eDART™ Balance Viewer: An Overview

Balance Viewer Tool We will cover balancing a tool at startup with cavity pressure, the same with temperature sensors and then detect an out-of balance condition. We will also show how the Balance Viewer can help you adjust hot runner system balance using in-cavity sensors. We also give you some examples of how to detect and solve problems using Balance Viewer.

Let's begin with balancing at startup Let's begin with balancing at startup. Here on the first shot you see a fairly dramatic imbalance. There is even a pattern with the center and outer cavities tending to be opposite from each other.

Then the tool warms up over the next few shots until it reaches a sort of natural 91 % fill time balance. The auto-scale mechanism on the balance viewer is set to keep about a 2% imbalance just visible from a distance.

Now balancing begins by adjusting, in this case, tip controller temperature settings. Numbers 7 and 10 seem a little fast so we lower the tip temperature settings for those two. Raising and lowering other tip temperatures eventually bring the process to a 97% fill time balance.

Selecting Peak or Cycle Integral shows the balance of packing instead of filling. These values usually relate to part dimensions or the probability of shorts and flash. Notice the dramatic difference in cycle integral even though the flow is balanced. The cycle graph shows a fairly tight group of pressure curves over the time visible on the graph.

But if we expand the cycle graph you now see that the cycle integral varies because of differences in mold deflection and the way the mold springs back onto the finished part. This "cavity shape" variable may also imply a difference in dimensions.

Here is an example of balancing a mold which has only temperature sensors in it. The eDART™ calculates the time from the start of flow until a temperature rise, in this case "Process Time / Temperature at End of Cavity." You can see at the beginning of the run that the flow front arrival time is wildly imbalanced.

With this much imbalance some of the bars hit the top and bottom of the graph. You can turn off the auto-scale and adjust the values so that you can see them all. By adjusting controller tip temperatures we eventually brought it close to fill balance.

As we get closer to a good balance we can turn the auto-scale on again As we get closer to a good balance we can turn the auto-scale on again. Of course this makes it look worse because it scales for that middle 2 percent at fixed size on the screen. So 86% balance looks poor. And it probably is.

The "Minimum" is the temperature of the steel just before the plastic arrives. Clicking the minimum button you see reasonably good balance between the cavity temperatures and thus the cooling. There is a pattern, though, showing that some are slightly colder than others.

Here is an example of a mold running with reasonable balance and a rogue cavity. As a quick diagnostic tool you can use the balance viewer to identify which cavity is the offender and decide whether it needs maintenance or adjustment. Notice that the other values show quite a different pattern of balance not related to fill time.

The cooling rate balance is terribly messy The cooling rate balance is terribly messy. This may be due to real cooling differences or to differences in the filling and packing of the cavities.

Here we start with a fairly well balanced fill Here we start with a fairly well balanced fill. Since the Balance numbers are just summary values like any other in the system you can set an alarm on them.

Here we'll set an alarm on the Balance / Cavity Fill value.

While trying to adjust the last pair of cavities into balance someone adjusted the temperature too far and in the wrong direction. This shows how tricky it is to use curves and cycle value numbers for balancing.

If someone had walked away and not looked back the tool could have run production out of balance. Then, when it gets too far out of balance, the alarm goes off. This would show up on the Advanced System Overview or light a light tree to get someone's attention.

Returning to the machine I see that location 6 is at fault and needs to be re-adjusted. Being low and slow I raise the temperature to where it is supposed to be...and it returns to proper balance.

For more information on this and other applications please contact: RJG, Inc. 3111 Park Drive Traverse City, MI 49686 Phone: 231-947-3111 Fax: 231-947-6403 Web site: www.rjginc.com