Creating and evaluating replicas of surfaces machined by laser beam

In industrial practice, we often encounter a problem when it is necessary to measure and subsequently evaluate the surface quality of the part produced by the water jet, laser cutting. In that case, it is very often difficult to evaluate the final surface because of its weight or bulkiness. However, the literature sources recommend using of material known under the commercial name Dentacryl™. Although this material is still being used in technical practice, its utilisation for creating the replicas of the polypropylene surfaces which is produced by the laser beam is not recommended due to its limited viscosity and mainly due to its health risk for allergic people. Therefore, this article will describe a method of an application the two-component dental material Siloflex© for the creation of the replicas of polypropylene surfaces formed after CO2 laser machining. Furthermore, the statistical approach for evaluation of the quality comparison of the original surfaces and produced replicas is necessary to surface quality of produced replicas. © The Authors, published by EDP Sciences, 2017.TBU in Zlin [IGA/FT/2017/002

Comparison of quantitative changes after passing the laser beam through polymeric material

The article focuses on laser machining of various polymeric materials. Specifically, it examines the possibility of undesirable changes in these materials as, due to the concentrated energy of the laser beam, the heat of the material is also transferred to the material near the cutting point and hence to the heat of the cut. Although the polymeric materials do not have a high thermal conductivity, it can be expected that due to the elevated temperature, different structural or chemical changes may occur near the cutting edge. Some high-molecular substances begin to split into low-molecular-weight products, and depolymerisation or degradation of the may occur. All these changes may have a negative impact on the product performance. The "Infrared Vibrational Spectroscopy" and X-ray Diffraction Analysis" were selected for experimental machining and subsequent assessment of possible change in selected polymer materials

Effect of concentrated energy of laser beam on polymer material

The article deals with the area of non-conventional technologies, specifically with the effect of concentrated radiant energy on the polymer material. There was studied the laser beam and its application to two different types of polymeric materials in details. PMMA, as a representative of the amorphous polymers and POM, which is a crystalline polymer, were used for experimental cutting as they frequently applied in industrial practice. The input technological parameters were changed during machining followed by evaluation of their interaction with the concentrated radiant energy of the laser beam. The results were subjected to statistical processing. © The Authors, published by EDP Sciences, 2017.TBU in Zlin [IGA/FT/2017/002

Quantitative analysis of surface irregularities resulting from flow-induced separation of highly filled compounds

During shear flow of highly filled (about 60 vol.% powder particles) polymer melts the occurring separation of particular material components has a detrimental effect on the surface quality of the resulting parts. Currently, there is a lack of reliable simulation approaches available to optimize the processing of such rheologically complex materials as well as tools describing separation in a quantitative way. The aim of the current research is to provide an approach to analyze this phenomenon quantitatively, and compare tendency to separation as a function of material composition and/or processing parameters. In this paper, surface quality of the resulting parts is determined with a contactless scanner with a First Interface Detection testing mode in order to obtain fractal dimensions of reject/fine surface structure of the final products

Mold surface analysis after injection molding of highly filled polymeric compounds

This work deals with an impact of abrasive particles used in powder injection molding (PIM) on a surface roughnessof the tool. For this purpose, the surface of new mold cavity was compared with the same mold cavity after2 000 injection molding cycles. Processed PIM compounds contained polymeric binder with around 60 vol. % ofmetal or ceramic particles (0.1 up to 20 μm). Surface analysis was performed on cavity impressions prepared froma special silicone imprinting substance in two directions by a 3D surface scanner. Investigated parameters weresurface roughness (Ra) and roughness depth (Rz) which have an influence on flow instabilities of highly filledcompounds such as wall slip affecting the final product quality. Obtained results showed a significant wear of themold cavity which was statistically confirmed by t-test and F-test parametric methods. A greater part of the moldcavity was smoothed during injection of PIM compounds, while the surface roughness increased near the pointgate (runner system) probably due to a high injection pressure in this part of the mold. © 2016. Published by Manufacturing Technology

Multi-parameter surface-quality analysis

Recent years have been rich in the research in the field of metrology. Firstly, the research focused on contact gauges, especially on contact profilometers. Consequently, with the investigation and development of materials, it was revealed that contact profilers were not sufficient and it was necessary to focus on 3D non-contact optical profilometers and surveyors. This article describes a new method of the surface control. It is a method of surface printing using the SILOFLEX© dental silicone and the subsequent evaluation. The surface-quality control is carried out using profile geometries that are divided into two basic groups. The first group consists of contact devices and the second group consists of non-contact devices. Both of these groups can use 2D- and 3D-measurement options. Subsequently, the surface quality is assessed using the amplitude parameters specified in the standards. These parameters have to be evaluated complexly using the multi-parameter analysis. This analysis is used today by more and more companies and has become an essential part of the control. It is utilized for all the material types from the engineering industry to medicine. The article deals with a non-contact measurement method. It also shows possibilities of an evaluation using the multi-parameter analysis.TBU in Zlin [IGA/FT/2017/002]; [IGA/FT/2017/010

Modelling of a transient-temperature field in plastics during laser cutting

This article deals with the area of non-conventional technologies. It reports, in detail, on a research of a laser beam and its use on different types of polymeric materials. The topic discussed in this article is mainly the thermal transmittance after the transition of the laser beam, cutting the polymeric materials. At a small distance from the cutting edge, various structural and chemical changes can occur due to the heat transfer to the material. An influence zone arises, which can play a significant role affecting the product capabilities. To establish the affected-zone width, models of the transient-temperature field were prepared, representing the distribution of the temperature in the vicinity of the cutting edge. Temperature functions of the material properties were considered with respect to extensive dependencies of the mechanical behaviour of polymers

On the possibilities of merging additive manufacturing and powder injection molding in the production of metal parts

Purpose: This study aims to enhance merging of additive manufacturing (AM) techniques with powder injection molding (PIM). In this way, the prototypes could be 3D-printed and mass production implemented using PIM. Thus, the surface properties and mechanical performance of parts produced using powder/polymer binder feedstocks [material extrusion (MEX) and PIM] were investigated and compared with powder manufacturing based on direct metal laser sintering (DMLS). Design/methodology/approach: PIM parts were manufactured from 17-4PH stainless steel PIM-quality powder and powder intended for powder bed fusion compounded with a recently developed environmentally benign binder. Rheological data obtained at the relevant temperatures were used to set up the process parameters of injection molding. The tensile and yield strengths as well as the strain at break were determined for PIM sintered parts and compared to those produced using MEX and DMLS. Surface properties were evaluated through a 3D scanner and analyzed with advanced statistical tools. Findings: Advanced statistical analyses of the surface properties showed the proximity between the surfaces created via PIM and MEX. The tensile and yield strengths, as well as the strain at break, suggested that DMLS provides sintered samples with the highest strength and ductility; however, PIM parts made from environmentally benign feedstock may successfully compete with this manufacturing route. Originality/value: This study addresses the issues connected to the merging of two environmentally efficient processing routes. The literature survey included has shown that there is so far no study comparing AM and PIM techniques systematically on the fixed part shape and dimensions using advanced statistical tools to derive the proximity of the investigated processing routes.DKRVO, (RP/CPS/2022/003); TBU in Zlin, (IGA/FT/2021/006); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMTTBU in Zlin [IGA/FT/2021/006]; Ministry of Education, Youth and Sports of the Czech Republic - DKRVO [RP/CPS/2022/003

Mechanical properties of bulk Sylgard 184 and its extension with silicone oil

Due to its simple curing and very good mechanical properties, Sylgard 184 belongs to the most widely and frequently used silicones in many industrial applications such as microfluidics and microengineering. On top of that its mechanical properties are further controllable through the curing temperature, which may vary from ambient temperature up to 200 °C; the lower the curing temperature the lower the mechanical properties (Johnston et al. in J Micromech Microeng 24:7, 2014. 10.1088/0960-1317/24/3/035017). However, certain specialised application may require even a softer binder than the low curing temperature allows for. In this study we show that this softening can be achieved with the addition of silicone oil into the Sylgard 184 system. To this end a series of Sylgard 184 samples with varying silicone oil concentrations were prepared and tested (tensile test, rotational rheometer) in order to determine how curing temperature and silicone oil content affect mechanical properties. Curing reaction of the polymer system was found to observe 2nd order kinetics in all cases, regardless the oil concentration used. The results suggest that within the tested concentration range the silicone oil addition can be used to soften commercial silicone Sylgard 184. © 2021, The Author(s).Ministry of Education, Youth and Sports of the Czech RepublicMinistry of Education, Youth & Sports - Czech Republic [RP/CPS/2020/006]Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: RP/CPS/2020/00

Solving the issue of discriminant roughness of heterogeneous surfaces using elements of artificial intelligence

This work deals with investigative methods used for evaluation of the surface quality of selected metallic materials’ cutting plane that was created by CO2 and fiber laser machining. The surface quality expressed by Rz and Ra roughness parameters is examined depending on the sample material and the machining technology. The next part deals with the use of neural networks in the evaluation of measured data. In the last part, the measured data were statistically evaluated. Based on the conclusions of this analysis, the possibilities of using neural networks to determine the material of a given sample while knowing the roughness parameters were evaluated. The main goal of the presented paper is to demonstrate a solution capable of finding characteristic roughness values for heterogeneous surfaces. These surfaces are common in scientific as well as technical practice, and measuring their quality is challenging. This difficulty lies mainly in the fact that it is not possible to express their quality by a single statistical parameter. Thus, this paper's main aim is to demonstrate solutions using the cluster analysis methods and the hidden layer, solving the problem of discriminant and dividing the heterogeneous surface into individual zones that have characteristic parameters. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.[IGA/FT/2021/006 TBU