In this paper the results of experimental tests aimed to determine the friction coefficient in sheet metal forming operations for various sheet metal materials and at different operative conditions are presented. The research has considered the frictional characterization of three kinds of drawing quality steels that are commonly used in automotive industry. These are a drawing quality steel (DQ), a deep drawing quality steel (DDQ), and extra deep drawing quality steel (EDDQ). For measurement of the sheet surface topography, a 3D stylus instrument Alicona InfiniteFocus was used. To determine the friction coefficient three tribological tests, i.e. a strip drawing test, a draw bead test and a pin-on-disc tribometer, have been conducted. The experimental results have ascertained several relationships showing the effect of sheet metal surface roughness, lubricant conditions and sheet orientation on the value of friction coefficient in sheet metal forming processes. The results further showed that the surface topography and sample orientation in the rolling direction of the sheet are significant factors that influence the friction coefficient. It was found that the tested steel sheets, selected from automotive industry applications, exhibit anisotropic resistance to the friction corresponding to the measured orientation in relation to the rolling direction of the sheet.

Traditional computer modelling is performed using CAD systems. Everything starts with a constructor idea. They present their concept on a technical drawing and then perform it in a virtual environment of a 3D model. This model may then be manufactured with the use of available methods. The problem arises when technical documentation of an object, for example, a tooth model, is not available.2D images are the traditional way of presenting anatomical structures; unfortunately, this method is sometimes ineffective. In advanced cases of dental conditions, there are difficulties in the recognition and proper interpretation of 2D images of the affected area. This is why other ways to show the shape of the complex internal structures have been researched, such as the (3DP and FDM). They were similarly aligned in the work space of both printers to maintain similar conditions of printing, and similar layer thicknesses of 0.1 mm and 0.13 mm were used. The printed models were scanned using a focus variation (FV) microscope. The scanned geometry of the models of the two teeth was compared with the geometry of the teeth after their segmentation and filtering. A fitting process was carried out using the best fit algorithm with a fitting condition of 0.001 mm. The achieved accuracy of the FV measurements was significantly higher than the accuracy of the used printing methods. FV can be applied to performing 3D scans of complex shapes such as the crown and roots of a tooth. 3DP models have more homogenous structure, whereas layer structure is easy to recognize for FDM models. Due to that, the 3DP models have to be strengthened using infiltration, which makes it more difficult to predict the final dimensions and to achieve required accuracy. Keywords: dental model, reverse engineering, rapid prototyping, focus variation Highlights • The accuracy of FDM and 3DP techniques were examined in terms of manufacturing dental models such as tooth models.• The infiltration applied to the 3DP models reduced in accuracy compared to FDM models.• For the FDM models, the values of mean deviation were negative and met the accuracy specified by the printer's manufacturer.• Due to infiltration the values of mean deviation of 3DF models were positive.• The infiltration also caused the models manufactured with the FDM to be more accurate than the 3DP ones.• It was determined that the focus variation method can be applied to measure parts with a complex shape, such as the crown and roots of a tooth.

During the operation of a single-layer grinding wheel (SLGW), irreversible changes occur on its active surface due to wear. The study of grinding-wheel microgeometry changes can be based on the measurement of the surface texture as well as the determination and analysis of its parameters. The article deals with the selection of suitable texture parameters and an appropriate mathematical model carrying information about the SLGW condition. In the study, samples of Pyrowear 53 steel were ground using electroplated cBN single-layer grinding wheels until they were completely worn out or removed assumed volume of the workpiece material. Each SLGW worked with constant process parameters. Among the 144 parameters tested, the highest sensitivity to changes in wheel active surfaces caused by wear was shown by the mean value of the mean island heights Zmean_m. In-depth research was conducted for Zmean_m and reduced peak height Spk. Compared to Spk, Zmean_m has proven to be a better measure of wear, especially when large areas of sticking occur. Moreover, the second-degree models linking Zmean_m and Spk to the process parameters and the specific material loss were better suited to the empirical data than the exponential models.

Measurements of the active surface microgeometry of the grinding wheel by contact and optical methods are commonly used to obtain a cloud of points representing the surface of the examined tool. Parameters that can be determined on the basis of the above-mentioned measurements can be universal parameters, which are commonly used to assess the geometric structure of a surface or parameters taking into account specific properties of the grinding wheel active surface (GWAS) structure. This article proposes a methodology for determining the average level of binder, which allows the definition the cut-off level required to separate from the measurement data: (i) the areas representing grains, (ii) the areas of gumming up of the grinding wheel, and (iii) deep cavities in approximately the same places on the investigated grinding wheel, regardless of the degree of its wear. This, in turn, allows one to track changes in characteristic parameters computed from measurements of texture in the above-mentioned areas due to different GWAS wear processes. The research was based on the analysis of data obtained from measurements of single-layer grinding wheels using the replica technique. The adopted measurement methodology enables measurement of approximately the same (94% coverage) areas of the GWAS at four stages of grinding wheel operation. Errors that were computed related to the determination of the volume of abrasive on the GWAS at various stages of wear using the developed methodology were lower, on average, by 48% compared to the automatic recognition of islands made with a commercial software.

The paper presents a method of forecasting the product surface topography after five-axis machining with a lens-shaped end-mill. Surface roughness is one of the key parameters considered when assessing the effectiveness of the machining process, especially in the aviation, automotive, tooling and medical equipment industries. The developed method, the first published, presented in the paper is based on the analytical equations of the trajectory of the cutting edge motion, on the basis of which the cutter action surface is generated. The developed model takes into account: cutting depth, cutting width, feed, lead angle and radial runout. Experimental studies were conducted using three different materials: 40HM steel, Al7035 aluminum alloy and Ti Grade 5 titanium alloy. Various values of the cutting width parameters and different feeds were used in the tests. Based on the results of the experimental tests, an empirical model (response surface model) was determined and was then used to verify the simulation model. The simulation results and the results of experimental tests were compared and conclusions were drawn regarding the developed models. The developed models supported by numerical simulation can be used to approximately estimate the influence of the width of cut br and feed ft on selected height characteristics Sa and Sz^ of the geometric structure of the surface (GSS) after machining with a lens-shaped end-mill in terms of the process parameters adopted in the tests. It was found that the influence of the ft on the Sa and Sz^ is greater for small values of br. The effect of br is greater with lower ft values. The cutting width br has the greatest influence on Sa and Sz^, and ft and the interaction of these parameters has the least influence.