161 |
Manufacturing of Electric Candle Preparing Industrial Production / Tillverkning av elektriskt stearinljus förberedelse för industriell produktionHamngren, Leonard January 2018 (has links)
Det här examensarbetet är en fortsättning på ett tidigare kandidatexamensarbete vars syfte var att bestämma form och funktion för ett elektriskt stearinljus som skulle se så verklighetstroget ut som möjligt. En prototyp av ljuset byggdes för att testa den nya tekniska lösningen. Syftet med föreliggande examensarbetet var att undersöka hur ljuset skulle kunna tillverkas industriellt. Vad som var optimal tillverkningsteknik och bästa material för varje komponent undersöktes. Svårigheten var att fatta välgrundade beslut för hur vissa komponenter skulle tillverkas, varför det krävdes fysiska experiment för detta. Ett exempel på en sådan komponent var ljusets låga vars uppgift är att sprida ljus, jämt i alla riktningar. Lågan behöver därför ha en skrovlig yta som kan sprida ljus. För att kunna tillverka lågan krävdes en teknik som gör det möjligt att producera dess komplicerade form tidseffektivt. Först bestämdes därför att lågan skulle formsprutas då det är är en teknik som möjliggör gjutning av avancerade former som går på kort tid. Det bestämdes även att lågan skulle göras i akrylplast då det är en plast med hög transparens. För att bestämma hur den skrovliga ytan skulle åstadkommas utfördes sedan ett experiment där olika gjutformar tillverkades. Dessa gjutformar ytbearbetades på olika sätt med bl.a. blästring, gnistbehandling, etsning och gravering. Genomskinlig plast användes för att formspruta i gjutformarna. Det resulterade i formsprutade plastbrickor med olika ytstrukturer. Dessa ytor belystes och dess ljusspridande förmåga mättes med två olika mättekniker. Det visade sig att den etsade ytan spred ljus bäst. Jämfört med ytan som fanns på prototypens låga så visade mätningar att den etsade ytan var något bättre på att sprida ljus. Även andra experiment gjordes för val av en fjäderkomponent och val av limmetod.Ytjämnhetsmätning av den etsade ytan visade att ytjämnheten var Ra 18 µm och på grund av skrovligheten i ytan kunde lågan inte gjutas i ett stycke utan fick delas upp i två halvor. En CAD-modell av ett formverktyg som gjuter en halv låga konstruerades med tillräckliga släppvinklar. Tack vare den etsade ytans goda ljusspridande förmåga behövde ljusets ljuskälla inte lysa starkare än 30 lumen vilket innebär att LED-lampans effekt inte behöver vara större än 0,5 W. De två AA batterier som strömförsörjer ljuset skulle då räcka i minst 15 timmar. / This master thesis is a continuation of an earlier bachelor projectwhere the purpos was to develop form and function for an electric candle that would look as realistic as possible. A prototype of the light was made to test the technical solution. The purpose of this master thesis was to find out how this candle should be manufactured in industry. Optimal manufacturing process and material were assigned to all the components. For some components it was harder to make well grounded decitions about the manufacturing process which is why physical experiments were needed. One of such components is the flame who’s function is to spread light even in all directions. Therefor the flame needs a rough surface that can scatter light. In order to manufacture the flame it required a manufacturing process that could make the complex form on short time. Acrylic plastic was choosen as the material for the flame due to its high light transmittance. To determine how the surface on the flame would be created an experiment was conducted were a couple of mold forms were made. The surface of the forms was processed with blasting, electrical discharge machining, etching and scraping. Transparent plastic was injection molded in these forms. That resulted in pieces of plastic with different surfaces. These pieces were lit and the light scattering properties were measured in two different ways. It showed that the etched surface scattered most light. Other experiments concerning spring testing and glue testing were made. The surface roughness were measured. The etched surface had a surface roughness of Ra 18 µm and because of the high roughness the flame could not be molded in one piece but was split in two. A CAD-model of a mould that makes a half flame was constructed with required draft angles. Thanks to the good light scattering of the etched surface, the lightsource did not need to be stronger than 30 lumen which meen the power of LED-light only had to be around 0,5 W. That meant that two AA batteries could power the light for 15 hours.
|
162 |
Validation of the modified rule of mixtures using a combination of fibre orientation and fibre length measurementsHine, P., Parveen, Bushra, Brands, D., Caton-Rose, Philip D. 04 May 2014 (has links)
No / The goal of this study was to investigate the fibre orientation distribution (FOD), and subsequent mechanical properties, of an injection moulded plate with two different number averaged fibre lengths, termed in this paper medium (1.35 mm) and long (2.40 mm). Fibre orientation measurements (FOD) were made using the 2D elliptical section method and an in-house developed image analyser. The samples were injected from a pin gate located at the centre and top of the plate. Expansion flow on the divergent flow front from this pin gate resulted in a core region with circumferential alignment, while through thickness shear resulted in the usual realignment of fibres in the flow direction either side of the core, termed the shell layers. Two interesting aspects were discovered from these measurements. First, and most importantly, the FOD was found to be independent of the two fibre lengths in this study, and so predominantly controlled by the mould shape and the interaction with the flow front. Second, the fibres in the core region were found to be much closer packed than those in the shell regions.
The interaction between the flow front and the mould shape resulted in a range of FOD across the moulded plate, from equal in-plane orientation at the centre of the plate, to highly aligned at the plate edge. This gave a very useful set of samples from which to test out the well known modified rule of mixtures (MROM). Often the fibre orientation distribution cannot be measured directly, but indirectly using the modified rule of mixtures model in reverse. The samples from this moulding (at two different average fibre lengths) gave an excellent opportunity to validate this often used approach.
Both the tensile modulus and strength (measured parallel to the injection direction) were found to show a strong correlation with the measured fibre orientation, with a significant increase in both measures between the centre and the edge of both plates. The increased length of the ‘long’ fibre plate was found to give only a small increase in tensile modulus but a much larger increase in tensile strength.
The tensile modulus showed a linear dependence with the measured fourth order orientation tensor average, 〈cos4 θ〉, with respect to the injection direction of the plate, as predicted by the modified rule of mixtures. Excellent agreement was found between the measured modulus and the predictions from the modified rule of mixtures, based only on measured quantities (matrix modulus, fibre fraction and average fibre length) for both plates.
|
163 |
Multi-scale modelling describing thermal behaviour of polymeric materials. Scalable lattice-Boltzmann models based upon the theory of Grmela towards refined thermal performance prediction of polymeric materials at micro and nano scales.Clark, Peter G. January 2012 (has links)
Micrometer injection moulding is a type of moulding in which moulds have geometrical
design features on a micrometer scale that must be transferred to the
geometry of the produced part. The difficulties encountered due to very high shear
and rapid heat transfer of these systems has motivated this investigation into the
fundamental mathematics behind polymer heat transfer and associated processes.
The aim is to derive models for polymer dynamics, especially heat dynamics, that
are considerably less approximate than the ones used at present, and to translate
this into simulation and optimisation algorithms and strategies, Thereby allowing
for greater control of the various polymer processing methods at micrometer scales.
|
164 |
A Study of Heat Transfer at the Cavity-Polymer Interface in Microinjection Moulding. The effects of processing conditions, cavity surface roughness and polymer physical properties on the heat transfer coefficientBabenko, Maksims January 2015 (has links)
This thesis investigates the cooling behaviour of polymers during the
microinjection moulding process. The work included bespoke experimental
mould design and manufacturing, material characterisation, infra-red
temperature measurements, cooling analysis and cooling prediction using
commercial simulation software.
To measure surface temperature of the polymers, compounding of
polypropylene and polystyrene with carbon black masterbatch was performed to
make materials opaque for the IR camera. The effects of addition of carbon
black masterbatch were analysed using differential scanning calorimetry and
Fourier transform infrared spectroscopy.
Sapphire windows formed part of the mould wall and allowed thermal
measurements using an IR camera. They were laser machined on their inside
surfaces to generate a range of finishes and structures. Their topographies
were analysed using laser confocal microscope. The surface energy of sapphire
windows was measured and compared to typical mould steel, employing a
contact angle measurement technique and calculated using Owens-Wendt
theory. A heating chamber was designed and manufactured to study spreading
of polymer melts on sapphire and steel substrates.
A design of experiments approach was taken to investigate the influence of
surface finish and the main processing parameters on polymer cooling during
microinjection moulding. Cooling curves were obtained over an area of 1.92 by 1.92 mm of the sapphire window. These experiments were conducted on the
Battenfeld Microsystem 50 microinjection moulding machine.
A simulation study of polymer cooling during the microinjection moulding
process was performed using Moldflow software. Particular interest was paid to
the effect of the values of the interfacial heat transfer coefficient (HTC) on the
simulated cooling predictions. Predicted temperature curves were compared to
experimentally obtained temperature distributions, to obtain HTC values valid
for the material and processing parameters.
|
165 |
Fibre Orientation and Breakage in Glass Fibre Reinforced Polymer Composite Systems: Experimental Validation of Models for Injection Mouldings. Validation of Short and Long Fibre Prediction Models within Autodesk Simulation Moldflow Insight 2014Parveen, Bushra January 2014 (has links)
End-gated and centre gated mouldings have been assessed with varying
thickness and sprue geometries for the centre gate. Alternative image analysis
techniques are used to measure the orientation and length of injection moulded
short and long fibres composite components. The fibre orientation distribution
(FOD) measurements for both geometries have been taken along the flow path.
In shear flow the FOD changes along the flow path, however the FOD remains
relatively constant during expansion flow. The core width and FOD at the skin
within a long glass fibre (LGF) specimen is different in comparison to a short
glass fibre (SGF) specimen. Fibre length measurements have been taken from
the extrudate, sprue and 2 positions within the centre gate cavity. The size of
the sprue has little influence on fibre breakage if the moulding is more than 1
mm thick
The SGF FOD prediction models within Autodesk Simulation Moldflow Insight
2014 (ASMI) have been validated against measured SGF data. At present, by
default, the models over-predict the <cos2θ> for most geometries. When the
coefficients are tailored for each model, drastic improvements are seen in the
FOD prediction. The recently developed SGF RSC model accurately predicts
the FOD in shear, in a thin geometry, whereas the Folgar-Tucker model predicts
the FOD accurately in expansion flow.
The measured LGF fibre length distribution (FLD) and FOD have been validated
against the LGF prediction models. The LGF models are currently under predicting the breakage and over-predicting <cos2θ>. The breakage prediction improves if measured FLD of the extrudate is input into the model. / Autodesk Ltd.
|
166 |
A new process chain for producing bulk metallic glass replication masters with micro- and nano-scale featuresVella, P.C., Dimov, S.S., Brousseau, E., Tuinea-Bobe, Cristina-Luminita, Grant, C., Whiteside, Benjamin R. 02 May 2019 (has links)
No / A novel process chain for serial production of polymer-based devices incorporating both micro- and nano-scale features is proposed. The process chain is enabled by the use of Zr-based bulk metallic glasses (BMG) to achieve the necessary level of compatibility and complementarity between its component technologies. It integrates two different technologies, namely laser ablation and focused ion beam (FIB) milling for micro-structuring and sub-micron patterning, respectively, thus to fabricate inserts incorporating different length scale functional features. Two alternative laser sources, namely nano-second (NS) and pico-second (PS) lasers, were considered as potential candidates for the first step in this master-making process chain. The capabilities of the component technologies together with some issues associated with their integration were studied. To validate the replication performance of the produced masters, a Zr-based BMG insert was used to produce a small batch of micro-fluidic devices by micro-injection moulding. Furthermore, an experimental study was also carried out to determine whether it would be possible by NS laser ablation to structure the Zr-based BMG workpieces with a high surface integrity whilst retaining the BMG’s non-crystalline morphology. Collectively, it was demonstrated that the proposed process chain could be a viable fabrication route for mass production of polymer devices incorporating different length scale features.
|
167 |
Process Fingerprinting of Microneedle Manufacturing Using Conventional and Ultrasonic Micro-injection MouldingGulcur, Mert January 2019 (has links)
This research work investigates the development and application of process
fingerprinting for conventional micro-injection moulding and ultrasonic micro injection moulding manufacturing of microneedle arrays for drug delivery.
The process fingerprinting method covers in-depth analysis, interrogation
and selection of certain process data features and correlation of these
features with product fingerprints which are defined by the geometrical
outcomes of the microneedle arrays in micro scale. The method was
developed using the data collected using extensive sensor technologies
attached to the conventional and ultrasonic micromoulding machines.
Moreover, a machine vision based microneedle product evaluation apparatus
is presented. Micromachining capabilities of different processes is also
assessed and presented where state-of-the-art laser machining was used for
microneedle tool manufacturing in the work.
By using process fingerprinting procedures, conventional and ultrasonic
micromoulding processes has been characterised thoroughly and aspects of
the process that is affecting the part quality was also addressed for
microneedle manufacturing. It was found that polymer structure is of
paramount importance in obtaining sufficient microneedle replication. An
amorphous polymer have been found to be more suitable for conventional
moulding whereas semi-crystalline materials performed better in ultrasonic
micromoulding. In-line captured micromoulding process data for conventional and ultrasonic moulding provided detailed insight of machine dynamics and
understanding. Linear correlations between process fingerprints and micro replication efficiency of the microneedles have been presented for both micromoulding technologies. The in-line process monitoring and product quality evaluation procedures presented in this work for micro-injection
moulding techniques will pave ways for zero-defect micromanufacturing of
miniature products towards Industry 4.0.
|
168 |
An experimental cost model for composite parts using vacuum assisted resin transfer moulding (VARTM)Vogt, Christian 03 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Vacuum assisted resin transfer moulding (VARTM) belongs to the category of resin infusion
techniques that use lower than atmospheric pressure to infiltrate a reinforced cavity. This
technique has various advantages; however, manufacturing costs can be relatively high due to
more difficult shapes fabricated and a lack of knowledge regarding cost driving factors.
The objective of this study was to develop a cost model for composite parts. Such a model
allows the estimation of manufacturing costs of shapes of different geometries. Therefore, it
provides a comparison to alternative manufacturing techniques, such as metal forming or
composite spray lay-up and helps to avoid unnecessarily expensive design features. The
proposal was made to split complex shaped composite parts into individual basic shapes,
which are further investigated here.
For the basic shapes, an experimental approach was used where the manufacturing times of
each process step are measured and then statistically analysed. Infusion simulation software
was used to obtain additional filling times to complete the design of experiments. This method
allows the estimation of manufacturing times of composite parts with different geometries.
The manufacturing times were validated to that of a complex shaped industrial part, with
reasonable results. Finally, a flexible cost model was developed to compare different
manufacturing techniques and to estimate the manufacturing costs. / AFRIKAANSE OPSOMMING: Vakuumgesteunde harsinspuitingsgietwerk (VARTM) behoort tot die kategorie
harsinspuitingstegnieke wat laer-as-atmosferiese druk gebruik om ʼn versterkte holte binne te
dring. Hierdie tegniek hou verskeie voordele in. Tog kan vervaardigingskoste betreklik hoog
wees wanneer dit by ingewikkelder vorms en ʼn gebrek aan kennis met betrekking tot
kostesnellers kom.
Die doelwit van hierdie studie was om ʼn kostemodel vir saamgestelde onderdele te ontwikkel.
Die model maak voorsiening vir die raming van die vervaardigingskoste vir verskillende
afmetings. Sodoende bied dit ʼn vergelyking met alternatiewe tegnieke, en help voorkom
onnodig duur ontwerpkenmerke. Daar is voorgestel dat dele met ingewikkelde vorms in
individuele basiese vorms verdeel word, wat dan hier verder ondersoek word.
Vir die basiese vorms word ʼn eksperimentele benadering gebruik waar die vervaardigingstye
in elke prosesstap gemeet en statisties ontleed word. Voorts word
inspuitingsimulasiesagteware gebruik om komplementêre inspuitingstye te bepaal ten einde
die eksperimentele ontwerp te voltooi. Hierdie metode maak dit ook moontlik om die
vervaardigingstye vir saamgestelde materiaal onderdele van verskillende afmetings te raam.
Die vervaardigingstye word dan bevestig aan die hand van dié van ʼn kompleks gevormde
industriële onderdeel, met redelike resultate. Uiteindelik word ʼn buigsame kostemodel
ontwikkel om verskillende vervaardigingstegnieke te vergelyk en die vervaardigingskoste te
raam.
|
169 |
Advanced Proportional Servo Valve Control with Customized Control Code using White SpaceLauer, Peter 27 April 2016 (has links) (PDF)
An industrial control valve has been designed by Eaton (AxisPro® valve). The servo performance valve has onboard electronics that features external and internal sensor interfaces, advanced control modes and network capability. Advanced control modes are implement in the valves firmware. With the help of the white space it is possilbe to execute custom code directly on the valve that interact with these controls. Small OEM applications, like rubber moulding machines, benefit from the comination of build in controls and custom code, to provide adaptations for their special machines.
|
170 |
The State Of Being Temporary : In Eleven Days I'll Be GoneHolmgren, Julia January 2019 (has links)
In this thesis and in my graduation project, I am taking a closer look at the word temporary. It is an investigation in the transition between the two states: temporary and permanent. I am using the contrasting state permanent as an anti-pole to get perspective and to have a fair comparison. I want to give the state of temporarily a shape or a face and to define time through the material and design, like a time capsule. As an interior architect I am questioning the usage of the temporary in the architectural and giving it attention by using architecture, furniture, states and materials as my framework.
|
Page generated in 0.1172 seconds