Carbide Drill Bit Research Articles

Micro UHMW‐PE column array molded by the utilization of PCB as mold insert

PurposeThe purpose of this paper is to present a method for ultrasonically molding polymer powder in a micro plastic part mold. In the method, a printed circuit board (PCB) in which micro‐hole arrays are drilled is used as a micro cavity insert. With the utilization of ultrasonic vibration, the polymer powder, which is prefilled and compacted in a micro cavity, mutually generates great sliding friction heat so as to be rapidly plasticized and molded.Design/methodology/approachMicro carbide drill bits of which the diameters are 100.0 μm, 150.0 μm and 200.0 μm, respectively, are used for drilling the PCB to form a micro‐hole array insert. Next, two kinds of various ultra‐high molecule weight polyethylene (UHMW‐PE) powder with various grain diameters are directly filled into a charging barrel and a mold cavity with the micro‐hole array insert. Proper process parameters are set on ultrasonic plasticizing and molding equipment so that a molding test can be performed. The melt of UHMW‐PE can be rapidly filled into the cavity. Finally, micro‐column array plastic parts are successfully prepared.FindingsThe micro‐hole array PCB is a mold insert which is quite applicable for the ultrasonic molding of the powder in the mold. When a molding material is the coarse UHMW‐PE powder with the grain diameter of about 350 μm, the diameter replication rates of the micro‐column array plastic parts become good in order with the increased micro‐hole diameter of the PCB. When the fine UHMW‐PE powder with the grain diameter of about 80 μm is adopted, the diameter replication rates of the micro‐column array plastic parts become good in order with the decreased micro‐hole diameter of the PCB.Originality/valueIn this paper, the micro‐column array plastic parts with good replicability are successfully prepared by a technique for ultrasonically plasticizing and molding in the cavity. The technique can be applied to the fields of medical treatment, communication, optics, chemistry and so on, such as biological micro needle arrays, micro biological chips, optical memories, and micro chemical reaction chips.

Effects of Different Parameters on Delamination Factor of Glass Fiber Reinforced Plastic (GFRP)

The experimental investigations of the delamination factor of glass fiber reinforced plastic at different cutting parameters are reported in this study. This paper has involved the determination of different factors affecting the hole quality and cause of delamination in a glass fiber reinforced plastic. The various process parameters like different twist drill bits of different materails, different point angle at different speed, feed rate have been taken. The thrust forces and torque values were measured using piezoelectric dynamometer. Mathematical model has been developed for different machining conditions using Minitab software with help of Taguchi design to plan the experiments. The Universal microscope has been used which determines delaminated diameter in GFRP specimens. The finite element method has been applied by using Ansys11.0 software which helped to find out delaminated diameter. It was experimentally observed that for the tungsten carbide and M50 drill bits, the thrust force and torque significant increases on increasing the point angle and feed rate.

Research on experiments with water vapor as coolant and lubricant in drilling Ti6Al4V

PurposeThe purpose of this paper is to develop water vapour as a new cooling and lubricating technique in drilling Ti6Al4V. Water vapor is an economical and eco‐friendly coolant and lubricant. However, it is necessary to study the drilling chip deformation, forces and drilling temperature when drilling Ti6Al4V using this new green drilling technology, which meets the development trend of green machining technology.Design/methodology/approachComparative experiments are carried out with HSS drill bits and YG6X (K10 type in ISO) cemented carbide drill bits in drilling Ti6Al4V under the conditions of oil water emulsion, water vapor as coolant and lubricant and dry drilling, respectively. The drilling forces, temperature and drill bit wear VBmax have been examined and analyzed. Further, a new type practical drilling quick‐stop device is developed for studying the chip deformation in drilling Ti6Al4V. The drilling forces distribution test in drilling Ti6Al4V is also developed.FindingsWhen water vapor is used as coolant and lubricant, the torque is reduced by 15‐25%, 5‐10% in comparison with dry drilling and oil water emulsion, respectively; the thrust is reduced by 5‐10%, 4‐5%; the temperature is reduced by 15‐20%, 5‐8% and the wear VBmax of drill bit is reduced by 60‐80%, 10‐15%, correspondingly. Also, the contact length in chip‐tool interface decreases and the drilling deformation is reduced. The coolant and lubricant conditions and feed rate have little impact on the drilling force distribution in drill bit cutting edges.Originality/valueA green machining technology, water vapor used as coolant and lubricant, is used in drilling Ti6Al4V; it can reduce drilling deformation, drilling forces, temperature and flank wear. A new drilling quick‐stop device is devised to obtain the drilling chip roots. Also, the drilling force distribution test was developed for obtaining the rate of drilling forces in cutting edges when drilling Ti6Al4V.

Regression Modeling Of Cutting Parameters� Effect To Cutting Forces And Hole Surface Qualities In Drilling Of Dievar Hot Work Tool Steel

In this study, cutting moments, surface roughness, dimensional accuracy and circularity deviation values were investigated during drilling on Dievar degree of hot work tool steels with various drill bits. The experiments, was completed with O16 mm diameter uncoated carbide drill bits and TiAlN coated self-reamed carbide drill bits using coolant fluid on vertical machining center. In experiments, feed rate 0,16 mm/rev and the cutting speed 36, 40, 44, 48 m/min rates were used. The results were modeled by the method of linear regression and polynomial regression curve. Then they were compared with values equal significance. At the same time by analysis of variance, the cutting speed and drill type were investigated on the results of axial feed force, cutting torque, surface roughness, dimensional accuracy and circularity the deviation.

Surgical Technique: Simple Technique for Removing a Locking Recon Plate With Damaged Screw Heads

The introduction of locking plates in the treatment of periarticular fractures was a major breakthrough in orthopaedic evolution. Removal of these implants is extremely difficult as a result of cold welding and stripping of screw heads. A 31-year-old man had a schwannoma of the left C5-C6 nerve roots and upper trunk of the brachial plexus. One year before presentation he had undergone excision of the lesion through an approach using a clavicular osteotomy. The osteotomy had been fixed with a titanium locking recon plate. While surgically removing the implant, only one screw could be removed. The remaining five screws could not be turned owing to cold welding; repeated attempts at removing the screws damaged the screw heads. A large bolt cutter was used to cut the plate between the holes, and the resulting rectangular sections with the screws then were unscrewed from the bone. Limited literature is available regarding techniques for locking screw removal. These include using a carbide drill bit or diamond-tipped burr, high-speed disc, or conical extraction screw. Not all centers have specialized instruments such as carbide drill bits to remove screw heads, but a large bolt cutter usually is available when screws cannot be unscrewed owing to cold welding. The technique of cutting is easily reproducible and does not require additional soft tissue stripping.

Study of the Damage of Drills in Dry Drilling of NM360 Steels

According to the characteristics of NM360, a contrast experiment for drilling performance in YG8 cemented carbide twist drill, high-speed steel twist drill and factories used in coating the ordinary high-speed steel twist drill has been done. Using microscope to observe the damage of drills, we found that form this experiment some causation in tool invalidation that tool breakage is main factor for the high-speed steel drill bits, brittle fracture is main factor for carbide drill bits. Brittle carbide cutting tools, feed speed too much impact load is too large, causing the blade fracture. As the tool edge wedge angle is too small, poor edge strength, easy chipping, edge wedge angle can not be too small.

Performance and wear of coated carbide drill in machining of carbon fibre reinforced composite/titanium stack

In this research we investigate the performance of drilling process in carbon fibre reinforced composite (CFC) material, titanium alloy and the hybrid stack of these two materials, using coated carbide drill bit. We study the effect of the process parameters such as the feed rate and speed on the induced forces and torques, also on the wear of drill and surface roughness of the holes. In the composite material the percentage of surface damage in both drilling CFC on its own and drilling in stack form is estimated. Also, the effect of worn drill on the surface damage is identified. In the titanium, the burr formation in stack and non-stack form is investigated. The wear of the drill results in increased forces and torques required for drilling. This increases the surface delaminations substantially at the entrance in drilling of CFC. However, the surface roughness of the holes reduces with the wear of the drill in CFC drilling. Also, the surface delamination and surface roughness of the holes in the CFC whilst drilled in hybrid form reduces significantly. This is despite the increase of the forces and torques required in drilling CFC in stack form.

Performance and wear of coated carbide drill in machining of carbon fibre reinforced composite/titanium stack

In this research we investigate the performance of drilling process in carbon fibre reinforced composite (CFC) material, titanium alloy and the hybrid stack of these two materials, using coated carbide drill bit. We study the effect of the process parameters such as the feed rate and speed on the induced forces and torques, also on the wear of drill and surface roughness of the holes. In the composite material the percentage of surface damage in both drilling CFC on its own and drilling in stack form is estimated. Also, the effect of worn drill on the surface damage is identified. In the titanium, the burr formation in stack and non-stack form is investigated. The wear of the drill results in increased forces and torques required for drilling. This increases the surface delaminations substantially at the entrance in drilling of CFC. However, the surface roughness of the holes reduces with the wear of the drill in CFC drilling. Also, the surface delamination and surface roughness of the holes in the CFC whilst drilled in hybrid form reduces significantly. This is despite the increase of the forces and torques required in drilling CFC in stack form.

The Simulation of the Influence of Honed Edge Radius on the Maximum Temperature in Drilling 42CrMo with K-Grade Carbide Drill Bit

This paper uses a metal cutting simulation software AdvantEdge FEM as the platform, and simulates the drilling process of 42CrMo with three different honed cutting edge K-Grade carbide drills. The aim is to study the influence of different magnitude of honed cutting edge on the maximum temperature of cutting area. According to the simulation, the maximum temperature does not absolutely increase with the honed edge radius increase. The cutting temperature reaches maximum when the honed edge radius is 0.06mm in this paper, meanwhile the margin of fluctuation in the smallest.

The Simulation of the Influence of Honed Edge Radius on the Cutting Force and Torque in Drilling 42CrMo with K-Grade Carbide Drill Bit

This paper uses a metal cutting simulation software AdvantEdge FEM as the platform, and simulates the drilling process of three different honed cutting edge K-Grade carbide drills. The aim is to study the influence of different magnitude of honed cutting edge on the the cutting force and torque. According to the simulation, the z-axis force and torque increase while the margin of the fluctuation decrease with the honed edge radius increase. In this paper, the z-axis force and torque reach the maximum and the margin of fluctuation in the smallest when using the honed edge radius of 0.10mm.

Experimental Investigations on Drilling GFRP Epoxy Composite Laminates Using Specialized and Conventional Uncoated Cemented Carbide Drills

The growing demand of the fiber reinforced plastics (FRPs) in lightweight engineering has led to a need for assessing and quantifying the workpiece material defects, like hole exit delamination, during their drilling process. This article presents the experimental investigations on in-process drilling load profiles and a quantitative analysis of the induced hole exit delamination in drilling glass fiber reinforced plastic (GFRP) epoxy composite laminates, using various uncoated carbide drill bits (two specialized and a conventional one). The aim of studying and analyzing the in-process load profiles, in this work, is necessary in better comprehending the interaction between the tool and the workpiece material, with respect to the induced peak loads. It may further be helpful for determining and assessing the root cause of the induced delamination damage. Moreover, it is shown that the design and geometry of a particular drill bit also plays a vital role regarding its cutting loads and delamination results. The specialized tools were found to be much better than their conventional counterpart. Furthermore, subsequent drilling was conducted onto some predrilled pilot-holes using the same specialized drills, to test the chisel edge effect. The research emphasizes a need to pay attention to the quality and design of a drill bit (cutting edge corner).

Nanocrystalline CVD diamond coatings for drilling of WC-Co parts

Drilling of pre-sintered cemented carbide parts is a challenging task due to the high hardness and abrasive nature of the WC grains. This operation is commonly done using uncoated cemented carbide drill bits but the tool life is very limited requiring tool re-sharpening after a few holes. A solution for the improvement of the tool performance is here exploited by the use of nanocrystalline diamond (NCD) films as high abrasion resistant coatings. These coatings were grown in a hot filament chemical vapor deposition (HFCVD) reactor. Filament temperatures in the range of 1940–1980 °C were crucial to obtain highly adherent and very uniform coatings at the cutting edge and on the surfaces of the flutes. The performance of the coated tools was evaluated in through-hole drilling of a pre-sintered cemented carbide showing outstanding cutting efficiency when compared to that of an uncoated tool: maximal 940 mm/min infeed rates (app. 1 s to drill 17 mm) instead of 20 mm/min for the latter; absence of tool wear in contrast to a flank wear of about 50 μm in the uncoated tool after only 4 holes; hole edge integrity even at the highest infeed rates while grain decohesion at the hole edge takes place when using bare drill bits.

Step Vibration Drilling for Micro Inclined Hole

In modern manufacturing industry, there are a great deal of micro inclined holes, which is a difficult problem to machining. A novel micro inclined hole drilling method, step vibration drilling, is adopted. The experiments are carried that 45 degrees inclined hole is drilled into the 45 steel workpiece with Φ0.5mm carbide drill bit. The notable result was obtained with the method of step vibration drilling for drilling 45 degrees inclined holes on 45 steel, which break the restriction of drill jig. The new approach is put forward for micro inclined hole.

Case Report: A Technique to Remove a Jammed Locking Screw from a Locking Plate

Locking titanium plates revolutionized the treatment of osteoporotic and metaphyseal fractures of long bones. However as with any innovation, with time new complications are identified. One of the problems with titanium locking plates is removal of screws, often attributable to cold welding of screw heads into the locking screw holes. Several techniques have been described to overcome this problem. We describe a new easy technique to remove a jammed locking screw in a locking plate that is easily reproducible and suggest an algorithm to determine the method to remove screws from locking plates. A 57-year-old man underwent removal of a locking titanium plate from the distal femur. Because the screws could not be readily removed, we used a new technique to remove the jammed locking screws. A radial cut was made in the plate into the locking screw hole and wedged with an osteotome. This released the screw head from the locking screw hole. The screw holes were connected with radial cuts and jammed locking screws were removed in a similar fashion. Instruments used for removal of locking screws, including conical extraction screws, hollow reamers, extraction bolts, modular devices, and carbide drill bits, have been described. However, these do not always work. Removing screws from locking titanium plates can be difficult. There is no method of implant removal that can be universally applied. Therefore, this new technique and our algorithm may be used when removing screws from locking titanium plates.

Cutting edge rounding: An innovative tool wear criterion in drilling CFRP composite laminates

An evenly and smoothly distributed abrasion wear, observed along the entire cutting edge of an uncoated carbide drill bit in drilling CFRPs, is due to the highly abrasive nature of the carbon fibres. A very few researchers have only quoted this wear mode as being responsible for giving rise to the rounding of the cutting edge, or its bluntness. However, this wear feature has seldom been investigated, unlike the conventional flank wear in practice. This paper offers a new approach in unveiling and introducing the cutting edge rounding (CER) – a latent wear characteristic as a measure of sharpness/bluntness – of uncoated cemented carbide tools during drilling CFRP composite laminates. Four different types of drills (conventional and specialised) were tested to assess the applicability and relevance of this new wear feature. Mechanical loads (drilling thrust and torque) were recorded, and the hole entry and exit delamination were quantified. For the utilised tools, the accruing magnitude of CER was also recorded, in parallel with studying their conventional flank wear. Very appreciable correlations between the CER and the drilling loads, and also the quantitative delamination results are observed. Results reveal that this new wear type develops almost similarly for the selected tools and is practically independent of their respective conventional flank wear patterns. Moreover, a distinct, non-zero magnitude of the CER for a very fresh tool state may provide researchers with some lucid information in further studying the results during wear tests, more emphatically. The CER correlations with quantitative delamination results are noticed quite comparable to those of the conventional flank wear via statistical linear regression analyses.

Back Propagation Wavelet Neural Network Based Prediction of Drill Wear from Thrust Force

The fast monitoring of tool wears by using various Cutting signals and the prediction models developed rapidly in recent years. Comparatively, various wear forecast models based on artificial neural networks (ANN) perform much better in accuracy and speediness than the conventional prediction models. Combining the prominent dynamic properties of back propagation neural network (BPNN) with the enhanced ability of a wavelet neural network (WNN) in mapping nonlinear functions, a Back propagation wavelet neural network (BPWNN) is newly established to perform prominent prediction of drill wear. In this work, a multilayer BPWNN with wavelet algorithm has been applied to predict the average wear of a K10 carbide drill bit for drilling on a high silicon aluminum work piece. Mean value of the thrust force, cutting torque, and drilling depth, spindle speed and feed-rate are inputs to the network, and drill wear is the output. Drilling experiments have been carried out over a wide range of cutting conditions and the effects of drill wear, cutting conditions (spindle speed, drilling depth and feed-rate) on the thrust force and cutting torque have been investigated. Performance of BPWNN has proved to be satisfactory by experimental result. The accuracy of the prediction of drill wear using BPWNN is found to be better than using BPNN, and that BPWNN can learn the pattern faster compared to BPNN and could be used advantageously in online drill wear monitoring and prediction.

Fuzzy Rule Based Modeling of Drilling Parameters for Delamination in Drilling GFRP Composites

Fiber reinforced composite materials are used in different industries because of their mechanical and other properties. Drilling is one of the most important operations and is mainly used for joining in the manufacturing sector. Often it is a final operation during assembly. Defects in drilling lead to rejection and impose heavy losses. In drilling of glass fiber reinforced plastic (GFRP) composites, delamination is an important factor and is to be controlled. In this study, drilling tests were carried out on GFRP composite specimens using solid carbide drill bits. A L27 orthogonal array was used for tests. A fuzzy rule based model is developed to predict the delamination in drilling of GFRP composites. Good agreement is observed between the predictive model results and experimental values. The Fuzzy rule based model can be used effectively for predicting the delamination in drilling GFRP composites.

Enhancement of Wet- and MQL-Based Machining of Automotive Alloys Using Cutting Tools with DLC/Polymer Surface Treatments

Machining experiments using tooling prepared with thin perfluoropolyether (PFPE) lubricant films, which were applied to diamond-like carbon (DLC) PVD coatings, were compared to traditional tooling used in wet-machining conditions for the drilling of a cast aluminum-silicon B319 alloy. Multi-layered DLC + PFPE coatings show promise under minimum quantity lubrication (MQL) machining conditions of aluminum alloys. The positive impact on performance of this surface treatment is compared to wet machining by studying tool life, wear behavior and chip formation using coated cemented carbide drill bits. Cutting torque was measured in situ together with the characteristics of the chips. Also the chip cross-section micro-structure was evaluated using a scanning electron microscope (SEM).

Wear Characteristics of Twist Drills in Machining Fluorophlogopite

The machinable fluorophlogopite was drilled with tungsten-cobalt carbide and high-speed steel drill bits, respectively. The wear widths of major flank were measured, and the wear characteristic of twist was analyzed during drilling fluorophlogopite ceramics.Drilling experiments were carried to consider influence factors of drill bit wear, such as tool materials, cooling condition, spindle speed and tool angles. Tool materials and cooling conditions are the major factors to affect wear of drill bits. High-speed steel drill bits are not suitable for drilling fluorophlogopite ceramics. Cooling condition affects wear remarkably. With the rising of spindle speed, the wear widths of major flank grows. But apex angle has little affects on the tool wear rate. Research results indicate that low tool wear can be obtain through optimizing tool material and machining parameters in drilling fluorophlogopite ceramics.

Development of a Protocol to Retrieve Microorganisms from Ancient Salt Crystals

Previous research has indicated that halophilic microorganisms are associated with salt crystals from ancient formations. However,this research has generally failed to convincingly demonstrate that these organisms were originally trapped inside the crystals during their deposition and were not recent surface contaminants. This paper presents techniques for crystal selection; verifiable, noninvasive, surface sterilization of salt crystals; and sterile extraction of biological material from the crystals. Immersing salt crystals in 10 M NaOH for 5 min; rinsing with sterile, saturated brine before immersing for 5 min in 10 M HCl; and rinsing with saturated brine is an effective method for surface sterilization. No growth has resulted from contamination tests of 216 faces from 36 natural salt crystals exposed to these treatments. Pure culture experiments using the halotolerant eubacteria, Halomonas elongata and Bacillus sp. (2-9-3), and the archeon, Halogeometricium borinquense, showed that exposure to either 10 M HCl or NaOH reduced the population of these organisms by a factor of 107 to 108 colony-forming units/ml. The fluid is extracted from inclusions by drilling into surface-sterilized salt crystals with a variable-speed drill using sterilized 0.5-mm-diameter carbide drill bits and extracting the fluid with a sterilized microliter syringe. Drilling and extraction are performed in a Class II biosafety cabinet. All procedures are carried out in a biosafety level 3 facility. All personnel involved wear cleanroom coveralls, shoe covers, hair caps, and gloves. The above protocol has resulted in the isolation of a Bacillus sp. from a Permian-age salt crystal.