Ball Nose Research Articles

Determination on the Effect of Cutter Geometrical Feature for Machining Polyetheretherketone (PEEK) Using Taguchi Methods

This paper details the application of Taguchi method to determine the effect of cutter geometrical features for machining Polyetheretherketones (PEEK) thermoplastic. The planned experiment was conducted by using Taguchi’s orthogonal array taking into account the ball nose geometrical parameters such as helix angle, rake angle, clearance angle and number of flute. The measured response is the machined surface roughness, which is important for the component functionality. In addition, ANOVA was used to validate the percentage contribution of each factor. The obtained results reveals that, less number of flutes is the main factor contributed towards fine surface roughness for this thermoplastic. Fewer flutes provide a smooth flow of chip ejection and minimize the friction on the cutting zone which is vital for polymeric material such as PEEK. High helix and rake angles also influence the machined surface roughness as both angles provide optimum shearing force to produced better surface finishing. However, it is found that clearance angle is less significant on roughness since the function of clearance angle is to control the process damping and stability. The main conclusion of this study is that there is significant effect on the cutter geometrical feature on machining performance and thus conclude the need of special design cutter for effectively machining PEEK plastic.

The Tool Life of Ball Nose end Mill Depending on the Different Types of Ramping

Abstract The article deals with the cutting tool wear measurement process and tool life of ball nose end mill depending on upward ramping and downward ramping. The aim was to determine and compare the wear (tool life) of ball nose end mill for different types of copy milling operations, as well as to specify particular steps of the measurement process. In addition, we examined and observed cutter contact areas of ball nose end mill with machined material. For tool life test, DMG DMU 85 monoBLOCK 5-axis CNC milling machine was used. In the experiment, cutting speed, feed rate, axial depth of cut and radial depth of cut were not changed. The cutting tool wear was measured on Zoller Genius 3s universal measuring machine. The results show different tool life of ball nose end mills depending on the copy milling strategy.

Multi-Objective Optimization Using Box-Behken of Response Surface Methodology for High-Speed Machining of Inconel 718

This study was carried out to investigate how the high-speed milling of Inconel 718 using ball nose end mill could enhance the productivity and quality of the finish parts. The experimental work was carried out through Response Surface Methodology via Box-Behnken design. The effect of prominent milling parameters, namely cutting speed, feed rate, depth of cut (DOC), and width of cut (WOC) were studied to evaluate their effects on tool life, surface roughness and cutting force. In this study, the cutting speed, feed rate, DOC, and WOC were in the range of 100 - 140 m/min, 0.1 - 0.2 mm/tooth, 0.5 - 1.0 mm and 0.2 - 1.8 mm, respectively. In order to reduce the effect of heat generated during the high speed milling operation, minimum quantity lubrication of 50 ml/hr was used. The effect of input factors on the responds was identified by mean of ANOVA. The response of tool life, surface roughness and cutting force together with calculated material removal rate were then simultaneously optimized and further described by perturbation graph. Interaction between WOC with other factors was found to be the most dominating factor of all responds. The optimum cutting parameter which obtained the longest tool life of 60 mins, minimum surface roughness of 0.262 μm and resultant force of 221 N was at cutting speed of 100 m/min, feed rate of 0.15 mm/tooth, DOC 0.5 m and WOC 0.66 mm.

A Review of the Main Modeling Methods for Ball Nose End Milling Processes

The ball nose end mills are highly used for complex sculptured surfaces in 3-5 axes milling. The modeling of the cutting process using ball nose end mills is more complex than in the case of simple end mills due to the fact that the cutting speed varies continuously along the cutting edge. By tilting the cutting tool relative to the surface to be machined, the modeling is getting more complicated due to the large number of input variables. This paper presents a review of the main modeling types, underlining the specificity, the advantages and disadvantages for each type in comparison to an own research on a parametric CAD model. There are also recommendations made towards the modeling process, based on the results obtained by the authors.

Machining of Injection Mould Materials for Different Cutting Flute in Low-Speed End Milling

The complexity of mould shapes and the hardness of the mould material contribute to difficulties in machining. Examination of the capability of atypeof cutting tool (Tungsten Carbide Ball Nose) towards machining mould material that is usually used in Injection Moulding Industries. Following this, an experimental work was detailed relating to the use of ball nose end mill to machine hardened injection mould materials (up to 62 HRC).Surface roughness, surface topography and tool wear data were presented. The relationships of all these three properties respect to each other were also investigated. By machining these materials (Stavax, Stainless Steel, DF3 and XW5), a major wear occur on cutting tool which is called flank wear. Theflank wear is increased by increasing the hardness of the material used. This fact was supported by the result obtained, in which the surface roughness increases when the material hardness increased. Surface topography isdescribed through wavy marks and surface tearing. For 2 and 4-flute cutting tools, the waviness phenomenal ondecreases when material hardness was increased. Meanwhile, for surface tearing, the rate of occurrence is proportional to the increment of the material hardness.

Tribological Characterization of the Cutting Zone in Milling Nickel Based Alloy

In the area of tribology, surface roughness has become one of the most important factors that contributed to the evaluation of part quality during machining operation. In order to understand the behavior of cryogenic cooling assistance in machining Inconel 718, this paper aims to provide better understanding of tribological characterization of liquid nitrogen near the cutting zone of this material in milling process. Experiments were performed using physical vapor deposition (PVD) - coated carbide inserts under cryogenic and dry cutting condition. The cryogenic results of the cutting temperature, cutting forces and surface roughness of the ball nose cutting tool have been compared with those of dry machining. Finally, experimental results proved that cryogenic implementation can decrease the amount of heat transferred to the tool up to almost 70% and improve the surface roughness to a maximum of 31% when compared with dry machining.

Mechanism investigation of friction-related effects in single point incremental forming using a developed oblique roller-ball tool

Single point incremental forming (SPIF) is a highly versatile and flexible process for rapid manufacturing of complex sheet metal parts. In the SPIF process, a ball nose tool moves along a predefined tool path to form the sheet to desired shapes. Due to its unique ability in local deformation of sheet metal, the friction condition between the tool and sheet plays a significant role in material deformation. The effects of friction on surface finish, forming load, material deformation and formability are studied using a newly developed oblique roller ball (ORB) tool. Four grades of aluminum sheet including AA1100, AA2024, AA5052 and AA6111 are employed in the experiments. The material deformation under both the ORB tool and conventional rigid tool are studied by drilling a small hole in the sheet. The experimental results suggest that by reducing the friction resistance using the ORB tool, better surface quality, reduced forming load, smaller through-the-thickness-shear and higher formability can be achieved. To obtain a better understanding of the frictional effect, an analytical model is developed based on the analysis of the stress state in the SPIF deformation zone. Using the developed model, an explicit relationship between the stress state and forming parameters is established. The experimental observations are in good agreement with the developed model. The model can also be used to explain two contrary effects of friction and corresponding through-the-thickness-shear: increase of friction would potentially enhance the forming stability and suppress the necking; however, increase of friction would also increase the stress triaxiality and decrease the formability. The final role of the friction effect depends on the significance of each effect in SPIF process.

Application of Magnetic Polishing With Ball Nose Shaped Tool for Microchannel Shape

In recent years, high quality and accuracy surface are needed for the microchannels such as to be used as micro-total analysis systems (micro-TAS) chips. On the other hand, we demonstrated that the use of smaller size machine tools is one of the effective methods to improve the environmental impact in small parts manufacturing fields. Then, in the present report, we focus on magnetic polishing for microchannels with a ball nose shaped tool, integrating end milling, and polishing processes with a desktop-sized machine tool. In the case of nonmagnetic material, the method had an effective for the bottom of microchannels.

Micro-milling performance of AISI 304 stainless steel using Taguchi method and fuzzy logic modelling

In this study, micro-milling of AISI 304 stainless steel with ball nose end mill was conducted using Taguchi method. The influences of spindle speed, feed rate and depth of cut on tool wear, cutting forces and surface roughness were examined. Taguchi's signal to noise ratio was utilized to optimize the output responses. The influence of control parameters on output responses was determined by analysis of variance. In this study, the models describing the relationship between the independent variables and the dependent variables were also established by using regression and fuzzy logic. Efficiency of both models was determined by analyzing correlation coefficients and by comparing with experimental values. The results showed that both regression and fuzzy logic modelling could be efficiently utilized for the prediction of tool wear, cutting forces and surface roughness in micro-milling of AISI 304 stainless steel.

Cutting speed modelling in ball nose milling applications

Cutting speed is a key factor that influences machined surface quality and tool life in milling. To date, the study of its distribution over a machined surface has not been established. This paper presents a mathematical model to evaluate cutting speed on the machined surface in 3-axis ball nose milling. The approximation errors introduced by surface shape, step-over and CNC interpolation are analysed. The model is used to predict visible areas which have different colour intensities on finished surfaces in the machining of a wood-plastic composite. A good agreement is obtained between the prediction and experimental results.

Investigation on Wear Behavior and Chip Formation During Up-Milling and Down-Milling Operations for Inconel 718

A comprehensive study and FEM simulation of ball nose end milling on tool wear behavior and chip formation had been performed on Inconel 718 (nickle-based superalloy) under minimum quantity lubricant (MQL) condition. In this paper, the investigation was focusing on the comparison of up-milling and down-milling operations using a multi-layer TiAlN/AlCrN-coated carbide inserts. A various cutting parameters; depth of cut, feed rate and cutting speed were considered during the evaluation. The experimental results showed that down-milling operation has better results in terms of tool wear compared to up-milling operation. Chipping on cutting tool edge responsible to notch wear with prolong machining. It was observed that the chips formed in up-milling operation were segmented and continuous, meanwhile down-milling operation produced discontinuous type of chips.

The Wear Measurement Process of Ball Nose end Mill in the Copy Milling Operations

The article deals with tool wear and the cutting tool wear measurement process of ball nose end mill in the copy milling. In the experiment, we studied cutting tool wear for different types of copy milling operations. The aim was to determine and compare the wear of ball nose end mill for upward ramping and downward ramping, as well as to specify particular steps of the measurement process. In addition, we examined and observed cutter contact areas of ball nose end mill with machined material. In this article, equations for the calculation of parameters of a hemispherical milling cutter are described. The machining strategy was applied to copy milling process for mould milling. For mould milling, DMG DMU 85 monoBLOCK 5-axis CNC milling machine was used. In the experiment, the cutting tool, cutting speed and cutting feed were not changed. The cutting tool wear was measured on Zoller Genius 3s universal measuring machine. The results show different cutting tool wear depending on the copy milling strategy.

2315 Too life assessment of untreated and aged hardening Inconel 718 during end milling

This article presents the tool life study of two different grades of Inconel 718. Tool life of ball nose cutting tools were investigated by considering the numerical parameters of cutting speed, feed rate, depth of cut and width of cut. The categorical factor is material grade. Two sets of different cutting parameters that were previously using design of experiment (DOE) approaches were combined and analysed using historical data of response surface methodology (RSM). This method can be used to determine the dominant factors to identify the interaction between cutting parameter and tool life. ANOVA result shows that the type of material with different grade is not significant in contributing to tool life compared to width of cut, cutting speed, feed rate, and depth of cut. The best combination for untreated Inconel 718 is Vc = 102 m/min, fz = 0.11 mm/tooth, ap = 0.52 mm and ae = 0.28 mm in order to obtain predicted too life of 127 min, whereas the best combination of double aging is Vc = 114 m/min, fz 0.11 mm/tooth, ap 0.61 and ae 0.21 to obtain 113 min of tool life. The study shows that Historical Data method is suitable for finding the optimization condition from different DOE approaches.

Deformation Mechanism Analysis of Single Point Incremental Sheet Metal Forming

Single point incremental forming (SPIF) is a new innovative and feasible solution for the rapid prototyping and the manufacturing of small batch sheet parts. The process is carried out at room temperature and requires a CNC machining centre, a spherical headed tool and a simple support to fix the sheet being formed. In incremental Sheet Metal Forming the blank is incrementally deformed in to a desirable shape by hemispherical or ball nose tool traveling along a prescribed path. Due to the various advantages including the reduced production cost and time of prototypes, improved formability, easy modification of part design etc. the ISF is being popular as a new innovative forming technology. In the present study experiments were conducted to analyze the deformation mechanism of commercial aluminum alloy. Beside this analysis result of the effect of forming angle, step size, tool diameter on formability and wall thickness distribution are presented.

Workpiece surface integrity when slot milling γ-TiAl intermetallic alloy

Slot milling is presented as a potential manufacturing route for aerospace component feature production when machining γ-TiAl intermetallic alloy Ti–45Al–2Mn–2Nb+0.8vol.% TiB2XD using 2mm diameter AlTiN coated WC ball nose end milling cutters. When operating with flood cutting fluid at v=88m/min, f=0.05mm/tooth, d=0.2mm, maximum flank wear was ∼65μm after 25min. SEM micrographs of slot surfaces show re-deposited/adhered and smeared workpiece material to a length of ∼50μm. Brittle fracture of the slot edges was restricted to <10μm with sporadic top burr formation observed up to ∼20μm. Cross sectional micrographs of the slot sidewalls showed bending of the lamellae limited to within 5μm.

Residual stresses formation after re-contouring of welded Ti-6Al-4V parts by means of 5-axis ball nose end milling

The major step of the process chain for regeneration of damaged components is the removal of excess weld material, called re-contouring. This material removal process influences the surface integrity and therefore the functional performance of components. But today the surface integrity, e.g. residual stresses, cannot be predicted to a satisfying degree due to the complex physical effects during the cutting process. This paper investigates the fundamental influence of cutting conditions, tool geometry and weld characteristics on the residual stress formation after 5-axis ball nose end milling of Ti-6Al-4V. It is shown experimentally, that the cutting edge radius is the most influencing factor on residual stresses. Furthermore it is shown, that the thermal effects during cutting have a minor influence on the residual stresses due to the properties of titanium and the ball nose end milling process. Finally a basic physical approach is given to explain the effects by considering only the uncut chip volume, which is generating the final surface.

Surface Integrity of a High Speed Milling FC300 Gray Cast Iron

The high speed machining (HSM) of gray cast iron for manufacture mold and dies involve many different cutting tool from deep hole drills to smallest ball nose end mills [. Due to the demand of fast and high productivity, high speed machining (HSM) has been increasingly used to produce mold and dies that are mostly used in automotive industry especially for stamping dies components. The process of HSM sometimes combined together with manual polishing to enhance the die surface into fine mirror finish. Although the manual polishing strongly depends by experience and skill of workers, this technique is the preferable option for polishing of moulds and dies. However, such extensive manual polishing will provide some drawback because of many human factors such as pressure and technique of polishing individual person uses. Therefore, the application high speed machining in manufacturing is still demanding as it can improve surface finishing by reducing manual polishing, reportedly account for up to 30% of the total time [2].

Blend of sharpness and strength on a ball nose endmill geometry for high speed machining of Ti6Al4V

The applications of titanium alloys are increasingly common at marine, aerospace, bio-medical and precision engineering due to its high strength to weight ratio and high temperature-withstanding properties. However, whilst machining the titanium alloys using the solid carbide tools, even with application of high pressure coolant, reduced tool life was widely reported. The generation of high temperatures at the tool–work interface causes adhesion of work material on the cutting edges, and hence, shorter tool life was reported. In order to reduce the high tool–work interface temperature-positive rake angle, higher primary relief and higher secondary relief were configured on the ball nose endmill cutting edges. Despite of careful consideration of tool geometry, after an initial working period, the growth of flank wear accelerates the high cutting forces followed by work material adhesion on the cutting edges. Hence, it is important to blend the strength, sharpness, geometry and surface integrity on the cutting edges so that the ball nose endmill would exhibit an extended tool life. This paper illustrates the effect of ball nose endmill geometry on high speed machining of Ti6Al4V. Three different ball nose endmill geometries were configured, and high speed machining experiments were conducted to study the influence of cutting tool geometry on the metal cutting mechanism of Ti-6Al-4V alloy. The high speed machining results predominantly emphasize the significance of cutting edge features such as K-land, rake angle and cutting edge radius. The ball nose endmills featured with a short negative rake angle of value −5° for 0.05∼0.06 mm, i.e. K-land followed by positive rake angle of value 8°, has produced lower cutting forces signatures for Ti-6Al-4V alloy.

Precision Milling of Hardened Steel with CBN Tools

The paper presents research of milling tool inclination angle δ influence (in relation to the cutting surface) on the free surface roughness. Rotational tools with curved cutting edges (ball nose cutter) performed translation movements on the spherical surface of hardened steel work piece (hardness of 50, 62 and 65 HRC). Milling tool with diameter d=1 mm was made of CBN. Roughness measurements were performed in different places of the milling surface with the Taylor Hobson profilometer.

Optical 3D Scanning of Cutting Tools

The paper shortly illustrates the general concept of Reverse Engineering, which includesalso the 3D scanning. In the main part of the paper the concrete 3D scanning process of chosen individual objects are described. The problems that occurred during 3D digitizing of individual parts are step by step discussed and solved. The paper deals with 3D scanning of ball nose end mills and screw drill. The article gives a procedure for digitizing and comparing the results of the scanned digital models of the two ball nose end mills and screw drill.