This informative blog allows plastics professionals to discuss plastics training and technology. Brought to you by Routsis Training: the plastic industry's premiere training provider.

Testing Volumetric Feed Systems

Don’t assume that when you are getting consistent feed with your volumetric feed system as this needs to be tested.


A customer was having significant issues with a PVC twin screw profile extrusion line where the line would break often during production without any obvious cause as well as provide profiles which would vary in dimensions over time. During investigation it was found that the die pressure fluctuated up and down approximately 10% in 2-3 minute intervals.


After checking some basic items we tested the material feed system and found that a 25% increase in feed (16RPM to 20RPM) resulted in a doubling of material feed (140lbs/hr to 280lbs/hr). After further testing we located a speed which provided the correct amount of material in a consistent manner to get the machine back up and running. After this correction, the inconsistency of the profile decreased.

Additional Thoughts:

You often have to check your equipment to ensure it is functioning properly. Just because a material feeder is turning at a steady rate does not mean the material is being conveyed properly in a consistent manner.

Torque for Clamping Bolts

Torque calculators are a great resource for the Scientific Molder as long as they take in effect the low strength of the cast platen.


We are trying to figure out what torque to use on our bolts when clamping in molds. I read that the bolt size and hole diameter make all the difference. If I send you those sizes, could you recommend those values for me?

My Response:

The proper way to determine max bolt torque is to use a calculator which allows you to select or enter strength of the platen material.

The grade of cast steel varies, but generally it has the strength of low grade cast steel around 30,000psi or 200 MPa. Since the integrity of most of these platen holes are generally suspect, it is safest to use a lower strength value such as 15,000-20,000psi or 120-160MPa.

Using a calculator such as the one below using a 5/8” steel bolt mating into a custom material with a yield strength of 20000, the recommended torque is 65ft-lb with a max of 86ft-lb – this falls in line with normal industry recommendations of using 50-60ft-lbs for 5/8” bolts (assuming you have at least 150% of the bolt diameter engaged).


Additional Thoughts:

Many people get confused because a 5/8″ bolt might be rated at hundreds of ft-lbs of torque, but this does not take in account the significantly weaker threads in the platen.

Routsis TechCert™ for Production Teams

Routsis’s TechCert™ delivers the most efficient workforce certification training available to the plastics industry. Specifically developed for processors, technicians, designers, and engineers, this certification program is a powerful combination of metered online training, course study guides, technical webinars, hands-on assignments, and instructor-led Q&A sessions. TechCert™ goes beyond merely preparing students for an exam. This learning model explains key processing concepts while instilling proper work habits — and requires participants to develop and demonstrate practical skills.

Routsis currently offers TechCert™ certification training programs for Injection Molding, Blow Molding, and Extrusion processors and technicians — and an Injection Mold & Part Design certification track for designers and engineers.

For more information, click here.

Free Online Gap Analysis Testing

GapQuiz™, from Routsis Training, quickly identifies potential gaps in the knowledgebase of your plastics industry personnel for Scientific Molding, Blow Molding, Single Screw Extrusion, Twin Screw Extrusion, and (coming soon) Injection Molded Part Design. There are no charges associated with the Gap Analysis quiz and companies can test an unlimited number of employees with confidential results emailed to the participant.

“We wanted to help individuals and companies determine critical training needs.” said Andy Routsis, president of Routsis Training. “With our new tool, this process can begin instantly.”

Users test their plastics experience – using a computer, tablet, or smartphone – in any of the five GapQuiz™ categories. The questions in each test are randomly selected from Routsis Training’s Professional Certification exams. These thorough exams are used to certify workers’ proficiency by testing important industry best practices and concepts. Testing covers a wide range of industry-specific topics, including: scientific processing techniques, plastic material properties, process documentation, important safety concerns, design, print reading, and troubleshooting.

Visit Routsis Training’s website to learn more about the new GapQuiz™ tool, professional certification, affordable training packages, or to request a free demonstration course.

Click the GapQuiz™ logo below to begin:

Mobile Learning Just Got Easier

Routsis Training’s new LMSBridge™ app provides an optimal learning experience on mobile devices.

There’s no denying that plastics processing facilities increasingly rely on online training to streamline productivity. Since the 1990s, Routsis Training has been a leader in developing and implementing such training materials. Like the rest of the web-browsing world, the online training landscape has been slowly shifting away from desktop computers and more toward handheld devices, such as smartphones and tablets.

“Some years back, I started noticing a few injection molders were using tablets on the production floor,” said Andy Routsis, president of Routsis Training. “I thought it would be great if they could start using our training materials in this way.”

In 2010, Routsis Training revamped all their online courses to be more mobile-friendly. But while the courses themselves were quite capable of being run on phones and tablets, the user experience varied greatly from device to device. According to Andy Routsis, “We found that while a course might run quite well on larger tablet, there was certainly room for improvement on smaller screens.” Mr. Routsis envisioned a not-so-distant future in which individuals and corporate employees alike would prefer to train on their smartphones — whether on the floor or in the break room, or at home or on the road. “So I asked my development team to start looking for solutions to the problem,” he continued.

By the end of 2019, the solution had taken the form of an app called LMSBridge™. Available for both iOS™ and Android™ devices, Routsis Training’s free app optimizes the presentation of their plastics training courses on handheld devices. In addition, it provides a unified experience on various devices — so that the courses function identically, whether played on Apple iPad™ or a Samsung™ smartphone.

Routsis’s LMSBridge™ app also provides their RightStart™ customers with convenient administrative access to their company’s online training portal. This feature gives trainers and managers greater flexibility in developing curricula, enrolling students, and viewing employees’ progress while away from their desks.

“We always look forward to learning new ways to help our customers maintain their competitiveness,” Mr. Routsis said. “I really feel this app is going to be a game-changer for a lot of plants.”

Visit Routsis Training’s website to learn more about LMSBridge™. Please note that while the app can be downloaded for free from the Apple App Store and Google Play, access to Routsis’s training materials requires an existing customer account. Please contact Routsis for a free demonstration course.