Welcome!

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.

VISIT OUR STORE
VISIT OUR WEBSITE

Understanding Shot Volume Factors…

I received this interesting question from a blog reader the other day…

Leslie

I recently came across this term: Shot Volume Factor and the units are in^3/in (cubic inches per inch). 

I speculate that it is some kind of volume conversion number that when used will allow a user to quickly convert shot size from machine to machine. 

What is this term and how is it calculated?

My Response

As the screw travels forward, it displaced a specific amount of volume as it travels forward. This factor is a machine-specific value which converts the linear displacement of the screw into the volume displaced within the barrel. 

The shot volume factor can be calculated by determining the

 surface area in front of the screw.


Just multiply pi times the radius squared: π*(r^2)

Imperial Example:
1.2 inch diameter screw

π*(r^2) = (3.14)*(0.6in)*(0.6in) = 1.1in^3/in

Metric Example:
30mm diameter screw

π*(r^2) = (3.14)*(15mm)*(15mm) = 707mm^3/mm

Additional Thoughts

Once determined, just multiply the distance the screw travels times the factor to determine the actual displacement of the screw.


Adversely, if you know the estimated shot volume, just divide the volume by the shot factor to estimate the linear displacement necessary to fill the mold.


Calculating this for each machine can be a great way to help your employees quickly identify the differences between each machine.


-Andy

6-Axis Robotics For Injection Molding…

I recently had a discussion with a friend of mine regarding robotics…

Al
We would love to use robotics, but our parts are very complex, and cannot be removed by a simple robot.

My Response
6-Axis articulated robotics are becoming increasingly common because of the following reasons:
1. They can perform complex movements – This allows injection molders to remove complex geometries from the mold, as well as simplify automation by allowing the robot to peroxide some of the secondary operations.
2. They are very reliable – Believe it or not, many 6-axis robotics are as reliable as their 2, 3, and 4-axis counterparts.
3. They are inexpensive – I have seem some 6-axis robots that are less expensive than many popular 4-axis robots.
Additional Thoughts
6-axis robotics tend to be slower than their 2, 3, and 4-axis counterparts. In most cases, the difference in speed tends to be less than 1 second increase for 6-axis robotics.
-Andy

When It Comes to Training…

I was recently forwarded a good article in Industry Week by Jill Jusko entitled: When It Comes to Training, Don’t Hope for the Best

Article Excerpt
When it comes to training, “what I often see happen is that people will invest in some training and then hope that the results will shine through,” says Ryan Hale, lead consultant with Stroud Consulting. Instead, he says, manufacturers must first understand what results they want to achieve and then pick the training and tools to achieve those results.
My Comments
This article highlights a common pitfall in employee training. Most companies don’t approach training with the intent of making concrete improvements… and as a result, they don’t structure the training to accomplish these concrete goals.
I recommend you consider reading Jill’s’ article When It Comes to Training, Don’t Hope for the Best as well as Selecting Your Training Metrics to learn more about the importance of monitoring training metrics.

-Andy

Processing With Older Injection Molding Machines…

I received this question today from a blogger…

Blogger
How should I proceed, when I want to adjust the process on an older pressure-controlled machine (not velocity controlled)?

My Response
Although each of these older machines have their own specific limitations… there is a basic strategy to use with open-loop pressure-limited injection molding machines:

1) Fill and pack using first stage pressure – The mold should be completely full with small sinks near the gate area

2) Transfer using time – Using second stage hold to eliminate any sinks at the gate area.

Additional Thoughts
Many of these molding machines have really accurate limit switches on the injection unit. Unfortunately, the variability in mold filling as a result of viscosity changes can often cause a process to bounce between shorts and flash.

-Andy

Load Sensitivity Test On Electric Molding Machines…

I was asked this question the other day…

Milan
Does it make any sense to perform a load sensitivity test on a electric machine?. I did few tests, but results were very good, range 0,016% to 0,105%.
Note: The Dynamic Load Sensitivity Test measures how much the injection time shifts with a change in resistance.
My Response
Most all-electric molding machines perform very well in the Dynamic Load Sensitivity Test. In most cases, a variation over 1% is very uncommon in newer machines.
In general, load sensitivity is not a concern with all-electric injection molding machines. Such tests are helpful once or twice a year as part of the general machine maintenance program. This will help you maintain a record of the machine’s performance, and will help you monitor or detect any degradation in performance over time.
Additional Thoughts
for more about the benefits of all-electric molding machines, please review: Are Hydraulic Machines Going the Way of the Dinasour…?
-Andy

  • Recent Posts

  • Recent Comments

  • Archives

  • Categories

    • © 2016 All Rights Reserved | Powered by Wordpress | Made with ❤ by Themely