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5. Improving the predictions of injection molding simulation software

Author

Vietri, U., Sorrentino, A., Speranza, V., and Pantani, R.

Subjects
Engineering -- Computer programs, Computer simulation -- Research, Injection molding -- Research, Computer-generated environments -- Research, Engineering software, Engineering and manufacturing industries, Science and technology
Abstract

Injection molding is one of the most widespread processes for plastic manufacturing. Software packages are often used in several steps of the production cycle, from mold design to the determination of processing conditions. In this work a method is reported to improve the predictions of the description of pressure profiles made by injection molding simulation software. The method is applied to two polymeric materials (a Polystyrene and a Polycarbonate) injection molded into line-gated rectangular cavities adopting different molding conditions and cavity thickness. The method, that is independent of the software adopted, in this article is illustrated adopting the commercial code Mold-flow ®. It is shown that the predictions of the description of pressure curves inside the cavity can be significantly improved by introducing the effect of pressure on viscosity and the effect of cavity deformation during molding. The former effect is taken into account by finding an appropriate value for the parameter which takes into account the effect of pressure in the equation which describes material rheology. The latter effect can be introduced by defining and implementing an apparent material compressibility. POLYM. ENG. SCI., 51:2542-2551, 2011. © 2011 Society of Plastics Engineers, INTRODUCTION The injection molding process is widely applied for polymer engineering materials. The process itself is a complex mix of time, temperature, and pressure variables (1) with a multitude of [...]

Published
2011
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8. Anisotropic shrinkage of injection molded Poly Vinylidene Fluoride samples

Author

Speranza, V., Pantani, R., Besana, G.B., and Titomanlio, G.

Subjects
Polyvinylidene fluoride -- Properties -- Measurement, Anisotropy -- Measurement, Plastics -- Properties -- Measurement, Injection molding -- Properties -- Measurement, Engineering and manufacturing industries, Science and technology, Measurement, Properties
Abstract

A study of as-molded shrinkage of Poly Vinylidene Fluoride (PVDF) injection molded samples was carried out in this work. The polymer was injected into a simple rectangular cavity under different holding pressures, and the dimensions of the resulting samples were accurately measured at room temperature 10 min after demolding. As expected, the relative difference between the sample dimensions and the corresponding cavity dimensions (namely the shrinkage) decreased on increasing holding pressure. Furthermore, the shrinkage increased on increasing distance from the injection point. A somewhat unexpected feature of experimental data was the fact that the shrinkage was much higher along the flow direction than along the transverse on-plane direction. A thorough characterization of the elastic properties of the solid samples also showed a marked anisotropy of the elastic modulus and of the coefficient of linear thermal expansion. The injection molding tests were simulated by a software developed at University of Salerno to obtain the evolution of temperature, pressure, and crystallinity inside the samples. The predicted pressure profiles were satisfactorily compared with the measured values. The simulated histories of temperature, pressure and crystallinity were used as input for a thermomechanical model for shrinkage evolution. It was found that the reason for anisotropy in shrinkage had to be ascribed mainly to the anisotropy in material properties. It was in fact shown that, adopting the correct anisotropic values for the elastic modulus and thermal expansion coefficient, a satisfactorily description of shrinkage data could be reached. POLYM. ENG. SCI., 47:1788-1795, 2007. © 2007 Society of Plastics Engineers, INTRODUCTION The dimensions of injection-molded products, measured after molding, differ from the corresponding local mold dimensions, and these differences depend on material characteristics as well as on processing conditions. The [...]

Published
2007

12. Relevance of Mold-Induced Thermal Boundary Conditions and Cavity Deformation in the Simulation of Injection Molding

Author

Pantani, R., Speranza, V., and Titomanlio, G.

Subjects
Plastics -- Molding, Thermoplastics -- Production management -- Research, Injection molding -- Research, Engineering and manufacturing industries, Science and technology, Research, Production management
Abstract

In this work an amorphous PS was injection molded into a simple line-gated rectangular cavity. The effect on post-filling pressure curves and temperatures (at the polymer-mold interface) of different holding pressures and times, and of two gate thickness configurations, was analyzed. Molding tests were simulated leading to a good description of pressure evolution in different positions along the flow path for all molding conditions analyzed. Comparison between simulation results and experimental data shows that: considering a rigid mold can lead to predicted values of post-filling pressure profiles much different from experimental ones; heat transfer coefficient description plays a minor role in the prediction of pressure evolution, but its effect is relevant on temperature evolution in layers close to the mold surface., INTRODUCTION Most of the industries involved in injection molding of thermoplastics rely on software codes for process simulation. Traditional goals for simulations (mainly limited to predictions of flow front advancement, [...]

Published
2001

25. Mechanical characterization of iPP injection molded samples on multiple length scale.

Author

Liparoti, S., Sorrentino, A., Speranza, V., and Titomanlio, G.

Subjects
INJECTION molding, POLYMERS, POLYPROPYLENE, DYNAMIC mechanical analysis, ATOMIC force microscopy
Abstract

The mechanical characterization at different length scales, from macro to nanometer scale, represents a very intriguing possibility to analyze the effect of developed morphologies on the properties of a molded polymer material. In this work, isotactic polypropylene molded samples, obtained with different processing conditions, have been mechanically characterized on different lengths scales. Dynamic Mechanical Analysis (DMA), micro Indentation and HarmoniX Atomic Force Microscopy (AFM) tests have been carried out to characterize injection molding iPP samples from millimeter to nanometer scale. Optical microscopy and AFM analyses show a complex morphology composed ? by a thin layer of globular elements at the sample surface, spherulites in the sample core and fibrils in the intermediate zone. The well organized and oriented structures, i.e. the fibrils, are characterized by higher values of mechanical modulus, whereas the globules, less organized structures, show very small elastic modulus values, close to the characteristic values observed in quiescent amorphous phase. Intermediate values of elastic modulus are observed in the sample core, where well developed spherulitic structures are characterized by both higher crystallinity and lower level of orientation. The elastic modulus obtained by HarmoniX AFM technique are in good agreement with the values obtained by Indentation tests in the same sample positions, confirming the complementarity of these techniques for a complete multi-scale sample characterization. The cross section modulus distributions nicely compare with DMA results. [ABSTRACT FROM AUTHOR]

Published
2018
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26. Effects of fast mold temperature evolution on micro features replication quality during injection molding

Author

Liparoti, S., Calaon, M., Speranza, V., Tosello, G., Pantani, R., Hansen, N. H., Titomanlio, G., Liparoti, S., Calaon, M., Speranza, V., Tosello, G., Pantani, R., Hansen, N. H., and Titomanlio, G.

Abstract

The growing demand to manufacture, with high accuracy, functional structures in the micro and sub-micrometer range polymer based microsystem products calls for reliable mass production processes. Being injection molding (IM) the preferential technology employed for polymer mass fabrication and mold temperature one of the most relevant process parameter to enhance polymer replication at the micro meter scale, the present study investigates effects of fast mold temperature evolution on final replication quality of produced injection molded parts. Micro features master geometries were produced by UV lithography and subsequent nickel electroplating. The mold temperature was controlled by a thin heating device (composed by polyimide as insulating layer and polyimide carbon black loaded as electrical conductive layer) able to increase the temperature on mold surface in a few seconds (40°C/s) by Joule effect and let the surface to cool down soon after. This heating device allowed to maintain mold temperature at a constant value for a time that could be equal to the filling time or longer. A fully characterized isotactic polypropylene was used as the polymer material during the injection molding experiments. The experiments revealed that the replication was mostly sensitive to cavity pressure and mold temperature. In particular, an increase of holding pressure and mold temperature enhanced the replication. Also, the heating time increased the replication quality.

Published
2017

33. Microsphere Contrast Enhancement of the Tricuspid Regurgitant Spectral Doppler Signal: Is it Still Necessary With Contemporary Scanners?

Author

Platts, D., primary, Sedgwick, J., additional, Hamilton-Craig, C., additional, Scalia, G., additional, Benjamin, A., additional, Kelly, N., additional, Sherman, J., additional, Chamberlain, R., additional, Fetherston, E., additional, Putrino, A., additional, Harten, M., additional, Hornick, A., additional, Ischenko, M., additional, Mein, G., additional, Tucker, A., additional, Speranza, V., additional, Rivett, M., additional, and Burstow, D., additional

Published
2016
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35. ERCP and acute pancreatitis

Author

Fausto Fiocca, Santagati A, Ceci V, Donatelli G, Mj, Pasqualini, Mg, Moretti, Speranza V, Di Giuli M, Minervini S, Sportelli G, Giri S, Fiocca, F, Santagati, A, Ceci, V, Donatelli, G, Pasqualini, Mj, Moretti, Mg, Speranza, V, Di Giuli, M, Minervini, S, Sportelli, G, and Giri, S.

Subjects
Adult, Aged, 80 and over, Cholangiopancreatography, Endoscopic Retrograde, Male, Pancreatitis, Acute Necrotizing, Humans, Female, Middle Aged, Aged, Ultrasonography
Abstract

Acute biliary pancreatitis (ABP) is a serious complication of biliary stones disease and is associated with significant morbidity and mortality. The role of ERCP in the management of ABP has been the focus of discussion in recent years. In this report, we evaluated a protocol of emergency Endoscopic retrograde Cholangiopancreatography (ERCP) (within 24 hours) and early ERCP (within 72 hours). From July 1997 to July 2000, were observed 45 patients (19 man and 26 women) with acute biliary pancreatitis. Mean age of patients was 63.4 years (range 21-87 years). Diagnosis of ABP was based on anamnesis and clinical assessment and was confirmed by specific laboratory data (hyperamylasemia, hyperlipasemia, total and fractionated bilirubinemia, gamma-GT, transaminase, alkaline phosphatase, hypocalcemia, hyperglycemia, leukocytosis). Ultrasound scanning within 24 h of admission was performed in 45 patients (100%) and it revealed gallbladder stones and muddy bile in 39 patients (87%). Computed tomography (CT) performed in all patients, showed a severe acute pancreatitis in the second or subsequent week following admission. The severity of acute pancreatitis was established by Glasgow's criteria and by clinical details of patients. ERCP and Endoscopic Sphinterotomy (ES) was performed in all 45 patients with acute biliary pancreatitis. Twenty-six patients (57%) were classified as having a severe attack (> 4) 19 as having a mild attack by Glasgow's criteria. ERCP associated with ES was performed within 24 hours in 22 patients (49%), 11 (50%) showed a severe attack and 11 (50%) showed a mild attack. A total of 2 complications (4%) occurred and the mortality was of 2 patients (4%). In 23 patients (51%) ERCP and ES was performed within 72 hours after conservative therapy, 8 (35%) showed a mild attack and 15 (65%) showed a severe attack. A total of 5 complications (9%) occurred and the mortality was of 3 patients (6%). Our study showed that ERCP with endoscopic sphincterotomy can be performed safely by skilled endoscopist, without adverse consequences soon after the onset of acute biliary pancreatitis even within the first 24 hours and it showed that is better than ERCP within 72 hours after conservative therapy.

Published
2003

40. THE SUCCESSFUL MANAGEMENT OF SERIOUS LEAD INTOXICATION IN A SIX-MONTH-OLD CHILD WITH ORAL CHELATION THERAPY

Author

Speranza, V, Gaar, G, Chambers-Emerson, J, and McNutt, T

Subjects
Lead poisoning -- Care and treatment, Succimer -- Health aspects, Chelation therapy -- Usage, Lead -- Health aspects, Environmental issues, Health, Pharmaceuticals and cosmetics industries
Abstract

Objective: To describe the presentation and treatment of a serious lead exposure in a 6-month-old child with oral Succimer (Chemet) therapy. Case Report: A six-month-old boy was referred to our hospital from the local health department for evaluation, after it was discovered that the older sibling had an elevated serum lead level of 68 mcg/ dL. When a screening intervention was performed on the six month old, an initial serum lead level of 83.5 mcg/dL was revealed. Upon further inquiry it was found that the child's parent had been giving the infant Azarcon, a Mexican home remedy used to treat stomach cramps. This product contains as much as 94% lead by weight. The mother had been administering this product daily to both children for as long as one week prior to admission. The Poison Center was consulted on the use of chelation therapy. Since the child was neurologically intact, it was decided to initiate chelation therapy with oral Succimer instead of parenteral chelation treatment. Within two days after initiation of Succimer therapy, the blood lead level dropped to 56 mcg/dL. A repeat serum lead level obtained 72 hours after Succimer therapy noted a reduction in the level to 40 mcg/dL. The child remained asymptomatic and was discharged home on the remaining doses to complete full course oral chelation therapy. The Succimer therapy was well tolerated in this patient. Conclusion: The use of oral chelation agents like Succimer can be successfully utilized to treat small children with significantly elevated blood lead levels ([is less than] 70 mcg/dL) who present with no clinical evidence of neurological toxicity from lead exposure., Speranza V, Gaar G, Chambers-Emerson J, McNutt T. Florida Poison Information Center-Tampa, Tampa, [...]

Published
2000

46. THE ATYPICAL TREATMENT OF A SUSPECTED CROTALIDAE ENVENOMATION

Author

McNutt, T, Speranza, V, Chambers-Emerson, J, and Normann, S

Subjects
Poisonous snakes -- Venom, Bites and stings -- Care and treatment, Antivenins -- Health aspects, Environmental issues, Health, Pharmaceuticals and cosmetics industries
Abstract

Objective: To describe the presentation and management of a suspected pit viper envenomation with 240 vials of crotalidae polyvalent antivenin. Case Report: A 47-year-old male presented to the ED with a suspected and severe pit viper envenomation of the right finger 2 days prior. His right hand and arm were severely swollen and ecchymotic. Bruising extended into anterior, lateral and posterior chest. He was admitted with severe pain, tachycardia, hypertension, and a history of vomiting for 2 days. A consultation was provided and our center's protocol was initiated. A follow-up call revealed that our protocol had been discontinued and a non-medical herpetologist was contacted and his recommendations were begun. An infusion of antivenin was started at 4 vials per hour for 4 hours, then 2 vials per hour for the next 112 hours, to a total of 240 vials of antivenin. Toxicology consults were offered repeatedly by our center without success. The only significant laboratory finding was a thrombocytopenia. The patient received 6 units of platelets. Pain control and antibiotic therapy were initiated. Follow-up office visits revealed full range of motion of affected extremity with minimal swelling of right hand and arm. No evidence of serum sickness was documented within the first two months of follow-up care. Conclusion: This is an atypical treatment of a suspected crotalidae envenomation with a positive outcome and no apparent adverse effects., McNutt T, Speranza V, Chambers-Emerson J, Normann S. Florida Poison Information Center-Tampa, Tampa, [...]

Published
1999

47. Use of three-dimensional speckle tracking echocardiography for quantitative assessment of global left ventricular function: a comparative study to three-dimensional echocardiography

Author

Luis, S., Yamada, A., Khandheria, B., Speranza, V., Benjamin, A., Ischenko, M., Platts, D., Hamilton-Craig, C., Haseler, Luke, Burstow, D., Chan, J., Luis, S., Yamada, A., Khandheria, B., Speranza, V., Benjamin, A., Ischenko, M., Platts, D., Hamilton-Craig, C., Haseler, Luke, Burstow, D., and Chan, J.

Published
2014

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