Burr Size Research Articles

A comparative study on the machinability of β-type novel Ti29Nb13Ta4.6Zr (TNTZ) biomedical alloys under micro-milling operation

β-type Ti29Nb13Ta4.6Zr (TNTZ) alloy is a new-generation alloy that does not contain toxic/allergic elements. The alloys have low Young's modulus (⁓60 GPa) close to the cortical bone, providing excellent biocompatibility over familiar commercial CP Ti or Ti6Al4V ELI. Different macro/micro-machining methods can be used to obtain the final shape of Ti alloys and impact on the implant's bio ecosystem and performance. This study compared the micro-mill machining performance of the TNTZ alloys with commercial CP Ti and Ti6Al4V ELI. Machining experiments were performed under similar and different cutting speeds and constant feed rate conditions. In the study, cutting forces, surface roughness, burr size and tool wear were obtained. The results showed that the Fx cutting forces for TNTZ are about 3 and 2 times higher than for CP Ti and Ti6Al4V alloys, respectively. Depending on the increasing cutting distance, the surface roughness of CP Ti and Ti6Al4V materials followed a similar trend. However, the surface roughness values for TNTZ alloy are higher and decrease with increasing cutting distance. Burr widths for CP Ti and Ti6Al4V are similar, but the milling direction at which maximum burr occurs varies. In the TNTZ alloy, the burr width is about 3 times higher, and the burr occurred inside the slot, not at the edge of the machined slot. The predominant type of damage in milling Ti6Al4V and CP Ti materials is abrasive and adhesive. The dominant damage type in TNTZ alloy is chipping. Increasing the number of revolutions in TNTZ causes the cutting forces and burr width to increase.

Influence of Size Effect in Milling of a Single-Crystal Nickel-Based Superalloy

This paper details an experimental investigation on the influence of the size effect when slot-milling a CMSX-4 single-crystal nickel-based superalloy using 1 mm- and 4 mm-diameter TiAlN-coated tungsten carbide (WC) end-mills. With all tools having similar cutting-edge radii (re) of ~6 µm, the feed rate was varied between 25-250 mm/min while the cutting speed and axial depth of cut were kept constant at 126 m/min and 100 µm, respectively. Tests involving the Ø 4 mm end-mills exhibited a considerable elevation in specific cutting forces exceeding 500 GPa, as well as irregular chip morphology and a significant increase in burr size, when operating at the lowest feed rate of 25 mm/min. Correspondingly for the Ø 1 mm micro-end-mills, high levels of specific cutting forces up to ~1000 GPa together with severe material ploughing and grooving at the base of the machined slots were observed. This suggests the prevalence of the size effect in the chip formation mechanism as feed per tooth/uncut chip thickness decreases. The minimum uncut chip thickness (hmin) when micromilling was subsequently estimated to be less than 0.10 re, while this increased to between 0.10-0.42 re when machining with the larger Ø 4 mm tools.

Excursus in Chorda-Facial Angle Variation in Cochlear Implant Surgery: Cadaveric Temporal Bone Study.

Facial recess approach through posterior tympanotomy is the most common & best appraoch for facilitating Cochlear Implant surgery through the round window. Sacrificing Chorda tympani nerve can be avoided by proper understanding of the anatomy of the Facial Recess & Chorda-Facial angles. Hence it is important to know the Chorda-Facial angle to prevent injury in Facial recess approach during Cochlear Implant surgery. Objective This study is done to know the Chorda-Facial angle variation with Round Window visibility during the Facial recess approach which is of relevance in Cochlear Implant surgery. Methods Thirty adult normal wet human cadaveric temporal bones were studied by performing by Posterior Tympanotomy & Facial Recess approach by using ZEISS microscope. Photographs were taken by digital camera of 26 megapixel, imported into computer, then Chorda-Facial angle were measured by Digimizer software & mean angle was calculated. Results The mean angle between the facial nerve & chorda tympani nerve was 20.232°. Bifurcation of chorda tympani nerve at the level of origin itself from the vertical segment of facial nerve was found in 6 Temporal bones out of 30. Round window visibility was noted in all 30 temporal bone specimens (100%). Conclusion The wide Chorda-Facial angle variations, especially the narrowest angle should be known to the otologist in particular to the Cochlear Implant surgeon, which may help avoid inadvertent damage to the CTN in facial recess approach during Cochlear Implant surgery & use diamond burr size of 0.6mm or 0.8mm.

Optimization of Titanium Alloy Drilling to Minimize the Secondary Burr after Deburring Process.

The formation of burrs on the edges of machined surfaces is one of the inherent problems during machining. The burrs are formed both on the tool entry surface and exit surfaces. The paper proposes a modification of the drill involving an additional cutting insert located in the shank part. This innovative solution allowed the drill and deburring insert to be integrated, enabling both processes to be performed within one machining operation. The impact of the selected insert geometry and deburring process parameters on the size of burrs was determined during the experimental studies. Using the proposed deburring process for the Ti6Al4V titanium alloy, with appropriately chosen tool geometry and cutting parameters, reduces the secondary burr height by more than 90% compared to the original value.

An improved burr size prediction method based on the 1D-ResNet model and transfer learning

Cutting burrs, which are common in the manufacturing process of aluminum alloy wheel hubs, can severely affect the quality of the wheel hub surface and increase the scrap rate. An accurate prediction of the cutting burr size is the basis for solving the burr problem using optimization means. However, wheel hub cutting burrs can be measured only by offline microscopy, which makes acquiring burr size samples challenging, and traditional data fitting and prediction methods perform poorly for limited number of samples. To solve this problem, this paper proposes an improved method for constructing a burr length prediction model. A constitutive model of the wheel hub material A356.2 aluminum alloy is constructed using mechanical tests. This constitutive model is applied to simulate the wheel cutting burr, and the simulation results are verified using cutting experiments. Then, a large amount of simulation is performed, and a one-dimensional residual network (1D-ResNet) is constructed and trained with the simulation data; the results show that the 1D-ResNet model has stronger stability and robustness and improved prediction accuracy compared to the traditional data processing methods. Based on the transfer learning method, the trained 1D-ResNet model is fine-tuned by using the cutting experimental data, and a burr size prediction model fusing the simulation data and the experimental data is constructed. The verification results show that the proposed method can achieve high prediction accuracy with limited number of samples, thus effectively solving the engineering problem of wheel cutting burr size prediction.

Rotational atherectomy: assessment of the effectiveness and safety

Abstract Background Rotational atherectomy (RA) enables percutaneous coronary intervention (PCI) for complex and calcified coronary lesions, despite limited data regarding long-term outcomes. Purpose We aimed to characterize success rate, safety, and long-term outcomes with this technique in a single-centre with over a decade of experience. Methods We retrospectively analysed all cases of RA performed in a single-centre between January 2009 and December 2020. Angiographic success was defined as the presence of less than 30% residual stenosis and grade 3 TIMI (thrombolysis in myocardial infarction) flow. Complications included coronary perforation or dissection, burr entrapment, wire fracture, slow flow/no-reflow, side branch occlusion, peri-procedural myocardial infarction (MI), or death. Long-term major adverse cardiovascular (CV) events (MACE) included CV and all-cause death, MI, and target vessel revascularization. Results Of the total of 14,527 PCI performed, 410 procedures (2.8%) included RA. Most patients were male (74.0%) with mean age of 72.3±9.3 years. There was high prevalence of hypertension (85.65%) and dyslipidaemia (74.2%) which increased significantly over time (p trend=0.008 and p trend<0.001, respectively). One-third presented with acute coronary syndrome, most patients had multivessel disease (38.4% two-vessel, 32.7% three-vessel), and 12.2% had significant left main disease. Over time there was an increase in disease complexity, reflected by the proportion of type B2/C lesions (p trend =0.003) and median SYNTAX score (p trend =0.003). The utilization of transradial access increased over time (p trend =0.003) and maximum burr size was ≤1.50 mm in most cases (88.0%), with smaller sizes over time. Overall angiographic success rate was 96.6% without significant variation over time while complications (9.0%) showed a temporal decline (p trend=0.029) (Figure 1). Most frequent complications were coronary dissection (n=17) and burr entrapment (n=6). After a median follow-up of 40 (16–76) months, MACE occurred in 27.7% of patients, mainly due to CV death. At one year of follow-up, MACE, all-cause mortality and target vessel revascularization occurred in 12.1%, 6.4%, and 5.6%, respectively, without variation over time. Conclusions RA is an effective and safe technique, with a declining rate of peri-procedural complications along with technical developments. The rate of long-term events is concordant with the CV risk profile and coronary lesion complexity. Funding Acknowledgement Type of funding sources: None.

New Left-Handed Milling Cutter and Process for Burrs-Free Machining of Precision Copper Electrode

Abstract With the increasing performance and appearance requirements of electronic products, higher standards have been put forward for the machining accuracy and quality of the precision copper electrode for product molds. The precision copper electrode is large in material plasticity and small in size. Burrs are easily generated during the cutting process, and subsequent cleaning is difficult. In this paper, according to the geometric features of the copper electrode, the distribution type and formation mechanism of burrs are deeply analyzed. The influence of cutting-edge geometry on burrs lateral dimension is investigated by simulation. Further, the new left-handed fillet milling cutter is designed that takes into account the simultaneous cutting of the end edge and the circumferential edge. Finally, based on the new milling cutter, burrs suppression machining process adapted to different geometric features is planned. Experiments show that the new cutter and process can greatly reduce the size of burrs and basically realize burrs-free machining compared with the conventional process of the ordinary right-handed milling cutter, and the service life of the new cutter is longer, which can meet the actual machining needs.

Mid-term results of stent-less coronary intervention using rotational atherectomy and drug-coated balloon for de-novo lesions in hemodialysis patients.

Although drug-coated balloon (DCB)-based stent-less percutaneous coronary intervention (PCI) for de-novo lesions has attracted more attention, outcomes of the DCB procedure for hemodialysis (HD) patients are reported to be inferior to those for non-HD patients, similarly to drug-eluting stent (DES). Recent several reports have shown that rotational atherectomy (RA) followed by DCB treatment (RA/DCB) could be an option of revascularization strategy particularly for calcified de-novo lesions even in the new-generation DES era; however, efficacy of the RA/DCB procedure for HD patients remains unclear. A total of 47 consecutive cases (53 lesions) undergoing RA/DCB for de-novo lesions were enrolled. According to the presence/absence of HD at baseline, the 47 cases were divided into the HD cases (N.=16) and the non-HD cases (N.=31), and the 53 lesions were divided into the HD lesions (N.=20) and the non-HD lesions (N.=33). The HD cases had a significantly lower prevalence of dyslipidemia and smoking than the non-HD cases. Final RA burr size, DCB diameter used, and angiographic success rate of PCI did not significantly differ between the 2 groups. Preprocedural, post-procedural, and follow-up QCA parameters were also similar between the 2 groups. Twelve-month clinical outcomes were comparable between the 2 groups. Mid-term outcomes of stent-less PCI using RA/DCB for de-novo lesions in HD patients might be comparable to those in non-HD patients, suggesting efficacy of pretreatment of RA prior to DCB treatment in HD patients.

Investigation on burr formation characteristics in micro milling of Ω-shaped reentrant microchannels

Reentrant microchannels show excellent heat dissipation capabilities and are promising for microchannel cooling systems in a variety of application areas. This study developed a micro milling method to fabricate a unique type of Ω-shaped reentrant microchannels in pure copper. The critical issues in micromilling, i.e., formations of side burr, entrance burr and exit burr in reentrant microchannels and their mechanisms, were comprehensively investigated with experiments and finite element (FE) simulations. It was found that side burrs in reentrant microchannels were mainly formed on the up-milling side, and some of them extended from the sidewall of circular cavity to the top exit slot. The restriction of top exit slot of reentrant microchannels played a significant role on the extrusion, squeezing and thrusting of deformed materials and chips, which contributed to the formation of side burrs. Moreover, the effects of spindle speed and feed rate on the side burr formation and their sizes were also explored. The side burr size firstly increased, reached the maximum, and then decreased with increasing spindle speed. Besides, it firstly increased, then decreased to be the minimum and finally increased with increasing feed rate. The ratio between the feed per tooth and cutting edge radius (fz/re), which combined both spindle speed and feed rate, is believed to be the critical factor for burr formation. The minimum uncut chip thickness seemed to be of 0.25 fold of the tool edge radius in micromilling reentrant microchannels. The fz/re of 0.42 with a spindle speed of 15,000 r/min and feed rate of 25 mm/min was suggested to be the optimal machining parameter to minimize the side burrs of reentrant microchannels.

Study on reducing burrs of super alloy through structures in water jet guided laser ablation

With the increase of thrust-weight ratio of aero-engine, the working temperature of core parts is becoming higher and higher. In order to improve the service life of core parts, many high-precision micro holes are machined on those core parts. To realize the fabrication of micro hole with less burrs on super alloy substrates, a novel water jet guided laser processing method is proposed in this paper. A material removal principle based on plasma detonation assistant machining is proposed and proved to be valid through experiments. Then a laser-induced plasma assisted ablation method using sacrificial layer in the machining of through holes and grooves on super alloy is approved. This method can get higher machining efficiency and avoid longtime trimming in subsequent experiments. The size of burrs in through hole decreases 57.89%, while the area of burrs decreases 42.32% after using 304 stainless steel as sacrificial layer in the machining of through hole. Grooves with fewer burrs are also achieved on super alloy with this method. That method can also be used to fabricate a variety of functional structures.

Rotational atherectomy via the transradial access: success rates, procedural parameters and complications

Radial access is recommended for percutaneous coronary intervention (PCI), but rotational atherectomy remains frequently performed via femoral access. Analyzing the procedural parameters, success rate and complications of rotational atherectomy, performed via radial in comparison to femoral access. We retrospectively analyzed 427 consecutive patients undergoing rotational atherectomy. Procedural parameters and outcome were determined in 171 patients, scheduled for radial and compared to 256 patients with femoral access use. In the radial access group (74 ± 9 years, 84% male), the LAD was most frequently treated (49%). Sheath size was 7F in 59% and 6F in 41%, burr size was 1.5 mm in 46% and 1.25 mm in 14% of patients. A temporary pacemaker was inserted in 14%. Procedural success rate stood at 97%. Access site complications occurred in 4% of patients, which was significantly less frequent than in in 256 patients treated via femoral access (13% p = 0.003). Compared to radial access, femoral access was associated with the use of larger sheaths (p < 0.001), more frequent treatment of non-LAD vessels (58.2% vs. 44.4%, p = 0.013) and a higher rate of temporary pacemaker use (27%; p = 0.001). No differences could be seen in procedural success (p = 0.83) and burr size (p = 0.51). Femoral access (OR 3.33; 95% CI 1.40–7.93), and female sex (OR3.40 95% CI 1.69–6.63) were independent predictors for access site complications. For coronary rotational atherectomy, radial access has a high success rate with overall use of smaller sheaths, but of equally sized burrs as well as a significant lower rate of access site-related complications than femoral access.

Analysis of the influence of the blanking clearance size to the burr development on the sheet of mild steel, brass and aluminium in blanking process

Purpose: This research aims to analyse the influence of blanking clearance size on the burr development for mild steel sheet, brass and aluminium. The main reason for this research is estimating the burr size on blank parts. It is still significant since the quality of the products is determined by evaluating the amount of allowable burr in the parts. Design/methodology/approach: For the blanking process on the 3.00 mm thick sheets, various sizes of blanking clearance for a 20 mm diameter of the die opening are employed, as is the technique for obtaining the parts. Then the height of the burr on each product was measured using a micrometre and toolmaker microscope. The height of burr for each size of blanking clearance have been recorded and compared using a graph. Comparison made to identify which measure of blanking clearance and which type of material will produce a small size of burr. Findings: For mild steel, brass, and aluminium, blanking clearance 0.15 mm produced burr heights of 0.088 mm, 0.015 mm, and 0.024 mm, and blanking clearance 0.13 mm produced bur heights of 0.192 mm, 0.055 mm, and 0.046 mm, respectively. The brass had a lower burr height than mild steel and aluminium, according to the results. More significant blanking clearance (0.15 mm) produced a smaller size of burr compared to a smaller blanking clearance (0.13 mm). Practical implications: This study focuses on burr height rather than the wear of the punch and die cutting edge; burr height can affect punch and die sharpness. It also can guide practitioners in estimating blanking clearance and the burr height of mild steel, brass and aluminium. Originality/value: This paper demonstrates that the gap between the punch and die influences the burr height. The material strength also affects the burr height, with a high tensile strength resulting in a larger burr.

Prediction of Burr Types in Drilling of Al-7075 Using Acoustic Emission and Convolution Neural Networks

The formation of exit burrs during the drilling of ductile metals such as aluminum is critical in precision manufacturing and manufacturing automation. Because drilling burrs are difficult to remove, methods to predict various burr types and/or implement burr minimization schemes that consider the various attributes of burrs must be devised. In this study, not only drilling process conditions, including feed, cutting speed, and drill diameter, but also an artificial neural network is implemented to predict the formation of burrs during the drilling of aluminum-7075, which is widely used in the aerospace and automobile industries. Based on the drilling conditions, the main exit burr characteristics, such as burr size and type, were classified experimentally. Three different types of exit burrs (uniform burrs, uniform burrs with caps, and transient burrs) were observed from the aluminum 7075 workpieces. The classification results were further analyzed using burr control charts and an empirical equation, which enables the understanding of the overall influence of the drilling conditions over the burr types. Moreover, acoustic emission (AE) sensor monitoring scheme was utilized to sample the sensitive time-series signals during drilling burr formation. Subsequently, burr types were predicted using artificial intelligence techniques, namely machining learning and deep learning. First, backpropagation (BP) neural networks were constructed using the drilling conditions and AE signals as input vectors. For a comparative prediction, a convolution neural network (CNN) was implemented to obtain spectrogram image inputs from the sampled AE data. The proposed scheme is useful in predicting drilling burr types by employing a sensitive sensor monitoring setup and advanced artificial intelligence techniques, where both prediction results are well matched with experimental results. In addition, the CNN model shows effectiveness for a commonly practiced manufacturing process as it predicts the burr types with better accuracy than the BP network model (0.9375 over 0.8571).

An Improved Burr Size Prediction Method Based on the 1d-Resnet Model and Transfer Learning

An Improved Burr Size Prediction Method Based on the 1d-Resnet Model and Transfer Learning

An Improved Burr Size Prediction Method Based on the 1d-Resnet Model and Transfer Learning

An Improved Burr Size Prediction Method Based on the 1d-Resnet Model and Transfer Learning

The influence of edge radius and lead content on machining performance of brass alloys

Considering industrial applications, three main brass alloys including lead-free, low-lead and leaded are being deployed. However, as these materials are used in potable water applications, low-lead and lead-free brass alloy are becoming preferred to leaded ones due to their health effect. On the other hand, Lead is the element increases machinability of such materials. Machining efficiency of these type materials can be raised by using round edge cutting tools. This paper presents experimental results of the machining performance of lead-free, low-lead and leaded brass alloys in terms of cutting forces, surface roughness, and burr height during milling operations. Moreover, it also takes into account the edge radius of cutting tools and its role on machining the performance. Empirical equations are derived to predict the machining behavior for each material. Increasing the edge radius results in larger cutting forces and tool vibration during the process, but better surface quality. Furthermore, reduction/elimination of the Lead element in alloy content has concluded into higher burr size on the machined surface edges.

OPTIMIZATION OF BELLOWS AND TUBES CUTTING BY DISC KNIFE TO ACHIEVE THE MINIMUM BURR SIZE

The paper solves the determination of the optimal size of the shear gap when dividing components with a circular cross section (hydroformed metal bellows and tubes) with a disc knife to achieve the smallest burr size on the divided surfaces. The analyzes were performed on bellows with an outer diameter of 15 mm and a wall thickness of 0.4 mm. During the experiments, the size of the shear gap between the inner disc knife and the outer knife was changed, and the pressing force of the inner disc knife was changed. The experiments were carried out using a cutting tool after 20,000 cuts and after 120,000 cuts. The optimal size of the cutting gap was determined, allowing the minimum size of the burr to be achieved, thus reducing the time to remove it by brushing or tumbling in the subsequent operation. The mentioned procedure can be applied to analogous cases of division.

Drilling and helical milling for hole making in multi-material carbon reinforced aluminum laminates

Dissimilar properties of the constituent materials in Fiber Metal Laminates (FMLs) make hole making a demanding task. Improper selection of the process and the process parameters can result in poor surface quality, dimensional inaccuracy, or even failure of the component. The work, therefore, compares the drilling and helical milling process for hole-making in carbon fiber aluminum laminates (CARALL). The comparison was carried out by evaluating the machining forces, chip morphology, machining temperature, surface roughness, hole size, and burr size. The experimental results revealed significantly lower machining forces and machining temperature during helical milling. Utilization of helical milling for hole making resulted in the production of holes within H9 diameter tolerance. Substantial reduction in the surface roughness was noted during helical milling by virtue of the discontinuous chips generated during the process. Furthermore, holes processed using helical milling showed relatively smaller-sized burrs in comparison to the drilling process. Overall, the initial evaluation exhibits the positive capability of helical milling for hole-making in CARALL FMLs.

Comprehensive experimental investigation on drilling multi-material carbon fiber reinforced aluminium laminates

The amalgamation of metallic alloys and fiber-reinforced composites has helped Fiber Metal Laminates (FMLs) like Carbon fiber reinforced aluminum laminates (CARALL), and Glasslaminatealuminum-reinforced epoxy (GLARE) overcome the limitations of standalone metals and composites. As a result, they have found increasing applications in the aircraft and defense industries. Moreover, the inhomogeneous nature and poor machinability of the materials make hole drilling challenging. Therefore, to enhance drilling performance, the paper reports a systematic analysis of the effect of spindle speed and axial feed on key performance measures, including thrust force, machining temperature, surface roughness, hole size, burr size, and chip morphology. Experimental outcomes indicate a significant reduction in the thrust force while utilizing higher spindle speed (4000 rev/min) and lower axial feed (0.1 mm/rev), while the surface finishes improved under high feed conditions (0.4 mm/rev). The analysis revealed that machining temperature increased with the employment of higher spindle speed and lower axial feed. Higher spindle speeds and axial feeds are desirable from the perspective of hole accuracy as they help produce holes within H9 diameter tolerance. Burr size was verified to be larger at the hole exit compared to the hole entry, with the size of the burr increasing with an increase in spindle speed and axial feed. The results show that the axial feed was the significant variable affecting chip size, followed by spindle speed. Higher axial feed (0.4 mm/rev) and spindle speed (4000 rev/min) helped improve the chip breakability, thus helping improve chip evacuation.

BURR FORMATION AT THE INTERFACE DURING BI-MATERIAL ORTHOGONAL CUTTING

To reduce the size of exit burrs induced by broaching, it is possible to use a low value martyred part clamped to the functional one on the tool exit side. Thence, this research work deals with an in-situ analysis of the burr formation at a bi-specimens interface in orthogonal cutting configuration. New mechanisms of burr formation at the interface formed by Inconel 718 and cast iron specimens are identified. In addition, a post-machining study is carried out to quantify the burr size obtained with and without the martyred part.