Waste In Manufacturing Process Research Articles

Mass-customisation of cross-laminated timber wall systems at early design stages

Low profitability of the building industry has driven the adoption of industrialised production methods in this sector. In an industrialised context, mass-customisation (MC) is a set of strategies aimed to offer tailored products at prices close to those of mass-production. MC can be achieved through integrating market knowledge and supply-chain processes into the building design. Nonetheless, the MC-related literature is slim in optimising designs for such an integration. The goal is to find optimal design configurations for the load-bearing spanning systems that incur minimum product waste and manufacturing process waste. The paper uses Cross-Laminated Timber (CLT) buildings as cases of highly prefabricated systems. The preliminary layout of a building is first mathematically modelled. Then, genetic algorithms are adapted to optimise wall dimensions and billet cutting plan. The example case demonstrated significant waste reduction compared to the building industry benchmarks. This highlights the practical benefits of the systematical implementation of MC from the early design stages. The present study contributes to the body of knowledge by introducing a novel design support tool that facilitates the adoption of MC in the building industry.

Measurements of nanomaterials in environmentally relevant water matrices using liquid nebulization/differential mobility analysis.

A liquid nebulization-differential mobility analysis methodology was evaluated for the measurement of the size distribution and quantitative mass concentration of nanomaterials in environmentally relevant aqueous media. The analysis time is 8 min, and the method requires little routine sample preparation and less than 8 mL of sample. The method can be used for rapid, direct analysis of nanomaterials in aqueous media with a particular application to dose verification in ecotoxicology studies, analysis of manufacturing process waste streams, and raw material analysis. Twelve reference materials having a diameter traceable to the National Institute of Standards and Technology were spiked into 6 different aqueous matrices that included drinking water, groundwater, industrial wastewater, as well as the algae and daphnia media used in ecotoxicology testing. Measurement of the diameter of a reference material was within the expected range for the reference material. Individual response factors for each reference material were determined in each medium and the accuracy and precision of the concentration measurements evaluated. In ecotoxicology test media, measurements of the concentration of nanoparticles having diameter ≥ 30 nm, had corresponding accuracies and precisions of 103% and 7%, respectively. Over 28 d 86% of the samples had concentrations within 20% of the initial concentration. The method limit of quantification depended primarily on matrix complexity and particle diameter; the limit of quantification ranged from 0.01 mg/L to 3 g/L.

INTEGRATION OF ENVIRONMENTAL FACTORS IN PRE-LAYOUT DESIGN OPTIMIZATION FOR PRINTED CIRCUIT BOARDS

Product design for environment (DfE) has been an area of emerging interest for electronics manufacturers in recent years. An important aspect of DfE is the linkage of manufacturing process waste emissions and energy consumption with parameters in product design. In this paper, a linkage is developed between the process wastes generated in printed circuit board (PCB) fabrication and board specifications. A set of process models for estimating waste mass quantities is combined with a multi-criteria health hazard evaluation scheme. A waste minimization formulation is presented for pre-layout board analysis. The emphasis of this formulation is on tiling of the boards on a panel and its impact on the waste stream generation, but a special feature of the formulation is that it respects the functional requirements for the board design by incorporating them as constraints of the waste optimization problem. A PCB design for a multi-layer board is presented to show the implementation of the procedure.

ENVIRONMENTAL FACTORS IN PARAMETRIC DESIGN OF COMPUTER CHASSIS

Environmental issues in industry have transformed from those of compliance to those of competitive advantage through increasingly stringent environmental regulations, the emergence of product take-back and recycling initiatives, and growing consumer preference for green products. While there has been much research devoted to systems-level disassembly and recycling of computer products, a significant life-cycle component of the wastes associated with the product occurs at the primary manufacturing stages. This paper examines the linkages between manufacturing process waste generation and decisions made at the component design stage. An application of this linkage is in the area of sheet metal components for computer chassis. Critical processes include blanking, punch, metal deformation, finishing and welding. The availability of data at several levels of aggregation is supplemented by the development of analytical models of process physics to derive a process-level inventory of energy utilization, primary scrap and secondary catalysts (tool, fluid and vapor waste streams). The mass flows of waste streams can be weighted by the impact on factors such as toxicity, carcinogenesis, reactivity, flammability and irritation using material safety data and survey of site-specific factors. The trade-offs between environmental, manufacturing and product performance factors are discussed, as well as the environmental impact of material selection and definition of geometric features. The methodology for estimating energy utilization and process wastes is demonstrated through calculations for the manufacture of a workstation chassis. Several case studies of chassis components are also presented to illustrate the influence of incremental component design decisions on environmental impact. The role of product specifications such as aesthetics, thermal requirements, shielding and structural requirements are examined.

Treatment of tetraethyl lead manufacturing wastes

A study was carried out in an effort to find an effective means of treating tetraethyl lead manufacturing process waste waters. The conventional method of coagulation was effective for the removal of inorganic lead compounds in the tetraethyl lead process streams whereas the organic lead compounds present in the waste waters were not amenable to coagulation. Of the various waste waters arising from the tetraethyl lead manufacturing process, those waste waters which are rich in organic lead compounds were passed through a macroreticular sulfonate type strongly acidic cation exchange resin and the exhausted resin was eluted by caustic soda to give eluate containing high concentrations of organic lead compounds. The ion exchange resin was used repeatedly in this way. The organic lead thus concentrated was converted to inorganic lead by the addition of chlorine gas. When the eluate thus enriched in inorganic lead is added to the process streams carrying chiefly inorganic lead and coagulation is carried out, an almost complete elimination of lead in the tetraethyl lead process discharges will be obtained.