#PROCESSINGTIPS

Materials

The Effects of Time on Polymers

Last month we briefly discussed the influence of temperature on the mechanical properties of polymers and reviewed some of the structural considerations that govern these effects.

Michael Sepe
, Michael P. Sepe LLC

Materials

The Importance of Melt & Mold Temperature

Molders should realize how significantly process conditions can influence the final properties of the part.

Injection Molding

Hot Runners: A View from the Bottom Up

Addressing hot-runner benefits, improvements, and everyday issues from the perspective of decades of experience with probably every brand on the market. Part 1 of 2.

Injection Know How

How to Set Barrel Zone Temps in Injection Molding

Start by picking a target melt temperature, and double-check data sheets for the resin supplier’s recommendations. Now for the rest...

Materials Know How

The Strain Rate Effect

The rate of loading for a plastic material is a key component of how we perceive its performance.

Materials Know How

Why (and What) You Need to Dry

Other than polyolefins, almost every other polymer exhibits some level of polarity and therefore can absorb a certain amount of moisture from the atmosphere. Here’s a look at some of these materials, and what needs to be done to dry them.

Injection Know How

Understanding Intensification Ratio

A first step in taking the “art” out of molding.

Materials Know How

The Effects of Stress on Polymers

Previously we have discussed the effects of temperature and time on the long-term behavior of polymers. Now let's take a look at stress.

Michael Sepe
, Michael P. Sepe LLC

Molds & Tooling

Tunnel Gates for Mold Designers, Part 1

Of all the gate types, tunnel gates are the most misunderstood. Here’s what you need to know to choose the best design for your application.

Materials

The Effects of Temperature

The polymers we work with follow the same principles as the body: the hotter the environment becomes, the less performance we can expect.

Injection Molding

Improve Quality & Productivity With Advanced Screw Design

Most molders are still running with screw designs that haven’t changed much in 30 years. But they don’t need to.

Stretch Blow Molding

Solve Four Common Problems in PET Stretch-Blow Molding

Here’s a quick guide to fixing four nettlesome problems in processing PET bottles.

Molds & Tooling

Improve The Cooling Performance Of Your Molds

Need to figure out your mold-cooling energy requirements for the various polymers you run? What about sizing cooling circuits so they provide adequate cooling capacity? Learn the tricks of the trade here.

Injection Molding

A Simpler Way to Calculate Shot Size vs. Barrel Capacity

Let’s take another look at this seemingly dull but oh-so-crucial topic.

Post-Processing

A Guide to Ultrasonic Welding Controls

Ultrasonic welding today is a sophisticated process that offers numerous features for precise control. Choosing from among all these options can be daunting; but this guide will help you make sense of your control features so you can approach your next welding project with the confidence of getting good results.

Commodity Resins

Formulating LLDPE/LDPE Blends For Abuse–Resistant Blown Film

A new study shows how the type and amount of LDPE in blends with LLDPE affect the processing and strength/toughness properties of blown film. Data are shown for both LDPE-rich and LLDPE-rich blends.

Injection Molding

How to Get Rid of Bubbles in Injection Molding

First find out if they are the result of trapped gas or a vacuum void. Then follow these steps to get rid of them.

Pipe, Profile & Tubing Extrusion

Medical Tubing: Use Simulation to Troubleshoot, Optimize Processing & Dies

Extrusion simulations can be useful in anticipating issues and running “what-if” scenarios to size extruders and design dies for extrusion projects. It should be used at early stages of any project to avoid trial and error and remaking tooling.

Injection Molding

The Importance of Gauging Residence-Time Distribution—Part 2

Each molecule in the molded product can have a different residence time. This variance is reflected in the Residence-Time Distribution, which you can learn how to determine below.

Extrusion

Troubleshooting Pressure Fluctuations in Piston-Type Melt Filters

Piston filtration offers many advantages over other systems. While pressure fluctuations could be regarded as their weakness, there are many ways to avoid them, both from the mechanical and the process side. Small adjustment can make a huge difference in the overall performance and efficiency of the system.

Pipe, Profile & Tubing Extrusion

When to 'Adapt,' When to Retool?

That is the question pipe and tubing processors typically confront when they specify a line for one product, only to have to add to the product mix when business conditions change. Here are some tips to guide you to the right answer.

Molds & Tooling

How to Optimize Pack & Hold Times for Hot-Runner & Valve-Gated Molds

Applying a scientific method to what is typically a trial-and-error process. Part 2 of 2.

Suhas Kulkarni
, Fimmtech Inc.

Purging Compounds

Got Streaks or Black Specs? Here’s How to Find and Fix Them

Determining the source of streaking or contamination in your molded parts is a critical step in perfecting your purging procedures ultimately saving you time and money.

Injection Know How

The 'Butterfly Effect' in Injection Molding—A Connected Process

In injection molding, a seemingly minor change in a setpoint can have a significant impact on part quality and process robustness and repeatability. That’s why Scientific Molding focuses on process outputs, not setpoints.

Stretch Blow Molding

Solving the Bane of Stretch-Blow Molding: Off-Center Gates

There are many reasons why off-center gates happen, and processors should be aware of all of them to quickly find the ones causing the problem.

Automation

People 4.0 – How to Get Buy-In from Your Staff for Industry 4.0 Systems

Implementing a production monitoring system as the foundation of a ‘smart factory’ is about integrating people with new technology as much as it is about integrating machines and computers. Here are tips from a company that has gone through the process.

Single-Screw Compounding

Follow These Guidelines to Select the Right Pelletizing System

Which pelletizing system is right for your application? Is the one you’re using today necessarily the right choice for tomorrow? Here’s is an analysis that can help you decide among the three major options.

Injection Molding

Process Capability and the ‘Hesitation Effect’

Understanding the concepts of pack and hold and applying them during process development is critical for molders to achieve consistent part quality.

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