Teaching Circular Economy and Lean Management in a Learning Factory

Traditionally, industries followed a linear process of resources consumption: taking raw materials from nature, transforming them into products, and selling them to consumers (who discarded them when they were no longer useful). Nowadays, due to the sustainable development concerns, there is an increasing awareness on the society for reuse, repair, recycling, and remanufacturing to avoid resource depletion and achieve waste reduction. Following this idea, with the aim to train students and practitioners in lean manufacturing and circular economy concepts and tools, a learning process organized in three sequential phases was developed, starting with the manufacture of a toy car (25 kg and over 100 pieces) using a traditional push system, then reengineering the process to implement pull system and lean manufacturing concepts, and finally, considering a circular economy pull system through the reuse and recycling of parts and components. In this way, the importance of reducing waste in manufacturing and the reduction in the use of raw materials by considering the 3Rs is highlighted.

Implementation of a Pull System – A Case Study of a Polymeric Production System for the Automotive Industry

This work, developed as a case study, propose, describe, and evaluates an implementation of a pull system in a SME company producing polymeric components for the automotive industry. The production system of the company was based on the push paradigm, which creates high stock levels and high lead times. The main purpose was to develop a pull production system controlled by Kanbans in the painting line. To achieve this goal, this case study demonstrates the application of relevant lean tools, such as, VSM, SMED, Kanban System, Supermarkets and Leveling. Through the SMED’s application, it was possible to reduce the setup times in 38% and make annual earnings of approximately 83000€. The application of a Kanban System, Leveling and Supermarket enabled the WIP’s reduction between injection and painting in 56% and, also, between painting and expedition in 45%. Also, the lead time decreased and the value-added time increased. Thus, this is an exemplary case study for the implementation of a pull system and can be used both by practitioners and researchers interested in this theme.

Push–Pull Effect on the Gas-Phase Basicity of Nitriles: Transmission of the Resonance Effects by Methylenecyclopropene and Cyclopropenimine π-Systems Substituted by Two Identically Strong Electron Donors

The gas-phase basicity of nitriles can be enhanced by a push–pull effect. The role of the intercalated scaffold between the pushing group (electron-donor) and the pulling (electron-acceptor) nitrile group is crucial in the basicity enhancement, simultaneously having a transmission function and an intrinsic contribution to the basicity. In this study, we examine the methylenecyclopropene and the N-analog, cyclopropenimine, as the smallest cyclic π systems that can be considered for resonance propagation in a push–pull system, as well as their derivatives possessing two strong pushing groups (X) attached symmetrically to the cyclopropene scaffold. For basicity and push–pull effect investigations, we apply theoretical methods (DFT and G2). The effects of geometrical and rotational isomerism on the basicity are explored. We establish that the protonation of the cyano group is always favored. The push–pull effect of strong electron donor X substituents is very similar and the two π-systems appear to be good relays for this effect. The effects of groups in the two cyclopropene series are found to be proportional to the effects in the directly substituted nitrile series X–C≡N. In parallel to the basicity, changes in electron delocalization caused by protonation are also assessed on the basis of aromaticity indices. The calculated proton affinities of the nitrile series reported in this study enrich the gas-phase basicity scale of nitriles to around 1000 kJ mol−1.

Solution of Bottlenecks in the Logistics Flow by Applying the Kanban Module in the Tecnomatix Plant Simulation Software

The presented article deals with the issue of solving bottlenecks in the logistics flow of a manufacturing company. The Tx Plant Simulation software tool is used to detect bottlenecks and deficiencies in the company’s production, logistics and transportation systems. Together with the use of simulation methods and lean manufacturing tools, losses in business processes are eliminated and consequently flow throughput is improved. In the TX Plant Simulation software environment, using Bottleneck analyzer, bottlenecks were defined on the created simulation model and a method of optimizing logistics flows was designed and tested by introducing the Kanban pull system. This resulted in an improvement and throughput of the entire logistics flow, a reduction in inter-operational stocks and an increase in the efficiency of the production system as a whole.

Kanban in Apparel Manufacturing: A Case Study

Pull system and Kanban are effective lean manufacturing tools. Though many companies in various manufacturing fields have successfully implemented pull manufacturing using Kanban systems, such studies in apparel manufacturing are rarely found. Kanban system was implemented in an apparel manufacturing company, which had implemented some of the lean manufacturing tools. The apparel manufacturing line was identified in four different sub sections and separate Kanbans were used in each sub section. The system was evaluated using two parameters: the number of Kanban cards in each point; the production output. Correct number of Kanban cards were found at all the time of the monitoring period of two weeks-the production efficiency has increased by 22%.

A push-pull system of repressors matches levels of glucose transporters to extracellular glucose in budding yeast

SummaryA common cellular task is to match gene expression dynamically to a range of concentrations of a regulatory molecule. Studying glucose transport in budding yeast, we determine mechanistically how such matching occurs for seven hexose transporters. By combining time-lapse microscopy with mathematical modelling, we find that levels of transporters are history-dependent and are regulated by a push-pull system comprising two types of repressors. Repression by these two types varies with glucose in opposite ways, and not only matches the expression of transporters by their affinity to a range of glucose concentrations, but also the expression of some to how glucose is changing. We argue that matching is favoured by a rate-affinity trade-off and that the regulatory system allows yeast to import glucose rapidly enough to starve competitors. Matching expression to a pattern of input is fundamental, and we believe that push-pull repression is widespread.