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.
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Influencing Wall-Thickness of Small Diameter Parisons
Many complex blow-molded parts demand wall-thickness influencing systems to achieve a regular wall-thickness distribution in the part. For small parison diameters the standard systems can not be employed because of the high stiffness of the used deformable metal rings. A new die concept with turnable elliptical rings and an elliptical mandrel allows to change the flow channel height over the circumference and the parison swell behavior at the die outlet can be influenced.
Nozzle Melt Density Sensor Application for a Hot Runner
When a hot runner mold manifold transfers a melt “shot size” into the mold cavity, the hot runner system reduces the shot size, but it also adds a second heat history to the melt.Since temperature has a dynamic impact on the molding process, a melt sensor was developed to measure Volumetric-Pressure-Temperature change and, consequently, confirm the consistency of the thermal state.This sensor was installed into a machine nozzle, and the injected melt fill-and-pack “density” was profiled for consecutive cycles. The sensor application for a hot runner mold and resulting profiles are presented.
Minimum Requirement for a Reliable Hot Runner Controller
There are many types of hot runner control designs. Some provide only basic features. There is a growing trend towards integrated or “GUI” (Graphic User Interface) styles of systems. However, despite the high-end features that many of these newer systems provide, they often have problems accurately measuring and therefore controlling temperature.This paper will discuss differences in system designs and how to detect the presence of potential problems.
Rapid Tooling - It’s Not Rocket Science
Rapid tooling (RT) pushed tool making into new areas. In the 1990s, rapid tooling using SLA, SLS, lasers, and other rapid prototyping (RP) technologies were the new wave. The promise of the processes threatened traditional machining methods, and mold-making shops pondered investment in exotic furnaces, raw materials and dedicated RP technicians.Looking at 2003, trends have changed. Rapid tooling is a reality, but the tooling is made using tied and true methods combined with better communication, verification of design and better machining. Rapid tooling changed the market. Now the question is what is the next step for RP and RT.
Significant Factors on the Dimensional Accuracy of Fused Deposition Modeling
This project investigated the dimensional accuracy of parts produced using the rapid prototyping method of Fused Deposition Modeling. Parts with six different features were created on a Stratasys FDM2000 out of ABS and then measured with a Coordinate Measurement Machine and digital micrometers. An analysis of 12 different measurements on parts produced using FDM identified that part size, location in the work envelope, and envelope temperature had a significant effect on the dimensional accuracy of FDM.
The New Role of Moldmaking, with the Combination of Other Disciplines Form a Powerful New Role for Moldmaking in Today’s Manufacturing World
Presentation of the processes utilized to satisfy customer requirements for on time quality tooling while supporting a world class molding operation using internal and external resources in a very unique way in today’s competitive world of mold manufacture.
The Next Generation of Stainless Mold Steels for the Plastics Industry
Uddeholm Tooling in Hagfors, Sweden, has developed a new grade of stainless mold steel. This new material, called Stavax Supreme, has undergone extensive testing to evaluate its response to heat treatment, corrosion resistance and impact toughness.The data from laboratory and field-testing indicates a significant improvement in both the mechanical and physical properties over existing 420- type stainless mold steels. As a result, larger and more complex tools can now be manufactured from a fully hardened stainless mold steel.
New Developments in Unscrewing Molds
There are two new developments in unscrewing mold technology. The first development is an unscrewing system that is machine ejector actuated, eliminating the need for externally mounted hydraulic cylinders. This system was developed to suit clean-room applications for small diameter closures. The second development is a cavity-side unscrewing system utilizing a rotating cavity and is suitable for large diameter closures. This system was developed to suit multi-level stack molds.
Challenges in Characterizing Sealant
Sealant is one of the very few major consumer products valued primarily for its rheological and adhesive properties. While, these materials may appear to be simple elastic solids, upon further examination, their behavior can be extremely complex. In this research, reasonable simplifications are developed to model the non-linear viscoelastic properties of cured sealant. Also included are modifications of the traditional instrumental design to allow for high throughput evaluation of a cured sealant’s mechanical properties.
Rheological Properties of HDPE-Wood Composites
A comparison of the rheological properties of HDPE-wood composites as measured by both capillary and rotational rheometry was made. The blends studied ranged from 0% (pure HDPE) – 50% 40-mesh size maple wood flour. The elastic behavior of these materials was studied through the measurement of storage and loss moduli, creep data and Bagley correction factors. The Cox-Merz rule was found to be invalid for these HDPE-wood composites. The effect of processing behavior on the rheological properties was also investigated.
Yield Stress Measurements in Gels, Block Copolymer Systems and Suspensions
We will discuss a new slotted-plate device to directly measure static yield stresses of complex multiphase systems. Possible wall effects associated with our earlier yield-stress plate instrument have been minimized . Our new setup avoids the disadvantages of the vane instrument. Yield stress values on a variety of systems have been obtained and have been compared with the values obtained via a variety of other methods.
Dynamic Rheology of Amorphous Poly-Alpha-Olfeins (APAOs) as Hot Melt Adhesives
Amorphous poly-alpha-olefins based on propylene were characterized over a wide temperature range by dynamic rheology. The rheological characteristics were useful in correlating Brookfield viscosity, ring-and-ball softening point, needle penetration, and open time with molecular structure and comonomer content.
Using Diode Lasers For Welding Thin Polymer Films
Highly reliable high power diode lasers are now being increasingly employed in industry as alternatives to conventional techniques for welding of plastics. New laser sources that have been developed for other applications in completely different industries are becoming available to allow novel bonding techniques to be developed. This may include materials and material forms that are difficult to join using conventional techniques. Joining thin films and joining thin films to sheet materials is one new area application area that is covered here.
Effects of Friction Stir Welding on Polymer Microstructure
Friction Stir Welding (FSW) technology has shown great promise as a method of joining polymeric materials. Welds in several materials have achieved over 90% of base material tensile properties. Flexural strength has reached 90% of base material properties in PP. Research has shown a correlation between the process weld microstructure and mechanical properties. A study currently being performed establishes the relationships between the process parameters, material microstructure, and mechanical properties.
Diode Laser Welding of EPDM Based Elastomers
Contour transmission laser welding has been carried out on EPDM and on various grades of Santoprene welded to PP containing glass fiber filler. The effects of welding parameters on shear pull strength, and on the nature of failure has been examined, and analyzed with the help of finite element simulation.
Pyrometer Measurements during Laser Welding of Thermoplastic Elastomers to Polypropylene and of Nylon to Itself
Pyrometer measurements were collected during the contour through-transmission laser welding of thermoplastic elastomers to glass-filled polypropylene as well as of unfilled nylon to itself. The elastomer-to-polypropylene samples were in shear-lap configuration whereas the nylon welds were between a ribbed flange and a web, representing a modified T-weld. Trends observed in the pyrometer readings are reported for both of these cases.
Ultrasonic Twin Converter Technology For Welding Large Plastic Parts or Packages
Patented Ultrasonic Twin Converter technology as an alternative to other sealing methods for sealing larger injection molded parts, vacuum formed parts, blister packs or foils. Principle of Ultrasonic Twin Converter technology and the Weld Horn Array technology. Advantages, challenges, possibilities and limitations. Comparison to the generally used single horn technology. Typical applications with longer continuous joints or larger weld areas, circumferences.
Polymer Welding of Powder Injection Molded Ceramics and Metals
Ceramic or metal-filled plastics are increasingly being used for the production of sintered parts today, with the function of the plastic being to ensure that the compounds can be processed on the standard types of injection molding machines currently in use.In this way, it is also possible to use the plastic matrix to join individual components and produce material composites of mold steel/structural steel, for example, before sending the joined parts to be debound and sintered.
Novel Foam Composite Having Thick Skin and Core-Stiffening Dividers
Using a conventional RM process, we have developed various types of foam composites having a hard skin and a foamed core which is finely separated in divisions by solid walls. One type has characteristics of light weight and good mechanical properties, and another of excellent thermal insulation.This report describes the production method and some properties of novel foam composites.
Rotational Molding of Micropelletized Polypropylene-Based Copolymers
Deficiencies in grinding performance of polypropylene homo- and copolymers have restricted their use for rotationally molded articles. This paper will demonstrate that micropelletization overcomes these deficiencies, allowing these resins to be processed into rotationally molded articles. Four different propylene-based copolymers were molded under varying conditions. Low temperature impact strengths, tensile and flex properties and oxidative induction times were determined. Results will be compared to commercial LLDPE products.
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