scholarly journals Additive Manufacturing of Thermoplastic M8 Fasteners Using Photopolymer Jetting Technology for Low-Strength Fastening Applications

2021 ◽  
Author(s):  
Parth Patpatiya ◽  
Anshuman Shastri
Keyword(s):  
Dimensional Stability ◽  
Food Packaging ◽  
Critical Conditions ◽  
Laser Sensor ◽  
Manufacturing Constraints ◽  
Dimensional Changes ◽  
Imaging Results ◽  
Thread Profile ◽  
Low Strength ◽  
Thermoplastic Resins

Abstract This study investigates the spatial accuracy of additively manufactured M8 fasteners fabricated using photopolymer jetting technology. A number of M8 bolts and their mating M8 nuts are fabricated using Stratasys Object 260 Connex 3 polyjet printer with Vero cyan, Vero magenta, Vero white, and Vero grey thermoplastic resins. Vero series thermo-plastics were used as they offer durability, strength, and flexibility. The additively manufactured nuts and bolts are fabricated with the intention of introducing thermoplastic fasteners that could eventually substitute metal fasteners in certain low strength joining applications such as in fluidics, electronics, biomedical engineering, food packaging, and automobile industries. Manufacturing constraints and critical conditions for fabrication are presented. Vital printing and manufacturing constraints, dimensional stability analysis, and the subsequent dimensional changes for the fabricated fasteners are thoroughly illustrated. Dimensional stability of the printed structures was examined under an ultra-compact 3D laser sensor and the imaging results are also presented. The fabricated thread profile superimposed precisely with the CAD model’s ISO thread profile dimensions. The dimensional performance of the fabricated M8 fasteners was examined in every orientation and along each axis of the fasteners. The high-quality manufacturing of fasteners using photopolymer jetting reached the maximum precision requirements and fitted under IT 06 transition fit grade.

Optimization of a High Pressure Industrial Fan

2021 ◽  
Author(s):  
Edward De Jesús Rivera ◽  
Fanny Besem-Cordova ◽  
Jean-Charles Bonaccorsi
Keyword(s):  
Pressure Rise ◽  
Critical Conditions ◽  
Manufacturing Constraints ◽  
Efficient Design ◽  
Machine Performance ◽  
Mass Flow Rates ◽  
Mining Tool ◽  
Automated Optimization ◽  
Cfd Optimization ◽  
Impeller Geometry

Abstract Fans are used in industrial refineries, power generation, petrochemistry, pollution control, etc. These fans can perform in sometimes extreme, mission-critical conditions. The design of fans has historically relied on turbomachinery affinity laws, resulting in oversized machines that are expensive to manufacture and transport. With the increasingly lower CPU cost of fluid modeling, designers can now turn to CFD optimization to produce the necessary machine performance and flow conditions while respecting manufacturing constraints. The objective of this study is to maximize the pressure rise across an industrial fan while respecting manufacturing constraints. First, a 3D scan of the baseline impeller is used to create the CFD model and validated against experimental data. The baseline impeller geometry is then parameterized with 21 free parameters driving the shape of the hub, shroud, blade lean and camber. A fully automated optimization process is conducted using Numeca’s Fine™/Design3D software, allowing for a CPU-efficient Design Of Experiment (DOE) database generation and a surrogate model using the powerful Minamo optimization kernel and data-mining tool. The optimized impeller coupled with a CFD-aided redesigned volute showed an increase in overall pressure rise over the whole performance line, up to 24% at higher mass flow rates compared to the baseline geometry.

scholarly journals Elastomeric Impression Materials: A Comparison of Accuracy of Multiple Pours

2011 ◽  
Vol 12 (4) ◽  
pp. 272-278 ◽  
Author(s):  
Dheeraj Kumar ◽  
Anand U Madihalli ◽  
K Rajeev Kumar Reddy ◽  
Namrataa Rastogi ◽  
NT Pradeep
Keyword(s):  
Clinical Significance ◽  
Dimensional Stability ◽  
Central Hole ◽  
Central Incisor ◽  
Impression Material ◽  
Maxillary Central Incisor ◽  
Dimensional Changes ◽  
The Third ◽  
Impression Materials ◽  
Time Periods

ABSTRACT Aim The aim of the present study is to compare the various elastomeric impression materials in terms of accuracy and dimensional stability, with respect to obtaining multiple casts from a single elastomeric impression at various times of pours. Materials and methods Three master dies were prepared for the impression making, two of these were made of brass containing a central hole with undercuts. The third die simulated a conventionally prepared typodont maxillary central incisor. Three elastomeric impression materials were chosen for the study. Each impression was poured at various time periods. Casts thus obtained were evaluated under a traveling microscope to evaluate various dimensional changes. Results Addition silicones provided dies which were shorter in height and bigger in diameter. Polyethers provided dies which were shorter in both height and diameter. Condensation silicones showed insignificant changes from the master die at the immediate pour but deteriorated rapidly after that in subsequent pours. Conclusion None of the impression material showed a consistent behavior up to the fourth pour. They occasionally showed deviation from the pattern, but all these values were statistically insignificant. Polyethers showed lesser ability than both the addition silicones as well as the condensation silicones to recover from induced deformation. Clinical significance Addition silicones as well as the condensation silicones have better ability to recover from induced deformation when compared to polyether. How to cite this article Kumar D, Madihalli AU, Reddy KRK, Rastogi N, Pradeep NT. Elastomeric Impression Materials: A Comparison of Accuracy of Multiple Pours. J Contemp Dent Pract 2011;12(4):272-278.

scholarly journals The Effects of Chemical Disinfection on Dimensional Stability among Different Type of Impression Addition Silicon Materials

2020 ◽  
Vol 5 (12) ◽  
pp. 645-649
Author(s):  
Salah A. Yousief ◽  
Khames T. Alzahrani ◽  
Suha M. Alhuwairini ◽  
Fai Y. Alharbi ◽  
Dalal A. Eissa ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Epoxy Resin ◽  
Dimensional Stability ◽  
Control Group ◽  
P Value ◽  
Impression Material ◽  
Dimensional Changes ◽  
The Mean ◽  
Master Model ◽  
The Cross

Introduction: Saliva and blood contaminated impressions are often a source of cross contamination between the clinic and dental laboratory. Explicit communication and observance of an infection control protocol for handling of dental impressions must exist among the office staff as well as between office and dental laboratories. Though disinfection of impression is routinely followed, autoclaving elastomeric impression is an effective method of sterilization them. Objectives: The purpose of this study was to evaluate dimensional stability and detail reproduction of a new addition silicon impression material after disinfection. Methods: In this study, a total of twenty impressions for the master model using heat resistant plastic stock trays. The twenty impressions were divided into two groups according to disinfection technique: (Table 2) Group 1: (n=10) Control group, untreated impressions. (C.G) Group 2: (n=10) Impressions were chemically disinfected. (D.G). after all impressions treatment, they were poured with extra hard stone (type IV) to get stone casts. Dimensional accuracy and detail reproduction of the impression material were evaluated indirectly through the recovered improved stone casts from impressions of the master model using the travelling microscope. Results: Cross arch distance (A): Epoxy resin master model cross arch distance measurement (A) was (41.36 mm). 1.1 Measurements of the cross-arch distance of stone casts Control group (C.G): The mean and standard deviation values of distance (A) in stone models obtained from C.G. were 41.553 ± 0.170 mm. Disinfection group (D.G): The mean and standard deviation values of distance (A) in stone models obtained from D.G were 41.368 ± 0.083 mm. ANOVA test showed that there was a statistically difference shrinkage between the groups (P-value = 0.006). 1.2 Measurement of the dimensional changes in the cross-arch distance of the different groups. The mean and standard deviation values of cross arch distance changes in stone models of C.G. were 0.191 ± 0.170 mm. while dimensional changes in stone models obtained from D.G. were 0.006 ± 0.082 mm. Conclusion: The purpose of this study was to evaluate dimensional stability and detail reproduction of a new addition silicon impression material after disinfection. In this study an epoxy resin master model was duplicated from a modified dentate mandibular model. Within the limitations of this study, it could be concluded that Chemical disinfectant of polyvinyl siloxane impression material can be successfully used in making fixed partial dentures.

Dynamic moisture sorption and dimensional stability of furfurylated wood with low lignin content

Holzforschung ◽  
2019 ◽  
Vol 74 (1) ◽  
pp. 68-76
Author(s):  
Tiantian Yang ◽  
Erni Ma ◽  
Jinzhen Cao
Keyword(s):  
Relative Humidity ◽  
Dimensional Stability ◽  
Furfuryl Alcohol ◽  
Lignin Content ◽  
Moisture Sorption ◽  
Dimensional Change ◽  
Poplar Wood ◽  
Sorption Coefficient ◽  
Dimensional Changes ◽  
Sinusoidal Shape

AbstractDegradation of lignin occurs naturally in wood due to the influence of microorganisms or photic radiation. To improve the properties of wood with low lignin content, furfuryl alcohol (FA) at the concentration of 25% was used to modify poplar wood (Populus euramericana Cv.) after partial delignification. Moisture sorption and dimensional stability of the samples were investigated under dynamic conditions where the relative humidity (RH) was changed sinusoidally between 45% and 75% at 25°C. Both the moisture content (MC) and the tangential dimensional change varied with a sinusoidal shape similar to the RH. Hygroscopicity and hygroexpansion increased after delignification, while furfurylation led to an inverse impact by reducing MC, dimensional changes, amplitudes of MC and dimensional changes, moisture sorption coefficient (MSC), and humidity expansion coefficient (HEC). After delignification and further furfurylation, the MC and the dimensional changes were reduced by about 20%, and the maximum drop in amplitudes of MC and dimensional changes was about 30%, while the MSC and the HEC decreased by over 15%. In addition, the furfurylated wood with low lignin content exhibited lower sorption hysteresis and swelling hysteresis.

scholarly journals Dimensional Stability and Process Capability of an Industrial Component Injected with Recycled Polypropylene

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1063 ◽  
Author(s):  
José Eduardo Galve ◽  
Daniel Elduque ◽  
Carmelo Pina ◽  
Isabel Clavería ◽  
Raquel Acero ◽  
...  
Keyword(s):  
Environmental Impact ◽  
Dimensional Stability ◽  
Process Capability ◽  
Coordinate Measuring Machine ◽  
Storage Conditions ◽  
Dimensional Changes ◽  
Injection Process ◽  
Recycled Polypropylene ◽  
Measuring Machine ◽  
Recycled Material

The usage of recycled polymers for industrial purposes arises as one of the most promising methods of reducing environmental impact and costs associated with scrapping parts. This paper presents a systematic study of the dimensional stability of a raw and 100% recycled polypropylene subjected to realistic environmental conditions occurring along its working life. The component studied is an internal part of an induction hob assembly. Industrial samples manufactured with both materials, in the same mold, and in the same injection machine, are subjected to ejection conditions, storage conditions (50 °C), and extreme performance conditions (80 °C). Induced dimensional changes are registered and analyzed using a coordinate measuring machine, and a tactile sensing probe. To verify the process capability of the samples manufacturing, Cp and Cpk values are calculated to evaluate the suitability of the recycled material as an alternative. Results conclude that, although the use of recycled material implies slight differences in terms of dimensional stability due to the changes induced in the polymer structure, these differences are not significant enough to affect the injection process capability. Therefore, recycling arises as one effective method to reduce both overruns associated with the consumption of raw polypropylene material and its environmental impact.

Dimensional stability of single jersey fabrics of lincLITE® and conventional yarns. II. Fabric dimensional changes

2007 ◽  
Vol 8 (1) ◽  
pp. 72-78 ◽  
Author(s):  
Shin-Woong Park ◽  
Stewart Collie ◽  
C. N. Herath ◽  
Bok Choon Kang ◽  
JaeSang An
Keyword(s):  
Dimensional Stability ◽  
Dimensional Changes ◽  
Single Jersey

scholarly journals Extended-pour and conventional alginates: effect of storage time on dimensional accuracy and maintenance of details

2021 ◽  
Vol 26 (3) ◽  
Author(s):  
Sandro Basso BITENCOURT ◽  
Isabela Araguê CATANOZE ◽  
Emily Vivianne Freitas da SILVA ◽  
Karina Helga Leal TURCIO ◽  
Daniela Micheline dos SANTOS ◽  
...  
Keyword(s):  
Dimensional Stability ◽  
High Stability ◽  
Digital Camera ◽  
Dimensional Accuracy ◽  
Dimensional Change ◽  
Clinical Results ◽  
Dimensional Changes ◽  
Plastic Bags ◽  
Significant Difference ◽  
Student’S T

ABSTRACT Objective: This study aimed to evaluate the dimensional stability and maintenance of details of conventional and high stability alginates up to 5-day storage. Methods: Two types of alginates were selected (n=10) for this study, conventional (Hydrogum) and high stability alginates (Hydrogum 5), which were produced with the aid of a cylindrical metal block and a ring-shaped metal mold (Specifications 18, 19, and 25, ANSI/ADA). Ten images were obtained from the molds for the dimensional stability test, which were taken immediately after their production and at each different storage periods (15 min, 24 h, 48 h, 72 h, 96 h, and 120 h) by a digital camera. The specimens were kept hermetically sealed in plastic bags (23°C) and then used to obtain 140 (n=70) dental stone models, used in the detail reproduction test, in which the angular accuracy of three grooves (20 µm, 50 µm, and 75 µm) was observed at each period. The details reproduction accuracy was classified using a predetermined score classification. Measurements of dimensional changes were made in the Corel DRAW X6 program. The data were submitted to the Student’s t-test (α?#8197;= 0.05). Results: A statistically significant difference concerning the size of the matrix was observed after 24h for both alginates, and a statistically significant negative linear dimensional change (contraction) was verified after 24 h of storage (1.52% for the high stability alginate, and 1.32% for the conventional alginate). The high stability alginate kept the full details for 72 hours, while the conventional alginate, for 24 h. Both alginates reproduced the 75 µm groove at all storage periods. Conclusion: Impressions made with both alginates presented satisfactory clinical results when the alginates were immediately poured.

scholarly journals Strategies for improving dimensional stability of concrete

2016 ◽  
Vol 43 (10) ◽  
pp. 875-885
Author(s):  
P.L. Ng ◽  
Albert K.H. Kwan
Keyword(s):  
Dimensional Stability ◽  
Cement Content ◽  
Drying Shrinkage ◽  
Sustained Load ◽  
Early Age ◽  
Test Results ◽  
Dimensional Changes ◽  
Shrinkage And Creep ◽  
Concrete Mix

Changes in dimension of concrete due to early-age heat generation, long-term drying shrinkage, and creep under sustained load could lead to significant movements of the concrete structure and lock-up stresses if the movements are restrained. The lock-up stresses are often large enough to cause cracking and water leakage, thereby adversely affecting the serviceability and durability of the structure. Whilst the dimensional changes are quite variable because of their dependence on the environmental conditions and applied loads, they are all related to the concrete mix proportions. Generally, the dimensional stability of concrete can be improved by reducing its cement content and paste volume. Moreover, since the aggregate also shrinks, the dimensional stability can be improved by suppressing the shrinkage of aggregate as well. In this paper, strategies for improving the dimensional stability of concrete are formulated based on experimental research. Test results are presented to demonstrate their effectiveness and applicability.

scholarly journals Evaluation of the Dimensional Stability of Black Poplar Wood Modified Thermally in Nitrogen Atmosphere

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1491
Author(s):  
Olga Bytner ◽  
Agnieszka Laskowska ◽  
Michał Drożdżek ◽  
Paweł Kozakiewicz ◽  
Janusz Zawadzki
Keyword(s):  
Dimensional Stability ◽  
Nitrogen Atmosphere ◽  
Thermal Modification ◽  
Poplar Wood ◽  
Dimensional Changes ◽  
Processing Times ◽  
Modification Process ◽  
Black Poplar ◽  
Tangential Directions ◽  
Modified Wood

Black poplar (Populus nigra L.) was thermally modified in nitrogen atmosphere. The effects of the modification process on poplar wood were evaluated for temperatures: 160 °C, 190 °C, and 220 °C applied for 2 h; and 160 °C and 190 °C for 6 h. The percentual impact of temperature and time of modification on the properties of modified wood was analysed. The study permitted the identification correlations between the chemical composition and selected physical properties of thermally modified poplar wood. The dimensional stability of poplar wood was improved after thermal modification in nitrogen. The higher the temperature of modification, the lower the equilibrium moisture content (EMC) of black poplar. At the temperature of 220 °C, EMC was two times lower than the EMC of non-modified black poplar. It is also possible to reduce the dimensional changes of wood two-fold (at the modification temperature of 220 °C), both in radial and tangential directions, independently of the acclimatization conditions (from 34% to 98% relative humidity, RH). Similar correlations have been found for wood that has been soaked in water. Higher modification temperatures and longer processing times contributed to a lower swelling anisotropy (SA).

scholarly journals Study of Thermal Stress Influence on Dimensional Stability of Silicone Molds

2014 ◽  
Vol 22 (34) ◽  
pp. 15-19
Author(s):  
Martin Bajčičák ◽  
Roland Šuba
Keyword(s):  
Thermal Stress ◽  
Dimensional Stability ◽  
Degradation Process ◽  
Temperature Influence ◽  
Melting Points ◽  
Dimensional Changes ◽  
Spin Casting ◽  
Size And Shape ◽  
Mechanism Of Degradation ◽  
Stress Influence

Abstract The paper is focused on the study of temperature influence on dimensional stability of silicone molds used for spin casting of the low melting points alloys. The silicone material denoted as TEKSIL Silicone-GP-S was used to produce samples during experiments. The samples were heated to temperatures in the range from 100 up to 250oC for 30 up to 120 min. Dimensional changes of the samples in the radial and axial directions aa well as their change of weight were evaluated. The results of experiments proved that thermal stress of silicone molds can influence the size and shape of mold cavities. These results can also explain the possible mechanism of degradation process of silicone molds under thermal stress.

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