PCD Inserts Research Articles

Roughness maps to determine the optimum process window parameters in face milling

Some industrial applications require structured surfaces with high roughness values to ensure their functionality (Ra > 1 µm, Rmax < 30 µm). In order to obtain these structured surfaces with high roughness values, face milling operation is commonly used in aluminium components employed in the automotive and aeronautical sectors. Polycrystalline diamond insert tools (PCD) are widely used to obtain those structured surfaces. However, one of the major drawbacks of using face milling is that the roughness presents a high variation across the width of cut. Nevertheless, it is possible to mitigate these variations by (i) modifying the micro-geometry of the inserts, (ii) displacing each tooth by small axial amounts from their nominal positions or (iii) varying the feed rate. Frequently, the definition of those parameters is carried out employing trial-and-error strategies, with consequent cost and time penalties. In this research work, roughness maps have been developed as a novel optimisation tool to define the micro-geometry of the PCD inserts, their axial position in the tool and the feed rate, reducing the time to design new cutting tools for face milling. The roughness maps are determined based on roughness indicators calculated from 3D face milled surfaces that are modelled as a split signal in two components: (i) the kinematic movements of the cutting edge and its geometry, and (ii) a novel approach considering the stochastic roughness, which embraces the chip removal process, material defects or vibrations. The model is validated by experimental face milling tests on A-356 aluminium alloy, showing good agreement with experimental results.

ANALYSIS ON MACHINABILITY OF GFRP COMPOSITE MATERIALS USING TURNING PROCESSES

Glass fibre reinforced polymer (GFRP) composite materials replace traditional engineering materials due to their properties. Accordingly, the need for accurate machining of composites has increased enormously. The advantages include high strength to weight ratio, high fracture toughness and excellent corrosion and thermal resistance. Even though the moulding process may produce GFRP parts, they require further machining to facilitate dimensional control for easy assembly and control of surface quality for functional aspects. The material removal mechanism is different from that of machining single-phase materials, such as metals. GFRP are extremely abrasive when machined. Thus, selecting the cutting tool and the cutting parameters is very important in the machining process. The machinability in turning operations of glass fiber reinforced plastics (GFRP) will be investigated by the super-hard cutting tool (PCD and Ceramic Inserts). A plan of experiments will be performed on controlled machining with cutting parameters prefixed in the workpiece.

Effect of preheating on machinability of titanium alloy

This works presents preheating method to improve the machinability of titanium compound. With the effect of warming work piece (pre-heating) using induction coil (heating) system, speed, feed and depth were investigated in the midst of end milling process on a vertical machining center (VC450-Spinner). Additionally, WC-Co PCD inserts were positioned 25 mm apart on the mill (R390-025B25-11M/R390-170408E-NLH13A) and the effects of preheating on tool life, smoothness of the surface, force of cut, vibration/chatter, irregularities, and chips/tool morphology were examined. The execution of uncoated WC-Co was greatly implemented (directionally around multiple times appeared differently compared to room temperature machining), the tool life estimations were essentially higher than those of PCD under room temperature machining. Preheating machining reduces vibration and chatter resulting in increased cutting force and extended tool life. In addition, chip-device contact length is extended and chip serrations are formed reducing equipment wear. As a result of the experimentation, it was found that the execution of uncoated WC-Co was greatly enhanced in the preheated method. Moreover, tool life estimations with PCD at room temperature are significantly improved.

ANALYZING THE PERFORMANCE OF CIRCLE SEGMENT END MILL WITH PCD INSERTS WITH LASER-MACHINED INTEGRAL CHIPBREAKER WHEN DRY MILLING OF ADDITIVE MANUFACTURED TI-6AL-4V TITANIUM ALLOY

Components with generally shaped surfaces requiring higher surface quality and dimensional accuracy are, in most cases, machined. Specifically, milling technology is involved very often, which can be supplemented by finishing operations. Besides standard ball-nose end mills, circle segment end mills are modern type of cutter that has begun to be used with the development of advanced computer aided machining software, that allows to work with these shaped tools. In this research, comparing the performance of these two modern shaped end mills was investigated. One tool was a commercially available coated solid carbide circle segment end mill. A second prototype end mill with the same profile but different geometry was made with a PCD insert, that additionally had a chipbreaker produced by laser technology. Machining was carried out on the workpiece material the Ti-6Al-4V that was manufactured by additive manufacturing (AM) technology – selective laser melting (SLM). The titanium complex parts are generally used in the transport industries and medicine. Milling tests were performed under dry cutting conditions. The evaluation was based on the force load, the roughness of the machined surface and tool wear. The higher total forces were measured by the tool with a PCD insert, because a different tool geometry was used, despite the use of integral chipbreaker, which allows a partial change of the cutting geometry of the insert. The geometry of end mills with brazed insert is limited by the production process.

High speed machining and optimisation of Al/SiC/Gr hybrid metal matrix composites using ANOVA and grey relational analysis

ABSTRACTThe objective of this work is to investigate the effect of graphite addition to Al/SiC composites manufactured by stir casting process. The reinforcement content of graphite was varied from 2.5 wt. % to 7.5 wt. %, for preparing three types of hybrid composites. Al/SiC/Gr hybrid composites prepared by stir casting method have uniform dispersion of SiC and Gr particle reinforcement. High-speed machining of Al/SiC/Gr was done in CNC machine using PCD insert at a cutting speed of 300, 400 and 500 m/min. From ANOVA analysis, cutting speed (48.76%) is the critical factor affecting surface roughness. Grey Relational analysis was done for simultaneous improvement of Material Removal Rate and surface roughness. Roughness values were predicted using Taguchi method and predicted values were compared with experimental results. Elemental chips produced during machining leads to reduced roughness values.

Influence of Machining Parameter on Tool Life While Machining Hybrid Metal Matrix Composites

A metal matrix composite constitutes a continuous metallic matrix and a discontinuous phase known as reinforcement. The hybrid metal matrix composites (Hmmcs) have been used to manufacture drive shafts, disc brake rotors, brake drums, connecting rods pistons, engine block cylinder liners for automotive and rail vehicle applications. The Hmmcs castings of diameter 120 mm and length 300 mm were prepared through sand mould technique following stir casting methodology. The cast components further subjected to evaluation of physical properties and machining tests using two grades of coated inserts and PCD inserts. The experiments were carried out following ISO 3685 standards. The coating thickness of the TiN coated and TiAlN coated inserts were measured using Kalo testing method; the results of the test show that the interface of the substrate and coating was free from the porosity, and the coating thickness of TiN coating was 4.84 microns and TiAlN coating was measured 4.6 microns. The results of the experiments show that performance of the PCD insert was better than coated inserts at 0.1 mm/rev feed; however at 0.2 mm/revolution feed PCD insert failed by micro chipping of cutting edge while machining Hmmcs. When TiAlN coated inserts were used to machine Hmmcs the coated inserts failed by gradual wear and BUE formation.

Tool wear and chip formation analysis of aluminium hybrid metal matrix composite

Since last two decades technology has changed rapidly in each industry from consumer goods to aerospace. To quench the thrust of technology advancement of industries, the research community has to develop novel materials. As a part of the ongoing process of material development and machinability study, present work carried out to find out the effect of reinforcement and machining parameter variation on the cutting tool. Furthermore, chip analysis was carried out to find out the effect of reinforcement and cutting parameter variation on types of chip formed. The desirability of the chips was decided based on the surface finish value. Pure aluminium was used as a matrix material while; B4C, Mg, Ti and Graphite were used as reinforcement. It was observed that the unfavourable machining parameter reduces tool life considerably and this phenomenon was more evident in the carbide coated insert compared to PCD insert. High tool wear was observed during machining of composite material compared to the aluminium matrix. An undesired chip produced when feed increases and speed reduces. Moreover, change in reinforcement amount also has an effect on the types of chip produces. The surface roughness value up to 0.50 μm was reduced by a combination of optimized cutting parameters and change in reinforcement amount.

Design of adjustable chip breaker for PCD turning tools

To obtain better chip breaking effect for most cutting parameters, a chip breaker which position on rake face of tool can be adjusted is designed and analyzed. According to the structure and installation features of the PCD insert, structure of adjustable chip breaker is designed. Through finite element simulation and cutting experiments, the influences of chip breaker parameters on the radius of chip curl curvature were analyzed to determine the parameters of chip breaker. Forces on chips and the chip breaking processes of PCD tool with chip breaker were analyzed. The geometric relationships between chip breaker and chip were established. According to the geometric relationship and the chip breaking criterion, the formulas of three chip breaker parameters were deduced. A design method for chip breaker parameters of PCD tool was proposed. The research results show that the radius of chip curl curvature decreases as the inclination angle increases and decreases as the position parameter decreases. There is a threshold for both inclination angle and the position parameter of the chip breaker, and if the threshold is exceeded, severe noise and chip build-up will occur. If the contact point between the chip and the chip breaker is located in the selected segment of chip, the extrusion force between the chip and the chip breaker will increase as the chip grows, which can cause the chip to crack and break easily. The influence mechanisms of inclination angle and the position parameter of chip breaker on chip curling are obtained. A simple set of equations are derived for designing chip breaker parameters, including inclination angle, position parameter and height. A design method for chip breaker parameters of PCD tool is presented. The application of the chip breaker can expand the chip breaking range of cutting parameters for PCD tools.

Effect of Turning Parameters and Reinforcement on the Surface Roughness of Hybrid Aluminium Metal Matrix Composite

Since last two decades, technology has changed rapidly in each industry from consumer goods to aerospace. To quench the thrust of technology advancement of industries, the research community has to develop the novel materials. As a part of the ongoing process of material development and machinability study, present work was carried out to find out the effect of various cutting parameters on surface roughness and machining time of aluminium Hybrid Metal Matrix Composites (AHMMCs). In this study, pure aluminium was used as a matrix material while; B4C, Mg, Ti and Graphite were used as reinforcement. It was observed that 2202 RPM spindle speed, 0.18 mm/rev feed rate and 1.1 mm depth of cut are the optimum turning parameters with PCD insert. While machining of same composites using carbide insert, optimum spindle speed, feed rate and depth of cut are 2091 RPM, 0.19 mm/rev and 1.1 mm respectively. Moreover, PCD insert provides better surface finish compared to carbide coated insert for same cutting conditions. Moreover, the effect of reinforcement particles presence on the surface finish was also investigated and it was concluded that reinforcement presence reduces the surface roughness considerably. Particularly presence of Mg and graphite reduces surface finish significantly.

Performance evaluation of novel chamfered inserts in high-feed turning of Ti-6Al-4V alloy

The present work aims to investigate the performance of recently designed chamfered inserts in high-feed turning of Ti-6Al-4V which is considered as the mainstream alloy for aerospace applications. So far, extensive experimental data has been published while turning this alloy using square-, round-, and rhombic-shaped inserts despite certain limitations associated with each insert design. Recently, a novel chamfer insert has been developed with an intention of combining the geometric benefits of aforementioned individual inserts into a single tool. The present work evaluates wear behavior and machining performance of this newly designed insert while turning Ti-6Al-4V without coolant under constant depth of cut of 1 mm at four levels of feed rate (0.14, 0.337, 0.45, 0.562 mm/rev) and three levels of cutting speed (55, 85, 110 m/min). For output responses of tool life and workpiece surface roughness, the novel chamfer inserts not only outperformed the conventional shaped tooling but more interestingly, they were seen to compete with much expensive PCD inserts. Flank wear was observed as the principle wear mode without any signs of crater formation. Chipping was evident at the lowest cutting speed (55 m/min) and low feed rate combinations (0.14 and 0.337 mm/rev). On the other hand, fracture was encountered when operated either at an intermediate cutting speed (85 m/min) with highest feed rate (0.562 mm/rev) or highest cutting speed (110 m/min) and medium to high feed rates (values ranging from 0.337 to 0.562 mm/rev). Workpiece surface roughness (Ra) values were within the range of 0.51 to 3.91 μm over the investigated regime of operating parameters. Strain-hardened layer that deepened up to 150 μm from the machined surface was observed without any microstructural damage.

Internal turning of sintered carbide parts: tool wear and surface roughness evaluation

Turning of sintered carbide parts has not been a common theme in the literature such as the case of other hardened materials. This is a statement made on the basis of recent research on this subject in which journals and conference proceedings were consulted. However, cutting of sintered cemented carbide parts, especially the turning operation, is an important task for a large number of applications where the typical properties of these materials are required. Therefore, the aim of this research was to carry out internal turning experiments in the manufacture of sintered cemented carbide dies used to forge beer cans. The focus of the experiments was to measure and analyze the workpiece surface roughness and wear of cutting edges used in internal turning process. Therefore, samples of sintered cemented carbide WC–Co (12% Co) were submitted to internal turning process with PCD insert tool. Cutting speed and feed rate were used as input variables in the experiments. It was found that, neither very low cutting speeds, nor high feeds can be used to avoid early breakage of the tool. Moreover, for the experiments where no early tool breakage occurred, the increase of feed caused the number of cutting passes prior to the cutting edge breakage to decrease and the workpiece surface roughness to increase. The experiments performed in this work confirm that sintered cemented carbide internal turning, besides being viable, is also feasible to be used to replace grinding operations, at least in terms of surface quality obtained.

Machining characteristics evaluation of aluminium composites based on cBN and PCD inserts

Today’s industrial trend encouraged the usage of advanced materials due to their superior properties like a high strength to weight ratio and good corrosion resistance. This advanced materials also termed as composite, especially aluminium based composite having a vast number of applications such as transportation, aerospace, automobiles and defence. Generally aluminium based composites were reinforced with alumina, silicon carbide, boron carbide and graphite etc., to improve their properties. Machining of composite materials is inevitable to realize the products or components. In this paper, it is aimed to present that the AA 6061–B4C–Graphite composite fabrication and its machining characteristics. The aluminium composite was fabricated through stir casting route. The turning experiment was conducted by varying the speed, feed and depth of cut. The machining performance was evaluated using PCD and cBN tools to the lesser tool wear attainment. SEM images analysis was carried out to assess the tool wear mechanism.

Influence of Modified Cutting Inserts in Machining of Ti-6Al-4V Alloy Using PCD Insert

In modern manufacturing industries, the emerging needs of modern metal cutting operation are to increase the tool life with good surface finish and higher material removal rate. These objectives can be achieved by reducing the cutting temperature at the cutting zones with proper cooling system. The present work involves the experimental study of MQL application through the micro-holes drilled on the cutting inserts during turning of Ti-6Al-4V alloy using PCD inserts. The effect of the micropool lubrication of cutting insert on cutting temperature, surface roughness and tool wear have been compared with normal insert machining. It has been observed that in micropool lubrication method, cutting temperature was reduced by 30-33% over normal insert machining. Micropool lubrication reduced the flank wear to a maximum of about 20-30% over normal insert machining. The experimental result of the current research work indicates considerable benefits of surface roughness and tool wear through reduction in cutting temperature due to the perforation of the cutting insert.

Improving the surface morphology of metastable austenitic steel AISI 347 in a two-step turning process

The material group of metastable austenitic steels offers the possibility of surface layer hardening, integrated into the machining process. The hardening results from the superposition of strain hardening mechanisms and deformation induced phase transformation from austenite to martensite. The deformation induced formation of martensite is favored by high passive forces and low temperatures in the workpiece surface layer. High passive forces can be achieved by negative effective rake angles and large undeformed chip cross sections. However, a low depth of cut is required since otherwise large quantities of the martensite produced in the surface layer will directly be removed. An increase in the feed rate leads to a quadratic increase in the average maximum height of profile Rz due to the kinematics of the turning process. There hence is a conflict between achievable surface quality and martensite formation.This study presents a two-step turning approach to generate martensitic surface layers with low surface roughness. The aim of the first machining step is to produce as much martensite as possible, regardless of the resulting surface topography, by means of very high feed rates and cryogenic cooling. To increase the passive forces, chamfered indexable inserts with varying chamfer angles are used in this process step. In the second machining step, the surface is finished with sharp-edged PCD inserts. The aim of the second machining step is to generate the final surface topography with significantly lower roughness values, whereby as little as possible of the deformation induced martensite generated in the first machining step is to be removed. The final result of this two-step turning process is a workpiece surface layer with enhanced mechanical properties and low surface roughness.

Kształtowanie siluminów z dodatkiem fazy węglikowej – analiza temperatury narzędzi podczas skrawania

The stability of PCD inserts in the machining of cast composite materials containing 10 vol.% of ceramic phase is presented. Tests were carried out using a polycrystalline diamond cutting tool and the turning and milling center Mori Seiki NL2000SY. The VBB wear parameters of inserts according to the standard PN-ISO 3685:1996 were determinated. The influence of the cutting parameters (speed, feed rate, depth of the cut) on the temperature of PCD inserts was investigated. The analysis of chip formation mechanism during the processing at different cutting parameters was performed. The study was carried out using the FLIR A655 thermal camera and the high speed camera Phantom MIRO M310.

Experimental study on quality of PCD tools machined by different electric discharge grinding processes

AbstractPolycrystalline diamond (PCD) is a promising tool material which is utilized to cut difficult-to-machine materials used in aerospace industry. Because of its ultra-hardness, electrical discharge grinding (EDG), a variation of electrical discharge machining, is often adopted to manufacture PCD tools to reduce manufacturing time. This paper investigates the quality of PCD inserts manufactured by two different EDG eroding methods: “2-step machining” and “3-step machining”. Surface roughness and residual stress were investigated after EDG process. An orthogonal cutting experiment was conducted to test the performance of each PCD insert. PCD tools machined with the two methods do not have significant difference in surface roughness. The residual stress status changed from compressive to tensile after EDG process. Also, after being eroded by 3-step EDG process, there was an over 30% declination of residual stress compared with 2-step machining. The results of the orthogonal cutting test showed that the ...

Evaluating the Effect of PCD End Mill’s Nose Radius on Machinability of Titanium Alloy Ti-6Al-4V in High Speed Milling

Tool nose radius is an important geometrical parameter in the design of the tool. Due to its direct contact with the workpiece surface it have significant effect not only on the resulting surface quality but also on the tool life. Use of an end mill without nose radius can easily blend during machining due to a lot of stresses acting on the edge of the tool while the large nose radius end mill can increase the strength and rigidity of the tool but can also contribute in increasing the friction between the tool and the workpiece. Therefore careful selection of tool nose radius is important and especially important for Polycrystalline Diamond, PCD insert as this tool material has recently shown great success in terms of tool life, surface roughness and productivity over coated and uncoated carbide tools in high speed end milling of titanium alloy Ti-6Al-4V and with the use of correct tool geometry it can be further helpful in increasing tool life and surface quality. This study therefore investigates the effect of various nose radii’s (R0.1,0.2,0.4,0.8,1.2,1.6,2.4,3.2) and complete round insert end mill on cutting forces and heat distribution between tool and the chip for PCD insert and compare the results with multi-layer (Al2O3+TiAlN+TiN) coated carbide tool at high speed cutting conditions using 3-D finite element numerical simulations. Results have shown that both tools due to their difference in thermal and mechanical properties have different behavior under the conditions studied especially when the complete round insert tool is used. The use of small nose radius tool when nose radius rn is less than the axial depth of cut ap, the forces and the temperature remains quite low and slightly increases with the increase of radius until rn is smaller than ap but when rn gets larger than ap and only some portion of nose radius is involved in cutting, then forces and temperature increases considerably. While when complete round insert end mill is used the forces and temperature significantly drops (more than 50% than the largest nose radius tool studied) at the same ap for PCD insert but for multi-layer coated carbide tool it drops only slightly (20% than the largest nose radius tool studied). The reason for this difference lies in the fact that PCD tool has lower toughness, high hot strength and is more brittle than carbide tools and therefore maximum advantage can be taken only when small nose radius is used or when complete round insert tool is used as complete round insert have uniform stress distribution and also provides more stability for PCD tool material while large nose radius tool increases friction and also has more heat penetration in the tool thus resulting in higher cutting forces and temperature thus ultimately contributing in high wear of tool. While on the other hand carbide tools are only beneficial when smaller nose radius tool is used rather than round shape because of lower hot strength of the material.

Evaluating the Effect of PCD &amp;amp; TialN Coated Carbide End Mill’s Rake Angle on Machinability of Titanium Alloy Ti-6Al-4V

This study evaluates the machinability of titanium alloy, Ti6Al4V in terms of tool-chip interface temperature, cutting forces and tool stresses by varying rake angle of PCD insert and compares the results with TiAlN coated carbide inserted end mill using finite element numerical simulations. It has been found that tool rake angle has significant effect and behaves differently for different evaluation parameters and also shows different behavior for two different cutting material inserts. It reduces cutting forces with every positive angle geometry, about 50% reduction is observed for both cutting tool materials for a change in angle from-7° to 34°, but for tool-chip interface temperature, 15% reduction has been observed when angle is changed from-7° to 15° but it starts rising again when angle is increased to 34° for PCD insert, but for TiAlN coated carbide insert a continuous drop of about 20% has been observed. For tool stresses tool rake angle has different effect. The stresses remains almost unchanged when angle is changed from-7° to 15° but increased by almost 20% when angle is changed to 34° for both insert materials. Results also have shown that PCD insert due to its excellent thermal conductivity and strength at elevated temperatures dissipates most of the heat into the chip and has almost half temperature near the tool edge as compared to TiAlN coated carbide insert and thus can be used for machining of Ti6Al4V alloy at much higher cutting speeds than TiAlN coated carbide insert with positive rake angle geometries (around 15°).

Effects of PCD and Uncoated Tungsten Carbide Inserts in Turning of In-situ Al6061-TiC Metal Matrix Composite

In the present investigation Al6061-TiC with 2 wt% TiC, 4 wt% TiC is produced by in-situ technique, SEM and EDX are performed on the fabricated composite for to know the presence of TiC reinforcement. The fabricated composite rod is subjected to turning experiments in dry environment for to find out the cutting force and surface roughness. The experiments are performed at five different ranges of cutting speed, feed rate and depth of cut by using PCD and uncoated tungsten carbide insert. From the experimental results it was find out that cutting force and surface roughness were decreasing with increase in cutting speed and increasing with the increase in feed rate and depth of cut. The experimental results also shows that the values of cutting force and surface roughness are increased by using uncoated tungsten carbide insert than that of PCD insert.

EFFECT OF MACHINING PARAMETERS ON SURFACE ROUGHNESS FOR 6063 AL-TIC (5 &amp; 10 %) METAL MATRIX COMPOSITE USING RSM

Metal matrix Composites are new class of material which offers superior Properties over alloys. Problem associated with MMCs is that they are very difficult to machine and quality of machining specially surface finish due to the hardness and abrasive nature of Carbide particles. Characteristics of machined surfaces are known to influence the product performance significantly since they are directly linked to the ability of the material to withstand stresses, temperature, friction and corrosion. This paper presents an experimental work on the analysis of machined surface quality on 6063 Al/TiC metal matrix composites with PCD insert in hard turning leading to Response surface methodology based model to predict the surface roughness. Index Terms: Metal matrix composite, Surface Roughness, Response surface methodology.