The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
DOE is a powerful tool used in various process optimizations. In many cases, time and resources are overextended, making this tool unaffordable or impractical. With experimentation, it has been demonstrated that the time-consuming task of using DOE to determine the contribution of a parameter to a welded product, as well as the development of a model that predicts behavior, can be drastically reduced if the parameter characterizations presented in this paper are utilized.
Laser marking continues to gain acceptance as a preferred means for decorating parts found in automotive interiors. Beam steered laser technology presents a versatile and robust means for applying any design to a wide variety of materials. This paper will cover the fundamentals of laser technology including an overview of key parameters that a design engineer will find useful in supporting a reliable implementation on the production floor.
Every day another company loses a pad printing application to a more efficient competitor. Many times a paradigm shift away from a vicious cycle of under-investment is necessary for companies to remain competitive.
A CFD-simulation is performed for an existing die and compared with the actual polymer flow and dimensions of the extrudate. Experimental validation of the simulation is used to improve new die design by integrating flow simulation through the 3-D die geometry and the free-surface flow with swelling after the die. Modified die-land-and-lip profile is optimized using the so-called inverse extrusion" simulation with an objective to improve accuracy of extrudate dimensions."
Three-dimensional flow of a low-density polyethylene in a spiral die for blown-film extrusion is simulated. Effect of elongational viscosity on the flow in the spiral die is analyzed. Elongational viscosity is found to have significant effect on the velocity distribution at the die exit and on the pressure and temperature distributions in the die.
In this work a previously developed die design code is used to optimise the flow distribution of a profile extrusion, using two alternative strategies. The numerical predictions are compared with experimental data gathered during extrusion experiments, the results of which are used to assess the rheological code and the effectiveness of the optimisation algorithm and design strategies implemented.
The investigation of the elimination of sharkskin using polymer processing aids (PPA) requires the consideration of factors such as: PPA domain size, operational shear rate and matrix/PPA viscosity ratio. In this work, the role of PPA droplet size in the elimination of surface melt fracture was investigated. The parameters monitored were the die entrance pressure, the PPA coating thickness and the extrudate appearance. We found a substantial enhancement in coating thickness and speed upon increasing the droplet size.
A recently proposed modification of the viscoelastic Leonov model is employed as a stress calculator in FEM analysis with a full u-v-p-? numerical scheme of the coextrusion flow in multi-manifold flat dies with 30 and 90 degree entrance angles. It is shown that the predicted stresses, interface location and streamlines fields are in a good agreement with the measurements. It is also revealed that the extensional viscosity has to be used in the modeling of the coextrusion flow to confirm experimental data.
Flows of a low-density polyethylene in a co-rotating twin-screw extruder and in a twelve-screw ring extruder are compared. Effect of the shear as well as elongational viscosity of the low-density polyethylene is included in the simulation. Even though the velocity and pressure distributions in the two extruders have many similarities, because the intermeshing regions constitute a larger fraction of the ring extruder than that of the twin-screw extruder, the degree of elongation, and hence, the quality of mixing, is found to be better in the ring extruder.
The kinematics model of solids conveying shows that the solids advance angle is a single empirical factor of solids flow in lieu of friction factors. Furthermore, solids advance angle can be linearly correlated with pressure for LDPE. The linear functions that approximate the solids angle are used with the kinematics model to calculate solids flow of LDPE. The calculations are compared to data to demonstrate the accuracy of the model.
Thermocouple meshes have successfully been used to measure melt temperature across the material exiting from a 60mm single screw extruder. Temperature profiles are shown to be dependent on screw geometry, set wall temperatures, throughput and material type. Differences in average temperature profile and transient fluctuations have been determined.
A design for a self-adjusting melt pressure regulator is presented for use between an extruder and one or more dies. The regulator is derived from a low force valve design that enables the outlet pressure to be directly regulated by a provided force on a valve pin without need for pressure sensors or a closed loop control system. Analytical and experimental results indicate an excellent level of response and consistency given the simplicity of the design.
Flow visualisation studies are preformed to determine the effects of die geometry on interfacial instabilities in coextrusion flows of a LDPE melt. Slit coextrusion visualisation cells with 30° and 90° convergent stream angles are used in this study. Stream ratios leading to interfacial instability in the LDPE melt are quantified and compared for each geometry.
Studies of blown film cooling were carried out to investigate interaction of cooling air flow and the heat transfer processes. Instabilities in the air flow were detected at several point in the cooling region which influences the local heat transfer.The results indicates the development of temperature fluctuation in the bubble which seem to be one of the main reasons for the formation of film thickness profile in extrusion direction.
This work investigates the effect of extrusion processing conditions and co-monomer type on the gas permeation properties of LLDPE films containing polyisobutylene (PIB). The results show improved gas barrier properties with increasing polymer density and increase in film crystallinity and orientation as a result of extrusion processing conditions such as blow up ratios.
A simple equation with only four physical parameters for the description of the bubble shape (including HDPE wine-glass shape) has been derived from variational principles. The proposed equation was used in modeling of the film blowing process for a variety of process conditions and polymer melts, and a very good agreement between measured and simulated data was found.
The effect of extrusion processing conditions on the mechanical and morphological properties of a range of nylon 12s and LDPEs was investigated. The results indicate that processing conditions had a more pronounced effect on the mechanical properties of nylon 12 tubes, in comparison to those produced from LDPE.
In this work a numerical code able to model the heat transfer in calibrators for extruded profiles is described and validated. For assessment purposes the numerical predictions are compared with analytical models and numerical results obtained with a commercial software. The routines developed are then used to identify the main process parameters and to estimate their relative importance.
For rheological design of spiral mandrel dies the most common calculation methods are segmenting the die into simplified geometries and calculating the characteristics of each flow segment analytically. In the past, one-dimensional flow was considered, but this assumption is deficient especially for low depth segments. In recent investigations IKV has studied three-dimensional flow conditions in a transparent test die and in 3D-FEA calculations. The results of these studies give the key to improve the calculation of spiral mandrel dies significantly.
This paper presents a theoretical approach to the prediction of melt temperature profiles in cooling extruders. The effect of screw design on cooling performance in discussed. A new screw geometry is presented will substantially improved cooling capability. Initial performance data on a 200-mm cooling extruder are presented.
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Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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