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The burr formed in the micro-milling of metal parts adversely affects the function of the part and is very difficult or often impossible to remove. In this study, the variation of the average height of the top burr formed on the down-milling side (DMS) as a result of channel micro-milling of Al6061 T256 aluminum alloy under different machining conditions (for varying feed per tooth and milling (channel) depth settings) was experimentally investigated. Up-milling operations were performed at different radial depth (RD) values (10, 15 and 20 micrometer) so that the upper burr formed in the DMS under different machining conditions could be removed by micro-milling. It was found that the burr formed in the experiments was continuous, its height varied along the channel and it was Poison type. It was determined that the RD=15 micrometer value significantly removes the formed burr (reducing the burr height by 80-84%), and the use of the higher RD was not further effective in burr removal., Metal parçaların mikro-frezelemesinde oluşan çapak parçanın işlevini olumsuz etkilemekte olup temizlenmesi oldukça zor veya çoğu zaman imkansızdır. Bu çalışmada Al6061 T256 alüminyum alaşımının farklı işleme koşullarında (değişken diş başı ilerlemesi ve işleme (kanal) derinliği için) kanal mikro-frezelemesi sonucunda eş-yönlü frezeleme tarafı (EYFT) üstünde oluşan üst çapağının ortalama yüksekliğinin değişimi deneysel olarak işlenmiştir. Değişik işleme koşullarında EYFT’nda oluşan üst çapağının mikro-frezeleme ile temizlenebilmesi için değişik radyal derinlik (RD) kullanılarak (10, 15 ve 20 mikrometre) zıt-yönlü frezeleme yapılmıştır. Deneylerde oluşan çapağın sürekli yapıda olduğu, yüksekliğinin kanal boyunca değişim gösterdiği ve Poison tipi olduğu görülmüştür. RD=15 mikrometre değerinin oluşan çapağı önemli ölçüde (çapak yüksekliğini %80-84 mertebesinde) temizlediği, daha yüksek RD kullanımının çapak temizlemede fazla etkili olmadığı tespit edilmiştir.

This paper presents a new burr formation model for predicting drilling burr sizes in consideration of tool wear. A new force model is established by combining the drilling thrust force with the ploughing force caused by tool wear. The traditional drilling burr formation model is modified by using the new force model to determine burr heights and thicknesses in terms of tool wear percentage. A series of drilling experiments are carried out on two commonly used aerospace aluminiums to validate and calibrate the model. A close agreement between simulation and experiment is achieved showing that burr height and thickness increase with the increase in tool wear, and at 50% of tool wear, the maximum burr height could triple and the maximum burr thickness could double.

Drilling of composite materials is a common manufacturing process which is widely used in various applications such as aircraft and automobile assemblies. Usually, drilling of composite materials is very challenging because of their high strength, non-homogeneous and anisotropic properties. Several undesirable failures such as deflection of workpiece, delamination and burr formation occur at exit side of machined surface due to lack of support under workpiece while drilling of the material. Therefore, it is necessary to develop cost-effective techniques to suppress drilling damages. The backup support technique is an important approach to prevent damages while machining at various machining parameters, tool geometries and with other machining strategies. This review paper summarizes the principle of the technique and its effectiveness on various composites towards suppressing material damages. The backup methods are categorized under active backup force, passive backup support, stack acts as backup and fabricated backing support technique. The above methods are reviewed with respect to tool geometry/material, drilling parameters and other machining strategies to bring out the importance of backup support and its influence on quality of machined surface.

Micro-milling through mechanical chip removal process has attracted much attention among researchers due to its flexibility and productivity that allow an extensive application for manufacturing several types of micro-components for the modern-day world. Its potential is continuously growing as the market demands continuous innovation in the manufacturing of high precision products with progressively smaller dimensions. Its global research and available literature increased very fast in recent years. Relevant topics like size effect, burr formation, surface quality, cutting forces, tool wear, vibrations, and process optimization as highlighted by a systematic bibliometric study during the period 2000–2019 must be properly addressed. The review work on such a scale was not attempted earlier by considering many parameters at a time. Hence, this study may provide a current view and future prospects of mainstream research on micro-milling worldwide.

Microchannels are attractive for their widespread applications in electronics, biological, chemical, and energy areas. Micro-milling provides an ideal method to fabricate microchannels, whereas problematic burr formations and inherent rough surfaces of microchannel bottom and sidewalls are still far from sufficiently known. In this study, micro-milling process of rectangular copper microchannels was conducted by a two-flute tungsten carbide micro-end mill. Burr formation mechanism was studied via 3D finite element simulation together with experiment observations. Surface quality of microchannels, i.e., burr size and surface roughness, was studied in different spindle speeds, feed rates, and depths of cut. It was found that the top burr sizes on the down-milling side of microchannels were much larger than those on the up-milling side. The top burr size on the down-milling side and surface roughness on bottom and both sidewalls of microchannels presented a monotonic decreasing trend when the spindle speed increased, and an increasing trend with increasing depth of cut. Nevertheless, they firstly decreased due to the plowing and extruding effect together with elastic recovery when the feed rate was smaller than the tool cutting edge radius, and then changed to increase due to the shearing and cutting process after the feed rate exceed the tool cutting edge radius. High spindle speed, small depth of cut, and moderate feed rate close to the tool cutting edge radius seem to be favorable to improve surface quality of micro-milled microchannels.

Based on burr fracture morphology and burr geometry, it is concluded that the main cause of burr formation is the overall metal slip caused by the feed force of sawing and shearing. Based on the assumption that the feed force is uniformly distributed along the incision plane, the burr thickness calculation model for sawing and shearing is formed by coupling the sawing and shear force model and the blanking force model. For preheating temperatures of 500 $\thicksim $ 900∘C, feeding speeds of 30 $\thicksim $ 90 mm/s, and saw tangent speeds of 3000 $\thicksim $ 9000 mm/s, 30 mm × 30 mm GCr15 square steel was used for experiments. Through the calculation model given in this paper, the rule for the influence of the process parameters on burr thickness was obtained. Finally, a sawing and shearing experiment was carried out, and the results show that the maximum relative error between the experimental data and the calculated results is 15%, which verifies the reliability of the calculation model.

Micro-milling is a micro-mechanical cutting method used to obtain complex and three-dimensional micro geometries. Micro-cutting tools are used in the manufacturing of micro-components and the type of workpiece is also important for good surface quality and minimum burr. In this study, micro machinability of Ti6Al4V alloy which is used most frequently in micro-component production is compared with Ti5553 alloy. Micro-milling of Ti5553 alloy and comparison of the minimum chip thickness with Ti6Al4V were performed for the first time in this study. Using different cutting parameters, the variation of surface roughness, burr width, and cutting forces were investigated. The cutting tests were carried out on a specially designed and high-precision micro-milling test system using a TiCN-coated two-flute end mill of 0.6 mm diameter. According to the results, minimum chip thickness is approximately 0.3 times the edge radius of the cutting tool and does not vary with the alloy type. At feed rates smaller than the minimum chip thickness, both the cutting forces increase and the surface quality decreases. For both alloys, reduced feed rate and increased depth of cut lead to increased burr width. The burr widths in Ti6Al4V alloy are higher. At the end of the study, the limits of the cutting parameters where plowing occurred for the both alloys are clearly determined. In addition, the limits of the cutting parameter causing plowing have been confirmed by cutting forces, surface roughness, and burr formation.

Micromachining technology is a challenge in industrial production to meet the demand for components for machinery. In this research, a study of the best parameters was required to produce the best hole accuracy and the lowest burr formation in the inlet and exit holes using micro-drilling. The work-piece material and cutting tool used respectively was a brass plate with a thickness of 0.5 mm and a micro drill with a diameter of 0.2 mm commonly used for electronic PCBs. The quality of holes was measured and observed by using a stereomicroscope (optical equipment). This microscope can zoom up to 50x objects to facilitate measurement. The microscope was attached by using a digital camera type YW-200 so that the object of observation could be measured using a computer. The result shows that the largest deviation of hole diameter (0.217 mm) occurred at a spindle speed of 14,000 rpm with the lowest feed rate (5 mm/min). Meanwhile, the smallest deviation of hole diameter (0.202 mm) occurred at a spindle speed of 20,000 rpm with a maximum feed rate of 10 mm/min. The maximum burr height (0.050 mm) occurred at a spindle speed of 17,000 rpm and a feed rate of 10 mm/min. In addition, the minimum burr height (0.038 mm) occurred at a spindle speed of 14,000 rpm and a feed rate of 5 mm/min. Therefore, it can be concluded that the deviation of hole diameter was inversely proportional to the spindle speed, and the height of the burr formation was directly proportional to the feed rate.

In this study, micro machinability of Mg5Sn4Zn (TZ54) alloy produced by a hot-pressing process (one of the powder metallurgy methods) is investigated. For this purpose, micro-milling experiments we...

The mechanism and region of burr formation in casting using a vertical-type high-speed twin-roll caster were investigated using a side-dam plate with a window. A383, an aluminum alloy typically used for casting due to its excellent fluidity at semisolid condition was used. The solid fraction of the semisolid metal ejected from the window was low. When solid metal was ejected from the window, no burr formed. The results suggest that a burr formed when the semisolid metal was ejected in gap between the side-dam plate and the side surface of a roll. The semisolid metal was ejected near the point where the semisolid metal on the two rolls met.

Miniature/micro-drilling of holes is increasingly utilized in manufacturing. While non-conventional machining methods (laser and spark erosion) were applied successfully for micro-drilling, mechanical drilling still of interest to industry due to its unmatched geometrical accuracy. However, tool wear and burr formation would hinder the economics of mechanical drilling supremacy. Hence, the need for understanding of tool wear, burr formation and cutting forces progression with process variables is a step towards comprehensive modelling of micro-drilling mechanics and subsequent enhanced process economics. The current research details experimental trials involving mechanical drilling of steel 1008/CR4 using twin-fluted twist drills of diameters 0.5, 1 and 1.5 mm. Full factorial design of experiments was utilized, and analysis of variance was accomplished to study the effects of feed rate and tool diameter (each of them at 3 levels) on tool flank wear and drilled hole quality. Entry and exit burr heights were increased by 80–150% when tool diameter and feed rate were two times higher. Progression of tool flank wear and usage of bigger tool diameter conversely reduced hole surface roughness. In addition, tool flank wear was increased when reducing of feed rate and using larger tool diameter. Catastrophic failure of 0.5-mm-diameter tool was noticed (after drilling of 46 holes at high feed rate level and after drilling of 97 holes at low feed levels) due to chip packing/jamming in the insufficient flute area.

Previous research on analytical models used to predict burr size in machining operations has usually been limited to simple geometries and mechanics models. This paper investigates the material side-flow and Poisson burr formation mechanism. An improved analytical model is developed to describe the surface (subsurface) plastic deformation and Poisson burr morphology. First, the theoretical model is established based on mechanical, geometrical, and material property considerations. Then, machining experiments are performed on high-purity copper, and the proposed model is validated by comparing the predicted burr height and thickness to the experimental measurements. The results show that the developed model provides two new methods to predict burr dimensions with considerable accuracy and that this model is suitable for ductile materials. Additionally, this article offers a basis for minimizing the energy required during deburring, suppressing the formation of burrs, and optimizing the machining parameters.

Burrs, being one of the most undesired obstructions generated during machining, affects work piece quality negatively in many aspects. Although deburring removes burrs, this extra process is time consuming, costly and might affect dimensional accuracy. This study investigates mechanisms, effects and variations on burr formation in most common machining processes such as drilling, milling, turning and grinding based on the information available in literature. The problems related to burrs as well as ways and methods to remove burr and control or minimize burr formation has critically discussed. Burrs can be minimised by selecting proper tool geometry, tool materials, coolant, machining parameters, work piece material, process planning and tool path design. As there is no method that can eliminate burr formation, thus deburring is essential to eliminate burrs after machining. Manual tools, abrasive blasting, abrasive flow, magnetic abrasive finishing, centrifugal barrel finishing, thermal melting and electrochemical effect are most commonly used for deburring depending on material, size and precision of parts.

First investigations focus on the usage, processing and material properties of polycarbonate (PC) based materials used in cable duct production. Test coupons were taken from in-situ cable ducts including further additives generally used in industry. Different mechanical and optical analytical methods were performed. Significant differences in tensile properties of polycarbonate/ acrylonitrile butadiene styrene (PC/ABS) compared to mineral reinforced PC were observed. The hardness of mineral reinforced PC is significantly dependent on the geometry of the cable ducts. The fracture behavior and morphology of the PC/ABS fracture surface is directly related to the coupon temperature during Charpy impact testing. The process temperature influences the failure behavior during high impact processing such as high speed punching. Due to the lower impact strength of mineral reinforced PC less film and burr formation compared to PC/ABS are likely. However, the mineral distribution is not homogeneous and therefore subject to further investigation. This study aims at a better understanding of process properties of PC/ABS products, parameter selection, quality improvement and general understanding of underlying microstructural and surface properties.

Capability of Additive Manufacturing (AM) technology in the production of complex parts with high flexibility has led to the growing interest in their application as an alternative for conventional manufacturing processes. Despite the outstanding benefits of the AM process, due to their poor surface quality, the precision parts produced by this method generally need to be machined, ground, or polished. This paper addresses the machinability of AM Ti6Al4V titanium alloy parts in the micro-milling process with a specific focus on cutting forces, specific cutting energy, burr formation, and surface quality. Additive parts were produced by Electron Beam Melting (EBM) technique and were compared with the extruded Ti6Al4V parts in the micro-milling process. No significant difference could be observed in the cutting forces of both materials at chip thicknesses between 7.4 and 37.3 μm, despite the higher hardness of the EBM Ti6Al4V compared to the extruded Ti6Al4V. However, micro-milling of the EBM parts produced finer surfaces. Cutting forces and specific cutting energies of EBM parts were less than those of extruded parts at minimal chip thicknesses (lower than 7.4 μm). Continuous wavy-type burrs were formed in micro-milling of the EBM Ti6Al4V and were larger than those of extruded Ti6Al4V.

Machining of carbon fiber-reinforced polymers (CFRP) still remains a difficult procedure in the whole manufacturing process. One of the reasons is the cutting mechanism varies during machining, causing the inconsistency of surface integrity. This study intends to investigate the continuous variation of cutting mechanism and the induced cutting responses and damages. A novel experiment, with square and circular workpieces involved in cutting, was designed. A three-dimension micro-scale cutting simulation model was built. The experiment and simulation were combined to analyze the evolution and the correlation of cutting forces, machined surface roughness, sub-surface damage and the burr formation. The effects of rake angle and tool edge radius on chip formation and sub-surface damage were also presented. The conclusions are helpful to understand the damages generation during machining of CFRP.

Use of conventional drilling process have been utilized by academia and industry alike for making holes in difficult to machine materials like titanium alloys. However nowadays helical hole milling process has been adopted due to the advantages it brings in. This work therefore aims to evaluate the traditional drilling process against the newer helical milling process for hole making in titanium alloy. The evaluation was carried out considering the thrust force, surface roughness, hole diameter and machining temperature. The morphology of chips generated and the burr formation were also investigated. The comparison of thrust force and machining temperature were found to be lower for the holes processed using helical milling process. The finish of the machined hole surfaces was better when helical milling process was used. Additionally, helical milling of holes resulted in relatively diametrically accurate and burr free holes. The preliminary results obtained show that helical milling process can be a promising alternative to traditional drilling process for machining difficult-to-machine material like titanium alloy provided the productivity of the process can be improved.

In precision manufacturing, especially in making of holes on the parts during drilling process for precision assembling of parts facing problems with burr formation. Drilling is one of the finishing operations in the production cycle, removal of burrs during drilling process is a time consuming and non-value added process to the manufacturing sector. In this paper, we developed an analytical models for thrust force, torque and burr size with variable clearance angle of drill bit geometry especially for Aluminium alloys used for automotive applications. An analytical model results were obtained by writing a code in MATLAB @ 2010 software for aluminium alloy series such as Al 6061, Al 2014 and Al 7075. In an economic front, de-veloped mathematical models are benefitted to reduce experimentation, these results reveal that at the beginning of the drilled hole due to indentation of chisel edge, more thrust and torque was identified, beyond that suddenly thrust force was lowered, cutting forces by the lip edges were increased from beginning of the process to progress of drilling process. The proposed model approach is helpful to the budding entrepreneurs in the related areas to select optimal combination of drilling parameters to attain multiple performance characteristics of responses especially in burr size to prevent the post finishing operations up to certain extent.

An insight into comprehension and optimization of exit burr formation in orthogonal machining case is presented in the work. Formation of exit burr has been simulated using a three dimensional FE based machining model. Variation of “pivot-point” (point of maximum bending stress, appearing at workpiece exit edge) location on workpiece end and its appearance with respect to tool position during cutting process has been correlated with burr formation process. To minimize the burr formation, machining process variables (including speed, feed and tool rake angle) optimization have been realized employing Abaqus®. Burr lengths at exit end along workpiece depth of cut (ap) are quantified and optimum machining parameters generating less burrs for dry machining of AA2024 are identified. Simulated results pertaining to chip and cutting forces are fairly matched with related experimental results in the published literature.

Micromilling is one subtractive manufacturing process where excess material is gradually removed from the workpiece in the form of micro-chips with the help of a miniaturized cutting tool in order to fabricate three-dimensional micro-features. Burr formation in micromilling is one important problem as excessive burr hampers dimensional accuracy and functional requirements of the miniaturized features. Top-burr formation in micromilling is attributed to the lateral plastic deformation of the workpiece material when a rounded edge of the tool compresses it. This article explores the role of spindle speed and axial depth of cut on top-burr formation during micromilling of industrially pure copper samples using 0.5 mm TiAlN coated tungsten carbide micro end mills in MQL cutting environment. It is observed that down milling side top-burrs are significantly wider and larger as compared to that of the up milling side. For constant spindle speed, the average top-burr width is found to increase with axial depth for both up and down milling sides. However, the average top-burr width decreases marginally with the increase in spindle speed. In both up and down milling sides, the influence of depth of cut on top-burr width is more pronounced as compared to the influence of spindle speed. It was also observed that the difference between down milling top-burr width and up milling top-burr width does not vary appreciably with spindle speed.

A novel analytical model to describe entrance burr formation when drilling ductile metals as a function of tool geometry (point/helix angles, diameter), operating parameters (cutting speed, feed rate) and workpiece material properties, was initially formulated. The model was further developed to account for interlayer burr dimensions when drilling CFRP-metallic stack arrangements. Data from validation trials performed on Ti–6Al–4V, AA7010 and AA2024 workpieces together with their associated CFRP stack assemblies over 4 different combinations of cutting speed and feed rate showed that the predicted sizes of entrance and interlayer burrs were all accurate to within 20% of the experimentally measured results.

Deburring of micro-parts is one of most complicated operations used in manufacturing of micro sized components. Therefore, restriction of burr formation is one of main objectives of micro-cutting processes. To achieve the aim, basic understanding of micro-cutting mechanism and selection of optimized parameter are required. In the present work, an attempt was made to study burr size in microgroove cutting process. Here, effect of parameters such as spindle speed, feed rate and depth of cut on burr height and thickness are studied under two types of micro-milling process i.e. up-milling and down-milling. The obtained results revealed that the type of milling process significantly influenced the values of burr height; where, application of up-milling causes a mean reduction of 100% in burr height with respect to down-milling process. It is also found from the results that irrespective to type of micro-cutting process, the burr height increases by increase of spindle (up to 2000 RPM) speed and depth of cut (up to 0.3 mm). However, feed rate shows different behavior, where increase of feed rate (up to 5 mm/tooth) causes further burr height in down-milling and less bur height in up-milling. About the burr thickness, the result revealed that the irrespective to variation of process parameters, up-milling process cause about 20% increase in burr thickness. On the other hand, it is found that irrespective to type of micro-milling process, the burr thickness increases by increase of spindle speed and it decreases by increase of feed rate. Moreover, the thickness shows a falling and rising behavior as the depth of cut increases from 2 to 5 mm/tooth. Keywords: Burr, Micro-cutting, Up-milling, Down-milling, Cutting parameters