Dimensional uncertainty in desktop 3D printers: measurement process, sources and compensation

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School of Engineering | Master's thesis
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2025-04-14

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Mechanical Engineering

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Master's programme in Mechanical Engineering

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en

Pages

46

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Abstract

Additive manufacturing is growing as a production method every year, but dimensional uncertainties are still an issue that needs to be addressed before the method can be used for components that require a high degree of precision to manufacture. To investigate how different machines interact with dimensional uncertainty a Gauge R&R analysis was performed with three machines of the same model instead of three operators. Different measurements in all three axes directions were taken to also research the length-dependent and non-length-dependent uncertainty differences. The experiment concluded that the machines had very low part-to-part variance, with uncertainties that were mainly due to the measurement system, which had an uncertainty of ±20𝜇𝑚 . The accuracies of the machines were not as impressive, with the mean being off by 0.05 mm from the nominal value on average for a dimension of less than 50 mm. The length-dependent uncertainty was very similar between machines and very close to the shrinkage of 0.3% that was specified as the shrinkage for PLA, the material that was used during the study. Compensation for these uncertainties should be done to create more precise parts along with designing the parts to work to the strengths of AM rather than failing on the weaknesses of it. The study in this thesis can be used to develop an efficient benchmark for AM processes. Performance indicators and factors that were observed to be in need of compensation can be implemented into the slicer to make compensation easy for a specific machine, material, and parameter combination.

Additiv tillverkning blir mera prevalent som tillverkningsmetod för varje Ă„r som gĂ„r, men dimensionella osĂ€kerheter Ă€r ett problem som mĂ„ste hanteras innan metoden kan anvĂ€ndas för tillverkning av precisionskomponenter. För att undersöka hur olika maskiner interagerar med dimensionell osĂ€kerhet gjordes det en Gauge R&R under- sökning med tre olika maskiner av samma modell istĂ€llet för tre olika operatörer av mĂ€tinstrumenten. MĂ€tningarna gjordes i alla tre dimensioner för att jĂ€mföra osĂ€ker- heten mellan de olika koordinataxlarna och dela in osĂ€kerheten i lĂ€ngdbaserad och icke-lĂ€ngdbaserad osĂ€kerhet. Resultatet var att maskinerna i sig sjĂ€lva hade mycket lĂ„g varians mellan komponenterna som producerades. Över hĂ€lften av osĂ€kerheten skapades av mĂ€tsystemet som i sig hade en osĂ€kerhet pĂ„ ungefĂ€r 20 mikrometer. Maskinerna producerade dock dimensioner som var lĂ„ngt ifrĂ„n referensvĂ€rdet. VĂ€rdena var i medeltal 0.05 mm ifrĂ„n det nominella vĂ€rdet, vilket Ă€r en relativt stor skillnad dĂ„ man talar om mĂ„tt pĂ„ under 50 millimeter. Den lĂ€ngdbaserade osĂ€kerheten var mycket nĂ€ra 0.3% som Ă€r krympningsfaktorn pĂ„ materialet PLA som anvĂ€ndes i experimentet. Ifall dessa faktorer kompenseras för kan man producera mycket mĂ€tnoga komponenter. Dessutom bör designprocessen anpassas för additiv tillverkning för att uppnĂ„ bĂ€sta resultat. Resultatet av experimentet kan anvĂ€ndas för att utveckla ett referenstest med vilket man lĂ€tt kan identifiera kompensationsfaktorerna för en process. Dessa faktorer kan ocksĂ„ inkorporeras i mjukvaran sĂ„ att de lĂ€tt kan kompenseras för och anpassas till olika material, parametrar och maskiner.

Description

Supervisor

Akmal, Jan

Thesis advisor

Akmal, Jan

Keywords

additive manufacturing, dimensional uncertainty, Gauge R&R, length-dependent uncertainty, non-length-dependent uncertainty, benchmark

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https://urn.fi/URN:NBN:fi:aalto-202505193813

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