Amount Of Scrap Research Articles

The detection of empty resist bottles or air in the resist lines of a photolithography coating tool

The process of photolithography uses light to imprint an image onto a wafer coated with photoresist in order to create integrated circuits or other technology such as read/write heads for hard drives. During this process, reservoir switching units can fail to detect resist on the photolithography tool or the Millipore pump, thus introducing air into the resist lines and ultimately causing scrap due to poor dispenses. This is difficult to detect via operator inspection. It is important to improve the dispense system of a photolithography coating tool because with the increasing cost of photoresist there is a need for less waste. There are more read/write heads on a wafer and larger wafers are being used; therefore, if the photolithography coating tool has a poor dispense which is not detected and a wafer is scrapped, this will increase manufacturing costs. By reducing the amount of scrap and reworks there will be a reduction in the time to produce a single wafer, thus reducing the overall production costs of making a single read/write head and staying more competitive in the hard drive market. This paper outlines a method for detecting empty resist bottles or air in the resist lines using programmable logic controller (PLC) technology in conjunction with a relay dispense system to monitor the dispense system from a remote station, thereby improving the process and reducing the cost of manufacturing read/write heads. Overall there are less dispense errors and thus less rework and scrap, meaning that the wafer yield has improved and therefore the cost of manufacturing a read/write head has reduced and the time to market has improved. Due to the success of the PLC control system, it will be implemented across other coating tools in the factory.

Environmentally Conscious Polishing System Based on Robotics and Artificial Vision

Polishing process is one of the manufacturing issues that are essential in the production flow, but it generates the major amount of defects on parts. Finishing tasks in which polishing is included are performed in the final steps of the manufacturing sequence. Any defect in these steps impliesrejection of the part, generating a big amount of scrap and generating a huge amount of energy consumption, emission, and time to manufacture and replace the rejected part. Traditionally polishing process has not evolved during the last 30 years, while other manufacturing processes have been automated and technologically improved. Finishing processes (grinding and polishing), are still manually performed, especially in freeform surface parts, but to be sustainable some development and automation have to be introduced. This research proposes a novel polishing system based on robotics and artificial vision. The application of this novel system has allowed reducing the failed parts due to finishing process down to zero percent from 28% of rejected parts with manual polishing process. The reduction in process time consumption, and amount of scrapped parts, has reduced the energy consumption up to 30% in finishing process and 20% in whole manufacturing process for an injection moulded aluminium part for automotive industry with high production volumes.

Process planning for closed-loop aerospace manufacturing supply chain and environmental impact reduction

A considerable amount of work has recently been applied to the development of processes to reduce negative environmental impacts of disposal products. Different waste reduction options such as direct reuse, repair, refurbishing, cannibalization, and remanufacturing were introduced to overcome these shortages. This paper studies an integrated system of manufacturing and remanufacturing using a capacitated facility in the aerospace industry, where products are returned after certain flight hours or cycles for overhaul. A mixed integer linear programming model is developed to maximize profit considering manufacturing, remanufacturing set-up, refurbishing, and inventory carrying costs. The model was tested through a set of experimental data. Further sensitivity analysis was conducted aiming at revealing the effects of certain factors on inventory carrying cost, profit, amount of scrap, and inventory turnover ratio.

Quality control planning to prevent excessive scrap production

This paper presents a risk-based approach for quality control planning of complex discrete manufacturing processes, to prevent massive scraps to occur. An analytical model is developed to optimize the quality control plan (QCP) subject to inspection capacity limitation and risk exposure objectives. The problem is then formulated as a constrained capacity allocation problem. A dedicated heuristic that solves a simplified instance of an industrial case study, from semiconductor manufacturing, is presented to provide insights into the applicability and the operational use of the approach and its potential gains in terms of risk exposure reduction. The main advancement resulting from this work is the proposal of a model of quality control allocation and an understandable algorithm to prevent the production of excessive amounts of scrap. The industrial illustration shows a decrease in potential losses by a factor of 3.

Characterization of Recycled Cemented Carbide and the Raw Materials

Nowadays, a large quantity of cemented carbide is being consumed, and the amount of scrap cemented carbide is increasing year by year. In this paper, crystal morphology, element content and phase structure of the recycled cobalt powder as well as recycled tungsten carbide powder were characterized by SEM, EDS and XRD. Hardness of the prepared W-Co alloy using recycled cobalt powder and recycled tungsten carbide powder as the raw materials was tested by Rockwell apparatus. Through analysis of these results, the existing problems in recycling of scrap cemented carbide emerged. As for recycling of scrap cemented carbide, the research results can provide theoretical basis for improvement of recycling technology and process control technology.

Flow Characteristics of Vacuum Assisted Resin Transfer Molding Process Depending on the Capillary Phenomenon

Reducing the cost of composite material production is significant for expanding its usage and application in many ways, such as in the fields of aerospace, aviation, ocean industry and so on. To do this, It is important to minimize the production process of the material and to decrease the amount of scraps or any unnecessary particles. The Vacuum Assisted Resin Transfer Molding (VARTM) process, which is known for having many advantages, has become recognized as one of the most low-cost manufacturing model. VARTM process can be divided into three main steps: performing, resin filling and hardening steps. The most important step among all these three steps is the Resin Filling stage, a process when resin is impregnated into the mat. Mostly, Resin Filling stage is greatly affected by the level of permeability, a characteristic of stiffener due to pneumatic resistant nature in the process. Other factors such as viscosity, technological vacuuming, or even stiffening process itself could also influence the production as well. During Resin Filling stage, Resin tends to spread out in the center first because of capillary phenomenon. In this research, the researchers examined the mechanical property and the pneumatic nature of Resin by dividing the pneumatic movement of the Resin into sections. Based on this result, the researchers found the correlations between the capillary phenomenon and Resin impregnation, and analyzed the movement mechanism in Resin filling stage.

Recycling of porcelain stoneware scraps in alkali bonded ceramic composites

Abstract Ground porcelain stoneware scraps have been recycled as a partially reactive filler in alkali bonded ceramic composites. Sandwich panels were prepared by varying the dimension and amount of scraps in the core and skins. The alkali bonding was realized by using highly reactive metakaolin powder and alkaline KOH/K2SiO3 aqueous solution. The setting was performed at 80 °C for 24 h. The thermal conductivity of the panels at room temperature was 0.7 W m−1 K−1. Investigations on the extent of capillary water absorption and water release indicated the possibility to exploit the water retention properties of the binder for cooling by water evaporation.

Steel research int. 4/2013

Cover Photo: The amount of scrap is limited by different factors. The presented article by C. Wang et. al. on page 387 describes a model of scrap blending in basic oxygen furnaces.

OPTIMIZING AN ALUMINUM EXTRUSION PROCESS

Minimizing the amount of scrap generated in an aluminum extrusion process. An optimizing model is constructed in order to select the best cutting patterns of aluminum logs and billets of various sizes and shapes. The model applied to real data obtained from an existing extrusion factory in Kuwait. Results from using the suggested model provided substantial reductions in the amount of scrap generated. Using sound mathematical approaches contribute significantly in reducing waste and savings when compared to the existing non scientific techniques.

Numerical Model of Scrap Blending in BOF with Simultaneous Consideration of Steel Quality, Production Cost, and Energy Use

AbstractAt its integrated steel plant in Luleå, SSAB EMEA produces high strength steel via two basic oxygen furnaces (BOFs), type LD/LBE. The BOFs are charged with a mix of hot metal, scrap, and slag formers. The scrap has several functions, for example, as coolant to balance excess heat, and it contributes to high steel production rate and decreased CO2 emission. The optimal scrap to hot metal ratio is influenced by several factors, for example, the excess heat generated in the BOF versus target value of tapping temperature, content of contamination elements versus contents allowed in the steel, possible use of alloys in scrap to decrease the need of alloy addition and the scrap price versus the production cost of hot metal. The first two factors also affect the maximum amount of scrap to be charged. Furthermore, the available scrap exists as several types with different composition, properties, size, and price. For most scrap types there are also uncertainties in composition, which has to be considered. An optimization model has been further developed in combination with some statistic analysis techniques. The present work is focusing on the possibility to use the model as a tool to optimize and control raw material/scrap blending into the BOFs. On the basis of the statistical analysis technique, the scrap sorting in the model will be described, as well as development and introduction of an extended BOF sub‐model. This model includes a scrap sorting function and a response on deviations in steel quality. Real production data is used to identify steel quality parameters with consideration of different combination of elements, for example, S, Cr, Ni, and Cu. The possible solutions with simultaneous consideration of steel quality, energy consumption and production cost are presented.

Fluorine‐Free Mould Powders for Billet Casting – Technological Parameters and Industrial Tests

AbstractThere is a clear trend in industry to eliminate fluorine from metallurgical slags. Regarding the continuous casting process, fluorine in mould powders is undesirable due to the following reasons: (i) evolves easily from slags producing health‐injurious gaseous substances like hydrofluoric acid, (ii) creates problems for storage and utilization of solid waste, and (iii) causes machinery corrosion. A collaboration among universities, mould powder supplier, and steel producer was established, aiming for the development of a new F‐free mould powder for billet casting. Firstly, technological parameters for a particular composition were determined: melting characteristics, viscosity, melting behavior, and crystallization tendency. Afterwards, industrial trials were performed in a Brazilian steelworks, doing some evaluations during the continuous casting process, such as ΔT between water cooling inlet and outlet, slag pool thickness, melting performance, powder consumption, Al2O3 pick‐up, and effect on SEN erosion. Comparable surface quality for the billets was obtained when using the F‐free mould powder, since the amount of scrap produced during the rolling process was not critical.

Future Steelmaking Model by Direct Reduction Technologies

Steel production requires iron ore and coal, and accompanies greenhouse gas emissions. The annual production of the world crude steel increased from 0.9 to 1.3 billion tonnes since 2002, and is anticipated to increase due to the continuous economic growth in developing countries especially in Asia.About two thirds of the crude steel is produced by BF–BOF route whose ratio in the total crude steel production has gradually been increasing. The BF–BOF process is an excellent process in terms of productivity and energy efficiency, the process, however requires high grade iron ore and coal, and the large steel production by the BF–BOF route will accelerate the exhaustion of the high grade raw materials. The CO2 emissions are also anticipated to increase as does the steel production, since approximately 2 tonnes of CO2 is generated per tonne of steel by the BF–BOF process.On the other hand, world in-use steel stock has been increasing year by year due to the continuous large steel production, and will be recycled as a large amount of scrap to the market in the future.Steelmaking by feeding Iron Nuggets to EAF together with the scrap can significantly decrease the CO2 emissions while satisfying the steel quality by diluting the impurities containing in the scrap, as well as conserving the natural resources of high grade iron ore and coal. Steel production by using the direct reduction processes together with the scrap is a suitable and reasonable solution for a sustainable iron and steel making.

The recycling of standard quality wrought aluminum alloys from low-grade contaminated scrap

In recent decades an increasingly large fraction of the world’s wrought aluminum alloys supply has come from the aluminum scrap recovered from industrial waste and discarded post-consumer items. However, replacing even a minor part of primary aluminum in wrought alloys with recycled counterpart originated from lower grades of scrap (typically scrap contaminated with various non-metallic impurities) without influencing the quality of the allay is very demanding from a metallurgical point of view. This article discusses the two approaches for achieving the requested chemical composition of wrought alloys made from recycled aluminum: (i) before melting, by combining the appropriate qualities and quantities of scrap, primary aluminum, and the alloying elements and (ii) during melting, by diluting impurity content with primary aluminum to the needed level and adding, at the same time, the necessary amount of alloying elements for achieving their standard concentration in diluted melts.

Chromium poisoning in rats feeding on tannery residues

The Brazilian tannery industry produces annually an enormous amount of scraps and leather shavings impregnated with chromium due to the tanning process. Technologies have been developed to remove chromium from this material. The resultant residue from the chromium removal process is high in protein with a high digestibility, suggesting that this residue may be used to feed monogastric animals. However, due to the nature of this residue, there is a risk of chromium poisoning and the introduction of botulism. The aim of this work was to establish the risks of adding tannery residues to animal feeds, using rats as an experimental model. Forty-eight Wistar rats were placed under eight treatments in a 2 by 4 factorial arrangement. The rats were fed over 60 days with a standard AIN-93 diet and the treatments consisted of replacing part of the diet with 0, 25, 37.5 or 50% of the chromium-tanned leather residue, in natura, known as ‘wet blue’, or the same percentages of this residue after chromium extraction. Industrial processing was able to remove 70–80% of the chromium from the residue. This high chromium level had a negative effect on the weight gain of the animals and caused lesions in the kidneys especially due to the chromium extraction material, suggesting that the removal process increases the biological activity of chromium, making it nefrotoxic. The gravity of this effect was directly proportional to the inclusion level. The results of this study indicate that until industrial processing is refined so that more of the chromium residue is removed, the use of the tannery residues in animal feeds is not safe.

Measuring the Deformation of a Flat Die by Applying a Laser Beam on a Reflecting Surface

The design of extrusion dies depends on the experience of the designer. After the die has been manufactured, it is tested during an extrusion process and machined several times until it works properly. The die is designed by a trial and error method which is expensive interms of time consumption and the amount of scrap. Research is going on to replace the trial pressing with finite element simulations that concentrate on material and tool analysis. In order to validate the tool simulations, an experiment is required for measuring the deformation of the die. Measuring the deformation of the die is faced with two main obstacles: high temperature and little free space. To overcome these obstacles a method is tried, which works by applying a laser beam on a reflecting surface. This cheap method is simple, robust and gives good results. This paper describes measuring the deformation of a flat die used to extrude a single U shape profile. In addition, finite element calculation of the die is performed. Finally, a comparison is performed between experimental and numerical results.

Material stocks and flows accounting for copper and copper-based alloys in Japan

The recovery of scrap metal for recycling contributes to the conservation of natural resources and the construction of a sound material-cycle economy. Dynamic material flow analysis (MFA) allows us to investigate the potential for scrap metal recovery in a given region. This paper performs a dynamic material stock and flow analysis of copper in Japan. Previous studies paid little attention to the grade of the materials; the present paper considers the division between high-purity copper and copper alloys. The paper applies a dynamic MFA model with greater detail than many earlier studies and demonstrates an additional level of disaggregated analysis on waste flows. The analysis of differing grades of copper quantified the flow of downgraded scrap from the pure copper cycle to the copper alloy cycle. In addition, the amount of scrap collected, as estimated by the dynamic MFA, was approximately consistent with that reported in the statistics. This result indicated the validity of the parameters used in the dynamic model. The current in-use copper stock in Japan was estimated to be 18.7 Tg including the mass of alloying elements, and the amount of cumulative uncollected copper was estimated to be 9.9 Tg. This uncollected copper could have been mixed with other metals (e.g., mixed in secondary steels), incinerated with combustible waste, landfilled, or exported in several forms. The amounts of copper to these final destinations were quantified. Finally, the Japanese pure-copper cycle and copper alloy cycle for 2005 were constructed.

Development of a Sand Mold Press Casting Process: “Post-Filled Formed Casting Process”

This paper presents the development of a sand mold press casting process called the “Post-Filled Formed Casting Process.” In this process, molten metal is directly poured into the lower mold; the upper mold then falls down on the lower mold, and both molds are then matched. This method does not use a sprue cup and runner. Therefore, both the quantity of scrap and energy consumption are enormously reduced. This means that the sand mold press casting process is an eco-friendly casting process resulting in a large reduction of CO2 gas. During the last few years, the author's group has been devoted to developing this method as a national project. Mold design for casting, pouring control, and velocity control of the press have been identified as key factors in manufacturing sound products. In this paper, we provide an overview of this novel casting method and present the fundamental results obtained.

450 kW plasma melting system

Plasma melting technology can be used to meet the scrap recycle needs of reactive metals, superalloys and refractory materials such as titanium, zirconium and uranium alloys. Fabrication involving these reactive metals, share the common problem of generating a large amount of scrap where both low and high density inclusions become highly prevalent. Plasma melting technology can be used for re-melting, refining and production of premium grade metal ingot. 450kW multi-torch plasma melting furnace is developed and commissioned by Laser & Plasma Technology Division for the re-melting and refining of metals and scraps under controlled environment. This paper presents the vacuum system design for 450 kW plasma melting furnace. The efficacy of vacuum system in cold condition is also tested and the results are included in the paper. The vacuum feed through design for the plasma torch handling mechanism is also discussed.

Optimization of a Classical Stamping Progression by Modal Correction of Anisotropy Ears

This work is a development from the Inetforsmep European project. We proposed to realize a global optimization of a deep drawing industrial progression (made of several stages) for a cup manufacture. The objectives of the process were the thickness decrease and the geometrical parameters (especially the height). This paper improves on this previous work in the aim of mastering the contour error. From the optimal configuration, we expect to cut down the amount of the needed material and the number of forming operations. Our action is focused on the appearance of unexpected undulations (ears) located on the rim of the cups during forming due to a nonuniform crystallographic texture. Those undulations can cause a significant amount of scraps, productivity loss, and cost during manufacture. In this paper, this phenomenon causes the use of four forming operations for the cup manufacture. The aim is to cut down from four to two forming stages by defining an optimal blank (size and shape). The advantage is to reduce the cost of the tool manufacturing and to minimize the needed material (by suppressing the part flange). The chosen approach consists in defining a particular description of the ears’ part by modal decomposition and then simulating several blank shapes and sizes generated by discrete cosine transformation (DCT). The use of a numerical simulation for the forming operation and the design of an experiment technique allow mathematical links between the ears’ formation and the DCT coefficients. An optimization is then possible by using mathematical links. This original approach leads the ears’ amplitude to be reduced by a factor of 10, with only 15 numerical experiments. Moreover, we have limited the number of forming stages from 4 to 2 with a minimal material use.

Controlling of the Solidification Structure for Recycling by Ultrasonic Vibration

The production of aluminum scrap is expected to exceed the domestic demand in japan around the year 2010. The key to the establishment of a resource recycling-based society is the zero emission process. However, recycling materials will produce an amount of scrap that cannot be recycled and will become waste. A design that considers the intended usages and includes recycling should be incorporated into the materials development to reduce as much waste as possible. Mixing iron impurities with aluminum leads to the formation of coarse needle-shaped intermetallic compounds during solidification and hinders the recycling capacity of the finished product. The application of ultrasonic vibration during solidification was carried out in this work with the aim of controlling the morphology of the material. Experiments were performed by melting an Al-Si alloy containing 4 mass% Fe (hereafter, mass% is abbreviated by %). The primary crystals formed from the liquidus line of this alloy were intermetallic compounds identified as Al 3 Fe, α-AlSiFe (Al 7.4 SiFe 2 ) and P-AlSiFe (Al 9 Si 2 Fe 2 ). A coarse needle-like intermetallic compound was formed in the Al-6Si-4Fe and Al-12Si-4Fe alloys, but the application of ultrasonic vibration resulted in the formation of a fine grained structure. In the Al-18Si-4Fe alloy, the structure could be modified from a coarse needle-like structure into a fine grained structure.