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Outlines development work on the surfing hopper, a new parts feeding system where chain conveyors with free rollers are driven by a variable‐speed motor and a flexible belt is pushed up partly by the free rollers to generate a wave in the belt. Describes how the wave effect keeps the stacked parts level and how experiments were carried out using different parts materials such as small water‐filled bottles and nuts made of steel. Looks at studies carried out on feeding correctly orientated parts to the assembly station and experiments on surfing feeding system with regard to part separation on the belt. Concludes that the surfing hopper can supply heavy parts intermittently at a rough definite supply ratio, without jamming and entangling the parts and without damage to the belt.

The purpose of this paper is to investigate the process of jamming of the hollow parts on the shaft and to derive a mathematical model for jamming in an assembly process.

The mathematical model for jamming of parts on the shaft in an assembly process is based on the sizes, geometry, angular declination of part and shaft axes, and the frictional factor.

The equation for angular positional tolerance of coaxial parts and shafts, based on their geometry and sizes and leading to jamming, was derived.

A mathematical model of parts jamming on the shaft is developed for assembly mechanisms. This research does not consider flexible deformations of components in assembly mechanisms, which results in the axis concentricity of part and shaft in the assembly process.

The results presented in the form of angular positional tolerance for coaxial parts and shafts based on their geometry and sizes make it possible to avoid the jamming of the parts. The results allow for formulating the angular positional tolerance of the assembly mechanisms that clamp the parts.

The proposed method for calculating the angular positional tolerance of coaxial parts and shafts for the assembly process should allow for increasing the reliability of the assembly process in the manufacturing industry.

The purpose of this research is working out of a new forming technology of flat parts with ribs from magnesium alloys with the application of a three-slide forging press (TSFP) for the aircraft industry.

New possibilities of forming aviation parts with ribs gives the application of a prototype TSFP. This press consists of three moveable tools and has wider technological possibilities than typical forging machines. It was assumed that this machine (press) application would allow for obtaining ribbed flat forgings from magnesium alloys of good functional and resistance qualities. A characteristic feature of such forgings forming is the working movement of two side tools, which upset the billet in the form of a plate; the result of their action is forming of one or more ribs in the plane central part. It is possible to use the upper punch to form appropriate rib outline. Theoretical research works based on simulations by means of finite element method were conducted for three cases of the process: semi-free forging of parts with one rib, semi-free forming of forgings with two ribs and forging in closed impression of parts with one rib of triangular outline. The first experimental tests were made on a TSFP for the variant of semi-free forging of parts with one rib.

Research results show that there exists the possibility of realization of forming process of parts with ribs according to the conception assumed by the authors. Positive results of theoretical analyses justify the purposefulness of conducting experimental verification for the proposed theoretical solutions of the forging processes of parts with one rib of triangular outline and with two ribs.

Production of flat parts with ribs from magnesium alloys basing on the worked out by the authors’ technology will allow for improving functional and mechanical properties of parts and for lowering their manufacturing costs. At present, such aviation parts are imported to Poland in the form of casts, which are expensive and not always fulfill the requirements. Additionally, large amount of machining at manufacturing of this type of parts generate larger price at their production.

Forging technology of parts with ribs in a TSFP is unique on a world scale. The advantages of this technology are the process material savings and better resistance properties of the formed forgings with ribs than parts obtained in a traditional way.

We study a programmable robotic part feeder that relies on a sequence of three conveyor belts to singulate and re‐circulate parts. In industrial practice, belt speeds are set in an ad hoc fashion. Experience with real feeders reveals that throughput can suffer owing to: starvation where no parts are visible to the camera; and saturation, where too many parts are visible, which prevents identifying part pose or grasping due to obstruction by nearby parts. This motivates our search for a systematic approach to setting belt speeds. Our goal is to optimize throughput, measured in terms of how many parts per second are delivered from the robotic feeder. We describe a 1D model of the belts with a Poisson arrival process to stochastically model how belt speeds affect throughput. Initially, we study the finite case where N parts are placed into the feeder and re‐circulated until they are all delivered by the robot. Our first insight is that the vision belt should be run at maximum achievable velocity. We run simulations to empirically determine optimal buffer belt velocity as a function of lot size. Finally, we develop a theoretical model for the case where N = ∞ which approximates common usage where the buffer is replenished before it becomes empty. From this model, we derive the optimal buffer belt velocity and show that it produces throughput five times greater than that achieved with ad hoc settings.

The paper aims to investigate theoretically and experimentally vibrational alignment of parts in an assembly position under kinematical excitement of the movably based part.

Presents developed mathematical model for vibrational alignment when the kinematical excitement of movable part is applied along the insertion axis. Dependencies of alignment duration on stiffness of basing elements and excitation frequency were defined numerically solving the mobile‐based part alignment equations. Alignment experiments of rectangular cross‐section and cylindrical parts under kinematical excitement were carried out.

The mathematical model and the experiments have demonstrated that alignment of the parts being assembled happens due to directed displacement of the movable part resulted by certain parameters of the system and excitement. In the course of the displacement, mating surfaces are aligned and the final mutual orientation of the parts before insertion is realized. Experiments have proved validity of the developed mathematical model. This process reduces allowable axial non‐coincidence and angular misfit of the parts to be assembled.

Impact and non‐impact regimes of the displacement exist depending on the excitement amplitude and initial contact force between the parts. Also, during the vibrational alignment it is possible to control dry friction force between parts by additional high frequency vibrations. Besides, the vibrational excitement can be not only harmonic, but also impulse, bi‐harmonic, etc. Only non‐impact regime of the motion without dry friction force control was investigated and presented in the paper.

The paper investigates the vibrational alignment method based on the directed vibrational displacement of the connecting part, which does not require high preciseness of the interdependent position of the parts in the assembly position.

Vibrational assembly devices of directional action enable compensation of errors of the parts' mutual positioning without use of sensors, feedback systems and control algorithms.

The article addresses the optimization of safety stock service levels for parts in a repair kit. The work was undertaken to assist a public transit entity that stores thousands of parts used to repair equipment acquired over many decades. Demand is intermittent, procurement lead times are long, and the total inventory investment is significant.

Demand exists for repair kits, and a repair cannot start until all required parts are available. The cost model includes holding cost to carry the part being modeled as well as shortage cost that consists of the holding cost to carry all other repair kit parts for the duration of the part’s lead time. The model combines deterministic and stochastic approaches by assuming a fixed ordering cycle with Poisson demand.

The results show that optimal service levels vary as a function of repair demand rate, part lead time, and cost of the part as a percentage of the total part cost for the repair kit. Optimal service levels are higher for inexpensive parts and lower for expensive parts, although the precise levels are impacted by repair demand and part lead time.

The proposed model can impact society by improving the operational performance and efficiency of public transit systems, by ensuring that home repair technicians will be prepared for repair tasks, and by reducing the environmental impact of electronic waste consistent with the right-to-repair movement.

The optimization model is unique because (1) it quantifies shortage cost as the cost of unnecessary holding other parts in the repair kit during the shortage time, and (2) it determines a unique service level for each part in a repair kit bases on its lead time, its unit cost, and the total cost of all parts in the repair kit. Results will be counter-intuitive for many inventory managers who would assume that more critical parts should have higher service levels.

As an advanced manufacturing method, additive manufacturing (AM) technology provides new possibilities for efficient production and design of parts. However, with the continuous expansion of the application of AM materials, subtractive processing has become one of the necessary steps to improve the accuracy and performance of parts. In this paper, the processing process of AM materials is discussed in depth, and the surface integrity problem caused by it is discussed.

Firstly, we listed and analyzed the characterization parameters of metal surface integrity and its influence on the performance of parts and then introduced the application of integrated processing of metal adding and subtracting materials and the influence of different processing forms on the surface integrity of parts. The surface of the trial-cut material is detected and analyzed, and the surface of the integrated processing of adding and subtracting materials is compared with that of the pure processing of reducing materials, so that the corresponding conclusions are obtained.

In this process, we also found some surface integrity problems, such as knife marks, residual stress and thermal effects. These problems may have a potential negative impact on the performance of the final parts. In processing, we can try to use other integrated processing technologies of adding and subtracting materials, try to combine various integrated processing technologies of adding and subtracting materials, or consider exploring more efficient AM technology to improve processing efficiency. We can also consider adopting production process optimization measures to reduce the processing cost of adding and subtracting materials.

With the gradual improvement of the requirements for the surface quality of parts in the production process and the in-depth implementation of sustainable manufacturing, the demand for integrated processing of metal addition and subtraction materials is likely to continue to grow in the future. By deeply understanding and studying the problems of material reduction and surface integrity of AM materials, we can better meet the challenges in the manufacturing process and improve the quality and performance of parts. This research is very important for promoting the development of manufacturing technology and achieving success in practical application.

To redesign the spare parts (MRO) inventory management at Company XYZ's warehouse, considering the conditions after the COVID-19 pandemic.

To address this research project, the authors integrated three methodologies: action research, Lean Six Sigma (DMAIC) and Cross Industry Standard Process for Data Mining. These methodologies integrated the Lean Six Sigma (LSS) 4.0 framework applied in this project.

The spare parts inventory value was reduced by 15%, and inventory turnover increased by 120% without negatively impacting the internal service level.

Practitioners leading or participating in continuous improvement projects (CIPs) should consider data quality (data available and data trustworthiness), problem-solving approach and target area involvement to achieve CIP goals. Otherwise, the LSS 4.0 could fail or extend its duration by several weeks or months.

This project shows the importance of controlling a target area before deciding to conduct a LSS 4.0 project. To address this problem, the LSS 4.0 team implemented 5S during the measure phase of the DMAIC. Also, this project offers significant practitioner and theoretical contributions to the body of knowledge about LSS 4.0.

For many types of automated manufacturing equipment there is a requirement to supply the equipment with parts which invariably need to be presented in a single orientation. For metal cutting and forming work there is limited applicability and invariably the parts to be presented are simple shapes. For assembly, many different and sometimes complex shapes need to be presented and it is in this activity that small parts feeding has its biggest application.