Papers by Keyword: Surface Quality

Abstract: In the most cases manufacturing of injection mold and its cavities comprise more than half of the total production time. Very fine finishing operations can increase production time and cost of injection mold. Appropriate choice of finishing operations and injection technological parameters can reduce price of injection mold production, shorten production time and thus lower price of small and thin injection molded parts. Tool material X38CrMoV5-1, used for cavity in injection mold, was finished by fine turning, grinding, lapping and polishing with different technological conditions to achieve various surface roughness. The main aim of this research is to find an influence of surface quality of cavity and injection technological parameters on the surface quality of injection molded parts.

Abstract: Potassium Dihydrogen Phosphate (KDP) crystal is widely used in laser frequency multiplications and electro-optical modulators, but its soft-brittle property and thermal sensitive characteristic make it a very difficult-to-machine material. In this paper, an in-house made diamond tool with one tooth is used to face-mill KDP crystal specimens on a high-speed micro CNC machining centre, based on a statistically designed experiment. The morphology and roughness of the milled KDP crystal surfaces are analyzed with respect to the process parameters. It has been found that cutting speed has the largest effect on surface roughness, while axial depth of cut and feed per tooth show a comparable effect on both the Ra and PV roughness measures. From this study, 3 m/s cutting speed, 3 μm axial depth of cut and 1 μm/z feed per tooth are recommended for single point diamond milling of KDP crystal.

Abstract: One of the most effective methods for descaling hot-rolled steel products is performed using highpressure flat jet nozzles. These descaling nozzles are arranged in rows in hot rolling mills and areset in such a way that each adjoining pair of nozzles creates an overlapping area of water jet streams.Good homogeneity of the pressure distribution over the width of the hot-rolled plate is often used as anindicator of quality of the homogeneity of descaling. The presented laboratory measurements examineone pair of adjoining nozzles with a particular focus on the pressure distribution in the overlappingarea. This paper deals with one particular setting of a pair of descaling nozzles with zero offset anglesfor the jet streams. A measured pressure distribution and an outcome of an erosion test on an aluminumplate are presented and discussed. The erosion test shows that spots with higher pressures do notnecessarily result in a higher amount of removed material during an erosion test. The erosion test differs from the expected outcome in such a way that a detailed discussion of this phenomenon is outlined with possible explanations.

Abstract: Machine tool vibrations cause uncomfortable noise, may damage the edges of cutting tools or certain parts of machine tools, but most importantly, they always have negative effect on the quality of the machined surface of workpieces. These vibrations are especially intricate in case of milling processes where complex tool geometries are used, like helical, serrated, non-uniform pitch angles, and so on. During the milling process, the arising vibrations include free, forced, self-excited, and even parametrically forced vibrations together with their different combinations. Regarding surface quality, the most harmful is the self-excited one called chatter, which is related to the regenerative effect of the cutting process. Its relation to machined surface quality is demonstrated in an industrial case study. The modelling and the corresponding cutting stability are presented in case of a helical tool applied for milling with large axial immersions. The extremely rich spectrum of the measured vibration signals are analyzed by means of model-based predictions, and the results are compared with the spectral properties of the corresponding machined surfaces. The conclusions open the way for new kinds of chatter identification.

Abstract: Surface quality is very important for the finished components. One of the most important parameters that define surface quality in milling is surface roughness . Depending on the cutting conditions chosen, different milling strategies can be applied. One of the ways to reduce the production costs is to optimize the number of inserts that are involved in machining. The aim of present paper is to investigate the behavior of surface roughness under the influence of the number of inserts used in an operation.

Abstract: Water jet cutting is one of the newest techniques in non-conventional machining processes. It is a flexible technology since the same equipment can be used to cut virtually any material, such as steel stainless steel, high-nickel alloys and polymer composites (usually, for these materials, the water jet is mixed with an abrasive material, the process being known as abrasive water jet cutting - AWJC) . Compared with the classical technologies, water jet cutting presents the following advantages: very low side forces during machining, it is rapid, it is silent, no thermal distortion, a good cutting accuracy and minimal burrs. To optimize the process, it is necessary to analyze the influence of process parameters on the quality of cut. The aim of this paper is to analyze the influence of distance between the cutting head and the working sample on the quality of cut, quantified by the following parameters: width of the processed surface at the jet inlet, jet outlet, deviation from perpendicularity, inclination angle and roughness.

Abstract: In the last years there has been an increased demand to lower the impact of industrial activities on environment quality. Cutting fluids, among other products, are an important pollutant but they have often been associated with the need for a higher productivity of machining processes. Cutting fluids are a mean of reducing temperature in the cutting area, friction and tool wear but they also represent 7% to 17% of the production costs. Other problems raised by cutting fluids are: microorganism infestation, which can cause pulmonary and dermatological diseases and poor lubrication or corrosion caused by some of the chemicals. Dry cutting is regarded as the cleanest cooling method, but it has a reduced heat dissipation efficiency and practically there is no lubrication. Other relatively new green solutions concern the use of minimum quantity lubrication (MQL) and cryogenic machining.

Abstract: In this paper we analyze the influence of cutting parameters on the surface quality, surface roughness respectively, processed by turning when heat treated bearing steel, also called hard turning, and processing by turning of bearing steel without heat treatment. We set parameters of the cutting regime influencing the achievement of roughness surfaces which must be within the predetermined requirements if bearing rings exceeding 500 mm in diameter. This analysis will be done by statistical methods using the software Minitab 14.

Abstract: The paper presents an application of the ANOVA method within the Selective Laser Melting (SLM) process. A new mathematical model was developed, to calculate the surface roughness of the SLM parts made from titanium powder, as function of the important SLM parameters: point distance, exposure time and laser power. Preliminary experiments were undertaken according to the Design Experts work plan and the new mathematical formula was tested by further experimental research, to validate the optimized SLM parameters.

Abstract: The objective of this paper is to predict and analyze the surface roughness during dry turning of austenitic stainless steel AISI 304. In this study a new carbide insert developed by Mitsubishi was used for the cutting of this material. By using the ANOVA method, the influence of the main processing parameters on the surface quality was analyzed. By using a mathematical regression method a mathematical model was developed. It can calculate the surface roughness taking into account the cutting speed, the feed rate and the depth of cutting.