Browsing by Author "Chekurov, Sergei"
Now showing 1 - 20 of 25
- Results Per Page
- Sort Options
- 3D-tulostamisen sovellus menetelmänä tulevaisuuden lentokonerungon tuotannossa
Insinööritieteiden korkeakoulu | Bachelor's thesis(2016-12-11) Bardy, Nikolas - 3D-tulostus koneenosien suunnittelussa
Insinööritieteiden korkeakoulu | Bachelor's thesis(2021-05-02) Tikka, Severi - Additive Manufacturing in Offsite Repair of Consumer Electronics
A4 Artikkeli konferenssijulkaisussa(2017) Chekurov, Sergei; Salmi, MikaSpare parts for products that are at the end of their life cycles, but still under warranty, are logistically difficult because they are commonly not stored in the central warehouse. These uncommon spare parts occupy valuable space in smaller inventories and take a long time to be transported to the point of need, thus delaying the repair process. This paper proposes that storing the spare parts on a server and producing them with additive manufacturing (AM) on demand can shorten the repair cycle by simplifying the logistics. Introducing AM in the repair supply chain lowers the number of products that need to be reimbursed to the customer due to lengthy repairs, improves the repair statistics of the repair shops, and reduces the number of items that are held in stock. For this paper, the functionality of the concept was verified by reverse engineering a memory cover of a portable computer and laser sintering it from polyamide 12. The additively manufactured component fit well and the computer operated normally after the replacement. The current spare part supply chain model and models with AM machinery located at the repair shop, the centralized spare part provider, and the original equipment manufacturer were provided. The durations of the repair process in the models were compared by simulating two scenarios with the Monte Carlo method. As the biggest improvement, the model with the AM machine in the repair shop reduced the duration of the repair process from 14 days to three days. The result points to the conclusion that placing the machine as close to the need as possible is the best option, if there is enough demand. The spare parts currently compatible with AM are plastic components without strict surface roughness requirements, but more spare parts will become compatible with the development of AM. - Additive manufacturing needs and practices in the Finnish industry
Insinööritieteiden korkeakoulu | Master's thesis(2014-06-09) Chekurov, SergeiThe purpose of this thesis is to present the current needs and practices of additive manufacturing in the Finnish industry. To obtain the necessary information, a survey of eight companies was carried out. An introduction to additive manufacturing and its applications is given to give the reader a better understanding of the survey. A survey was designed and the process explained. The main tool, the questionnaire, was chosen to be the best option to conduct the survey and was designed to consist of a combination of open questions and scale questions. The questionnaire was presented to eight companies of varying size in the research and development industry. Fifteen people from these companies were chosen for the survey. All of the qualitative answers were analytically quantified and expanded upon. The findings of the survey were compared to the findings of other worldwide reports. The results obtained through this study include data regarding familiarity of AM technologies, ownership of machinery, outsourcing practices, and general perception of AM in Finnish companies. It was found that while the Finnish industry is somewhat lagging behind on some fronts of AM usage, the trend is showing that AM is becoming more widely understood and its usage in more advanced applications is on the rise. - Additively manufactured high-performance counterflow heat exchanger
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2019-03-01) Chekurov, Sergei; Kajaste, Jyrki; Saari, Kari; Kauranne, Heikki; Pietola, Matti; Partanen, JouniThe purpose of this article is to demonstrate that additive manufacturing is a viable method for producing counterflow heat exchangers that have a very high power to volume ratio. For this study, a heat exchanger with 144 flow channels in a checkerboard pattern was designed and additively manufactured from AlSi10Mg. The heat exchanger was tested by measuring the heat transfer between two liquids in a counterflow set-up, where it reached exceptionally high performance when considering its volume and weight. The heat transfer properties of the heat exchanger were verified analytically through calculations, which identified that the high surface roughness of the channels provides a significant improvement in heat transfer properties. The heat transfer capabilities were measured on two separate occasions to investigate the possible change of properties of additively manufactured heat exchangers over time when used with tap water. A moderate decrease in heat flow and increase in pressure drop were noted between the measurements. The deterioration of heat transfer capabilities could present a significant challenge for additively manufactured heat transfer applications and will be closely examined in future research. - The applicability of the 40 TRIZ principles in design for additive manufacturing
A4 Artikkeli konferenssijulkaisussa(2018) Kretzschmar, Niklas; Chekurov, SergeiThe theory of inventive problem solving methodology (TRIZ) is a well-established accelerator to support problem solving by linking specific engineering problems and solutions to general patterns. TRIZ can be applied in conjunction with Design for Additive Manufacturing (DFAM) to create novel geometries, shapes, and enhanced functionalities. In this study, the applicability for DFAM of each of the 40 inventive principles of TRIZ is evaluated and classified. Examples for three TRIZ principles (i.e. asymmetry, nested doll, blessing in disguise) are evaluated further in the context of DFAM, outlining their advantages in functionality and performance. This study is particularly helpful to practitioners who are unfamiliar with the concept of DFAM. © 2018, Danube Adria Association for Automation and Manufacturing, DAAAM. All rights reserved. - Assessing industrial barriers of additively manufactured digital spare part implementation in the machine-building industry: a cross-organizational focus group interview study
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2021-04-27) Chekurov, Sergei; Salmi, Mika; Verboeket, Victor; Puttonen, Tuomas; Riipinen, Tuomas; Vaajoki, AnttiPurpose: Although additive manufacturing (AM) has been demonstrated to have significant potential in improving spare part delivery operations and has been adopted to a degree in the aviation and automotive industries, its use in spare part production is still limited in other fields due to a variety of implementation barriers. The purpose of this article is to assess the significance of previously reported barriers in the context of the machine-building industry. Design/methodology/approach Adoption barriers are identified from the literature and formulated as hypotheses, which are verified with a set of focus group interviews consisting of original equipment manufacturers (OEMs), AM service providers and quality inspection and insurance institutions. The results of the interviews are reported qualitatively, and the transcripts of the interviews are subjected to quantitative content analysis. Findings The article identifies distrust in quality, insufficient material and design knowledge among stakeholders and poor availability of design documentation on spare parts as the key barriers of adopting AM in the production of spare parts. The three key barriers are interconnected and training engineers to be proficient in design and material issues as well as producing high-quality design documentation will yield the highest increase in AM implementation in spare parts. Originality/value The article offers a unique approach as it investigates the subjective views of a cross-organizational group of industrial actors involved in the machine-building industry. The article contributes to the theory of digital spare parts by verifying and rejecting presented barriers of AM implementation and how they are interconnected. Keywords - Classification of end-use industrial applications of additive manufacturing
A4 Artikkeli konferenssijulkaisussa(2018-01-01) Chekurov, Sergei; Kretzschmar, NiklasAdditive manufacturing (AM) has recently been gaining traction in the manufacturing of industrial end-use components and has found success in a variety of applications, which have varied from the production of superior high value components to the reduction of costs associated with procuring simple products, such as spare parts for consumer electronics. This spectrum of applications is causing confusion for companies who are willing to adapt AM in their operations and slowing down the rate of propagation of AM in industrial settings. This paper attempts to clarify the opportunities of AM in end-use components by proposing a categorization system from the point of view of Design for Additive Manufacturing (DfAM). The categories are obtained from the existing DfAM literature and are “Components designed for AM”, “Components redesigned for AM”, and “Components not designed for AM”. The article presents the categories in detail, explains when they should be used, and provides examples for each category. - Design of an elevator button assembly for additive manufacturing
Insinööritieteiden korkeakoulu | Master's thesis(2017-10-30) Puttonen, TuomasAdditive manufacturing, with its recent technological developments, has increasingly disrupted how products are designed and manufactured. Within additive manufacturing, there has been a shift from the production of visual models and rapid prototyping applications to direct digital manufacturing of end products. Additive manufacturing provides intriguing possibilities in the design of new and existing products. These radical, pioneering designs have already redefined whole industries. This thesis provides a practical case study for an additive manufacturing redesign together with a literature review of the current additive manufacturing technologies and applications. The target of the redesign was a low volume elevator button assembly. Concepts were prototyped and tested in contrast to the current industry specification. As a result of the thesis, a functional button assembly was produced and tested. The part count, material usage, and costs were reduced compared to the original. However, all industry requirements were not met. A need for a more systematic material and process selection was identified. Nevertheless, additive manufacturing was proven to be a serious alternative in the production of low volume plastic products and should be researched further. - Design-dependent shrinkage compensation modeling and mechanical property targeting of metal FFF
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-03-01) Ait-Mansour, Ilies; Kretzschmar, Niklas; Chekurov, Sergei; Salmi, Mika; Rech, JoelMetal-fused filament fabrication is gaining traction due to its low cost and high availability compared to metal powder bed fusion. However, the achievable mechanical properties and effects of shrinkage of this process should be understood thoroughly before it can be implemented as a direct digital manufacturing technology. This study investigates the influence of infill levels and different build orientations on the mechanical properties and shrinkage behavior of 3D-printed, debinded, and sintered components made from BASF Ultrafuse 316LX. The final objective of the work is to define a function for multi-directional shrinkage prediction for any given part geometry to achieve parts with a high degree of dimensional conformity by modifying the original designs accordingly. The Design of Experiment includes tensile and compression testing according to ASTM E8 M-04 and ASTM D695-15, respectively. Tensile testing samples are manufactured in three different build directions and compression testing pins are made with six infill levels. Furthermore, a complex part is printed and its dimensional shrinkage analyzed using 3D scanning. Finally, the multi-directional shrinkage behavior is measured for all samples to establish a shrinkage predictability function by applying linear regression models. Results show that material infill levels have no effect on the shrinkage behavior of printed components. Compressive strength increases with infill level and ultimate tensile strength of parts printed flat indicates the highest tensile testing results, followed by flipped and vertically printed parts. A complex part was manufactured successfully for spare part production, which helped to establish a function with moderate confidence levels for shrinkage predictability. - Developing an instructional model of VVER-1200 nuclear reactor for additive manufacturing
Insinööritieteiden korkeakoulu | Bachelor's thesis(2020-11-30) Tollet, Arthur - Development, Implementation, and Assessment of a Creative Additive Manufacturing Design Assignment: Interpreting Improvements in Student Performance
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-06-09) Chekurov, Sergei; Wang, Meng; Salmi, Mika; Partanen, JouniThe purpose of this article is to present a design for additive manufacturing assignment focused on creativity rather than functionality and to analyze its results (N = 70) acquired during five years. The assignment teaches the unique advantages of additive manufacturing to engineering students and encourages learning from failure to achieve designs that are possible to manufacture. The students of the course assignment were in their fourth year of studies and pursued master’s degrees in mechanical engineering. The article presents the design for additive manufacturing course assignment in enough detail for it to be applied by educators in the sphere of additive manufacturing. The result assessment is performed with a numerical method and a jury method. The statistical significance of the correlation of the numerical approach with the jury approach is evaluated. The study conducts a multi-point creativity assessment on a large sample of parts created by students acquired over five years with the support of 10 jury members. This assessment process gives insight on how creativity in design for additive manufacturing can be quantified and can be readily applied by educators. The data of the jury evaluation are verified with an interrater reliability evaluation. Our results indicate that conducting the course assignment for multiple years increases the quality of the student work. The improvement of the results is theorized to be partly due to students gaining inspiration from an increasing number of high-quality parts from previous years of the assignment. The numerical method of result assessment can be used for evaluation when resources are scarce; however, the jury method should be used if possible. - Digitaaliset varaosat
D4 Julkaistu kehittämis- tai tutkimusraportti tai -selvitys(2018) Salmi, Mika; Partanen, Jouni; Tuomi, Jukka; Chekurov, Sergei; Björkstrand, Roy; Huotilainen, Eero; Kukko, Kirsi; Kretzschmar, Niklas; Akmal, Jan; Jalava, Kalle; Koivisto, Satu; Vartiainen, Matti; Metsä-Kortelainen, Sini; Puukko, Pasi; Jussila, Ari; Riipinen, Tuomas; Reijonen, Joni; Tanner, Hannu; Mikkola, MarkkuDigitaaliset varaosat on konsepti, jossa varaosat ja niihin liittyvä valmistustieto säilytetään ja siirretään digitaalisessa muodossa. Varaosien valmistus tapahtuu 3D-tulostamalla tarpeen mukaan yleensä lähellä loppukäyttäjää. Varaosien digitalisoinnilla tavoitellaan parempaa, joustavampaa ja nopeampaa varaosien saatavuutta sekä pienempiä varastointi-, valmistus- ja kuljetuskustannuksia. Nopeammalla varaosien toimittamisella voidaan myös pienentää seisokkiaikoja, mikä voi tarkoittaa merkittäviä kustannussäästöjä. Oleellista yritysten varaosien digitalisoinnissa on löytää varaosakirjastoista ne osat, joiden säilyttämisestä digitaalisessa muodossa ja valmistamisesta 3D-tulostamalla saadaan suurin hyöty. Tällaisia osia ovat etenkin vanhojen laitteiden ja koneiden osat sekä hitaasti kiertävät osat, jotka ovat geometrialtaan monimutkaisia. 3D-tulostamalla voidaan nykypäivänä valmistaa suorituskykyisiä kappaleita ja menetelmä soveltuu erinomaisesti yksittäiskappaleiden tai pienten sarjojen valmistamiseen. Digitaalinen valmistus antaa myös mahdollisuuden kehittää varaosia, mistä esimerkkinä voidaan mainita päivitetyt ja älykkäät varaosat. Tiedot yritysten varaosista ovat hajallaan monissa järjestelmissä ja varsinkin valmistukseen liittyvää tietoa voi olla vaikea löytää. Alkuvaiheessa on tärkeää tunnistaa 3D-tulostettavat osat varaosakirjastoista ja digitalisoida osat mukaan lukien niin 3D-mallit kuin kaikki muu valmistustieto materiaaleista ja toleransseista tarvittaviin jälkikäsittelytietoihin. Varaosien digitalisointi vaatii 3D-suunnitteluosaamista sekä 3D-tulostusprosessien tuntemusta ja tulostettaviin materiaaleihin perehtymistä. Varaosia on harvoin tarkoitettu valmistettavaksi 3D-tulostamalla ja toisaalta 3D-tulostettavien materiaalien valikoima on vielä kohtuullisen rajallinen, mistä syystä joudutaan todennäköisesti tilanteisiin, joissa valmistetaan osa jostakin korvaavasta materiaalista. 3D-tulostusprosessit tuottavat omanlaista rakennetta ja pinnanjälkeä, mistä syystä myös 3D-tulostettavien osien jälkikäsittelyt kuten lämpökäsittelyt ja viimeistelyt on valittava huolellisesti. Tavoite on, että 3D-tulostamalla valmistettujen osien ominaisuudet ovat vähintään yhtä hyvät verrattuna perinteisesti valmistettuihin osiin. Raportissa esitetyn digitaalisten varaosien tiekartan visio on, että noin kymmenen vuoden päästä 10% varaosista on digitaalisia ja valmistusteknologia on luotettavaa ja laadukasta. 3D-tulostusteknologioilta edellytetään siis laadun tosittamista, niihin liittyvän materiaalikirjon laajenemista sekä prosessien automatisointia. 3D-tulostaminen avaa uusia mahdollisuuksia kehittää osien, laitteiden tai kokonaisten prosessien toimintaa. 3D-tulostettuihin osiin voidaan upottaa tunnisteita ja sensoreita, joiden avulla voidaan seurata osien liikkumista toimitusverkostossa sekä suorittaa ennakoivaa kunnonvalvontaa. Tulevaisuuden varaosa osaa tilata automaattisesti uuden osan digitaalisesta varaosakirjastosta, jolloin uusi osa saadaan vaihdetuksi kuluneen tilanne juuri oikeaan aikaan ennen koneen rikkoutumista tai prosessin pysähtymistä. - Digital Spare Parts
D4 Julkaistu kehittämis- tai tutkimusraportti tai -selvitys(2018) Salmi, Mika; Partanen, Jouni; Tuomi, Jukka; Chekurov, Sergei; Björkstrand, Roy; Huotilainen, Eero; Kukko, Kirsi; Kretzschmar, Niklas; Akmal, Jan; Jalava, Kalle; Koivisto, Satu; Vartiainen, Matti; Metsä-Kortelainen, Sini; Puukko, Pasi; Jussila, Ari; Riipinen, Tuomas; Reijonen, Joni; Tanner, Hannu; Mikkola, MarkkuDigital spare parts is a concept where the spare parts and the related manufacturing data are stored and transferred in digital form. The spare parts are manufactured using 3D printing according to need, usually close to the end user’s premises. The digitalisation of spare parts aims for a better, more flexible and quicker availability of spare parts, and lower storage, manufacturing and transport costs. The quicker delivery of spare parts can also reduce downtime, which can mean significant cost savings. It is essential in the digitalisation of the companies' spare parts to find the parts in the spare part libraries that bring the greatest benefit when they are stored in digital form and manufactured by 3D printing. Such parts include, in particular, parts of old equipment and machines and slowly circulating parts with complex geometries. Today, 3D printing can be used to manufacture high-performance pieces, and the method is excellently suited to the manufacturing of individual pieces or short-run batches; it also allows the improvement of the spare parts, with updated and intelligent spare parts as examples. Information on a company's spare parts is scattered between multiple systems, and manufacturing data in particular may be difficult to find. At the initial stage, it is important to identify the 3D printable parts in the spare part libraries and digitalise them, not only with regard to 3D models but all other manufacturing data from materials and tolerances to the required post-processing data. The digitalisation of spare parts requires 3D design competence, knowledge of the 3D printing processes, and familiarisation with the printable materials. Spare parts are rarely designed to be manufactured by 3D printing; on the other hand, the selection of 3D printable materials remains reasonably limited, due to which situations where a part is manufactured from a replacement material will likely occur. 3D printing processes produce their own kind of a structure and surface finish, due to which the post-processing of 3D printable parts, such as heat treatments and finishing, must be carefully chosen. The goal is that the properties of parts manufactured by 3D printing are at least as good as those of conventionally manufactured parts. The vision of the roadmap for digital spare parts presented in the report is that after ten years or so, 10% of spare parts are digital, and the manufacturing technology is reliable and is of a high quality. In other words, quality verification, the extension of the related material selection and the automation of processes are required of the 3D printing technologies. 3D printing creates new possibilities for the development of the operation of parts, equipment or entire processes. IDs and sensors can be embedded into 3D printed parts, allowing the tracking of their movement in the supply network and anticipatory condition monitoring. A spare part of the future will be able to automatically order a new part from a digital spare part library so that it can be replaced by the new part just at the right time before the machine breaks down or the process stops. - Evaluating the Readiness Level of Additively Manufactured Digital Spare Parts: An Industrial Perspective
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2018-10-07) Kretzschmar, Niklas; Chekurov, Sergei; Salmi, Mika; Tuomi, JukkaAdditive manufacturing of digital spare parts offers promising new possibilities for companies to drastically shorten lead times and to omit storage costs. However, the concept of digital spare parts has not yet gained much footing in the manufacturing industry. This study aims to identify grounds for its selective rejection. Conducted from a corporate perspective, outlining a holistic supply chain network structure to visualize different digital spare part distribution scenarios, this survey study evaluates technical and economic additive manufacturing capabilities. Results are analyzed and discussed further by applying the Mann-Whitney test to examine the influence of the company size and the presence of 3D-printed end-use components within supply networks on gathered data. Machines’ limited build chamber volumes and the necessity of post-processing are considered as the main technical challenges of current additive manufacturing processes. Furthermore, it can be concluded that company sizes have a significant effect on perceived technological limitations. Overall, the results lead to the conclusion that the readiness level of the digital spare parts concept demands for further development. - Implications of lattice structures on economics and productivity of metal powder bed fusion
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-01-01) Flores, Inigo; Kretzschmar, Niklas; Azman, Abdul Hadi; Chekurov, Sergei; Pedersen, David Bue; Chaudhuri, AtanuThe cost-effectiveness of metal powder bed fusion (PBF) systems in high-throughput production are dominated by the high cost of metallic powder materials. Metal PBF technologies become more competitive in production scenarios when Design for Additive Manufacturing (DfAM) is integrated to embed functionality through shape complexity, weight, and material reduction through topology optimization and lattice structures. This study investigates the value of DfAM in terms of unit cost and manufacturing time reduction. Input design parameters, such as lattice design-type, part size, volume fraction, material type and production volumes are included in a Design-of-Experiment to model their impact. The performance variables for cost and manufacturing time were assessed for two scenarios: (i) outsourcing scenario using an online quotation system, and (ii) in-house scenario utilizing a decision support system (DSS) for metal PBF. The results indicate that the size of the part and the lattice volume fraction are the most significant parameters that contribute to time and cost savings. This study shows that full utilization of build platforms by volume-optimized parts, high production volumes, and reduction of volume fraction lead to substantial benefits for metal PBF industrialization. Integration of DfAM and lattice designs for lightweight part production can decrease the unit cost of production down to 70.6% and manufacturing time can be reduced significantly down to 71.7% depending on the manufacturing scenarios and design constraints when comparing to solid infill designs. The study also provides a case example of a bracket design whose cost is reduced by 53.7%, manufacturing time is reduced by 54.3 %, and the overall weight is reduced significantly with the use of lattices structures and topology optimization. - Industrial Opportunities of Additive Manufacturing - Workflow planning and decision making of additively manufactured end-use components
School of Engineering | Doctoral dissertation (article-based)(2019) Chekurov, SergeiThe progression of additive manufacturing—from being limited to producing prototypes to being a valuable technology in producing end-use components—has been noted by many researchers and companies. Nevertheless, the industrial opportunities of this progress are not clear to new users of the technology because the number of end-use applications for additive manufacturing is vast and growing rapidly. The major advantages of using additive manufacturing lie in the increased freedom of design and the possibility to produce components that have previously been impractical. On the other hand, additive manufacturing can also be used in situations where the component does not benefit from the additional design freedom. In such cases, the advantage of using additive manufacturing must come from operational benefits, such as improved delivery speed or cheaper manufacturing cost. To clarify the opportunities, the thesis proposes categorizing the end-use applications from the point of view of design into "components designed for additive manufacturing", "components redesigned for additive manufacturing", and "components not designed for additive manufacturing". Each of these categories has their use in industrial applications and can help achieve specific technical and operational benefits. In the thesis, the categories are provided with design workflows that draw from the design process of Pahl & Beitz and are augmented with relevant previous research from the field of design for additive manufacturing. To investigate the industrial opportunities in the form of technical and operational advantages of the categories, the thesis demonstrates the use of the categories and their workflows by providing a case study for each. In the case studies, the design process of the components is demonstrated with the help of the developed design workflows, and the technical and operational benefits of each component are evaluated. The case studies of the categories involve the design of a novel high-performance heat exchanger, the redesign of a digital hydraulic valve manifold, and the production of a memory cover for use in the repair of a portable computer. In addition, the thesis contains a focus group study in the category "components not designed for additive manufacturing" to discover in which scenarios it could be employed. In the final section of the thesis, the technical and operational advantages of using additive manufacturing in each of the categories are collected and presented. The main technical advantages discovered in the investigations were the creation of new functionalities and improvement of performance, and the main operational benefits were the simplification of supply chains and shorter repairs. The thesis gives researchers in the field of design for additive manufacturing a framework to communicate their findings in a way that can be understood easily by practitioners not previously intimately familiar with designing for additive manufacturing. - Influence of feature size and shape on corrosion of 316L lattice structures fabricated by laser powder bed fusion
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2023-01-05) Puttonen, Tuomas; Chekurov, Sergei; Kuva, Jukka; Björkstrand, Roy; Partanen, Jouni; Salmi, MikaLaser powder bed fusion (LPBF) has become an established method for manufacturing end-use metal components. Exploiting the geometric freedom of additive manufacturing (AM) offers broad possibilities for part optimization and enables performance enhancements across industry sectors. However, part shape and feature size have been found to locally affect residual stresses, melt pool cooling rates, microstructure, and thus the mechanical properties of components. Even though the mesoscale structure can locally induce microstructural changes, there are no prior studies on how it influences corrosion. Using AM-produced, optimized parts in critical applications necessitates a better understanding of their long-term performance. In this study, lattice structures were used to probe the influence of feature size and shape on corrosion susceptibility and its spatial localization. The susceptibility of submillimeter LPBF-fabricated 316L stainless steel lattice structures to corrosion was investigated by conducting a 21-day immersion corrosion test in an aqueous 3.5 wt% NaCl solution. Schoen gyroid and Schwarz diamond triply periodic minimal surface lattices were manufactured with three unit cell sizes and wall thicknesses (0.867, 0.515, and 0.323 mm). The nominal surface and cross-sectional areas were the same for the two geometries. X-ray microcomputed tomography (microCT) scans before and after the corrosion test were compared for volumetric losses. In addition, the mechanical properties and microstructure of the samples were evaluated. As part of the study, a workflow to register, index, and analyze volumetric changes of consecutive microCT image stacks was developed. The reported method is applicable to any time-lapse studies with microCT. Three out of five of the 0.323 mm wall thickness lattices displayed visually aggressive pitting. Based on the microcomputed tomography data, the mass losses were localized either in the entrapped powder particles or partially melted surface globules. Corrosion did not occur in the dense base material. The total mass losses ranged from 8 to 19 mg. Despite visual indications to support a higher corrosion susceptibility for the smallest lattice sizes, the mass loss values did not confirm this conclusion. The tensile test results did not provide any clear indications of latent corrosion effects on mechanical properties. - Materiaalia lisäävillä menetelmillä valmistetut metallit ja niiden käyttökohteet lääketieteessä
Insinööritieteiden korkeakoulu | Bachelor's thesis(2018-08-30) Selkama, Senni - New business from digital spare parts
Commissioned report(2020) Metsä-Kortelainen, Sini; Reijonen, Joni; Riipinen, Tuomas; Vaajoki, Antti; Puukko, Pasi; Salmi, Mika; Chekurov, Sergei; Björkstrand, Roy; Kretzschmar, Niklas; Akmal, Jan Sher; Puttonen, Tuomas; Partanen, JouniThe report summarises the results of the New Business From Digital Spare Parts project (DIVALIITO), managed and implemented by VTT and Aalto University during the years 2018-2020. In the project, methods for identification of 3D printable parts from the spare parts libraries were developed, and information available on materials for additive manufacturing were compiled, produced and compared with the conventional manufacturing materials and methods. New spare part concepts such as smart spare parts with embedded intelligence were investigated, and the connections of the process steps of the whole manufacturing chain of the digital spare part were clarified, especially from the workflow, quality control and automation perspectives. The report is a compilation of results and it contains links to original documents where the results are presented more widely.