SPE Library

Real-Time Process Optimization With In-Mold Sensors and Machine Learning

Dr. Alexander Chaloupka, May 2023

Plastic manufacturing can be unpredictable. Deviations in material batches, moisture content, machine calibration, among other variables, lead to issues in manufacturing quality and final part properties. This webinar will introduce how dielectric analysis (DEA) sensors be used to directly measure material behavior in-mold. New technology has been developed to combine dielectric analysis with machine learning and material models, allowing for dynamic adjustments to machine settings, removing uncertainty from your process, and optimizing cycle times. The material covered will include:

• Fundamentals of dielectric analysis and applications for plastic processing
• How dielectric analysis and machine learning can be combined for dynamic process optimization
• Case studies demonstrating how dielectric analysis is being used in industries ranging from automotive composites to electronic encapsulation

Viscoelasticity

Jeff Jansen, November 2022

Plastics are viscoelastic materials, meaning that they exhibit both viscous and elastic characteristics when undergoing deformation. This is due to their unique molecular structure. The polymer molecules consist of long chains with high molecular weight. Those individual polymer chains are and tangled into each other, but are mobile and can slide past each other because they do not share chemical bonds with the other chains. Because of their viscoelastic nature, the mechanical properties of plastics vary depending on the conditions under which stress is applied. Most commonly, the mechanical properties of plastics will vary with temperature, time under load, and strain rate. Their viscoelastic nature is important to those designing, manufacturing, or using plastic components. and is a fundamental concept of plastic behavior that needs to be understood. It is important to recognize the viscoelastic nature of plastic materials so that their behavior in the intended application can be understood. This webinar will expose the attendees to the following concepts:

• The viscoelastic nature of plastics is attributed to their molecular structure.
• Thermoplastic materials have both long-term and short-term properties – they flow due to the application of stress over time.
• Most mechanical testing of plastic materials is actually testing the material’s viscoelasticity – how the plastic flows when different stresses are applied.
• Plastics are time, temperature, and strain rate sensitive.

Polymer Characterization – Indentation and Scratch

Mark Haase, November 2022

Polymers, in their various forms, are a vital part of our material infrastructure and continue to grow in importance and utilization. Due to their unique and diverse mechanical properties, they offer solutions to technical challenges in many applications. Whether their role is as a bulk material, composite, or coating, quantifying the resulting properties and responses to stress is vital to development and production. As these applications grown in complexity and shrink in size, quantification by traditional means becomes increasingly difficult. It is also increasingly vital, as tolerances tighten and conditions become more extreme. This presentation will review the mechanical properties that are quantifiable by modern instrumented indentation and scratch testing systems. It also includes practical examples exploring those properties and their relevance to a range of applications.

An Introduction to Dynamic Mechanical Analysis

Jeff Jansen, October 2022

Dynamic Mechanical Analysis (DMA) is a thermoanalytical technique that measures the stiffness (modulus) and damping (tan delta) of polymeric materials to assess the viscoelastic properties as a function of time, temperature, and frequency. Polymeric materials display both elastic and viscous behavior simultaneously, and DMA can separate these responses. Polymers, composed of long molecular chains, have unique viscoelastic properties, which combine the characteristics of elastic solids and Newtonian fluids. As part of the DMA evaluation, a small deformation is applied to a sample in a cyclic manner. This allows the material’s response to stress, temperature, and frequency to be studied. The analysis can be in several modes, including tension, shear, compression, torsion, and flexure. DMA is a very powerful tool for the analysis of plastics and can provide information regarding: This webinar will provide an introductory look into DMA and how it can be applied to better understand plastic behavior, both long-term and short-term.

1. Modulus
2. Damping
3. Glass Transition
4. Softening Temperature
5. Creep Behavior
6. Stress Relaxation
7. Degree of Cure

UV Effects on Plastic Materials: Degradation, Testing and Protection

Jeff Jansen, May 2022

If you work with plastic components that include outdoor exposure, then "Ultraviolet (UV) Effects on Plastic Material" will provide you with information that will enhance your understanding of the interaction between UV radiation-based weathering and plastic resins, and help prevent premature failure. Topics covered during this session include an introduction to UV degradation and an explanation of the failure mechanism characteristic of UV radiation/plastic interaction. Case studies associated with UV radiation exposure will be presented. You will learn…

• The mechanism of UV degradation
• The materials susceptible to and most affected by UV degradation
• The effects of UV degradation on plastic materials
• How the use of stabilizers can improve UV resistance of plastic materials
• How testing can be used to determine whether plastic materials are susceptible to UV degradation

Polymer Molecular Weight: A Key Factor in Plastic Performance

Jeff Jansen, March 2022

The characteristic properties exhibited by plastics are the direct result of their unique molecular structure. Plastics are polymers of very high molecular mass. To enhance their properties, they often contain additives, however, the underlying attributes of a plastic material are determined by the polymer. The molecular weight of the base polymer is a fundamental factor in the characteristics of plastic materials. This includes the mechanical, thermal, chemical, and environmental properties of the material, and ultimately the formed part. Through the polymerization process, polymers - materials of relatively high molecular weight, macromolecules - are produced. Higher molecular weights are associated with longer molecular chains, and this results in a greater level of entanglement. This has important implications, as higher-molecular-weight grades of plastics will have superior mechanical, thermal and chemical resistance properties compared with lower molecular-weight grades of the same material. Through this webinar, the viewers will:

• Gain an appreciation of the criticality of Molecular Weight on the performance of polymeric materials
• Get insight as to how Molecular Weight can be altered during life cycle of the polymer
• Identify different analytical tools to measure Molecular Weight, and recognize which is best in different circumstances

Outline

• Polymerization
• Molecular Weight and Its Relationship with Plastic Properties
• Molecular Weight Distribution
• Molecular Degradation
• Molecular Weight Measurement
• Complementary Methods for Assessing Molecular Degradation

Rubber O-rings

Jeff Jansen, March 2022

O-rings function as a means of sealing, essentially closing off a passageway to prevent the escape or loss of a fluid, either a liquid or a gas. An O-ring has a toric shape, and is typically manufactured from an elastomeric material. The seal is established by placing the O-ring into a cavity, known as a gland. The gland acts to compress the O-ring, and produces a zero-clearance condition, which effectively blocks the flow of the fluid. The sealing effect is produced through axial or radial compression of the O-ring. In general, O-ring seals are considered to be particularly reliable due to the simplicity of the O-ring/gland design and overall material resilience. However, under a number of circumstances failure can occur. O-ring failure can range from minor leakage to catastrophic equipment breakdown. Regardless of the magnitude, an O-ring failure can be diagnosed through proper visual and analytical techniques. This webinar will review:

• O-ring Function
• Failure Modes
• Sealing System Design Factors
• O-ring Materials – Selection and Specification

Fourier Transform Infrared Spectroscopy in Failure and Compositional Analysis

Jeff Jansen, January 2022

Fourier transform infrared spectroscopy (FTIR) is a fundamental analytical technique for the analysis of organic materials. It provides critical information in the evaluation of polymeric materials, including material identification, contamination, and degradation. The webinar will present a fundamental understanding of the technique and the following topics will be covered:

• Theory of Infrared Spectroscopy
• Test Result Interpretation
• Application to Polymeric Materials
  • Material Identification
  • Contamination
  • Degradation
• Sample Preparation Supplementing FTIR With Other Techniques
• Cases Studies

Thermal Dependency of Plastics

Jeff Jansen, December 2021

Because of their molecular structure, polymeric materials have different properties compared to other materials, like metals. Due to their viscoelastic nature, polymeric material properties our temperature dependent. As the temperature is increased, the polymer chains are further apart, there is more free volume and kinetic energy, and the molecules can slide past one another and disentangle more easily. The physical properties and performance of polymeric materials, such as strength, stiffness, and impact resistance, are highly dependent on the temperature at which the stresses applied. Over a temperature range, polymers will pass through key transitions, such as beta transitions and glass transitions, as well as softening and melting. Understanding the implications of these transitions and their correlation to molecular structure is useful in material selection and avoiding premature failure. The goal is that this webinar will provide:

• A better understanding of how plastic mechanical properties change as a function of temperature.
• The ability to recognize that there are both lower-end and upper-end temperature limits for polymeric materials.
• Familiarity with the testing that can be utilized for evaluating the effects of temperature on plastics, as well as tests that are commonly used but provide very little useful information.

Outline

• Viscoelasticity
• Temperature
• Thermal Transitions
• Thermal Performance
• Elevated Temperature
• Low Temperature
• Understanding Continuous Service Temperature Limits

Plastic Datasheets: What They Do and Don't Tell Us

Jeff Jansen, November 2021

UL Prospector lists tens of thousands of different plastic resins. When tasked with material selection, 99% of us turn to the typical property data sheet. What are the issues with the single point numbers listed on these datasheets? Why does sole reliance on this information often lead to failed product? What should we be doing instead? Selecting the proper material for an application requires the right data. While plastic project have evolved over the past 50 years, the data we are given has not evolved. This webinar will present the deficiencies of the information presented on plastic data sheets, and suggest what is really needed.

Failure of Plastics Session 2

Jeff Jansen, October 2021

This 2-part webinar series will cover a considerable range of topics important in understanding, diagnosing, and preventing plastic component failure. The most efficient and effective approach to plastic component failure is by performing a systematic failure analysis. Someone once said, “if you don’t know how something broke, you can’t fix it”, and this certainly highlights the importance of a thorough understanding of how and why a product has failed. This webinar series will introduce the attendees to information they need to gain this understanding.

• The material covered will include: Essential knowledge of why plastic components fail, 

• The five factors affecting plastic part performance, 

• The process of conducting a failure investigation and methods for understanding how and why a product has failed, 

• The importance of ductile-to-brittle transitions and their role in plastic component failure, 

• The major plastic failure mechanisms, 

• Failure analysis case studies

The webinar series will focus on practical problem-solving techniques and will utilize case studies to illustrate key aspects of plastic failure and prevention. Participants will gain a better understanding why plastic components fail, and how to avoid future failures by applying the knowledge learned.

Failure of Plastics Session 1

Jeff Jansen, October 2021

This 2-part webinar series will cover a considerable range of topics important in understanding, diagnosing, and preventing plastic component failure. The most efficient and effective approach to plastic component failure is by performing a systematic failure analysis. Someone once said, “if you don’t know how something broke, you can’t fix it”, and this certainly highlights the importance of a thorough understanding of how and why a product has failed. This webinar series will introduce the attendees to information they need to gain this understanding.

• The material covered will include: Essential knowledge of why plastic components fail, 

• The five factors affecting plastic part performance, 

• The process of conducting a failure investigation and methods for understanding how and why a product has failed, 

• The importance of ductile-to-brittle transitions and their role in plastic component failure, 

• The major plastic failure mechanisms, 

• Failure analysis case studies

The webinar series will focus on practical problem-solving techniques and will utilize case studies to illustrate key aspects of plastic failure and prevention. Participants will gain a better understanding why plastic components fail, and how to avoid future failures by applying the knowledge learned.

Polypropylene: Commodity Resin, I Don't Think So

Jeffrey A. Jansen, June 2021

Polypropylene is often referred to as a “commodity resin”, however, is this really the case? Polypropylene is a versatile thermoplastic that can be processed through a variety of processing techniques. It is utilized in a wide range of applications, including packaging, automotive, infrastructure, appliances, healthcare, and electrical. Its wide use is based upon several key strengths, including:

• Good chemical resistance
• Good electrical insulation properties
• Flexural strength and modulus
• Relatively low coefficient of friction
• Readily available and relatively inexpensive

The implication of the interchangeability of polypropylene resins does a disservice to the complexity of this material and the plastic industry in general. The properties of polypropylene are highly dependent on molecular weight and molecular weight distribution, crystallinity, type and proportion of comonomer and the tacticity. Hopefully, at the conclusion of the webinar, attendees will

• Gain an understanding of the general properties of polypropylene.
• Have more insight into how the molecular structure of polypropylene determines its performance properties.
• Appreciate the diversity of polypropylene.

Integration of Polycarbonate Thermoplastic in LED Lighting

Nicolas J. Sunderland | Jim Lorenzo, May 2021

Thermally conductive (TC) polycarbonate was utilized as aluminum metal replacement in LED lighting luminaires, along with transparent, diffusion, and reflective polycarbonate thermoplastics in order to describe a light weight, design-friendly, cost efficient part. To assess suitability of the TC polycarbonate, the part was subjected to thermal testing. Results showed very similar thermal characteristics as aluminum.

Designing for Six Sigma (DFSS) - A Systematic Approach to Robust Plastic Part Design

Vikram Bhargava, May 2021

Designing for Six Sigma (DFSS) - A Systematic Approach to Robust Plastic Part Design To design and manufacture today's complex plastic components, product designers are under tremendous pressure to produce robust designs at a minimum cost and in the fastest possible time. Leading author David Wright wrote in his book titled “Failure of Plastics and Rubber Products” that design issues account for almost 20% of product failures. The fact is that many errors that manifest themselves as material, tooling or processing can also be attributed to design issues. Conventional plastic flow simulation does not necessarily help diagnose and avoid common design issues. Decisions made at the design stage impacts manufacturing quality, product cost, and delivery lead times. Taking a proactive approach by including Six Sigma philosophy upfront into the early design stage can help develop high quality, profitable products eventually bringing sustained value to customers and markets. The Paper will discuss the Design for Six Sigma (DFSS) philosophy and best practices and tools for its incorporation into new plastic product development. This will include: • Understanding the DFSS concept and popular methodologies such as DMAIC and DMADV • Learning how to use DFSS Methodology in early part of plastic product design lifecycle • Applying DFSS techniques and available simulation and DFM tools for successful implementation

Analysis of the State of the Art of Technical Drawings of Plastic Molded Parts Regarding Tolerances

Anja Falke | Friedrich-Alexander | Martin Bohn | Tim A. Osswald, May 2021

The plastic-specific material properties are often not taken into account in the specification of technical drawings of injection molded parts. As a result, tolerance requirements are specified, that are too tight and sometimes even impossible to manufacture, which result in high production expenses. To avoid this, it is necessary to coordinate the functionally required accuracies of plastic components with the technical possibilities available for injection molding production.
In this paper a systematic analysis of drawings from practice is used, to show the current state of the art regarding geometric product specification and tolerance assignment of plastic molded parts. In addition to the quantification of the number of specified features, the unambiguousness of the product specification is assessed. Beyond that, the degree of accuracy of the tolerance requirements is quantified and the manufacturing feasibility is checked in accordance with ISO 20457 in order to then determine the resulting production expense that is necessary to achieve the required tolerances. It is proven that for almost a fifth of the plastic parts tolerance requirements are specified that are not feasible to be produced in the injection molding process. Additionally, it is found that all drawings examined do contain ambiguously specified features, that do not allow for an unambiguous verification.

The Most Frequent Design Flaw That Leads to Part Failure

Paul J. Gramann, Ph.D., P.E., May 2021

The topic presented in this paper is not new. There are numerous reasons why sharp transitions should not be present in a plastic part. However, the number of failures that are occurring at sharp transitions is still very common. In most cases, they can easily be avoided by simply removing metal from the mold to make a smooth transition. This paper will review where most of these transitions are being found, and why they are common in critical parts. A tensile testing study was performed to better understand the effect of geometric transitions. Two cases studies are given showing why the sharp corners can significantly reduce the lifetime of a plastic part.

Fused Filament Fabrication Feedstock Characterization via In-Line Rheology

A.R. Colon | D.O. Kazmer | A. Peterson, May 2021

An instrumented hot end has been developed to monitor the pressure in Fused Filament Fabrication, and is used as an in-line rheometer to characterize the viscosity of an acrylonitrile butadiene styrene (ABS) material. Additional analysis was performed on the transient pressure data to consider compressibility effects and nozzle drool. The range of flow rates was identified at which the pressure in the hot end was most stable. Stabilization time given compressibility effects was also evaluated.

Lifetime Prediction of Continuous Fiber-Reinforced Plastics Based on Nonlinear Damage Accumulation

Simon Rocker | Reinhard Schiffers | Lars Gerdes | Daniel Hülsbusch | Frank Walther, April 2021

Full Title: LIFETIME PREDICTION OF CONTINUOUS FIBER-REINFORCED PLASTICS BASED ON NONLINEAR DAMAGE ACCUMULATION AND FINITE ELEMENT SIMULATIONS Abstract: This paper presents an approach for lifetime prediction of fiber-reinforced plastics based on nonlinear damage accumulation. Already established damage accumulation laws, such as Palmgren-Miner, are to be modified with nonlinear parameters in order to characterize the damage evolution of fiber-reinforced plastics in a more accurate way. For this purpose, cyclic investigations were carried out on glass fiber-reinforced polyurethane with quasi-isotropic layer setup to determine basic mechanical characteristics. The stiffness-based characteristic values, recorded to develop the simulation model, are generated from hysteresis loops, which are also used to calibrate the material model. The experimentally determined stiffness degradation is converted into a damage curve by assigning the first measured value to degree of damage 0 and the failure value to degree of damage 1. Therefore, a hysteresis loop for each degree of damage between 0 and 1 is present, so that a damage dependent stress-strain ratio can be determined and transferred to the material model cali-bration. In addition, a characteristic damage development is derived from the damage curves, whereby the stress level and the influence of sequence can be taken into account for a nonlinear damage accumulation model on global level. Based on the global findings an algorithm is presented that transfers those to the local level in finite element simulations. This approach provides the fundamentals for a lifetime prediction of fiber-reinforced plastics with varying fiber orientations under cyclic loading.

Developing Photopolymerizable Acrylate Resin Formulation for Impact Modified 3D Printed Thermosets

Chinmay Saraf | Amy Niu | Alan J. Lesser,, April 2021

This contribution focuses on engineering photopolymerizable acrylate resin formulations for a superior fracture energy absorption of 3D printed acrylate thermosets. Herein, we report a polydimethyl siloxane-based block copolymer as an impact modifier, compatible with the UV curing process, which undergoes reaction induced phase-separation during the 3D printing process to form a rubbery phase sufficient for enhanced impact properties. A systematic investigation of the effect of concentration of the impact modifier on the morphology of rubbery domains and fracture toughness was conducted. Results show that at an optimum concentration of 15 wt.% and particle size of 57 nm, an order of magnitude improvement in the fracture energy release rate is realized. Fractographic analysis of the impact modified thermosets using optical microscopy indicates the presence of significant plastic deformation in an otherwise brittle material. Notably, the engineered acrylate thermosets, at an optimum concentration, exhibit similar improvements in the impact properties irrespective to the print layer thickness and independent of the crack orientation with respect to the printed interphase. Detailed investigation of the failure mechanisms for impact modified thermosets show that the block copolymer diffuses to the interphase during the 3D printing process, resulting in preferential localization of the impact modifier near the print interphase resulting in an isotropic enhancement of the fracture toughness.