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Adding Guarding to Outdated Equipment…

Recently, I was at a customer site and saw a ‘tabletop’ machine from a machinery supplier who is no longer in business. The excellent thing about this machine is that the customer added full guarding around the machine. This was pretty simplistic and inexpensive, but it served the purpose very well and I made a point of thanking them for the effort.

So, if you have a machine which has much older and inadequate guarding, remember that safety is not grandfathered in. Even though the machine was built when lower standards were in place, there is no reason to allow the machine to continue being unsafe. Always keep this in mind when you purchase a machine used machinery, or from a country which has a significantly lower safety standard.
-Andy

What is SCORM…?

I have seen a lot of confusion about this topic…

SCORM Compliance
According to Wikipedia: Sharable Content Object Reference Model (SCORM) is a collection of standards and specifications for web-based e-learning.
Basically, this is not a standard data protocol or format. Any SCORM-compliant course can be played by a SCORM-compliant player. This does not mean the course meets any specification regarding content quality, but it does meet a specific playback protocol.
For comparison, a PDF,  ‘Portable Document Format’,  file is a standardized document which can be opened using a compatible .PDF reader. The.PDF does to relate to the quality of information in the file, just the way it can be viewed.
-Andy

Injection Unit Inertia…

I was in some online discussions lately and this question came as a follow-up via email…

John
I have an older {brand name} molding machine and it has a very large & heavy injection unit. What is the best way to compensate for overshoot?
My Response
Once the machine transfers, the ideal result would be for the screw to go directly into packing. Unfortunately, the inertia of the injection unit can cause additional material to be injected during 1st stage. In most cases, you can just transfer from 1st stage to 2nd stage early to compensate. Unfortunately, the inertia creates force applied to the screw resulting in a pressure-controlled situation. Although the slowdown is typically consistent, some high-precision applications need more precise control near the end of fill.
If more control is required, and you cannot change machines, then you can create a slowdown profile at the end of fill. In this situation, the profile should closely match the natural slowdown of the screw using a couple steps. The benefit to this approach is that you have a more consistent slowdown than just allowing the screw to slow down.
Additional Thoughts
This correction should only be used when the natural slowdown of the screw provides inadequate consistency during transfer.
-Andy.

Ausplas 2011…

This post is to remind you that Ausplast is taking place on May 24-27, 2011.

The official website can be found here: http://ausplas.com/
Since it occurs once every three years, there will be a relatively large number of important exhibitors present.
If you wish to see a small promotional feature about the upcoming Ausplas show click
here
I hope to see some of you at the show.
-Andy

Short Shot During 1st Stage Fill

I recently joined in on a discussion in a Linked-In forum. I addressed one of the concerns, which I will add here…

Concern
Is the better have a 98% filled only parts with lower speed (not very close to knee of rheology curve) or 80% with higher speed or use multiple speeds fast to slow to get 98%?

My Comments
The theoretical point with respect to processing is that you have a short shot during 1st stage fill, assuming it is a velocity controlled machine with adequate injection pressure. The purpose of this practice is to use second stage packing to complete filling and compensate for normal variation in material viscosity. A faster injection speed tends to promote a more consistent process since you are processing after shear thinning occurs, but you should not exceed the machine’s capability to maintain a consistent process.
In many machines, typically older ones, you need to use a profile near the end of fill to counteract complications such as overshoot, undersized 2nd stage pump, avoid a pressure-limited process, or slow responding microprocessors. Such numbers are general rules of thumb which often distract the processor from the intent.
-Andy

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