Punch Tool Research Articles

Increasing the stamping tools lifespan by using Mo and B4C PVD coatings

Prestigious brands of cookies usually use metallic tins as packaging to distribute and sell their products, trying to impress the customer through the appearance of the packaging and avoiding smashing or damages to the cookies during logistics operations. These packages are commonly made in a tin coated (2.8g/m2) thin steel sheet (ARCELOR electrolytic Tin plate), which causes severe wear problems on both die and punch tool components during the stamping process at room temperature. The border of the package presents an inconsiderable deformation, despite its almost perpendicular orientation to the top surface, but this top is usually patterned, which also implies the flow of the sheet between the top and bottom die surfaces. Due to the softness of the Tin coating, it easily adheres to the die, generating premature wear and several other concerns in maintaining the required final shape of the tin lid. Lubrication would be an easy way to solve the problems referred above, but lubrication operations should be avoided because these kind of packages are for food purposes.This study started by identifying the main wear mechanism developed in the stamping tool main surfaces, characterized by the Tin coated steel sheet used in the packages and testing two advanced PVD coatings (B4C and Mo) leading to the improvement of punch and die wear behavior under these work conditions. The transfer of Tin material from the metallic sheet to the punch and die was also studied, as well as the friction coefficient of this sheet against some selected coatings, while also trying to minimize the Tin adherence to the tool surfaces. Tribological tests under medium loads were carried out in order to ascertain what kind of coating presents better wear behavior in those work conditions. Regarding the results obtained, some improvements will be applied to the coating structure to adjust the deposition parameters in order to go forward to industrial tests. Worn surfaces were studied by Scanning Electron Microscopy (SEM) and material transfer was analyzed by Energy Dispersive Spectroscopy (EDS).Results obtained with some of the tested coatings confirm that it is possible to minimize the Tin transfer from the covered steel sheet to the die and punch, ensuring a longer life of these parts, decreasing the tool maintenance operations and improving the Overall Equipment Efficiency (OEE) of that stamping process.

Punch tool based out-of-plane shear behaviour of GFRP composites

In this experimental work, the behaviour of unidirectional glass fibre-epoxy composites under a cutting force was studied, in order to better understand the cutting mechanisms of processes involving but not limited to composite materials.Starting from composite panels manufactured by resin infusion process, dedicated specimens were obtained and subjected to a quasi-static punch-shear test. Eight different fibre orientation angles with respect to the direction of the cutting force were considered.For each case, different stress-strain behaviours were observed and discussed. The differences were also investigated, in terms of damage propagation, by means of microscopic observations of the cutting zone.

Experimental and numerical analysis of hydrodynamic deep drawing assisted by radial pressure at elevated temperatures

Nowadays, due to the demand for lightweight construction and fuel consumption reduction, especially in automotive and aerospace industries, the use of aluminum alloys has drawn much attention. Nevertheless, poor formability at room temperature is the main drawback of using these alloys. To overcome the problem, the work material is formed at elevated temperatures. In the present paper, Hydrodynamic Deep Drawing assisted by Radial Pressure (HDDRP) process has been selected over other forming methods. The aim of the study is to investigate the applicability of this process in conjunction with warm forming. For this purpose, experimental and numerical attempts have been made on warm forming of flat-bottom cylindrical cups in isothermal condition. At first, a series of warm hydroforming experiments were performed to determine the effect of tool temperature and forming speed on the thickness distribution of the final part and on the required forming load. Then, a set of finite element analyses (FEA) were performed using ABAQUS explicit to extend the findings. The Response Surface Method (RSM) was then used to build the relationship between the input parameters such as temperature and forming speed, and output responses including minimum part thickness and maximum punch force. It is demonstrated that the required forming force was decreased with increase in punch speed and tool temperature. Additionally, minimum thickness of the part is increased with increasing temperature and decreasing punch speed. Studying the Limiting Drawing Ratio (LDR) revealed that elevating the forming temperature causes reduction in LDR, while rising the punch speed leads to a slight enhancement in it. For the evaluation of part dimensional changes after forming, springback analysis was done via studying the through-thickness hoop stress distribution. It is found that using warm isothermal HDDRP in high forming rate results in more uniform stress distribution and lower level of stress and so a better springback behavior.

Topical Aloe Vera (Aloe barbadensis Miller) Extract Does Not Accelerate the Oral Wound Healing in Rats.

The effect of topical application of Aloe Vera (Aloe barbadensis Miller) extract was assessed on the healing of rat oral wounds in an in vivo model using 72 male Wistar rats divided into three groups (n = 24): control, placebo and Aloe Vera (0.5% extract hydroalcoholic). Traumatic ulcers were caused in the dorsum of the tongue using a 3-mm punch tool. The Aloe Vera and placebo group received two daily applications. The animals were sacrificed after 1, 5, 10 and 14 days. Clinical analysis (ulcer area and percentage of repair) and histopathological analysis (degree of re-epithelialization and inflammation) were performed. The comparison of the differences between scores based on group and experimental period, both in quantitative and semi-quantitative analyses, was performed using the Kruskal-Wallis test. The significance level was 5%. On day 1, all groups showed predominantly acute inflammatory infiltrate. On day 5, there was partial epithelialization and chronic inflammatory infiltrate. On the days 10 and 14 total repair of ulcers was observed. There was no significant difference between groups in the repair of mouth ulcers. It is concluded that treatment using Aloe Vera as an herbal formulation did not accelerate oral wound healing in rats.

Seasonal and reproductive effects on wound healing in the flight membranes of captive big brown bats.

ABSTRACTThe flight membranes of bats serve a number of physiological functions important for survival. Although flight membrane injuries are commonly observed in wild-caught bats, in most cases the damage heals completely. Previous studies examining wound healing in the flight membranes of bats have not taken into consideration energy constraints that could influence healing times. Wound healing results in increased energy demands, therefore we hypothesized that wound healing times would be slower during periods of energy conservation and/or energy output. In this study we used an 8 mm diameter circular punch tool to biopsy the wing membranes of healthy adult female big brown bats (Eptesicus fuscus) from a captive research colony to test the hypothesis that healing times will vary with seasonal temperature changes between the summer and winter seasons, and with reproductive condition between lactating and non-reproductive females. As expected, membrane biopsies took significantly longer to heal during the winter when bats were hibernating compared to the summer when bats were active. Surprisingly, no difference in healing time was observed between lactating and non-reproductive females. The wings of most bats fully healed, although some individuals showed wound expansion demonstrating that impaired healing is occasionally observed in otherwise healthy subjects.

Computer-aided design of blank forging production facilities for aircraft engine compressor blades

The computer-aided design (CAD) system is specified for the preproduction engineering of the aircraft engine compressor blades. This system is characterized by a high quality of designing the finishing cutoff and reducing dies. It is shown that a high level of unification and integration in CAD permits the time of designing the punch tool sets to be significantly reduced.

A Novel Technique for Sculpting Costal Cartilage in Microtia Repair and Rhinoplasty

Transforming a block of costal cartilage into a complex 3-dimensional framework that reflects the contours of a normal ear or nasal bridge requires the creation of many subtle curves, concavities, and convexities. Thus, specialized instruments for microtia repair and rhinoplasty, with specifically curved sharp blades, are used for delicate carving without the need for excessive force, which can damage the framework. Several challenges are associated with these specialized instruments. To describe a novel alternate technique using disposable skin punch biopsy instruments for sculpting cartilage, which have the potential to decrease cost, ensure consistently sharp blades, and provide a variety of sizes to allow precise, controlled contour changes. Surgical technique adapting a commercially available skin punch tool for costocondral sculpting. Academic tertiary care medical center. Patients undergoing microtia repair and rhinoplasty requiring sculpting of costocondral cartilage. Feasibility and reliability of cartilage contouring. This novel technique has been used in microtia repair and rhinoplasty with excellent results. This alternate technique of costocondral sculpting should be included as an additional tool in the reconstructive surgeon's armamentarium. NA.

Ductile fracture model in the shearing process of zircaloy sheet for nuclear fuel spacer grids

Features of sheared edges are predicted based on material properties of Zircaloy obtained from the tensile test and ductile fracture model such as the Gurson-Tvergaard-Needleman (GTN) and Johnson-Cook models. The sheared edges formations are numerically analyzed in each ductile model. An appropriate ductile fracture model is selected to study the relative depth of sheared edges with respect to process parameters. The tendency of failure parameters that are affected by sheared edges and fracture duration is investigated. We applied changes on parameters of failure models to show that the punch force curve and the ratio of characteristic lengths could be coincided, which led us to conclude that the GTN and Johnson-Cook models are equivalent. In the Johnson-Cook model, however, the characteristic length of the sheared edges does not change as each failure parameter reaches a critical value. Hence, the FE prediction model for forming defects is developed using the GTN failure model. Finally, the characteristic length of sheared edges have been measured using the FE prediction model for shearing process parameters such as punch velocities, clearance, and tool wear. Our results showed that the punch-die clearance is the most significant factor that affects forming defects when compared to other factors.

English

The tools used in the Blanking process are subjected to heavy forces, such that attends to break the profile of the tool, if it is not designed properly. The main aim of this project is to analyze and redesign a tool which is subjected to frequent breakage, due to the heavy impact force, a necessary condition for the Blanking operation. Tungsten carbide is a material used for a number of industrial applications and it is characterized by its high strength, toughness, hardness and it is having carbide grain size (0.2 – 50 microns , binder contents (up to 30%), as well as by the addition of other carbides. By varying the grain size of the tungsten carbide and the binder content in the matrix, engineers have access to a class of materials whose properties can be tailored to a variety of engineering applications. In the field of industrial engineering the factors reduction of cost, improved mechanical properties such as wear, corrosion ,very high or very low temperature resistant with good harden ability and mach inability characteristics are involves important role. An attempt on optimize design and analysis of blanking punch tool to increase its strength and life by applying ceramic coating over the tool material. The analysis of tool parameters like load, stress and life of the tool are the main causes of tool wear and their model generations are created through ANSYS software. Analyses and comparison of HCHCr & Tungsten carbide material tool which can be redesigned without affecting the final blanked profile for its strength and durability and to withstand the said extreme conditions. In this process the redesign of the tool is done initially in ProE and the final model is analyzed in ANSYS.

Wound Healing in the Flight Membranes of Big Brown Bats

Biologists routinely punch the flight membranes of bats to collect tissue for molecular analyses, or to mark animals in the field, or both. The current standard is to biopsy the wing membrane (chiropatagium) because it is easy to access and is less vascularized, and thus bleeds less, than the tail membrane (uropatagium). Although flight membrane biopsies are assumed not to affect the bat's ability to fly or capture prey, almost nothing is known about wound healing times and the optimal punch size or location for tissue excision. We measured wound healing in the wing and tail membrane of 32 big brown bats (Eptesicus fuscus) biopsied with 2 circular punch tool sizes, and quantified the concentration of DNA extracted from the excised tissue. Our results show that tail wounds healed significantly faster than wing wounds for both 4-mm- and 8-mm-diameter biopsy wounds. We also were able to extract significantly more DNA from tail biopsies than from wing biopsies of the same size. The newly healed tissue remains unpigmented for considerable time after wound closure, and this allows identification of individuals for an extended period. We hypothesize that the increased vasculature in the uropatagium contributes to faster healing times compared to the chiropatagium. Examination of our data indicates that tissue biopsy for molecular analyses in bats should be taken from the tail membrane, although biopsies of the wing membrane are useful for marking associated with recapture programs because the wound and scar will persist longer.

Practical effects of ion implantation for micro-scale punch tools

Micro electro-mechanical system (MEMS) devices fabricated by photo lithography techniques require expensive equipment and resources. MEMS devices such as acceleration sensors, pressure sensors, and optical scanners are only components of more complex devices, and therefore their fabrication must involve inexpensive processes to be cost-effective. We proposed to use the die-forming that is a possible inexpensive process in MEMS manufacturing facilities. Die-forming is a traditional fabrication system and has only been applied to sheet materials. Its advantages include low cost, high throughput, and assembly of parts made using the same die. This technique uses micro-scale punch tools to shear, and currently the lifespan of these tools is too short for use in mass production of MEMS. In this study, to increase the lifespan, ion implantation was applied to a Co–WC micro punch tools used to punch 150-μm holes in a 0.2-mm-thick stainless spring steel. Co–WC was selected as the material due to its hardness and its high resistance to compressive stress, although its resistance to tensile stress is low. This low tensile strength causes a Co–WC punch tool to fracture, and thus determines the lifespan of the tool. The friction between the punch tool and the punched material actually induce tension of the tool. To improve the friction relate to the tensile strength, and therefore the lifespan, of a Co–WC punch tool, in this study this tool was implanted with gold ions accelerated at 75 keV at doses 1 × 10 16 cm − 2 (1 × 10 20 m − 2 ) and then annealed at 700 K for 30 min. Cross-sectional transmission electron microscopy was used to observe the changes in the fabricated tool induced by the implantation and annealing, and a sliding test was also applied to evaluate the friction coefficient of surface modified samples. The heavy gold ions were expected to break the crystal lattice and boundary between Co and WC, and the post annealing to rearrange the disordered lattice and thus improve the toughness of micro punch tools. Gold ions also act as a catalyst to oxidize the Co–WC. In conclusion, gold ion implantation and post annealing process together increased the lifespan of the punch tool by a factor of 16. Such punch tools can therefore be used in mass production of MEMS devices.

Micro-Hole Multi-Point Punching System Using Punch and Die Made by EDM

In this research a multi-point micro punch and die system was developed. The process of electric discharge machining (EDM) was used to produce both the punch and die. The punches were machined from a 5 mm diameter tungsten and a 10 mm diameter tool steel round rods by wire electric discharge machining (WEDM), using a 200 µm diameter wire electrode. The die holes were made using the punch as the electrode. The EDM process of the holes was carried out on a newly developed desktop EDM machine. The punch and die placed on a micro-die set and then on a micro press were used to produce micro-holes using an automatic control system developed for this process. Experiments to produce 50 µm to 67 µm square micro-holes on 50 µm thick aluminum, 30 µm thick copper and 20 µm thick stainless steel foils were conducted. The capabilities of multi-point punching using the tungsten punch and a tool steel punch were examined and tungsten was chosen as the material of choice for making the punch tool. A scanning electron microscope confirmed that the holes produced are clean, and the sheared surfaces smooth. The punch tool showed no signs of deformation or cracks even after repeated punching.

Material transfer phenomena and failure mechanisms of a nanostructured Cr–Al–N coating in laboratory wear tests and an industrial punch tool application

In this research, CrAlN and TiN coatings were deposited on AISI M2 tool steel substrate test coupons and on industrial punch tools by electron beam plasma-assisted physical vapour deposition (EB-PAPVD). The microstructure and morphology of the coatings were investigated by XRD, XPS, TEM, and SEM with EDX. Pin-on-disc tribotests were conducted on the coatings against AISI 52100 steel counterface material in order to investigate their wear performance, with particular emphasis on the material transfer phenomena during the sliding tests. After industrial trials on piercing high strength steels, the worn uncoated as well as CrAlN- and TiN-coated punches were also studied. The results showed that the nanostructured CrAlN coating exhibited less material transfer and thus better adhesive wear protection than the TiN coating under both laboratory pin-on-disc tribotests and industrial trial conditions. It was also found that the coating morphologies replicated the surface finish of the punch substrates, and that local coating spallation appeared to be initiated at machining grooves on the punches, which were detrimental to the coating lifetime.

The die failure prediction and prevention of the orbital forging process

The die failure occurs if the stress is too large. In this paper, the die stress analysis of the orbital forging process had been carried out to obtain the die stress distributions and predict the die failure. The different installation positions of punch, preforms, and profiles of punch tip and tool configurations were proposed to find the die failure conditions. The results of this study showed the installation error, punch tip with long mandrel and split die configuration had resulted in significant die stress and die failure occurred. The new punch profile and preform shapes had been designed to prevent the die failure and product defects. FEM code had been adopted to simulate the forging process and analyze the die stress. The upsetting tests had been carried out to obtain the flow stress parameters of AISI 4115. A PXW-200 orbital forging press had been adopted for the orbital forging tests. The failures of punch were observed in the experimental tests and precisely predicted by the simulation.

Improved lifespan of micro-scale punch tools by ion implantation

Micro-scale tools, such as punch tools, used in die-forming processes to fabricate micro-scale mechanical devices currently have a relatively short lifespan. The ion implantation method studied in the 1980s shows promise for improving the lifespan of micro punch tools. In this study, 150 micro m-diameter holes were punched in a 0.2-mm-thick stainless spring steel by using a punch tool. Ion implantation of the punch tool using silicon or gold species decreased the lifespan of the tool. However, the punch tool was then annealed at 700 K for 30 minutes after ion implantation, the silicon-ion implanted punch tool apparently restored its lifespan to that of an 'un-processed' punch tool (no ion-implantation or annealing). Moreover the gold-ion implanted punch tool had a lifespan 10 times longer than an un-processed punch. In conclusion, rearrangement of the disordered lattice caused by ion-implantation damage improves the toughness of micro punch tools.

Effect of Water on Shear Strength of Glass Ionomer Cements for Luting

This study examined the effect of ambient water on the shear strength of glass ionomer cements for luting. Disk specimens were fabricated from four commercially available glass ionomer cements with different setting modes. At one hour after the start of mixing, the specimens were stored at 37 degrees C for 24 and 168 hours in dry condition or in deionized water. Shear strength was then determined using a punch tool. The shear strengths of both conventional cements were significantly greater for the specimens stored dry as compared to those kept in deionized water (p < 0.05). Conversely, resin-modified cement specimens stored dry had significantly lower strength compared to the specimens kept in deionized water (p < 0.05). This was because the ambient water surrounding the resin-modified glass ionomer cements helped increase the shear strength of the cements under the experimental conditions tested.

Stamp forming of polypropylene based fibre–metal laminates: The effect of process variables on formability

In stamp forming of sheet materials, the quality of the part and the robustness of the process are determined by a number of variables. This study looks at the application of the stamping process to a fibre–metal laminate (FML) material system and the effect of the blankholder force, punch feed rate and tool radius on the quality of a channel formed laminate. The results indicate that increasing feed rate reduces shape error and delamination significantly and reduces the variation between repetitions of the same test. Furthermore, analysis of the bend radii reveals that the normalised deviation in bend radius from the tool radius is constant for the range of radii investigated. This suggests that FML materials can possess superior formability characteristics compared to monolithic aluminium.

Evaluation of wear mechanisms of Y-TZP and tungsten carbide punches

Tool wear is one of the major concerns in the tooling industry. A comparative evaluation of different tool materials and tool wear will help preventing frequent replacement of tools thus reducing the costs incurred due to such replacements. In this paper, tool wear mechanism of tetragonal zirconia polycrystal (TZP) punch is compared with that of commercially available WC (tungsten carbide) punch during stamping. The tool life for the TZP punch was found to be over 2.5 times higher than that of commercial tungsten carbide. The worn-out tools were analysed using scanning electron microscope and optical microscope for studying the tool wear mechanisms. Tool wear and chemical action possibly cause the failure of the tungsten carbide punch, whereas wear of TZP punch is predominantly caused by mechanical shearing of asperity and plastic deformation. Due to their inherent high melting point and the absence of the second-phase binder, ceramics materials do not soften at higher temperature unlike the carbide tools. Hence, they can be used at high cutting speeds without initiating deformation/diffusion wear. This assists in improving the tool life significantly. In addition, TZP ceramics is inert, corrosion resistant and non-wetting when contacting metals. Exposed carbide grains act as a site for increased wear and metal pickup during precision, high-speed metal stamping and forming. Moreover, cobalt-depleted carbide tools can create burring of the strip being stamped, leading to poor part quality. The performance of TZP punch tool will be evaluated thoroughly based on experimental data in this paper.

Surgical Pearl: Double-trephine punch biopsy technique for sampling subcutaneous tissue

M any dermatoses can affect the subcutaneous tissue. The clinical presentation is polymorphous as in cutaneous polyarteritis nodosa, exhibiting the spectra of inflamed nodules, deep ulcers, digital infarcts, livedo reticularis, and stellate scars. Consequently, a reliable, clinically guided, histologic examination is crucial in achieving an accurate diagnosis. Unfortunately, clinicopathologic incongruity is not uncommonly encountered–the fault occasionally lies in sampling of inadequate tissue. To circumvent this problem, incisional wedge biopsies have been considered as the gold standard for the evaluation of these disorders.1 The potential disadvantage of incisional biopsies, however, is the time consumption of using this technique on multiple locations. Sampling of tissue with intense, perilesional fibrosis and necrosis such as an ulcer makes hemostasis and closure of an elliptic defect nearly impossible. Another limitation of the incisional biopsy is that the sample is taken along a single axis. For example, a biopsy of an ulcer aligned in the 12 o’clock to 6 o’clock axis would, therefore, not be able to include histologically relevant tissue at the 3 o’clock edge. To address these issues, we describe a technique called the “double-trephine punch.” Although the trephine punch tool used in hair transplants has been previously proposed for the diagnosis of panniculitis, the tool is not readily available in a dermatology clinic,2 and subcutaneous tissue would also be difficult to recover from such a small and deep defect (Fig 1). Our proposed technique can be regarded as a compound punch biopsy using common, disposable, cutaneous punch tools. Sampling may occur at various locations along the margins and within the center of the lesion. Such a procedure is quickly and easily performed and would not require a second office visit for more involved biopsies. The tools necessary to perform the double-trephine punch are simply that which are used in a standard punch-biopsy procedure. An additional 8-mm punch tool is necessary, and the optional availability of electrocautery and Gelfoam (Pharmacia & Upjohn Company, Kalamazoo, Mich). The site for sampling is chosen to ensure the highest yield. Observing standard, clean, surgical procedure techniques, the lesion is prepared and locally anesthetized. Countertraction is applied with the nondominant hand, and the 8-mm punch tool is inserted to the hilt of the instrument to obtain the initial sample (Fig 2, left). Once the superficial core is removed, subcutaneous tissue should be readily

The softly‐softly approach of robotic waterjet cutting

An extremely high‐pressure jet of water is an efficient method of cutting soft materials, and combining the waterjet process with industrial robots is an economic alternative to the traditional punch tool method of producing complex‐shaped components for car interiors, such as floor carpets, headliners and door trims. Applications are given of robotic waterjet systems installed in the USA, France and Iran as well as news of a new cutting box introduced by ABB‐IR Waterjet Systems. A further development of the waterjet process is described in which the addition of abrasives enables aluminium castings to be fettled and cleaned.