Home  About us  Contact
 

Molding Machine (molding + machine)

Distribution by Scientific Domains
Polymers and Materials Science57%

Kinds of Molding Machine

  • injection molding machine
    		•

    Selected Abstracts

    The continuous cooling transformation (CCT) as a flexible tool to investigate polymer crystallization under processing conditions

    ADVANCES IN POLYMER TECHNOLOGY, Issue 2 2009
    V. Brucato
    Abstract An experimental route for investigating polymer crystallization over a wide range of cooling rates (from 0.01 to 1000°C/s) and pressures (from 0.1 to 40 MPa) is illustrated, using a method that recalls the approach adopted in metallurgy for studying structure development in metals. Two types of experimental setup were used, namely an apparatus for fast cooling of thin films (100,200 ,m thick) at various cooling rates under atmospheric pressure and a device (based on a on-purpose modified injection molding machine) for quenching massive samples (about 1,2 cm3) under hydrostatic pressure fields. In both cases, ex situ characterization experiments were carried out to probe the resulting structure, using techniques such as density measurements and wide-angle x-ray diffraction (WAXD) patterns. The cooling mechanism and temperature distribution across the sample thickness were analyzed. Results show that the final structure is determined only by the imposed thermal history and pressure. Experimental results for isotactic polypropylene (iPP), poly(ethylene terephthalate) (PET), polyamide 6 (PA6), and syndiotactic polystyrene (sPS) are reported, showing the reliability of this experimental approach to assess not only quantitative information but also a qualitative description of the crystallization behavior of different classes of semicrystalline polymers. The present study gives an opportunity to evaluate how the combined effect of the cooling rate and pressure influences the crystallization kinetics for various classes of polymer of commercial interest. An increase in the cooling rate translates into a decrease in crystallinity and density, which both experience a sudden drop around the specific "crystallizability" (or "critical cooling rate") of the material examined. The exception is sPS where competition among the various crystalline modifications determines a minimum in the plot of density vs. cooling rate. As for the effect of pressure, iPP exhibits a "negative dependence" of crystallization kinetics upon pressure, with a decrease of density and degree of crystallinity with increasing pressure, owing to kinetic constraints. PA6 and PET, on the other hand, due to thermodynamic factors resulting in an increase in Tm with pressure, exhibits a "positive dependence" of crystallization kinetics upon pressure. Finally, recent original results concerning sPS have shown that the minimum in the density vs. cooling rate curve shifts toward larger cooling rates upon increasing pressure. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:86,119, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20151 [source]

    A generic controller for part surface temperature on a plastic injection molding machine

    ADVANCES IN POLYMER TECHNOLOGY, Issue 1 2006
    R. Dubay
    A new approach for controlling part cooling in plastic injection molding is developed using a PI controller and coolant flow rate as the manipulated variable. The method uses an average part surface temperature within the mold as the setpoint parameter. A mechatronic control system was developed for providing variable coolant flow rates. The control strategy was simulated using plant models, implemented and tested on a 50-tonne plastic injection-molding machine with good closed loop responses. © 2006 Wiley Periodicals, Inc. Adv Polym Techn 25: 1,12, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20053 [source]

    Control of rotational molding using adaptive fuzzy systems

    ADVANCES IN POLYMER TECHNOLOGY, Issue 4 2005
    D. I. Abu-Al-Nadi
    Abstract Rotational molding is a method for manufacturing hollow plastic parts. In the work reported here, adaptive fuzzy logic techniques have been used to relate the machine oven temperature to other manipulated parameters of the process. The objective is to design a reliable control system for the rotational molding process. An adaptive fuzzy network was developed to correlate changes in oven temperature to changes in the opening of the control valve on the fuel system. The network parameters were optimized using real-valued genetic algorithms. This network gave good results when its performance was compared with experimental data from a commercial rotational molding machine. The network was successfully utilized to design a control system, which works well in regard to set point tracking and load rejection. © 2005 Wiley Periodicals, Inc. Adv Polym Techn 24: 266,277, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20047 [source]

    Online pressure,volume,temperature measurements of polypropylene using a testing mold to simulate the injection-molding process

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2010
    Jian Wang
    Abstract To obtain accurate prediction of service performance and service life of polymers and to optimize the processing parameters, a modified online measurement was used to measure the pressure,volume,temperature (PVT) properties of polymers under certain processing conditions. The measurement was based on an injection molding machine, and it was used to obtain the PVT data of polymers directly with a special testing mold under normal processing conditions. The PVT properties of a semicrystalline polymer, polypropylene, were measured through both an online testing mold and a conventional piston,die dilatometer. The PVT properties were correlated by a modified two-domain Tait equation of state. The differences between the two groups of PVT data measured were investigated, and relative differences, especially in the rubbery state because of different cooling or heating measuring modes and sample forms, were observed. Numerical simulations of injection-molding processes were carried out by Moldflow software with both of the types of PVT data. The resulting online PVT data exhibited improvement in the accurate prediction of shrinkage and warpage. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Effect of Processing Parameters on the Mechanical Properties of Injection Molded Thermoplastic Polyolefin (TPO) Cellular Foams

    MACROMOLECULAR MATERIALS & ENGINEERING, Issue 7 2008
    Steven Wong
    Abstract In this study, the effects of processing parameters on the mechanical properties of injection molded thermoplastic polyolefin (TPO) foams are investigated. Closed cell TPO foams were prepared by injection molding process. The microstructure of these foamed samples was controlled by carefully altering the processing parameters on the injection molding machine. The foam morphologies were characterized in terms of skin thickness, surface roughness, and relative foam density. Tensile properties and impact resistance of various injection molded TPO samples were correlated with various foam morphologies. The findings show that the mechanical properties are significantly affected by foam morphologies. The experimental results obtained from this study can be used to predict the microstructure and mechanical properties of cellular injection molded TPO foams prepared with different processing parameters. [source]

    The occurrence of surface roughness in gas assist injection molded nylon composites

    POLYMER COMPOSITES, Issue 2 2000
    Shih-Jung Liu
    Gas assist injection molding has increasingly become an important industrial process because of its tremendous flexibility in the design and manufacture of plastic parts. However, there are some unsolved problems that limit the overall success of this technique. The purpose of this report was to study the surface roughness phenomenon occurring in gas assist injection molded thermoplastic composities. The materials used were 15 % and 35% glass-fiber filled nylon-6 composites. Experiments were carried out on an 80-ton injection molding machine equipped with a high-pressure nitrogen-gas injection unit. Two "float-shape" axisymmetric cavities were used. After molding, the surface quality of molded parts was measured by a roughness meter. Various processing variables were studied in terms of their influence on formation of surface roughness: melt temperature, mold temperature, melt filling speed, short-shot size, gas pressure, and gas injection delay time. Scanning electronic microscopy was also employed to characterize the composites. It was found that the surface roughness results mainly from the exposure of glass fiber in the matrix. The jetting and irregular flows of the polymer melt during the filling process might be factors causing the fiber exposure. [source]

    Real-time monitoring of injection molding for microfluidic devices using ultrasound

    POLYMER ENGINEERING & SCIENCE, Issue 4 2005
    Y. Ono
    Real-time process monitoring of the fabrication process of microfluidic devices using a polymer injection molding machine was carried out using miniature ultrasonic probes. A thick piezoelectric lead-zirconate-titanate film as an ultrasonic transducer (UT) was fabricated onto one end of a 4-mm diameter and 12-mm long steel buffer rods using a sol gel spray technique. The center frequency and 6 dB bandwidth of this UT were 17 MHz and 14 MHz, respectively. A signal-to-noise ratio of more than 30 dB for ultrasonic signals reflected at the probing end was achieved. The probe can operate continuously at 200°C without ultrasonic couplant and cooling. Clear ultrasonic signals were obtained during injection molding of a 1-mm-thick part having test patterns on its surface. Shrinkage of the molded part and part detachment from the mold were successfully monitored. Surface imperfections of the molded parts due to a lack of the sufficient holding pressure is discussed with regard to the ultrasonic velocity obtained. The presented ultrasonic probes and technique enable on-line quality control of the molded part by optimizing the holding pressure and improvement of process efficiency by reducing the cycle time. POLYM. ENG. SCI., 45:606,612, 2005. © 2005 Society of Plastics Engineers [source]