The Effect of Process Parameters on Thickness Distribution in Thermoforming

Ekşi, Olcay; Karabeyoğlu, Sencer Süreyya

doi:10.12913/22998624/71147

Cited by 7 publications

(5 citation statements)

References 11 publications

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“…Aligners are produced by a thermoforming process. 26 Thermoplastic polymers melt and then flow because of heating. SmartTrack (LD30; Align Technology) material is a multilayer aromatic thermoplastic polyurethane/ copolyester.…”

Section: Discussionmentioning

confidence: 99%

Micro computed tomography evaluation of Invisalign aligner thickness homogeneity

Mantovani¹,

Parrini²,

Coda³

et al. 2021

The Angle Orthodontist

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Objectives To measure the thickness homogeneity of Invisalign (Align Technology Inc, San José, Calif) aligners with micro-computed tomography (micro-CT) scans. Materials and Methods Starting from micro-CT scanning of 20 different aligners, multiplanar reconstructions were obtained. An orthodontist blinded about the study measured aligner thickness in different regions (molar, canine, incisor) and in different sites (gingival–buccal, buccal, occlusal, lingual, and gingival–lingual). To assess various thicknesses in different aligner sites and regions, the sample was stratified into subgroups and linear regression analysis was performed. Results Descriptive analysis showed that mean thickness of aligners in the incisor region ranged from 0.582 mm to 0.639 mm, in the canine region from 0.569 mm to 0.644 mm, and in the molar region from 0.566 mm to 0.634 mm. Student's t-tests showed no significant differences in the aligner thickness of different regions when data were stratified by different sites. Student's t-tests showed significant differences in thickness homogeneity for the molar region when the data were stratified by tooth (mean difference = 0.068 mm; 95% confidence interval, 0.009–0.126 mm; P = .024). Conclusions Invisalign aligner thickness is characterized by small differences. The only significant difference was revealed in the molar region where thickness of the gingival–lingual edge is significantly thinner than that measured at the occlusal aspect. From a clinical perspective, the results of the present study could be considered to explain the reduced predictability of several orthodontic tooth movements in the molar region.

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Section: Discussionmentioning

confidence: 99%

Micro computed tomography evaluation of Invisalign aligner thickness homogeneity

Mantovani¹,

Parrini²,

Coda³

et al. 2021

The Angle Orthodontist

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show abstract

“…Pada penelitian sebelumnya, beberapa studi telah dilakukan untuk mengkaji pengaruh parameterproses terhadap distribusi ketebalan dinding dan akurasi dimensi dalam proses thermoforming [5] [6]. Namun, penelitian yang lebih rinci dan terfokus masih diperlukan untuk memperoleh pemahaman yang lebih mendalam tentang interaksi antara parameter-proses tersebut.…”

Section: Pendahuluanunclassified

Pengaruh Parameter Proses Thermoforming Terhadap Distribusi Ketebalan dan Akurasi Dimensi Produk

Budiyantoro,

Kurniawan

2023

JMPM

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Penelitian ini melihat pengaruh parameter-proses thermoforming, yaitu waktu pemanasan, pre-stretching degree, dan tingkat evakuasi vakum, terhadap distribusi ketebalan dinding dan akurasi dimensi produk plastik yang diproses dengan thermoforming. Penelitian dilakukan serangkaian percobaan dengan tiga variasi parameter-proses tersebut. Waktu pemanasan divariasikan masing-masing 30, 35 dan 40 detik, pre-stretching degree dari 0,1 hingga 0,3, dan evacuation rate dalam nilai 6 mm/detik, 8 mm/detik dan 10 mm/detik. Hasil penelitian menunjukkan bahwa parameter yang mampu meminimalkan radius pada sudut specimen adalah: tingkat evakuasi 10 mm/detik, waktu pemanasan 40 detik dan derajad pre-stretching 0,1 Vst. Hasil produk vacuum forming dapat dioptimalkan dengan kombinasi tingkat evakuasi vakum yang tinggi, waktu pemanasan lebih lama dan derajad pre-stretching rendah. This study examines the influence of thermoforming process parameters, namely heating time, pre-stretching degree, and vacuum evacuation rate, on the distribution of wall thickness and dimensional accuracy of the product. The research involved a series of experiments with three variations of these process parameters. Heating time was varied at 30, 35, and 40 seconds, pre-stretching degree ranged from 0.1 to 0.3, and evacuation rates were set at 6 mm/s, 8 mm/s, and 10 mm/s, respectively. The results showed that the parameters capable of minimizing the radius at the specimen's corners were a vacuum evacuation rate of 10 mm/s, a heating time of 40 seconds, and a pre-stretching degree of 0.1 Vst. The findings suggest that the vacuum forming products can be optimized by combining a high vacuum evacuation rate, longer heating time, and low pre-stretching degree.

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“…Thermoforming consists in plasticization of a thermoplastic plate or sheet in a forming mold to ge nerate tensile stresses that cause its plastic deformation and adherence to the mold cavity; after that, the finished part is cooled and released [11,12]. Thermoforming has many variants which differ in aspects such as the applied stretch factor, the part of the mold in which stretching takes place and the application of pre-stretch which can also be caused by different factors [13][14][15][16]. Although this process is similar to other polymer processing me thods [17][18][19], it requires separate studies due to its specificity.…”

Section: Wykorzystanie Funkcji Użyteczności W Optymalizacji Procesu Termoformowaniamentioning

confidence: 99%

The use of utility function for optimization of thermoforming

Sasimowski

2018

Polimery

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The paper describes a utility function -based method for optimization of a thermoforming process for producing finished parts made of polystyrene sheet by vacuum forming and vacuum assisted drape forming with and without pre-blow. Not only does the proposed method enable determination of optimum thermoforming conditions, it also provides information about interactions between these conditions as well as about their impact on the properties of finished parts and polymer heating time, a factor which affects efficiency of this process. The determined optimum thermoforming conditions significantly differ for thermoforming without pre-blow and thermoforming with pre-blow, which results from different ways of forming individual regions of polystyrene sheet during both processes. The employed method enables determination several optimum criteria, the number of which can be extended as desired, which is significant for practical applications of machines and devices.

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The Effect of Process Parameters on Thickness Distribution in Thermoforming

Cited by 7 publications

References 11 publications

Micro computed tomography evaluation of Invisalign aligner thickness homogeneity

Micro computed tomography evaluation of Invisalign aligner thickness homogeneity

Pengaruh Parameter Proses Thermoforming Terhadap Distribusi Ketebalan dan Akurasi Dimensi Produk

The use of utility function for optimization of thermoforming

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