Drag Finishing Research Articles

The influence of the process parameters of drag finishing on the surface topography of aluminium samples

Tribofinishing techniques are superfinishing processes that enable surface roughness improvement due to the mechanical action of abrasive media. A wide variety of kinematics can be employed and these abrasive media can have various trajectories and speeds when impacting the treated surface (normal, oblique, tangential, etc.). This work focuses on the drag finishing process, and in particular on the effect of spherical abrasive media impacting normally the surface of an aluminium part (6061T6). It investigates first the influence of the initial surface roughness and the diameter of spherical media when a lubricant is used. Secondly, it analyses the effect of a chemical accelerator surrounding abrasive media and the surface. An original experimental set-up was designed to observe the evolution of various surface roughness parameters and to identify local physical and chemical mechanisms. The results show that the final surface finishing greatly depends on the size of the abrasive media, and that a chemical additive can accelerate the material removal rate and improve the roughness when compared to a lubricant.

PCD coating polishing effect on the tool wear in high-speed milling of graphite

The manufacture of molds with increasingly shorter deadlines and costs requires tool manufacturers to improve their manufacturing processes. One of the ways is improving their electrode machining, because this process will affect directly in the result of the dimensional precision and production time of the mold. The usage of graphite as raw material for electrodes is known to be highly satisfactory since the graphite has the advantage of machining faster and allowing a great variety of geometrical forms; however, its main disadvantage is that the graphite also has a high level of wearing during the machining process. The cutting-edge preparations are used in order to reduce the effects of this problem, increasing the durability of the tools. In that interest, this paper has researched the effect of edge preparations, through the polishing of the PCD coating, on the wear of tools, in milling of graphite electrodes. Therefore, experimental tests were performed with untreated and polished tools, with abrasive brushes, and by drag finishing. The tests consisted in machining electrodes with analysis of tool wear, roughness, and characterization of the tools. The findings indicate that the edge preparation results in modifications on the coating surface, reducing the roughness value by a mean of 23%, and in the case of drag finishing process, a variation of the values reduction, since this process is more reliable and reproducible. With regard to the tools’ wear, gains such as reduction of flank wear and a cutting length increase of up to 63% were noticed, in comparison with the original tools.

Influence of drag finishing parameters on the cutting edge radius of solid carbide mills

Paper deals with the cutting-edge preparation of milling tools by drag finishing. The aim of the experiment was to determine the optimal parameters of the process on a prototype device for edge preparation. The prototype device was based on a 3-axis milling centre and the drag finishing media used was Al2O3 granulating. Tools for the experiment were manufactured on a tool grinding machine Reinecker WZS 60 from the cemented carbide rod with chemical composition WC+Co (10%). After that, the tools were drag finished. Then, cutting edges radii were measured on a Zeiss SURFCOM 5000 surface and form measuring machine. The effect of process parameters such as spindle rotation speed, feed rate and time of the drag finishing on the size of the cutting-edge radius and shape was examined. The experiment design was described as well as measurement and evaluation of the output values. Purpose of the experiment and multi-criteria analysis described in this article was to determine the influence of process parameters on the cutting-edge radius sizes when drag finishing the cemented carbide mills.

Using multi-criteria analysis to evaluate the impact of drag-finishing technological parameters on the carbide tool radius

Abstract Article describes the usage of multi-criteria analysis of drag finishing in order to determine the optimal parameters of the process on a prototype device for edge preparation. The prototype device was based on a 3-axis milling center and the drag finishing media used was Al2O3 granulate. Tools for the experiment were manufactured on a tool grinding machine Reinecker WZS 60 from the cemented carbide rod. After that, the tools were drag finished. Then, cutting edges radii were measured on a Zeiss SURFCOM 5000 surface and form measuring machine. The effect of process parameters such as spindle rotation speed, feed rate and time of the drag finishing on the size of the cutting edge radius and shape was examined. The experiment design was described as well as measurement and evaluation of the output values through multi-criteria analysis in the Minitab software. The results of the multi-criteria optimization were summarized and compared. Purpose of the experiment and multi-criteria analysis described in this article was to determine the influence of process parameters on the cutting edge radius sizes when drag finishing the carbide tools – special carbide milling tools

Influence of lubrication condition on the surface integrity induced during drag finishing

Abstract Tribofinishing is one of the most popular polishing process in industry. The action of small abrasive media around parts enables to reduce significantly surface roughness and at the same time, to induce compressive residual stresses in the external surface layer. However, few scientific investigations have been made about this process. Whereas most of the previous works were focused on the effect of abrasive grains, the influence of lubrication and especially the filtering of the lubricant on the surface integrity have never been investigated before. This paper aims to study the influence of the presence of debris coming from the part and the media in the polishing process. For that purpose, rough surface parts (Ra~15 µm) have been tribofinished without and with lubrication filtering. Roughness parameters (Ra, RSm and Rsk), the offset between surface profiles and residual stresses have been compared. It is revealed that the lack of filtering leads to the presence of debris coming from the part and the media. This modifies tremendously the action of the media and prevent the surface from being polished properly. The reduction of roughness is saturated and the material is excessively deformed as a consequence of debris incrustations in the surface.

Cutting edge radius preparation

Abstract The paper deals with the cutting edge preparation of milling tools by drag finishing. The aim was to determine the influence of parameters of cutting edge preparation on the cutting edge radius size of cemented carbide milling tools. The article describes the influence of cutting edge preparation on milling process, the tool treatment, surface roughness of machined material. The cemented carbide material with chemical composition WC + Co (10%) was used for this research. The tools were manufactured on the Reinecker WZS 60 grinding machine from cemented carbide rod. The cutting edge radius size and surface roughness were measured on Zeiss SURFCOM 5000 measuring machine. Prototype machine based on Dugard EAGLE 1000 milling machine with container which contained Al203 granulate was used for the cutting edge preparation. In this experiment, spindle rotation speed, feed rate and time were varied

Effect of edge preparation technologies on cutting edge properties and tool performance

Edge preparation has gained widespread use due to its low cost and high impact. Various edge preparation methods are reported in the literature. Choice of edge preparation techniques influences the edge properties and the ensuing tool performance. The current work investigates the influence of three different edge preparation methods, brushing, drag finishing, and wet abrasive jet machining on the performance of tungsten carbide inserts during orthogonal turning. Edge preparation not only changes the geometry but also the properties of the edge. Experimental results show that a drag finished edge has the lowest edge surface roughness (Ra = 0.42 μm), while abrasive jet machining can induce 63% greater compressive residual stress than the unprepared tool. Reduction in tool wear was observed at the same stage of cutting length in the prepared edges alongside improved edge hardness. A thermomechanical finite element analysis is performed to evaluate the thermomechanical behavior of all the cutting edges. Results demonstrate that the use of prepared cutting edges enhances stress distribution and reduces the temperature. Experimental results confirm that the drag finished edge has the best overall performance out of the three edge techniques with lower cutting temperature, better stress distribution, lower cutting forces, reduced flank wear, and reduced roughness of the machined surface finish.

Developments in pre- and post-treatment of thin films and their influences on surface topography and coating adhesion strength of cutting tools

Due to the increased requirements on machining of metallic and non-metallic materials, the pre- and post-treatment of hard thin films has been an important topic in several researches in the past decade. The main improvement in tool properties by a reduction of surface inhomogeneities is reached by an additional mechanical or chemical treatment before and/or after the coating process. Especially the cleaning before coating has to be considered to reduce the amount of debris of the pre-treatment which may negatively effect surface quality after the coating process. The mainly used processes of mechanical treatment to enhance surface topography before and after coating are several machining processes such as abrasive jet machining or drag finishing. This paper introduces a novel process for the pre- and post-treatment of coated cutting tools by elastically bonded diamond grinding wheels. Both the removal rate of surface inhomogeneities, the influence of surface topography before and after coating and the influence of the initial tool surfaces regarding coating adhesion strength were investigated to underline the potential of this pre- and post-treatment. Additionally, a new method for characterizing and describing the number of coating defects and proportion area of coating defects per $${\hbox {mm}}^{2}$$ is presented.

The Influence of Surface Treatment of PVD Coating on Its Quality and Wear Resistant

The article deals with a determination of the influence of a cutting edge preparation on the quality and wear resistance of coated cutting tools. Cutting inserts made from a sintered carbide with a deposited layer of PVD coating were selected for measurement. Non-homogeneity caused by the creation of droplets arises in the application layer during the process of applying the coating by the PVD method. These droplets make the surface roughness of the PVD coating worse, increase the friction and thereby the thermal load of the cutting tool as well. Also, the droplets could be the cause of the creation and propagation of droplets in the coating and they can cause quick cutting tool wear during machining. Cutting edge preparations were suggested for the improvement of the surface integrity of deposited layers of PVD coating, namely the technology of drag finishing and abrasive jet machining. After their application, the areal surface roughness was measured on the surface of coated cutting inserts, the occurrence of droplets was tracked and the surface structure was explored. A tool-life test of cutting inserts was carried out for verification of the influence of surface treatment on the wear resistance of cutting inserts during the milling process. The cutting inserts with a layer of PVD coatings termed as samples A, B, and C were used for the tool-life test. The first sample, A, represented the coating before the application of cutting edge preparations and samples B and C were after the application of the cutting edge preparation. A carbon steel termed C45 was used for the milling process and cutting conditions were suggested. The visual control of surface of cutting inserts, intensity of wear and occurrence of thermal cracks in deposited PVD layers were the criterion for the evaluation of the individual tests.

Innovative method for cutting edge preparation with flexible diamond tools

The micro geometry of the cutting edge is of central importance for the performance of cutting tools. It influences all essential parameters in the machining process: chip formation, thermal and mechanical load on the tool and the workpiece, tool wear and the resulting workpiece quality. The effect depends on the size and shape of the cutting edge rounding. Depending on the machining process, asymmetrical roundings often show the greatest potential. In addition to increasing tool life, the quality of the surfaces produced can be improved by a specifically designed asymmetrical rounding. For edge preparation, blasting, brushing and drag finishing are used in industrial applications. However, an economic production of asymmetrical cutting edge geometries on cutting tools with complicated cutting edge geometry, such as solid carbide tools with helical cutting edge, cannot be achieved with these methods. Therefore, a novel method for preparation of the cutting edge rounding using flexible bond diamond polishing tools is introduced. Hence, the conducted research in this study analyzes the basic mechanisms and influencing factors using the new preparation method. For this purpose, polishing tests are carried out on carbide indexable inserts. The results show that the polishing tools can be used to create both asymmetrical and symmetrical roundings in an industrially relevant dimension.

The effect of post-processing operations on surface characteristics of 316L stainless steel produced by selective laser melting

Metal additive manufacturing is an emerging method to fabricate components used in the aerospace and biomedical industries. However, one of the significant challenges in this approach is the surface quality of the fabricated components. After metal additive manufacturing operations, post-processing is essential to meet the expected surface quality. This study presents the surface characteristics of as-built specimens manufactured by selective laser melting (SLM), where improvement of the surface can be achieved by post-processing operations. The post-processing operations in focus are finish machining (FM), vibratory surface finishing (VSF) and drag finishing (DF) operations. Surface topography, average surface roughness, microhardness, microstructure and XRD analysis have been carried out to examine the surface characteristics resulting from the post-processing operations. This study demonstrates that the drag finishing operation can be used for post-processing to meet the surface quality requirement of SLM manufactured parts.

Influences of Cutting Edge Microgeometry on Durability when Milling ISO S Material

This article investigated the influences of the cutting edge microgeometry on durability. Combination of cutting edge geometry, cutting conditions and the properties of the machining material all influences the cutting process. It is necessary to modify the cutting edge to increase of cutting tool life and cutting process efficiency when machining materials, which are difficult to machine, such as Inconel 718 nickel alloy. Increasing the cutting tool durability and resistance are the main goals with difficult to machine materials. The cutting edge radius is the main parameter, which is modified during the experiment described in this article. After modification of the cutting edge radius, the cutting tools are tested when milling Inconel 718. Twelve cutting tools are tested. The radii of the cutting edge of these cutting tools are 15 μm, 20 μm and 25 μm. Drag finishing and abrasive water jet are used to modify the cutting edge. The cutting tool durability was evaluated by wear measurement on the clearance surface on the cutting tool. The critical cutting tool wear was 150 μm. Linear type of wear (VBB) was measured on a Multicheck optical microscope.

Predictive Modelling of Surface Roughness for Double Vibropolishing in Trough System

Vibratory finishing is a ubiquitous surface finishing process administered to components of various functionalities. Alongside the development of more complex finishing techniques such as drag finishing and abrasive flow machining, significant progress on numerical simulation has also been achieved, e.g. computational fluid dynamics, discrete element method. Yet, search into predictive roughness modelling has been insipid. In this study, multi-variable regression and artificial neural network modelling was done using experimental data obtained from subjecting rectangular test coupons to double vibropolishing in a vibratory trough. Two regression models, i.e. exponential and power, and several Multi-Layer Perceptron (MLP) architectures were trained using experimental data, and were subsequently evaluated for generalization ability. Model selection was done by comparing the mean-absolute percentage error and r-squared values from both training and testing datasets.

Design Process Control for Improved Surface Finish of Metal Additive Manufactured Parts of Complex Build Geometry

Metal additive manufacturing (AM) is increasingly used to create complex 3D components at near net shape. However, the surface finish (SF) of the metal AM part is uneven, with surface roughness being variable over the facets of the design. Standard post-processing methods such as grinding and linishing often meet with major challenges in finishing parts of complex shape. This paper reports on research that demonstrated that mass finishing (MF) processes are able to deliver high-quality surface finishes (Ra and Sa) on AM-generated parts of a relatively complex geometry (both internal features and external facets) under select conditions. Four processes were studied in this work: stream finishing, high-energy (HE) centrifuge, drag finishing and disc finishing. Optimisation of the drag finishing process was then studied using a structured design of experiments (DOE). The effects of a range of finishing parameters were evaluated and optimal parameters and conditions were determined. The study established that the proposed method can be successfully applied in drag finishing to optimise the surface roughness in an industrial application and that it is an economical way of obtaining the maximum amount of information in a short period of time with a small number of tests. The study has also provided an important step in helping understand the requirements of MF to deliver AM-generated parts to a target quality finish and cycle time.

Influence of surface preparation on the tool life of cathodic arc PVD coated twist drills

Cutting tool micro-geometry and surface integrity have been critical aspects to be considered for successful application of PVD thin films for cutting tool life enhancement. The present study examines in detail the role of pre-coating surface preparation (micro-blasting and drag finishing) on the tool life of coated cutting tools. TiN coating was deposited on different kinds of pre-treated (Micro blasting, Edge rounding and a combination of both) HSS and WC drills using cylindrical cathodic arc deposition method. They were subsequently characterized for surface roughness (Ra), adhesion strength and machining performance on EN 24 material. Pre-coating surface roughness (developed due to pretreatment) has a major influence on the adhesion strength of the coating. A lower pre-coating surface roughness with optimized edge rounding led to higher adhesion and edge strength which in turn resulted in a notable increase in tool life. Further underlining the importance of the present study, commercial TiN coatings deposited on HSS substrates were tested. The tool life obtained in the current study prolonged the tool life by a factor of 3 in comparison to the commercially available tools in the present day market.

Influences of Holders Speed on the Cutting Edge during Drag Finishing

The article deals with the influence of the holders speed on the final radius size of the cutting edge. The reason why is investigated radius of cutting edge is that its size affects important parameters in machining process. For example, these parameters are geometrical accuracy of machined components, cutting tool life and stability of machining. Futhermore, it is forces on the cutting edge and thermal influence on the tool. In the experiment five variants are used, prepared by drag finishing. The main variable parameter is holder speed. The aim is to confirm or refute the imput idea. This idea is based on the theory, that the higher holders speed will increase the intensity of drag finishing process. The results are measured and analysed on microscope IFM G4.

Influence of Edge Preparation Parameters on the Cutting Edge in Drag Finishing

Tool edge preparation can eliminate defects and realize hone cutting edge, which can improve the quality of the workpiece surface, elevate the stability of cutting process and the tool life. In order to better investigate the edge preparation mechanism, the influence law of the edge preparation process parameters on the cutting edge is analyzed. The paper presents the single factor experiments and orthogonal experiments with the cemented carbide milling tool spindle rotation rate, edge preparation time, abrasive size and abrasive ratio in drag finishing. The edge preparation mechanism is revealed in the paper, which provides basis for the structure optimization of cutting edge contour.

Discrete Element Modelling of Drag Finishing

Drag finishing is a machining process that is used to improve the surface topology of workpieces. Workpieces are moved through a bulk of differently shaped abrasives, the so called media. Material removal is caused by the relative motion between workpiece and media. The material removal rate is mainly depending on the contact intensity between workpiece and media. Up to now there is no viable way to determine the intensity of single contacts empirically. However, a sound understanding of single contacts with respect to impact forces and velocities could greatly improve process comprehension and reduce trial and error process design efforts. For that reason the movement of media and workpiece is modelled using the Discrete Element Method (DEM). In this paper a comprehensive approach is presented covering formulation, calibration, validation and utilization of the DEM. Media is considered as an aggregation of elastic particles that are subject to contact, damping and gravitational forces causing particle movement. Geometric boundary conditions, i.e. workpiece and drag finishing bowl, are implemented as elastic facets. Contact forces are calculated according to a non-linear, simplified Hertz-Mindlin contact force model. Energy is dissipated by viscous damping and friction at contacts. Necessary parameters of the model are determined experimentally. The validation of the model's behaviour shows good agreement with experimental data. Finally the model is used to determine local contact intensities on the workpiece surface and between particles. By analysing simulated contact forces, the formation of dominant contact chains between particles is observed and investigated.

Influence of form Factor of the Cutting Edge on Tool Life during Finishing Milling

The article is focused on the influence of the cutting edge form factor, which is usually marked as K, on tool life and roughness of machined surface during finishing milling. The K factors were 0.55, 0.6, 1.6 and 2.5 and were made by drag finishing method. The tool edge rounding was 15μm. There was used a cutter head with just one indexable insert for finishing machining. The article can answer to question, if the K factor can help to increase the tool performance, because the influence of the asymmetrical form factor will be compared with symmetric form factor, it means K = 1. Tool edge was prepared by the technology of drag finishing.

Investigation of cutting edge preparation for twist drills

The edge preparation of tools increases tool performance, which has an important role in the manufacturing process. The drag finishing process has several input parameters which have an effect on the quality of the prepared tools. During this case study, the parameters of this edge preparation process were investigated and a phenomenological mathematical model was developed in order to estimate the edge radius of the examined twist drill. The calculated model created with design of experiments (DOE) is appropriate for setting the parameters of the edge preparation device in order to achieve the desired edge radius for twist drills.