Effect Of Tool Diameter Research Articles

Tool path planning of ball-end milling of free-form surfaces as a search algorithm

This paper introduces an innovative approach for generating three-axis CNC tool paths for machining free-form surfaces. The method is designed to minimize variations in the effective tool diameter, addressing a common challenge encountered when using ball-end tools for machining free-form surfaces. These surfaces exhibit varying inclinations, leading to fluctuations in the tool’s working diameter from one point to another, resulting in inconsistent cutting speeds and milling parameters despite a constant spindle speed. Consequently, the machined surface tends to lack uniformity. In contrast to conventional tool path planning techniques, the proposed method calculates the working diameter at each adjacent point and guides the tool’s movement towards the point where the smallest change in working diameter is anticipated. This approach reduces fluctuations in cutting speed and promotes the generation of a more homogeneous surface.

Evaluation of Non-Planar Tool Interaction in Milling of Shaped Surfaces Using a Copy Milling Cutter

When milling complex parts or curved surfaces, we encounter several problems that must be addressed in the production process. Various factors affect the quality and accuracy of production. The main objective of this paper was to analyse the size of the effective tool diameter when machining a shaped surface concerning the selected position, namely at the perpendicular position of the tool. At the same time, the distribution of the engagement area on the tool surface was evaluated by extracting the area content and volume data at the point of contact. This study highlights the importance of the choice of finishing strategy in a CAM system. The results showed that the tool engagement size corresponded to the extracted data describing the area and volume for each tool position with regards to the curvature of the surface. The negative deviations obtained by the scanning method were due to machining near the tool centre, which was affected by the changing effective tool diameter.

Collision-free and smooth path generation method of five-axis ball-end milling considering effective tool diameter change

Ball-end cutters are widely used in five-axis sculptured surface machining. It is desired to avoid drastic changes of rotary axis movements for improving the kinematics performance of machine tools while ensuring collision-free during five-axis machining. It cannot acquire the optimum solution when cutter orientations are first generated and then adjusted to avoid collisions. The cutter orientations should be generated and optimized in their feasible regions wholly while the computation load is usually large. Different relative postures between a ball-end cutter and workpiece during the machining process will produce different effective tool diameters of the ball-end cutter, resulting in different cutting speeds. Using a variable cutting speed along a tool path can unfavorably affect the process' technological effects (e. g. surface quality, tool life). It is desired to keep the effective tool diameter constant or at a very slightly varying value during five-axis ball-end machining. Moreover, it is also desired to make the cutting point in a high position of the ball-end cutter tool edge, increasing the effective tool diameter. A smooth and collision-free tool path generation method of five-axis ball-end machining while minimizing the effective tool diameter variation and increasing the effective tool diameter of the ball-end cutter along a tool path is proposed. Tool orientations along a tool path are generated and optimized within their feasible regions and the proposed method solves the smoothness tool path generation problem by applying sequentially for the rough and fine search spaces to reduce the computing time. The numerical examples and the machining experiment illustrate the effectiveness of the proposed method.

Effect of process parameters on formability in two-point incremental forming-machining of planar and twisted AA5083 blades

The deformation machining process (DMP) involves machining and incremental forming of thin structures. It can be applied for manufacturing products such as curved-surface blades without using 5-axis computerised numerical control machines. This work presents the effect of tool diameter and forming temperature on spring-back and dimensional accuracy of a simple fabricated part. The results of the first phase of the study are utilised to design the fabrication process of a curved surface blade. A feature-based algorithm is used to design the tool path for the forming process. The dimensional accuracy of the final product is improved through warm forming, two-point incremental forming, and extension of the bending zone to the outside of the product edges. The results show that DMP can be used to fabricate complex curved-surface workpieces with acceptable dimensional accuracy.

Experimental investigation and optimization of wall deflection and material removal rate in milling thin-wall parts

The selection of optimal process parameters is essential while machining thin-wall parts since it influences the quality of the product and affects productivity. Dimensional accuracy affects the product quality, whereas the material removal rate alters the process productivity. Therefore, the study investigated the effect of tool diameter, feed per tooth, axial and radial depth of cut on wall deflection, and material removal rate. The selected process parameters were found to significantly influence the in-process deflection and thickness deviation due to the generation of unfavorable cutting forces. Further, an increase in the material removal rate resulted in chatter, thus adversely affecting the surface quality during the final stages of machining. Considering the conflicting nature of the two performance measures, Non-dominated Sorting Genetic Algorithm-II was adopted to solve the multi-objective optimization problem. The developed model could predict the optimal combination of process variables needed to lower the in-process wall deflection and maintain a superior surface finish while maintaining a steady material removal rate.

An experimental study on geometric accuracy in hybrid incremental sheet forming

ABSTRACT In the present experimental study, influence of process parameters in hybrid incremental sheet forming (HISF) is studied. Stretch forming combined with ISF is used for forming of conical parts. Stretch forming or preforming is done in order to get the intermediate shape and thickness distribution. On the same setup final part shape is obtained using the conventional ISF process. A low cost hemispherical-ended wooden preforming tool is used for the preforming purpose. Tools used for ISF process are also hemispherical-ended in shape but having smaller diameters and are made up of stainless steel SS-305. Experiments are designed according to design of experiment (DOE) Taguchi method. Analysis of variance (ANOVA) is used to analyse the effect of process parameters namely preforming depth, tool diameter and pitch on response geometric accuracy. It is found that there is considerable effect of tool diameter on geometric accuracy of the formed part. Also, forming time is reduced considerably due to the preforming operation.

CAD/CAM interfaced algorithm reduces cutting force, roughness, and machining time in free-form milling

A ball-end cutting tool is usually chosen to mill free-form surfaces in finishing operations. The cutting speed, which is calculated considering the nominal tool diameter, reduces along the tool path, according to tool-surface contact and the effective tool diameter. This brings several drawbacks to the manufacturing process. The current work presents a new algorithm to optimize CNC codes for milling free-form surfaces by parametrizing and adjusting the spindle frequency and the feed rate, considering the tool-surface contact. The proposed algorithm introduces new values for spindle frequency (S) and for feed rate (F) at each line of the CNC code, according to the surface topography. Machining experiments show that the proposed algorithm can reduce the milling time up to 40%, as well as reduce the machining force up to 21%, compared to the ordinary CNC codes. By keeping the cutting speed and feed rate constant, the surface roughness was improved—confirmed by ANOVA analysis—due to the increased shear mechanism rather than ploughing, especially in areas where the effective tool diameter is smaller.

An Experimental Investigation on Bushing Geometrical Properties and Density in Thermal Frictional Drilling

In thermal friction drilling (TFD) operations, the geometrical dimensions of bushing shape, height and wall thickness are the most vital consequences, since these increase the connecting length and strength. In this paper, AA7075-T651 aluminum alloys with 2, 4, 6, 8, and 10 mm thicknesses were drilled with the TFD process in order to investigate density, volume ratio, and height and wall thickness of the bushings. The experiments were conducted at constant spindle speed and feed rate conditions by using High Speed Steel (HSS) conical tools of 5, 10, 15, and 20 mm in diameter. It was experimentally found that the bushing height and the wall thickness had a tendency to increase linearly with the increase in both material thickness and tool diameter. The effect of tool diameter was found to have more influence on the measurable values than the thickness of the drilled material. The density of the bushing changed trivially. Approximately 70–75 percent of the evacuated material formed the bushing shape in TFD operations.

Deciphering the deformation mechanism in single point incremental forming: experimental and numerical investigation

In the present work, deformation mechanism in single-point incremental forming (SPIF) of drawing quality steel with a fully ferritic microstructure was studied. The effect of tool diameter and vertical step size on the micromechanisms of plastic deformation in SPIF was investigated by observing changes in microstructure and lattice rotation. It was observed that the fraction of grains with {111} ‖ normal direction (ND), which constitutes the gamma fiber in BCC materials, decreased with decrease in tool diameter and vertical step size. It is known that the state of deformation in SPIF is near to plane strain with the direction of major strain being always perpendicular to tool travel direction and negligible strain parallel to tool movement direction. Microstructural evidence for this observation and also for the presence of through thickness shear (TTS) components at smaller step size and tool diameter was observed. Viscoplastic self-consistent (VPSC) simulations revealed that the activity of $$ \left\{112\right\} $$ slip system decreased in comparison to $$ \left\{110\right\} $$ slip system in the presence of TTS which manifested as the deviation from {111} ‖ ND position at smaller step size and tool diameter.

Optimization of drilling parameters for thermal bone necrosis prevention.

Bone drilling is a mandatory process in orthopedic surgery to fix the fractured bones. Excessive heat is generated due to the shear deformation of bone and friction energy during the drilling process. This paper is carried out to optimize the bone drilling parameters to prevent thermal bone necrosis. The main contribution of this work is instead of only consider the influence of rotational speed and feed rate, the effect of tool diameter and drilling hole depth are also incorporated for optimization study. Response surface methodology (RSM) was used to develop a temperature prediction model. Drilling experiments were performed using finite element software DEFORM-3D. Analysis of variance (ANOVA) was conducted to investigate the drilling parameters' effect. Desirability function in RSM was used to determine the optimum combination of drilling parameters. Results indicated that one applicable combination of drilling parameters could increase the bone temperature by less than 0.03%. To avoid thermal bone necrosis, eight reasonable combinations of drilling parameters were proposed. 3.3∘C residuals between in-vitro experiments and predicted values were demonstrated. It is envisaged that finite element simulation with RSM can simplify tedious experimental works and useful in the clinical application to avoid bone necrosis.

Effect of tool diameter in ECDM process with powder mixed electrolyte

Electro Chemical Discharge Machining (ECDM) combines the basic principles of Electro Chemical Machining (ECM) and Electro Discharge Machining (EDM) using the advantages of both the techniques to machine non-conducting, hard to machine materials like a variety of glasses, ceramics and composites. In the current paper, ECDM is carried out with powder mixed electrolyte with stales steel tool of various diameters. Output responses are measured according to MRR and ROC. From the experimental results smaller diameter tools has shown higher MRR with lower ROC.

Micromilling of Ti-6Al-4V Titanium Alloy Using Ball-end Tool

The present work experimentally investigates the characteristics of micromilling of Ti-6Al-4V workpiece using ball-end tool. Micromilling were performed using 400 ¼m ball-end milling tool with the consideration of effective tool diameter. The effective tool diameter in ball-end milling is different from flat-end milling due to variation in cutting zone with axial depth of cut which accounts actual cutting speed and feed the machining. Process input variables includes cutting speed, feed per tooth and axial depth of cut, each with three levels, whereas cutting forces and surface roughness as process responses. Response surface methodology (RSM) based quadratic regression analysis was utilized to develop the correlation between process inputs and responses. Experimental results of present study on micromilling of Ti-6Al-4V using ball-end tool showed that axial depth of cut and feed per tooth could significantly influence the cutting forces and surface roughness. However, present study shows cutting speed has least effect on process responses. Finally, suitable set of process variables were proposed based multi objective optimization approach to obtain minimum cutting forces and surface roughness which were also validated with conformation test results.

The influence of tool-surface contact on tool life and surface roughness when milling free-form geometries in hardened steel

Machining process planning for milling hard materials with free-form surfaces using a ball nose end mill still requires empirical determination of the machining parameters, which can limit the efficiency of the process, reduce tool life, and adversely affect workpiece surface quality. Milling free-form surfaces differs from ordinary milling because the tool-surface contact changes constantly, causing the cutting speed to vary from the programmed value (in regions where the tool touches the surface with its nominal diameter and the tool axis is parallel to the surface) to zero (in regions where the center of the tool tip cuts the material and the tool axis is almost perpendicular to the surface at the point of contact). This paper focuses on this issue and investigates the influence of effective cutting speed and tool-surface contact on tool wear and surface roughness. High-speed milling experiments were carried out in which convex circular surfaces of hardened D6 steel were machined with a ball nose end mill keeping the effective tool diameter along the tool’s circular trajectory constant in each experiment. The input variables were the lead angle (and consequently the effective tool diameter, which was kept constant in each experiment but varied from one experiment to another) and feed direction (ascendant and descendant). As the effective tool diameter increased from one experiment to another, the feed rate decreased. The results show, in contrast to other findings in the literature, that contact between the center of the tool tip and the workpiece can increase tool life and reduce roughness when milling free-form surfaces in hardened steels. Furthermore, machining time is reduced as the smaller effective tool diameter leads to a higher feed rate. A relationship was also observed between the axial machining force and process stability when the tool tip is involved in the cutting process.

Experimental force modeling for deformation machining stretching mode for aluminum alloys

Deformation machining is a hybrid process that combines two manufacturing processes—thin structure machining and single-point incremental forming. This process enables the creation of complex structures and geometries, which would be rather difficult or sometimes impossible to manufacture. A comprehensive experimental study of forces induced in deformation machining stretching mode has been performed in the present work. A table-type force dynamometer has been used to record the deforming forces in three Cartesian directions. The influence of five process parameters—floor thickness, tool diameter, wall angle, incremental step size, and floor size on the deforming forces—is investigated. Individual as well as combined empirical models of the parameters with regard to the forces have been formed. The results of this study indicate that the average resultant force primarily depends on the floor thickness to be deformed and the incremental depth in the tool path. This could be due to the variation in local stiffness of the sheet with change in floor thickness. The effect of tool diameter, deforming wall angle, and floor size is not significant.

<i>In Situ</i> Topology Measurement of Micro Structured Surfaces with a Confocal Chromatic Sensor on a Desktop Sized Machine Tool

In this research a confocal chromatic point sensor was implemented in a desktop sized machine tool. The sensor was used to detect the surface in z-direction. Data from the machine control of the x- and y-axes is extracted and combined with the z- information of the sensor to directly scan surfaces. With the presented sensor, micro structures as small as 5 μm can be characterized. Based on the possibilities of this measuring system, face milling before the actual micro machining can be avoided by determining tilts and waviness of the workpiece. Also the effective tool diameter can be determined and compensated. After machining, the structure can be measured for quality control. Based on this measurement system, a micro machining process was developed broadening the potential for the use of desktop sized machine tools.

An experimental study on the influence of tool path, tool diameter and pitch in single point incremental forming (SPIF)

Incremental forming process has become more and more popular because of its ease of forming and capability to produce different part shapes using same machine set-up. This article describes an experimental study on the influence of process parameters in single point incremental forming (SPIF) on the surface roughness and thickness of formed part. Experiments are performed on aluminium alloy (Al-1050) sheet on a 3-axis CNC milling machine. Hemispherical-headed tool of stainless steel (SS-304) is used to study the effect of tool path, tool diameter and pitch on the surface roughness (Ra) and thickness (t) of formed part. Design of experiment (DOE) full factorial plan is used, and results are plotted using ANOVA. Considerable effect of tool diameter is found on the surface quality of formed part.

Optimizing tool diameter for friction stir welded brass/steel lap joint

A 3.0-mm-thickness brass plate used as a top plate, was lap jointed to a 5.0-mm-thickness structural steel bottom plate by friction stir welding. Five kinds of tools with different probe and shoulder diameters were used in this study. The effect of tool diameter on microstructure and mechanical properties of the joints was studied. Grain size at the stirred zone, tensile shear fracture load and the tensile shear strength of the joints varied significantly with tool diameter. A mutual diffusion zone of dominant elements of each plate was found at the joint interface.

Research on Tool Wear of PCD Micro End Mill in Machining of ZrO<sub>2</sub> Ceramics

This paper presents a study on the tool wear of micro PCD end mill when machining ZrO2 ceramics. The cutting tool used was a self-designed PCD micro end mill with 1 mm in diameter and single flute. Experiments were conducted on a self-developed micro-milling machine tool. The tool wear characters and progress during the groove milling has been observed. The cutting force and machining accuracy of the grooves also have been studied. Based on the results, it is found that tool wear is mainly on the bottom surface; the cutting force increases with the progress of tool wear; tool wear also affect the width of machined grooves due to the decrease of effective tool diameter.

Influences of the tool path strategy on the machining force when milling free form geometries with a ball-end cutting tool

Milling of free form geometries is an usual machining operation in dies and moulds industry. A ball-end cutting tool is frequently used because its geometry allows the finishing and semi-finishing milling operations of any complex shape. However, unlike the ordinary milling machining, the tool-surface contact alternates constantly what makes the process unstable. Due to the geometrical characteristics of this process, the value of the effective tool diameter depends on the depth of cut and the surface curvature, which alters the lead angle (angle formed between tool axis and surface normal direction). The effective tool diameter alternates constantly along the machining. Moreover, it can be zero when the tool is using its centre to remove material, what makes the cutting speed null. A preview work has shown the severe alteration on the Cartesian components of the machining force when milling free form geometries. Such force oscillation is still not predictable by the up methods, and its cutting phenomenon is still not clear. The current work aims to quantify the influences of the lead angle and the engagement of the tool tip centre into the cutting region, which may lead to improvements on the choice of milling strategy in machining research and application. To do so, the machining force and its Cartesian components were investigated according to the process variables, such as: (1) tool path direction, (2) cutting way, (3) cutting speed, and (4) tool-surface contact (lead angle); when milling free form geometries with a ball-end cutting tool. Geometrical analyses together with milling experiments were carried out. The results show that the tool-surface contact had the greatest impact on the forces, because it can either be related to the effective tool diameter or with the tool tip on the cutting zone. In this area, the material is removed part by shearing and part by ploughing (plastic deformation), which increases the forces. The ascendant feed direction propitiates more stable process than its counterpart, and the cutting speed had also an influence on the forces, regardless the contact between the tools with the machined surface.

Experimental Study on the High Speed Machining of Hardened Steel

In the present paper, experimental study is made to investigate the effect of cutting parameters on surface roughness in dry high speed milling of hardened tool steel using two cutting tools (diameter of 20 and 40mm). The cutting parameters considered include cutting speed and feed per tooth. Experiments are conducted in up-cut and down-cut milling. Based on the experimental data, the effect of tool diameter on the surface roughness is analyzed. The good surface roughness can be achieved in high speed machining of examined steel but rapidly tool wear is observed.