Metal Tools Research Articles

FORGING ON COPPER BETWEEN CRAFT AND CREATIVITY

Minerals are one of the most abundant elements in nature, and they have a strong and distinctive presence and influence in human civilization, as they have contributed, with their multiple capabilities, to achieving many achievements, starting from simple metal tools to powerful compounds. The discovery of minerals is a revolution in the history of the development of human thought, as it moved from the era of stone use to the era of metal use and the subsequent discovery of its strength and uniqueness, and one of the most important minerals that had a great impact on industrial development is copper metal, which was used in the past in the manufacture of weapons and tools.

Новые находки металлических орудий Эпохи бронзы на территории лесостепного Подонья /

Новые находки металлических орудий Эпохи бронзы на территории лесостепного Подонья /

Controlling the pressure force to obtain a better quality of aluminum 6061 friction stir welded joint

Friction stir welding (FSW) is one of the mechanical joint methods that need no filler metal. The heat is obtained from the friction force between the base metal and friction tool. The FSW is proposed by The Welding Institute – TWI in 1991 which is hoped to overcome problems to weld metals with low weldability. Parameters of FSW determine the quality of the joint and in this paper the normal force as an independent parameter varied at 13,000, 14,000 and 15,000 N. The rotation and feeding speeds are controlled at 1,092 RPM and 200 mm/min respectively. From the experimental results, it is found that 15,000 N provided the strongest joint (specimen 1). The highest heat input was claimed to cause a better joint. This high heat input provides enough weld nugget and time for the aluminum to grow its grains, which in turn increase the tensile strength of the FSW joint.However, from the average values and the trend line it cannot be assumed that the greater pressure force always produces higher tensile strength. The tensile strengths were almost at the same level (115.44±1.56 MPa) meanwhile the calculated heat input is linearly dependent on the pressure force: 73.59, 79.25 and 84.91 J/mm for pressure forces equal to 13,000, 14,000 and 15,000 respectively. The recorded temperature, which indicates heat input showed the same trend with tensile strength, it was on the same level, those are: 491.55±2.22 °C. There must be some aspects which were not taken into account in the heat input mathematical model. Or maybe, the assumption of higher heat input is not always accomplished by the higher pressure force. Based on the literature, it is found that the yield strength is mitigated at a higher temperature. This lower yield strength decreases the friction force for a constant normal force which in turn causes declining heat input which contradicts the previous assumption.Another literature that inspected the coefficient of friction as a function of temperature showed that the coefficient is altered due to temperature.And finally, the higher normal force does not mean a stronger joint can be produced by means of Friction Stir Welding

ADVANCEMENT IN ULTRASONIC VIBRATION AND MAGNETIC FIELD ASSISTED MICRO-EDM PROCESS: AN OVERVIEW

Micro-machining of components has been emerged as a peak demand in the world of micro-manufacturing. Micro-EDM is proved to be the most suitable for micro drilling purposes. It is very essential to fabricate micro holes as well as features with very high dimensional accuracy and precision. The major drawbacks in micro-EDM processes are the low metal removal, tool wear and surface roughness. Researchers have carried out several investigations to compensate the various machining problems in the micro EDM process. So, there evolves a need for development of more sophisticated machining features in micro-EDM process combining with additional techniques. This paper presents a brief review on the latest advancement in ultrasonic vibration and magnetic field assisted techniques to improve machining efficiency and surface qualities of machined features in micro-EDM process. Latest industrial applications of micro EDM have been presented.

In-vitro experimental study of histopathology of bone in vibrational drilling

Drilling is a common surgical procedure for fracture treatment and reconstruction in multiple surgical fields, including orthopaedics, neurology, and dentistry. Drilling delicate tissue (such as bone) with a hard metallic tool is considered notorious for inducing mechanical and thermal damage, which can adversely affect osseointegration and may weaken the bond between the bone and implant, or other fixative devices anchoring the bone. The aim of this study is to explore the benefits of vibrational drilling (VD) in overcoming the complications associated with conventional drilling (CD). Drilling tests were performed on fresh cortical bone with the intention of investigating the effect of a range of frequencies, in combination with drilling speed and feed rate, on biological damage around the drilling region using histological sections of skeletally mature bone. The study examined the most influential factors and optimal combination of parameters for safe and efficient drilling in bone. Results from Taguchi grey relational analysis showed that a lower drilling speed and feed rate combined with a frequency of 20 kHz were favourable parameters for safe drilling in bone. Accordingly, VD using controlled parameters may be an alternative to CD in bone surgical procedures.

The exceptional abandonment of metal tools by North American hunter-gatherers, 3000 B.P.

Most prehistoric societies that experimented with copper as a tool raw material eventually abandoned stone as their primary medium for tool making. However, after thousands of years of experimentation with this metal, North American hunter-gatherers abandoned it and returned to the exclusive use of stone. Why? We experimentally confirmed that replica copper tools are inferior to stone ones when each is sourced in the same manner as their archaeological counterparts and subjected to identical tasks. Why, then, did copper consistently lead to more advanced metallurgy in most other areas of the world? We suggest that it was the unusual level of purity in the North American copper sourced by North American groups, and that naturally occurring alloys yielded sufficiently superior tools to encourage entry into the copper-bronze-iron continuum of tool manufacture in other parts of the world.

Nickel release from metal tools in the German hairdressing trade-A current analysis.

Nickel is one of the most common contact allergens. Despite EU regulations concerning the maximum permissible release of nickel from metal objects, nickel release at inappropriately high levels from metal objects has been detected in various studies. To screen current nickel release from metal tools in the German hairdressing trade. Two hundred and twenty-nine metal tools from the German hairdressing trade were tested with the dimethylglyoxime (DMG) test for nickel release. Additionally, an employee survey was conducted to collect data about the metal tools. The DMG test showed that 21 of 229 metal tools (9.2%) released nickel. Nickel release was detected in 8 of 45 hair clips (17.8%), 2 of 27 tail combs (7.4%), and 11 of 17 tweezers (64.7%). It must be assumed that hairdressers in Germany have prolonged skin contact with nickel-releasing metal tools. This should prompt further testing for nickel release from metal tools, and the development of regulations to eliminate nickel-releasing metal tools in the (German) hairdressing trade.

A method for representation and analysis of conformal cooling channels in molds made of functionally graded tool steel/Cu materials

Advances in additive manufacturing technology (AMT) enable the direct fabrication of thermally conductive molds with heat sinks or conformal cooling channels. Although tool steels (e.g., P21, H13, SUS420J2) are popularly used as die materials because of high dimensional stability, tool steels are inefficient for cooling mold dies due to low thermal conductivity. Hence, the adoption of functionally graded tool steel/Cu materials (FGMs) has good potentials for thermally conductive molds to avoid thermal stress concentration while improving thermal conductivity. In this sense, this paper presents a new method for the representation and analysis of conformal cooling channels in molds (injection or blowing) made of functionally graded tool steel/Cu materials. A heterogeneous sweep operation combined with 2D material blending was proposed to construct heterogeneous solid models for conformal cooling channels. In addition, one-dimensional P21/Cu FGMs were fabricated using DMT (laser-aided direct metal tooling). Material properties (such as density, specific heat, thermal conductivity, coefficient of thermal expansion, and hardness) were evaluated to obtain more accurate analysis results and to verify the feasibility of such a multi-functional mold. An example is shown to illustrate the entire representation and analysis procedure.

Lithic or metal tools: Techno-traceological and 3D analysis of rock art

Techno-traceological studies in rock art are dedicated to reveal the properties of gestures and tools used for making petroglyphs. The purpose of this kind of research is to identify technological tendencies in figurative traditions, for that we have to analyze a great number of figures. Determination of the tools demands large efforts for manual classification, but today the procedure is much simpler thanks to 3D visualization. We aim at supporting techno-traceological studies of petroglyphs by 3D shape classification algorithms. We use 3D segmentation approach to determine the shapes of tool marks and classification algorithms to reveal the difference (for lithic/metal tool traces). We applied the approach to experimental and archaeological test on 3D models of petroglyphs. As a perspective in developing a complete analytical tool we think of creating a more accurate classification.

Archaeometallurgical studies on corrosion behaviour of Cu-As alloys from "Lama" (2nd millennium BC), Iran

The Lama cemetery is located in west of the Zagros Mountains in Iran. The excavated materials are bronze objects, silver rings, iron items and pottery that were scattered in the graves. Pottery with continuous painted lines and triangular patterns and metal tools were the main evidence for dating the cemetery to the Middle Elamite II, III and Neo-Elamite I periods (1400-800 B.C). The objects were analyzed by means of ICP-OES, OM and SEM-EDX in order to obtain data on the metal composition and alloying process. The results show various compositions concerning the Cu/Sn ratio in the metallic core of the objects. The variety of tin content proves that the objects were not made by using a particular proportion of alloying elements. An uncontrolled process was used to produce tin bronze, such as co-smelting, cementation, recycling or smelting copper- tin bearing ores.

Ultra-Thin Sheet Forming Analyses Considering Size Effects

Based on robust numerical formulations and various material models, finite element (FE) analysis becomes a powerful tool in conventional sheet metal forming process. Unfortunately, the present constitutive equations irrelevant to thickness that describe well conventional sheet deformation modes have difficulties being applied directly to ultra-thin sheet deformation modes. In the present study, a constitutive equation considering size effect is established by introducing a scale factor that represents size effects through thickness and width directions. Uniaxial tensile tests were used to evaluate the scale factor of different thicknesses together with the parameter identification. The developed constitutive equation reveals that thickness is the most important factor effecting on the constitutive relation of ultra-thin sheet. 2D draw forming process of C7035 ultra-thin sheet is analyzed using JSTAMP/NV introducing the developed constitutive equation. The analysis results show that there are obvious differences in the punch forces and loading geometries according to the size effect through thickness direction. Specimen width has slight effect on the flow stress although specimen thickness has strong effect on the flow stress. It is expected that the proposed constitutive equation gives good applicability to FE analysis of micro-scale forming.

3D Metal Printing from an Industrial Perspective\u2014Product Design, Production, and Business Models

This paper is focused on automotive stamping tools and dies as well as the impact of 3D metal printing and metals related 3D-printing on design and production of such tools and dies. The purpose has been to find out the current industrial potential of 3D-printing as far as lead time, costs, shapes, material usage, metal piece size, surface roughness, hardness, strength, and machinability are concerned. The business transformational impact of 3D-printing is also addressed in this paper. The obtained results show that the lead time can be halved, the costs are somewhat higher, and the strength, hardness, surface roughness, and machinability of the 3D-printed metallic tools and dies are as good as those of the conventionally made. The maximum size of a metal piece that can be 3D-printed today by Powder Bed Fusion (PBF) is, in the best case, 500 mm × 500 mm × 500 mm. 3D-printing can also be used for the pattern to make the mold box in iron and steel casting. It is also possible to eliminate the casting pattern, since the mold box can be 3D-printed directly. All this has started to have a large business impact, and it is therefore of great significance to outline and execute an action plan almost immediately.

From Stone to Metal: the Dynamics of Technological Change in the Decline of Chipped Stone Tool Production. A Case Study from the Southern Levant (5th–1st Millennia BCE)

The shift from stone to metal has been considered one of the main technological transformations in the history of humankind. In order to observe the dynamics underlying the disappearance of chipped stone tools and their replacement with metal implements, we adopt an approach which combines two different levels of analysis. At the first, by focusing on the Southern Levant as a case study, we consider the developmental forces internal to the technology itself and the conditions favorable to the invention, spread, continuation, or disappearance of technical traits. At the second, by considering specific historical scenarios, we test the existence of general principles which guide technological changes. Flint knapping and metallurgy, and notably their relationship, are particularly appropriate to observe regularities which operate at different scales, the first one within the developmental lines of objects, techniques and technologies, and the second one within the conditions of actualization of technological facts. On the one hand, following the “rules” of technical tendencies, a techno-logic perspective allows observation of how metal cutting objects, overcoming the “limits” of knapping technology, represent the logical development of flint tools. On the other hand, the analysis of the socioeconomic contexts in which chipped stone tools were produced permits identification of regularities which conditioned changes in lithic production systems, their decline, and the final replacement with metal tools.

Uptake and Fractionation of Thallium by Brassica juncea in a Geogenic Thallium-Amended Substrate.

This study shows thallium (Tl) concentrations in Brassica juncea (Indian mustard) tissue are more than an order of magnitude higher (3830 μg/kg) than that of the substrate (100 μg/kg) and are strongly influenced by the underlying mineralogy; i.e., Tl bioaccessibility depends on the mineral structure: K-feldspar > Mn nodule > hendricksite mica. The majority of Tl for all substrates is contained in edible parts of the plant, i.e., leaves (41% of total Tl, on average) ≥ flower stems (34%) > seed pods (11%) ≈ stems (10%) > flowers (3%). We also show that Tl isotope fractionation induced by B. juncea is substantial, at nearly 10 ε205Tl units, and generates systematic plant-specific patterns. Progressive plant growth strongly fractionates Tl isotopes, discriminating against 205Tl as the plant matures. Thus, 205Tl values are systematically higher in the early formed stem (ε205Tlavg = +2.5) than in plant elements formed later (ε205Tlavg = -2.5 to +0.1), which demonstrates the large degree of translocation and the associated effects during plant growth. This study establishes the potential of Tl isotopes as a new tool for understanding heavy metal (re)distribution during anthropogenic and geologic processes and the utility of such information in environmental and health-related planning and in phytomining or bioprospecting.

Application of CFD and vapor bubble dynamics for an efficient electro-thermal simulation of EDM: an integrated approach

Micro-chip removal and heat dissipation are two important and essential utilities of dielectric medium along with its vital contribution in plasma channel formation, which has a significant influence in metal removal, tool wear, and surface integrity. The vapor bubbles, which are formed after every progressive spark, expand and collapse in the electric field and finally condensed inside the dielectric medium. As the localized heat and excess temperature of the eroded spot increases, the dynamic properties of the bubbles accelerate and develop a lower pressure region, which is responsible for dielectric flushing. In this paper, the integrated approach of vapor bubble dynamics and computational fluid dynamics is used to study the dynamic behavior and heat dissipation of dielectric fluid through the plasma channel. At the very beginning of machining, the excess temperature is comparatively low; so, the detached bubbles are condensed inside the fluid medium and are not able to move above the free surface. However, as the temperature of the machined zone rises, excess temperature also increases and bubbles are able to carry the heat up to the free surface of the dielectric medium and finally condense. This phenomenon is very much analogous to the boiling process. Earlier, many simulation processes are used by researchers to investigate heat flux and heat dissipation rate of the dielectric fluid, but, here, vapor bubble dynamics and periodic heating are introduced to consider heat absorption by vapor bubbles, which gives more accurate heat transfer analysis of electric discharge machining. It is observed that the adopted model has the accuracy level of more than 95% with 4.5–4.6% of average prediction error and 1.5–2% more efficient than the existing models.

Phytochelatin database: a resource for phytochelatin complexes of nutritional and environmental metals.

Phytochelatins (PyCs) are a diverse set of plant compounds that chelate metals, protect against metal toxicity and function in metal homeostasis. PyCs are present in plants consumed as food by humans and could, in principle, impact absorption and utilization of essential and toxic metals such as selenium and cadmium, respectively. PyCs vary in terminal amino acid composition and chain length, exist in multiple oxidation states and reversibly bind multiple metals; consequently, PyCs include a large set of possible structures. Although individual PyC-metal complexes have been studied, no resource exists to characterize the diversity of PyCs and PyC-metal complexes. We used the scientific literature to develop a database of elemental formulas for polymer forms varying in chain length from 2 to 11 glutamyl-cysteine repeats. Using elemental formulas, we calculated monoisotopic masses using the most abundant isotopes of each element and calculated masses for complexes with 13 metals of nutritional and toxicological significance. The resulting phytochelatin database (PyCDB) contains 46 260 unique elemental formulas for PyC and PyC-metal complexes. The database is available online for download as well as for direct mass queries for mass spectrometry using an accurate mass annotation tool for user-selected PyC types, metals and adducts of interest. We performed studies of a commonly consumed food—onion—to validate the database and test utility of the tool. Onion samples were analyzed using ultra-high resolution mass spectrometry-based metabolomics. Mass spectral features were annotated using the PyCDB web tool and the R package, xMSannotator; annotated features were further validated by collision-induced dissociation mass spectrometry. The results establish use and a workflow for PyCDB as a resource for characterization of PyCs and PyC-metal complexes.

Machining performance and influence of process parameters on stainless steel 316L using die-sinker EDM with Cu tool

Abstract In the present work, experimental investigation of stainless steel 316L was conducted on die sinker type EDM with copper tool using reverse polarity. Taguchi’s criterion was employed for experimental design generating L9 orthogonal array with the aid of Minitab software to observe the influential machining factors affecting output responses in terms of MRR, TWR and SR. Each experiment was run for a fixed duration of 30 minutes and the weight of workpiece and tool was measured using digital weighing scale upto three decimal places after each run to calculate metal removal rate and tool wear rate. The most significant parameters showed maximum MRR (20.83 mg/min) also exhibited highest TWR (17.92 mg/min). The most appropriate value for surface roughness (0.443µm) was achieved with current value of 20 Amps and low pulse-on-time of 60µs. SEM investigation depicts recast layer, voids and cracks on machined surface. Furthermore, the relationship between applied factors and output responses was analyzed using Regression Model Analysis.

Production of tungsten carbide nanoparticles through Micro-EDM and its characterization

Abstract The development of nano technologies have created renewed interest among researchers and scientist about various ingenious applications of these nano technologies. Production of nanoparticles with controlled morphology, size, shape and composition, is crucial step toward nano-technological applications. The present paper is focused on production of tungsten carbide nanoparticles through micro-EDM. In micro-EDM process after discharge high heat is generated, this is responsible for melting and evaporating of material in dielectric medium to form nanoparticles. Change in dielectric show the remarkable effect on the Metal Removal Rate (MRR) and Tool Wear Rate (TWR), size, morphological structure of produced nanoparticle. The generated tungsten carbide nanoparticles were characterized by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy. EDS result shows the sample contains carbon and tungsten which form tungsten carbide.

Experimental investigation of cutting parameters in CNC machining for surface roughness, temperature and MRR for Ti alloys

Abstract Nowadays, mechanical machining processes are involving the use of different cutting parameters. Because cutting parameters help to improve machining performance as well, as prolong tool life by reducing temperature and friction during machining. This system is very effective to reduce the heat in a machine zone. Optimum cutting parameters are very important to reduce the surface roughness, temperature and increase metal removal rate and tool life. In the present study titanium, alloys were used as a work material because of its inherent properties like high heat resistance, low density compared to steel. The application in all most all industries in aerospace, biomedical etc., three different carbide-cutting tools selected to machine titanium materials. Different speeds, feed rates and depth of cut are used as an input machining parameters. Minitab software was used to design the experimental plan to reduce wastage of material, cutting tools and machining time with help of Taguchi L9 array. Experimental results show that feed rate is a most dominating factor on surface roughness, depth of cut is the most influential factor on tool life and speed is the most influential parameter on temperature followed by the depth of cut. Finally experimental values are compared with predicted values and are in good agreement with machining conditions.

Assessment of Metal Cutting Tools using Cost Performance Ratio and Tool Life Analyses

Critical raw materials (CRM) are extensively used in tools for metal cutting, such as in cemented carbide tools (cobalt and tungsten), because they provide desired characteristics of high fracture toughness and wear resistance. Both academia and industry are examining CRM-free material alternatives, such as tools based on polycrystalline diamond (PCD) or ceramic materials. These materials are generally more cost intensive as compared to cemented carbide but could also provide higher efficiency in terms of material removal rate. Material removal rate and tool costs have a substantial influence on the final part cost. When deciding on tool material, the manufacturing industry is either looking for the most cost effective alternative or the alternative providing the highest productivity output. The purpose of this paper is to provide industry with decision support for selection of tool and cutting data that provide the financial most sound production set-up.This work aims to present a novel methodology combining the Colding tool life model and a previously presented model for cost performance ratio. A previous publication provided a method to assess technological solutions and investments based on final part cost. The developed methodology in this article combines cutting performance and production performance to allow a comprehensive cost assessment for a production process. The assessment includes cutting data, tool life and costs of tooling, quality rejections, process availability, equipment investment, personnel and facility. A case study based on experimental data is presented to verify the proposed methodology.