Smooth Cut Surface Research Articles

Development and parametric study of reversible motion-wire electrochemical spark machining (RM-WECSM) setup for micro-width curve profile cutting on Al2O3 epoxy nanocomposites

The development of wire electrochemical spark machining setup is always challenging in the form of industrial viable for machining advanced engineering materials such as polymer nanocomposites, quartz, glass, ceramics, etc. Because of some drawbacks associated with it, like irregularity in kerf width, poor surface finish, no spark formed at high wire velocity, wire breaking at high voltage, etc. In the present work, a newly developed hybrid machining process that is reversible motion-wire electrochemical spark machining (RM-WECSM) has been developed for curve profile cutting, especially on non-conducting workpieces such as aluminum oxide epoxy nanocomposite of 3.5 mm thickness. The effect of NaOH concentration, applied voltage, reversible wire velocity, pulse on-and-off time, on material removal rate and average surface roughness have been studied using a one-parameter-at-a-time approach. Sparking occurred from the electrolyte surface to 10 mm above the electrolyte surface to cut the workpiece. The spark length is equal to the workpiece thickness. A continuous, stable spark has been formed at a high reversible wire velocity (19.8 m/min). Simultaneously, self-electrolyte flow has been generated, due to which melted materials have been washed out of the cut-surface and provided the smooth (1.987 µm) cut-surface of the workpiece. The maximum MRR is found as 1.63 mg/min. Thermal cracks, heat-affected zones and recast layers were not found on the curve cut-surface, and it was analyzed by a field emission scanning electron microscope.

Quantitative evaluation of the sheared edge of woven glass epoxy laminate after mechanical punching

Fiber-reinforced composites have a wide range of industrial applications owing to their light weight, high modulus, and good specific strength. Trimming using a mechanical punching tool is the fastest way to post process fiber-reinforced composites. However, quantitative analyses of the defects and process parameters are required to analyze the damage mechanisms and achieve high-quality cut surfaces. In this study, we quantitively investigated the defects on the sheared edge of woven glass epoxy laminates subjected to mechanical punching and explored the correlations between these defects and key process parameters, including punch-die clearance, weave alignment angle, and laminate thickness. The results demonstrate the necessity of considering glass fiber burr length and the dimensions of the cracked area simultaneously to evaluate the quality of the sheared surface. This study provides qualitative data on the interfacial damage mechanisms that occur during mechanical punching, which will help to tailor the process parameters of mechanical punching for fiber-reinforced polymers to obtain smooth cut surfaces.

Naturally Occurring Rock Type Influences the Settlement of Fucus spiralis L. zygotes

The settlement of spores and larvae on hard substrates has been shown to be influenced by many factors, but few studies have evaluated how underlying bedrock may influence recruitment. The characteristics of coastal rock types such as color, heat capacity, mineral size, and free energy have all been implicated in settlement success. We examined the influence of naturally occurring rock types on the initial attachment of zygotes of the brown alga Fucus spiralis Linnaeus 1753. We also assessed the dislodgment of zygotes on four bedrock types after initial attachment in laboratory experiments using wave tanks. Settling plates were prepared from limestone, basalt, schist, and granite, found in the region of Orrs Island, Maine, USA. The plate surfaces tested were either naturally rough or smooth-cut surfaces. We measured the density of attached zygotes after 1.5 h of settlement and subsequently after a wave treatment, in both winter and summer. The pattern of initial attachment was the same on natural and smooth surfaces regardless of season: highest on limestone (range 7.0–13.4 zygotes/cm2), intermediate on schist (1.8–8.5 zygotes/cm2) and basalt (3.5–14.0 zygotes/cm2), and lowest on granite (0.8–7.8 zygotes/cm2). Patterns of survivorship following the wave treatment were similar to those of initial settlement with the mean survivorship varying from 60.1% (SE = 3.8) (limestone, smooth substrate) to 31.8% (SE = 0.59) (granite, natural substrate), and with the highest mean survival on limestone, basalt, and schist, and the lowest on granite. Our results suggest that rock type has a significant effect on zygote attachment and persistence. Patterns of attachment were the same on smooth and rough surfaces, indicating that surface roughness is not the predominant factor controlling the difference in successful attachment among rock types. Other properties of bedrock, possibly grain size, surface free energy, or chemical interaction with the adhesives used by the zygotes, directly affect the attachment of these algal propagules. These results suggest that patterns of benthic community structure could be determined in part by the distribution of bedrock types.

Glass precision micro-cutting using spark assisted chemical engraving

Manufacturing industry faces new challenges with the emergence of the need for the production of small batches of personalized parts. Such production methods demand for a capability to integrate multiple machining operations in one manufacturing process to reduce setup and calibration time and tooling costs. This requirement is especially challenging for difficult-to-machine materials such as glass, since there exist only a limited number of glass machining technologies and further these technologies often require specialized tooling. Glass cutting is among the crucial machining operations, which is frequently required for glass products.The presented study discusses free-form micro-cutting by Spark Assisted Chemical Engraving (SACE), determining cut parameters, in terms of tool feed-rate F and depth-of-cut p in function of machining voltage. A simple model is discussed allowing to predict the maximal product F⋅p which can be used to cut glass by SACE. The presented data and model allow to reduce the time-consuming trial and error process in determining appropriate cutting parameters. An interesting finding is that lowest cutting times can be achieved with tools of 100-μm diameter. Cut surface roughness of initial cuts can be reduced by deploying subsequently incremental finishing (polishing) passes performed at lower machining voltage, lower tool feed rates and higher angular tool rotation. It is demonstrated that very smooth cut surfaces (Rz ~ 1 μm) can be achieved.

Fabrication of clean cut surface on high strength steel using a new shaving die design

A shaving process is commonly applied to achieve a smooth cut surface thorough the workpiece thickness and a square cut-edge, also known as a finishing operation. However, this process is rarely successful for high-strength steel sheets, which is a major problem. In the present study, finite element method (FEM) simulation was used to clarify the main causes of this problem by comparing the shaving mechanisms between medium carbon steel grade SPCC (JIS) and high-strength steel grade SPFH 590 (JIS). Results show that in the case of SPFH 590 based on material flow, stress distribution, and strain distribution analyses, the shaved chip was difficult to form by sliding along the punch face. Moreover, the tensile stress generated in the shearing zone was increased and readily generated cracks. The shaving process was developed in the present study by generating the cutting-edge angle and rake radius on the punch. The cutting edge angle was designed to generate high compressive stress in the cutting-edge vicinity and shearing zone, and the rake radius was designed to tear a shaving allowance off and move it along the rake radius instead of moving downward along the punch movement direction, thereby decreasing the tensile stress in the shearing zone. Under these mechanisms, the increases in the generated tensile stress in the shearing zone could be delayed, and cracks could thus be prevented. The effect of the punch geometry on the cut surface characteristics and cutting forces were also investigated. Laboratory experiments were performed to validate the FEM simulation results. Experimental results agreed well with the FEM simulation results. Therefore, a smooth cut surface thorough the workpiece thickness of high-strength steel sheets could be successfully achieved by using the developed shaving process.

Investigations on AWJ cutting process of hybrid aluminium 7075 metal matrix composites using nozzle oscillation technique

Difficult-to-machine materials like composites, super alloys and ceramics are cut by Abrasive water jet cutting (AWJC). However, the failure of the jet to cut through the work piece is a major issue particularly in thicker materials. The jet’s inability to produce longer smooth cut surface, minimum surface roughness and minimum kerf taper are the major challenges the researchers are trying to find solutions. This paper addresses the three issues in cutting of aluminum 7075 hybrid metal matrix composites. The hybrid composite is developed by incorporating two reinforcements (B4C and TiC) into Aluminum matrix. Cutting experiments were carried out on Pure AL7075, AL7075 + (2.5%B4C + 2.5%TiC), AL7075 + (5%B4C + 5%TiC)AL7075 + (7.5%B4C + 7.5%TiC). The surface generated, smooth cut region and kerf taper were analyzed on the all composite machined using AWJC machine.

Experimental Comparison of the Performance of Cutting Bone and Soft Tissue between Piezosurgery and Conventional Rotary Instruments

Piezosurgery is an innovative technique widely used for osteotomies in the field of oral and maxillofacial surgery. The surgical technique has been clinically supposed to cut mineralized bone selectively with reducing the risk of damage to adjacent soft tissues. However, none of the previous literature has reported any evidence of scientific experiments to examine performance of the piezoelectric device, i.e. the time required for cutting bone and the effect on soft tissues under the standardized conditions. This study was designed to test the hypothesis that cutting time of the piezoelectric device is longer than that of rotary instruments while the cut surface of bone is smoother and soft tissues are less damaged with piezosurgery under the standardized experimental system. We measured the time for cutting bone and soft tissues of rats with the piezoelectric device and rotary instruments. Damage to soft tissues was examined histologically, and the cut surface of bone was investigated using scanning electron microscopy. Our study demonstrated experimentally that piezosurgery provides a smooth cut bony surface with no damage to soft tissues and takes longer time to cut bone than conventional drillings. We propose that piezosurgery is beneficial for medical safety and usability.

Super-high-thickness high-speed wire electrical discharge machining

High-speed wire electrical discharge machining (WEDM-HS) of materials of super-high thickness (more than 1000 mm) is a challenging problem. First, sufficient energy is required to maintain the inter-electrode normal discharge. Next, there must be adequate inter-electrode dielectric fluid. Third, in order to generate a smooth cut surface, it is necessary to suppress the vibration of the wire electrode to reduce vibration lines on the cutting surface. To better understand these challenges, the energy and the flow of the medium between two electrodes were analyzed, allowing the establishment of a relevant model. The results indicated that for super-high-thickness machining, the pulse energy must be adequate to compensate for the energy consumed in the molybdenum wire and inter-electrode working liquid. In addition, the running speed of the wire electrode should be improved to ensure that there is a sufficiently high flow rate of the dielectric fluid. The servo control mode of the existing machine tools and dielectric fluid were improved and then a process experiment was performed. The experimental results show that the process can be carried out efficiently and stably and the workpiece surface can be cut smoothly using the improved working liquid and servo control mode.

Robotic guided waterjet cutting technique for high tibial dome osteotomy: A pilot study.

Oscillating saws generate high levels of heat (up to 150°C), which can lead to tissue necrosis, delayed healing and infection. Abrasive waterjet-cutting techniques have been described as a new tool to perform bone cuts, with less heat generation. Four lower-limbs of four human alcohol conserved cadavers were tested. Navigation references were attached to the tibia and an intraoperative fluoroscopy-based 3D scan was obtained. A 1.2mm diameter nozzle was attached to a robotic arm, which was guided to follow a pre-specified path. In addition, a self-designed jet-absorber was applied to protect the posterior neurovascular structures. Magnesium was added as an abrasive substance to improve the cutting ability of the waterjet. In all four cadavers, the osteotomies could be carried out as planned, resulting in smooth cut surfaces. No damage to the soft-tissues was observed. The advantages of abrasive waterjet-cutting give it great potential in orthopaedic surgery. A current disadvantage is the amount of magnesium solute that is left on the surgical field and can be harmful to the patient.

Cut Surface Features in Various Die-Cutting Processes

Currently, the shaped parts combined with straight, concave, and convex portions are increasingly fabricated. To produce the straight portion, the shearing theory is usually applied. As well as, to produce the concave and convex portions, the punching and blanking theories are usually applied. However, with the same die-cutting process parameters, the comparison of cut surface features of straight, concave, and convex portions has not been investigated yet. Therefore, in the present research, the comparison of the cut surface features in various die-cutting processes, including shearing, blanking, and punching processes are investigated. The finite element method (FEM) was used as a tool to investigate these cut surface features. The cut surface features were investigated and clearly identified via the changes of the stress distribution analyses. The results elucidated that with the same die-cutting process parameters, the different cut surface features were obtained. Specifically, the crack formations were easily generated in the case of blanking process, following by the shearing and punching processes, respectively. Therefore, the smooth cut surface was smallest in the case of blanking process, following by the shearing and punching processes, respectively. The laboratory experiments were carried out to verify the accuracy of the FEM simulation results. Based on the cut surface features, the FEM simulation results showed good agreement with the experimental results in terms of the cut surface features. Therefore, to design the die-cutting process parameters to meet the product requirements of complicated shapes, the understanding on these working process parameters being upon the shaped parts is necessarily.

Overflow-assisted laser machining of titanium alloy: surface characteristics and temperature field modeling

Underwater laser machining process is a promising method to cut materials with less thermal damage. A variation of underwater technique is overflow-assisted laser ablation. This process can introduce a higher thermal convection and more uniform water layer than the typical underwater method. Such characteristics can encourage the damage-free fabrication and also stabilize the laser ablation in water. In this study, cut profile and temperature distribution of workpiece induced by the overflow technique were investigated. Titanium alloy (Ti-6Al-4V) used as a work sample was grooved by a nanosecond pulse laser under different overflow conditions. The effects of laser power, laser repetition rate, and water flow velocity were experimentally and numerically examined. A clean and smooth cut surface can be fabricated when the overflow technique was used. Microcracks and porosities found on the laser-ablated area were also addressed in this study. The temperature field of titanium alloy under the different ablation conditions was simulated by using the finite difference computation. The transient heat conduction model was implemented together with the enthalpy method and temperature-dependent material properties. By using the developed model, the groove depths obtained from the experiment and simulation were in a good agreement.

Experimental Analysis of the Feasibility of Shaving Process Applied for High-Strength Steel Sheets

In recent years, the engineered materials were developed to improve their mechanical properties. A high-strength steel sheet is one of them, developed to serve the requirement of reducing weight of vehicles. Therefore, as a new material, many researches have been carried out to examine the use of sheet metal forming process applied for high-strength steel sheet. However, the feasibility of shaving process applied for it has not been investigated yet. In the present study, this feasibility was revealed by using experiments on two types of high-strength steel sheets: SAPH 440 and SPFH 590Y (JIS). The relationship between shaved surface feature and shearing clearance of high-strength steel sheets corresponded well with those of their conventional metal sheets. However, due to the high ultimate strength of these materials, it was revealed in this present study that there were not any suitable conditions of shaving process that could be applied to achieve the requirements of smooth cut surface overall material thickness.

Case report: benign cellular leiomyoma with intravascular leiomyomatosis

Background Intravascular leiomyomatosis (IVL) is an intraluminal growth of benign smooth muscle cells in the uterine or pelvic lymphatic or venous vessels beyond the confines of a leiomyoma. Case report A 35-year-old female was admitted for elective total abdominal hysterectomy for menorrhagia secondary to a fibroid uterus. Macroscopically, the fibroid measured 130 mm and had a smooth whorled cut surface. Histological examination confirmed the presence of a cellular leiomyoma with degenerative changes and multiple intravascular permeations outside the confines of the leiomyoma consistent with IVL. No necrosis, atypia or excessive mitotic activity was seen. The leiomyoma was positive for smooth muscle, oestrogen and progesterone markers. CD31 and CD34 positivity confirmed vascular permeation. Endometrial stromal sarcoma and leiomyosarcoma were subsequently excluded. Discussion Intravascular leiomyomatosis is a growth pattern variant of benign uterine leiomyoma. Benign leiomyomas with IVL should be especially distinguished from endometrial stromal sarcoma and also leiomyosarcoma, as they differ in their behaviour, management and prognosis. The main treatment modality is hysterectomy and excision of any uterine or extra-uterine tumour if feasible. Anti-oestrogen therapy is recommended for controlling the growth of an unresectable tumour.

Effects of Parameters on Fine Blanking of Steel Synchronizer Ring Teeth

The influences of parameters on fine blanking of steel synchronizer ring teeth have been studied in this paper. Based on the finite element (FE) analysis software DEFORM-3D, a three-dimensional FE model of fine blanking of steel synchronizer ring teeth was established. By analyzing the distribution of hydrostatic stress, the length of smooth cut surface and the height of die-roll, the influence of parameters (i.e., counterforce, blanking clearance and V-ring indenter form) on the cut surface of synchronizer ring teeth were discussed. The quantitative relationships between parameters and the cut surfaces were established. The results show that: Increasing counterforce, decreasing blanking clearance and V-ring indenter located on die are conducive to increase the length of smooth cut surface and to decrease the height of die-roll. These results have a certain guiding significance on the production process of fine blanking of steel synchronizer ring.

ハイテン材の平滑・高精度切り口面を得る方法

Methods by which smooth and high-precision cut surfaces of high strength steel sheets with strength of up to 980MPa class have been investigated using a servo press in which the average punching speed can be varied from 2 to 140mm·s-1. A method called finish blanking has been performed, and the other method called press shaving has also been conducted to obtain either smooth cut surfaces or highly precise product shapes and dimensional sizes. The results show that both methods can yield good cut surfaces if appropriate working parameters including punch/die clearance, edge radius and punching speed are used. However, as regards shape and dimensional accuracies, the press shaving method yielded the most satisfactory results.

Application of Finite Element Method to Analysis of Ductile Fracture Criteria for Punched Cutting Surfaces

Many types of punching processes are utilized in the production of automobile parts and other components. In normal punching with a punch and a die, a sheared surface and a fractured one are usually formed on the cut surface. Here, to produce highly accurate parts, it is important to estimate the ratio of the sheared surface to the cut surface and to economically produce smooth cut surfaces, optimal tools and punching conditions must be selected within the limits of cost constraints. The finite element method (FEM) has been applied to the analysis of the ratio of the sheared surface to the fractured surface on the cut surfaces. For this, the ductile fracture criteria for the fracture initiation of the cut surface have been proposed by several researchers. It is difficult to determine the fracture criteria on the cut surface by tensile tests or bending tests because the punching process consists of many complicated steps. In this study, we apply the FEM to four punching arrangements to evaluate the ductile fracture criteria proposed by Oyane and by Cockcroft and Latham. We find that the morphology of the cut surface is affected by clearance between the punch and the die, by blank holding conditions and by ductile fracture criteria. [doi:10.2320/matertrans.P-M2013811]

Die Design in Fine-Piercing Process by Chamfering Cutting Edge

The hole quality on sheet metal parts is directly dependent on the die design and process parameters. In conventional piercing process, the secondary operations such as shaving, reaming and grinding are needed for manufacturing the precise-dimensioned holed parts without any cracks, resulting in the increase of both production time and costs. The fine-piercing process, referenced to the fine-blanking principle, is used to produce the precise-dimensioned holed parts with smooth-cut surfaces over the whole material thickness in a single operation. However, it is difficult to achieve the suitable die design and process parameters for meeting the part requirements. In this study, the die design by chamfering punch cutting edge was investigated on both the experiments and the finite-element method (FEM). The results were compared with the results obtained when the conventional die design with the punch cutting-edge radius was used. The FEM-simulation results showed the amount of die-roll, smooth-cut surface, and cracks agreed well with the experimental results. The results showed that an application of punch cutting-edge chamfer results in a superior fine-pierced hole surface could be achieved. Furthermore, the mechanism and effects of the punch cutting-edge chamfer have been theoretically clarified on basis of the material-flow analysis and stress distribution.

Application of Back-Up Ring in Fine-Blanking Process

Considering the advantages of the fine-blanking process, the smooth-cut surface without further operation could be fabricated. However, one of the major problems of the fine-blanking is the occurrence of the die-roll formation. This problem is the main factor which affects the quality of the fine-blanked parts. In this study, to reduce the amount of die-roll formation, the application of back-up ring was proposed. The finite element method (FEM) was used to investigate the effects of back-up ring. In addition, the effects of bridge width were also investigated. The FEM simulation results illustrated that the mechanism of back-up ring and the effects of bridge width could be theoretically clarified base on the material flow analysis. The FEM simulation and experimental results showed the good agreement with each other. Therefore, the application of back-up ring could reduce the amount of die-roll formation on the fine-blanked parts. In this study, the amount of die-roll formation increased as the bridge width increase and it was constant at the bridge width of over 15 mm.

Finite-element analysis of V-ring indenter mechanism in fine-blanking process

In fine-blanking process, V-ring indenter is very important in increasing the edge quality of the blanked part. Previous research in this field was mainly experiment-based; therefore, the theoretical mechanism was not clarified. In this study, the V-ring indenter mechanism was investigated using the finite element method. The mechanism and effects of the V-ring indenter could be theoretically clarified on the basis of material flow analysis and stress distribution. The application of the V-ring indenter increased compressive stress before the cutting phase, and significantly suppressed the increased rotation of material flow during the cutting phase. This, in turn, caused increased hydrostatic compressive stress, resulting in a larger smooth cut surface.

Diabetic (lymphocytic) Mastopathy With Exuberant Lymphohistiocytic and Granulomatous Response

We report a case of a 66-year-old woman who presented with multiple painless masses in both breasts. Prior bilateral biopsies were diagnosed as Rosai-Dorfman disease (Sinus Histiocytosis with Massive Lymphadenopathy). A recent lumpectomy specimen revealed a gray-white smooth cut surface with a discrete masslike lesion. The histopathology demonstrated a fibrotic breast parenchyma with foci of dense fibrosis and scattered inconspicuous breast epithelium surrounded by lymphocytes that formed aggregates and follicles with germinal centers. The inflammation was in a periductal, perilobular, and perivascular distribution. In addition, an exuberant inflammatory response with histiocytes and fibroblasts was present. This inflammatory response focally surrounded areas of fat necrosis and formed noncaseating granulomas with rare multinucleated giant cells. This process had infiltrative, ill-defined edges and involved the subcutaneous tissues. The overlying epidermis was normal. The final diagnosis was diabetic mastopathy with an exuberant lymphohistiocytic response. The differential diagnosis included Rosai-Dorfman disease, inflammatory myofibroblastic tumor, granulomatous mastitis, sclerosing lipogranulomatous response/sclerosing lipogranuloma, lupus panniculitis, and rheumatoid nodules. Immunohistochemical studies and flow cytometry confirmed the polyclonal nature of the lymphoid infiltrate. After the histologic evaluation, we inquired if the patient had a history of diabetes mellitus, and learned that she did have type 2 noninsulin-dependent diabetes mellitus. In conclusion, we report a case of diabetic mastopathy that presents with bilateral tumorlike masses and an unusual exuberant lymphohistiocytic response with granuloma formation. The pathologist may not be provided with a history of diabetes mellitus, but the characteristic fibrosis, lymphocytic ductitis/lobulitis, and sclerosing lobulitis with perilobular and perivascular lymphocytic infiltrates should provide clues for an accurate diagnosis, even when an exuberant and an unusual lymphohistiocytic response is present. A timely accurate diagnosis can help limit repeat surgeries in this vulnerable group of patients.