Ball End Research Articles

Effect of polishing fluid composition on forces in ball end magnetorheological finishing process

Ball end magnetorheological finishing is a nanofinishing process that uses magnetorheological polishing (MRP) fluid containing carbonyl iron particles (CIPs) and polishing grade abrasives to remove materials from the workpiece surface. The composition of the MRP fluid greatly influences the finishing forces. Using a dynamometer both normal and shear forces applied by the MRP are recorded on-line. A central composite design of experiments is used to plan the experiments and ANOVA to correlate these forces and process parameters. The process parameters selected here are vol.% of CIPs and vol.% of abrasives which are varied from 5% to 25% and 5% to 20% respectively to measure the forces during experimentation. Both normal and shear forces increase with increase in the CIPs content in the fluid. In case of abrasive concentration, it is observed that the forces initially increase with increase in abrasive content but begins to decline after a certain point.

Research on Grinding of Micro Ball End Mill with Equal Normal Rake Angle and Equal Radial Relief Angle

Research on Grinding of Micro Ball End Mill with Equal Normal Rake Angle and Equal Radial Relief Angle

Advanced process design for re-contouring using a time-domain dynamic material removal simulation

The repair of components often requires the removal of excess weld material. This removal is considered as re-contouring. Re-contouring processes have to be designed individually for each case of damage to fulfil the high quality requirements. Therefore, a prognosis of the machined surface topography is crucial. The material removal simulation introduced in this paper allows the prediction of process stability and surface topography for 5-axis ball end milling including dynamic effects. Different process strategies for re-contouring of Ti-6Al-4V welds are examined. It is shown, that selecting suitable process parameters can lead to high surface quality while maintaining productivity.

Effect of cutting edge micro geometry on surface generation in ball end milling

Surface generation in machining processes is affected by a complex interaction between cutting edge and workpiece material, leading to surface artefacts, so that the surface topography deviates considerably from the kinematic one. This paper shows how to model such interaction, taking into account cutting edge topography, material deformation and cutting edge trajectory errors to achieve a reliable prediction of surface topography generation in ball end milling. The model is experimentally validated in upward raster ball end milling of copper and tool steel.

Influence of tool variables on wear when milling iron aluminide alloy Fe25Al1.5Ta [at.-%

Non-ferrous high-performance materials such as titanium- and nickel-base alloys are of great importance for the aerospace industry due to their advantageous properties. However, the high material prices of these alloys are a disadvantage. At the same time, iron aluminide alloys can feature similar mechanical and thermal properties combined with a significant economic advantage over other high-performance alloys. Thus, iron aluminides present a promising alternative to high priced non-ferrous alloys and have the potential to substitute established materials for components such as turbine blades.In aerospace part production, milling represents an important finishing process. Iron aluminides are considered difficult to cut materials. Therefore, occurring tool wear and its mechanisms are the primary issues in machining. These topics are not yet covered in depth by the prevailing knowledge base. In this paper, near-net-shape cast iron aluminide cross-samples were machined using ball end milling cutters to analyze the occurring tool wear and the performance of different milling tool systems. The results show a fundamental influence of the tungsten carbide substrate and the tool coating on tool wear when milling iron aluminide. The tools’ macro and micro geometry affect the active forces and stabilize the cutting edge. The present study provides insights about preferable tool variables that contribute to extending tool life in iron aluminide turbine blade production.

Prospects for using T-splines for the development of the STEP-NC-based manufacturing of freeform surfaces

For successful development of the intelligent manufacturing of freeform surfaces using STEP-CNC with online toolpath generation capability, it is required to make a choice of the optimal representation of a 3D model which will be used for machining. Traditionally, most existing CAD-CAM systems use NURBS to design freeform surfaces and to perform toolpath generation in order to machine them. The introduction of T-splines to CAD systems and some reported results of using them in manufacturing makes it possible to consider T-splines, or more generally T-NURCCs (Non-Uniform Rational Catmull-Clark Surfaces with T-junctions), as a good solution for the development of the STEP-NC-based manufacturing of freeform surfaces because of their advantages over NURBS. Therefore, this paper gives an overview of the main arguments in favor of choosing the T-spline surface representation for integration within STEP-CNC systems. We examine the prospects for T-splines to become an integral part of modern manufacturing systems, and highlight some important properties of T-splines which are the most beneficial for manufacturing processes. The paper presents the results of the development of a complete T-spline-enabled STEP-CNC system which can strategically support online toolpath generation for three-axis ball end machining of simple T-spline surfaces using four different freeform strategies defined in ISO 14649-11. These results represent the implementation of the first stage of the development process of intelligent STEP-CNC systems, and in the future more research is needed in this direction.

Ball End Mill with Curved Cutting Edge and Constant Cutting Geometry

A design method is proposed for a ball end mill with constant inclination of the cutting edge to the spherical section. The tooth profile specified in the normal cross section is the generatrix, while the curved cutting edge at the sphere in the form of a loxodrome is the directrix.

Selection of Surfaces for Endurance Tests of Ball End Mills

Selection of Surfaces for Endurance Tests of Ball End Mills

Tool design and cutting parameter optimization for side milling blisk

As the core component of the aircraft engine, high-efficiency manufacture of blisk is very difficult, because of its complex structure, high precision, and whose material belonging to difficult-to-machine materials such as titanium alloy, high temperature alloy and so on. It is one of the effective methods to solve the above problems by applying the side milling technology to the manufacture of blisk; the design and manufacture of ball end milling tool and the optimization of cutting parameters are of great significance to the advantage of the side milling process. Firstly, by analyzing the sectional line of tool, the mathematic models of tool edge line and tool escape curve are established. Based on these models, the parameterized model of the tool is finished, which paves the way for the subsequent analysis and optimization of the tool. After optimization, it is found that the ball end milling tool with a rake angle of 10°, a first rear angle of 12°, and a spiral angle of 38° has the best cutting effect on titanium alloy; secondly, the finite element method is used to design and analyze the geometrical structure of tool, and the modal analysis of the tool is carried out by DEFORM-3D to ensure the stability of cutting process, and the designed tool was manufactured by using the tool grinder; finally, the experimental research on the side milling titanium alloy was carried out by using the manufactured tool, and the influence of cutting parameters on the cutting force and the surface roughness was analyzed, and the model of cutting force and surface roughness and machining efficiency is completed. Based on the NSGA-II algorithm, the multi-objective optimization of the cutting parameters with cutting force, surface roughness, and metal removal rate as index is completed; the optimized results are as follows: vc = 70.2 m/min, fz = 0.03 mm/z, ae = 0.7 mm, and the axial depth is ap = 7.6 mm. This set of cutting parameters can guarantee small surface roughness and high machining efficiency under the condition of small cutting force, which is expected to provide a better theoretical reference and technical support for the tool design and high efficient manufacture of blisk.

Evaluation of machinability in milling by controlling chip thickness using NC simulation

In this study, the machinability of the machining method for controlling chip thickness during the cutting operation was evaluated using simulation based on NC data. A comparative three-dimensional cutting test with a ball end mill was performed using both original and modified NC data. The modified NC data was created for the purpose of controlling the chip thickness generated when cutting with a constant rotation value and changing the feed rate of the original NC data. The results indicated that the actual chip thickness exceeded that of the calculated value although the thickness fluctuation was suppressed. The results revealed that the maximum cutting force and the fluctuation range of cutting force were low, and tool wear after cutting was suppressed using the modified NC data. The application of the method to the cutting of complicated shapes with high removing volume led to reductions in the cutting time by 31 %.

Power consumption optimization strategy in micro ball-end milling of D2 steel via TLBO coupled with 3D FEM simulation

The present challenge in the manufacturing industry is to improve efficiency of production activities while reducing wastage of power consumption. Past research focused on multi response optimization of process parameters to improve performance of the process. The present study proposed an optimization-based strategy to reduce power consumption in micro ball end milling of D2 steel. As the power consumption is directly proportional to cutting forces, the process parameters such as cutting speed, feed and depth of cut were optimized to reduce cutting forces using teaching learning based optimization (TLBO) technique coupled with 3D finite element method (FEM) simulation. During the optimization, amplitude of cutter vibration and surface roughness were taken as constraints as 60 µm (ISO 10816) and 2 µm (ISO 1302) respectively. Three best combinations of cutting speed, feed and depth of cut were obtained for minimum cutting force. Among them, combination of cutting speed of 15 m/min, feed of 112.5 µm/tooth and depth of cut of 85.25 µm has low power consumption of 67 W with tool vibration of 36.5 µm. However, remaining two combinations were also considered to be the next best optimal cutting conditions. Numerical simulation was carried out for the three best solutions and the cutting forces and amplitude of cutter vibration were predicted. There was good agreement between simulation results and experimental results that verified the acceptance of the simulation. It was also found that the three best candidate solutions were having same the cutting speed of 15 m/min (minimum cutting speed). Hence, the induced stresses in the work piece were found to be with low values around 350 Mpa.

Experimental and theoretical investigation on cutting forces in off-centre micro ball end milling

Free-form surfaces and micro features are finish machined by a micro ball end mill by removing steps left behind by flat end mill in the previous operation. For effective machining, off-centre ball end milling is employed in such a way that rubbing zone near ball tip is avoided. After confirming the limits of angular immersion from full-slot experimental results, both down and up off-centre milling experiments are conducted on edges of steps created on a test piece. The micro milling forces in off-centre mode are also investigated theoretically using a mechanistic model that considers the geometry of micro ball end mill and basic mechanics of cutting. The amplitudes of predicted forces match well with experimental values and the deviations in the experimental values arise out of micro level unevenness in the step edge. The up milling with lower transverse force is found to be more suitable for machining of thin features.

Closed Loop Ball End Magnetorheological Finishing Using In-situ Roughness Metrology

Ball end magneto rheological finishing (BEMRF) is a recently developed advanced finishing process. Over the past decade the analytical and qualitative research has been established on various materials with this process. No work is done to automate the BEMRF process; this research work first establishes a time based reduction in roughness for the surfaces in BEMRF process. Suitable machining parameter sets are found for optimum time based finishing, a parameter selection algorithm is developed to select the next best parameter set to achieve maximum ΔRa in the next finishing cycle. A dedicated NC part program controls the operation of BEMRF process automatically. An in-situ roughness measurement system is used to get the roughness feedback after every finishing cycle to determine the initial Ra for next finishing cycle. Using the NC part program and developed algorithm the closed loop implementation of BEMRF process is carried out. Using closed loop finishing roughness parameter Ra from 800 nm range is brought down to 60 nm range in finishing time of 200 min, the same roughness reduction is achieved in 360 min of finishing time if finishing is carried out using individual parameter set. Thus by implementing closed loop finishing the optimum time for roughness reduction is achieved while conducting the whole process automatically.

Nanofinishing of FDM-fabricated components using ball end magnetorheological finishing process

ABSTRACTFused deposition modeling (FDM) is among the extensively used and the most economical additive manufacturing processes. Currently, the surface finish obtained for FDM additive manufactured parts are not at par with the current industrial application. To overcome the limitation of high surface roughness of 3D printed parts, a novel finishing technique has been proposed which includes primary and secondary finishing processes. While facing and lapping has been used as primary finishing technique, the secondary finishing involves the use of ball end magnetorheological finishing (BEMRF) process. BEMRF process is an unconventional finishing process which utilizes an advanced approach to impart finish on magnetic as well as non-magnetic materials that may be flat or freeform in shape. This article presents the experimental and analytical study to finish a polylactic acid (PLA) workpiece material manufactured by FDM process and finished using the BEMRF technique. The surface roughness of the FDM component has been reduced from initial surface roughness Ra = 20 µm to final value of Ra = 81 nm by combined primary and secondary finishing processes. The effect of magnetorheological polishing (MRP) fluid’s composition and finishing time is discussed and is followed by optimization of MRP fluid for maximum percentage reduction in surface roughness.

Machinability of Thermo-Plastic Carbon Fiber Reinforced Plastic in Inclined Planetary Motion Milling

The study deals with an improved method of milling thermo-plastic CFRP with a radius end mill. The authors use inclined planetary milling to carry out a fine CFRP boring technique. The inclined planetary motion milling consists of the two independent spindle motions of tool rotation and revolution. The eccentricity of the tool rotation axis is realized by a few degrees of inclination from the revolution axis. The movement of eccentric mechanism can be reduced by comparing it with that of orbital drilling. The inclined planetary motion milling reduces inertial vibration and decreases cutting force. Owing to the geometrical cutting principle, material delamination and burrs can be decreased. Thermo-plastic CFRP has recently been under development as an alternative structural material for the next generation of automobiles and in response to demands for bored fastening holes. The shape of the cutting edge of the ball end mill is suitable for the inclined planetary milling, as revealed by results of past experiments done on thermo-set CFRP. However, the ball end mill has left burrs and melted matrix on the exit side in the case of thermo-plastic CFRP. The radius end mill has the advantage over the ball end mill in terms of finishing fine boring. Based on the consideration of the schematic model and experiments using the Taguchi method, the improved milling conditions are examined.

Wiarygodność pomiaru mikroskopowego geometrii frezu kulistego oraz jej wpływ na nierówności powierzchni po frezowaniu kopiowym

New ball end mills in various lighting conditions were examined and detailed 3D models were obtained. Differences in the geometry of the tool tip resulted in a surface with drastically different parameters. The effect of the edge break was observed. The obtained 3D models were used to create a map of the material loss on the cutting edge of cutting tool.

Direction of chip flow for milling of shaped surfaces by ball end mill

There investigated the direction of chip flow on the front surface by machining with non-cylindrical original instrumental surface end mills.

Methodology for optimizing cutting parameters on milling process

Obtaining a better surface roughness with less time and energy consumption is an essential consideration in machining today. Choosing the right strategy for finishing milling is a difficult task to achieve when milling complex surfaces. It is essential to improve production rate and cutting quality. This paper presents a way to optimize the milling process based on the tool path trajectory type for inclined or complex surfaces machined with a ball end mill. In this case the speeds and feeds differ because the depth of cut changes according with the effective diameter for a ball nose mill. The research is based on several steps: the cutting regime is calculated with the classic formulas, then the part is machined and the quality of the resulting part is analysed by roughness measurement; a correction coefficient is calculated and the feederate is adjusted. The procedure is resumed and the tool setup is done, the part is machined and time, roughness and length of the trajectory are measured in order to validate the correction coefficient

Study on metrological relations between instant tool displacements and surface roughness during precise ball end milling

The study presents an analysis of relations between the instantaneous tool displacements and surface roughness formed during ball end milling of surface with inclination towards the tool’s axis. A novel experimental method for the estimation of ball end mill’s working part vibrations, considering displacements correlated with the geometrical errors of tool-toolholder-spindle system and deflections caused by milling forces has been proposed. The experiments have been conducted on hard-to-cut low carbon hardened alloy steel. Milling tests involved the use of monolithic ball end mills varied in terms of overhang l values. In the first stage, the finishing machining of inclined surface with variable cutting speeds vc was carried out. During the experiment, the instantaneous tool’s joining part displacements have been measured with the application of laser displacements sensor. Subsequently, in order to obtain the tool’s tip instantaneous displacements, the analytical extrapolation method has been proposed. In the next stage, the machined surface roughness has been measured with the application of stylus and optical profile meters. The investigations show that the value of tool’s overhang significantly affects the mechanisms of surface roughness generation during finishing ball end milling. In case of milling with the rigid tool (l = 35 mm), the surface roughness is strongly correlated with kinematic-geometric model, as well as with geometrical errors of machining system. Nevertheless, in case of milling with the slender tool (l = 85 mm), the surface roughness formation is mainly affected by the tool’s working part dynamic deflections caused by milling forces.

A new approach for predicting wear overlap geometry in ball end finish milling

The inclination angles of sculptured surface and tilting angles of 5-axis machining change cutting time distributions (CTD) on cutting contact (CC) points. The models of element wear (EW) function of the CTD on each CC points are overlapped to form wear overlap (WO) geometry. However, the WO geometry has not been taken into account in most current tool wear models. This paper proposes a new approach for modeling of the WO geometry associated with the overlapping zones in the 5-axis machining of sculptured surfaces. The EWs in response to CTD at each CC points are modeled using probability density function. The EW is changed to the linear function of time by deforming the tool wear unit. Afterward, for each overlapping point, the WO value is calculated by using the method of the linear addition of linearized EWs. Then, the WO geometry is obtained by the inverse deformation of the unit. The proposed approach is demonstrated and validated through a case study. The predictions of WO geometry present good accordance with experimental observations in constant tilting angle and flat convex surface finish milling process.