Shewhart control charts are suitable for stable but repetitive production processes used for the subsequent identification of random deviations while indicating breached quality limits. They provide information on process variability and, at the same time, make it possible to obtain information on the reliability of monitored processes. The objective of this paper is to assess the quality characteristics of plastic mouldings for the needs of the automotive industry with the application of the control charts method, specifically Shewhart control charts. The Shewhart control charts were applied to evaluate the quality characteristics, or, more specifically, to evaluate the measured width and length of the produced plastic mouldings by statistical analysis. Statistical analyses show that the set parameters are not met in the first two days of the test series. An improvement in the process is observed on the last day of the test series. The process is well set, as confirmed by our verification of the stability of the process. An important condition for setting the control charts is to observe the correct chronological arrangement and regular acquisition of measured values. Solving tasks in the future must be oriented to an evaluation of the capability of the production process of the monitored product. The proposal for future research will be oriented toward the evaluation of this capability via process capability indices that derive continuous data by using the classical method.

This paper describes the synthesis of tungsten disulfide (WS₂) powder by the sulfurization of tungsten trioxide (WO₃) particles in the presence of additive potassium carbonate (K₂CO₃) in nitrogen (N₂) atmosphere, first at lower temperature (200 °C) and followed by reduction at higher temperature (900 °C). In addition, the ultrasonic spray pyrolysis of ammonium meta-tungstate hydrate (AMT) was used for the production of WO₃ particles at 650 °C in air. The HSC Chemistry^® software package 9.0 was used for the analysis of chemistry and thermodynamic parameters of the processes for WS₂ powder synthesis. The crystalline structure and phase composition of all synthesized powders were analyzed by X-ray diffraction (XRD) measurements. The morphology and chemical composition of these samples were examined by scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX).

Fine-grained fraction (<1.25 mm) of industrial zinc ash was characterized in terms of chemical and phase compositions as well as leaching behaviour in hydrochloric acid solutions. Waste product contained about 55% Zn, 14% Cl, and less than 0.4% of other metals (Fe, Pb, Al, etc.). It was a mixture of metallic zinc, simonkolleite, zinc oxide, and zinc hydroxide chloride. Dissolution of metals from the zinc ash was determined depending on the solid-to-liquid ratio (1:80-1:20), acid concentration (0.23-2.0 M), and temperature (20-60ºC). The best results (almost 100% zinc recovery) were obtained for 2M HCl at 20ºC, S:L ratio 1:20, and leaching time 30 min. The final solutions were contaminated mainly by iron and lead ions (both below 0.15 g/L). Further treatment of the solution to obtain metallic zinc or zinc chloride was also proposed.

This article describes a methodical framework that combines two specific methods of Lean management, namely the ABC method and the MRP planning method. The article further argues that combining the ABC inventory method with subsequent MRP planning is beneficial if the combination is implemented in practice. To demonstrate the benefits, the framework is tested using a case study company. The presented case-study problem is to reduce the number of changeover downtimes in the environment of an engineering production company. The researched company deals with the problem of setting up production lines in a way to minimize the number of downtimes within one work shift. Within the solution, four possible variants of the production plan are presented. By combining the ABC and MRP methods, up to four changeovers can be saved, which in financial terms represents a saving of about EUR 450,000 per year.

This study presents a theoretical and practical evaluation of zinc evaporation from bottom zinc dross (hard zinc) as a secondary zinc source (zinc content approximately 94–97%), which originates in the batch hot-dip galvanizing process. The thermodynamics of the zinc evaporation process were studied under the normal pressure (100 kPa) in the inert atmosphere, using argon with flow rate 90 mL/min. Samples were subjected to the evaporation process for 5, 10 and 20 min under the temperature of 700 °C and 800 °C, respectively. For the theoretical thermodynamic study, HSC Chemistry 6.1 software was used and final products, as well as residuals after the evaporation process, were analyzed by SEM (Scanning Electron Microscopy) and EDX (Energy Dispersive X-ray). Calculated and experimental argon consumption in the process of zinc evaporation has been compared. A high purity zinc with efficiency over 99% was reached. Due to a dynamic regime, argon consumption at the temperature of 700 °C and 800 °C were 7 times and 3 times, respectively, less than calculated.

Waste generation is a part of every technological process, including galvanizing. The presented paper deals with the characterization of flue dust generated in the process of hot-dip galvanizing, and proposes possible methods for zinc recycling. The flue dust is released into the atmosphere as a white fume above the zinc bath, which is caused by the decomposition of ammonium chloride and zinc chloride present in the flux. This dust is classified as hazardous waste and is a material with a particle size below 90 µm. In addition to zinc and iron compounds, it contains water vapor and oils. The presented elemental, phase, and other characteristic methods of flue dust are important for the subsequent selection of a suitable method for processing the material. At present, this waste is not processed separately due to its low production, which is approximately 0.3 kg per 1 tonne of galvanized steel. The proposed hydrometallurgical recycling method enables the processing of flue dust on a small scale and enables the recovery of high-purity zinc in the form of metallic zinc or zinc oxide.