Plitko gravurno kovanje s aspekta mikrooblikovanja

U radu je provedena eksperimentalna i numerička analiza procesa plitkog gravurnog kovanja s aspekta mikrooblikovanja. To je novi pristup rješavanju problema oblikovanja proizvoda malih dimenzija koji uzima u obzir utjecaj veličine kristalnog zrna na parametre procesa. Izvršena su mjerenja elastičnog povrata materijala rondele početne visine 2 mm za tri različite veličine kristalnog zrna i to kod slobodnog kovanja i kovanja u gravuri. Mjerena je sila oblikovanja potrebna za zadovoljavajuće popunjavanje gravure ukovnja kod istih veličina zrna. \Načinjena je i numerička analiza promjene koeficijenta kontaktnog trenja također za različite veličine kristalnog zrna. Radom je pokazano kako se prilikom plitkog gravurnog kovanja javlja značajna razlika u ponašanju materijala obratka kod različitih veličina kristalnog zrna te oprečno ponašanje parametara procesa prilikom slobodnog kovanja i kovanja u gravuri. Time je proces plitkog gravurnog kovanja nesumnjivo svrstan u procese mikrooblikovanja. Numeričkom analizom dobivena je teorijska zavisnost promjene veličine kontaktnog trenja obzirom na promjenu veličine kristalnog zrna kod specifičnog slučaja slobodnog kovanja

Multirotor UAV Design and Development – Case Study

This paper proposes the development and production of multirotor UAV parts using additive manufacturing. A new smart design approach is needed to take advantage of additive manufacturing in terms of reducing the product weight and making the product more customizable and specific purpose-oriented while also reducing the time and cost of product development and production. This paper provides a brief overview of three additive technologies: fused deposition modelling, stereolithography, and selective laser sintering. Two different UAV modules, the avionics module and GPS holder assembly, are described and produced. Also, some design ideas and approaches are explained, such as snap-fit joints and thread joints using hex bolt pockets and metal screws. The goal of this paper is to develop and manufacture special purpose UAV parts that are durable, sustainable, and low cost. For this purpose, the additive manufacturing process is proposed and described, from the idea to the final product

Selection of an Optimal Supplier

The paper describes the selection of an optimal supplier from China based on three obtained bids to produce 120,000 forged pieces, which is the primary process for shaft production. The choice was made using the AHP method based on the Expert Choice software program and Multiple-Criteria Decision-Making (MCDM). The key information when choosing the optimal supplier of large number of forgings is to define the objective of the task, decision tree with weighted criteria and sub-criteria, consistency checking and possible reconsideration using brain storming when defining the strength of criteria/sub-criteria. To some extent, this may reduce initial subjectivity in the decision-making process in the Decision Support System

Image Artefacts in Industrial Computed Tomography

Computed tomography is a method that has been used for many years in medicine and material analysis, and recently it has also been introduced in dimensional measurements. The method has a lot of advantages compared to other 3D measurement methods, with the largest one being the possibility to perform a non-destructive measurement of an object’s inner geometry. However, it is a complex method with a large number of parameters that influence measurement results. Some of these parameters are image artefacts that occur in the scanning and reconstruction process. An artefact is any artificial feature which appears on the CT image, but does not correspond to the physical feature of an object. In order to achieve metrological traceability, it is necessary to eliminate and minimize the influence of image artefacts on measurement results. This paper presents and explains image artefacts in industrial computed tomography as the consequences of different influence parameters in the CT system