evaluate the geometric accuracy and surface roughness of polymeric samples manufactured by Digital Light Projection (DLP) Stereolithography. The standard cubic samples with dimensions 5 mm х 5 mm х 5 mm were printed of two polymers: NextDent C+B (white-yellowish color A3.5, VITA shade guide) and NextDent Cast (dark-red color), in two ways of placement to the base – horizontally and inclined at 45^о. The samples were printed with two different layer’s thickness – 35 μm and 50μm. It was established that the samples of both polymers, manufactured in horizontal position with the lower layer’s thickness (35μm) possess highest dimensional accuracy and lowest interval of deviation. The most accurate are the dimesons parallel to the basis, while these, parallel or inclined to the print direction, have the highest deviations. The interval of the deviations of the dimensions of samples, manufactured inclined at 45^o, is nearly 2-3 times higher, as the interval of the samples, made of NextDent Cast, is more than 50% higher than that of NextDent C+B. The horizontally printed samples have 1.5-2 times lower surface roughness compared to the samples, printed inclined at 45^o. The surface roughness of the samples, made of NextDent Cast, is 30-50% higher than that of NextDent C+B independently of the layer’s thickness. The increase of the thickness from 35 μm to 50μm leads to 1.5-2 times higher surface roughness in the two samples’ positions. The optical properties of both polymers in the research strongly influence the geometric characteristics, dimensional accuracy and surface roughness of the objects, manufactured by DLP stereolithography.

The article deals with a fundamentally new methodology for optimization, assessment, and control of the roughness of surfaces that can be applied in all production facilities. What is meant by optimization is the choice of the most appropriate roughness from among all the practically possible values that can be achieved in certain production conditions. The given methodology is used as a basis for the assessment of the influence of surface roughness on the strength of a joint formed through the process of hot pressing.