MAGUIRE FLEXBUS Lite, Installation Operation & Maintenance

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DISPENSE TIMING : (DATA line 3)
The second number is the number of milliseconds calculated to dispense the material. If these times are
consistent but the weight of the first dispense varies, then the material does not flow well, or consistently.
Another possibility is excessive vibration or interference with the weigh bin.
Excess vibration, particularly on small dispenses, may cause incorrect weight readings even though the
weight dispensed was, in fact, correct.
If the timing number is very small, 40, 50, 60 milliseconds, perhaps this is asking too much from a slide
valve. Very short times mean you want small amounts, but are using a high rate dispense valve to do the
job. An auger, a vertical valve, a horizontal valve with a flow restrictor, or a smaller valve would help to
improve accuracy and control.
If the timing number is below 20, you are operating in a range where it is difficult for the blender to perform
well.
The LAG time parameter adds time to every dispense. This is to compensate for the time at the beginning
of a dispense when the solenoid valve shifts and air pressure builds, before the valve starts to move. LAG
times are always set slightly longer then the necessary minimum. If a calculated dispense time is very
short, the Lag time that is added, while small, may interfere with accuracy, and cause an over dispense.
PERCENTAGE ERRORS : (DATA line 1)
When looking at errors of percentage of color or additive dispensed, look for the following.
1. First, look for indications of "retries". Retries are evidence of a problem that will also cause
percentage errors.
When FIRST time dispense, (DATA line 3), does not equal FINAL dispense, (DATA line 1), one or
more retries have occurred. This means the hopper ran out of material, or the flow rate is so erratic
that the first dispense was short for no good reason. Parameters _RT and _RP determine what
shortage error is necessary to force a retry.
Inconsistent loading resulting in large variations in hopper material level can cause retries.
Excessive vibration can also cause bad weight readings, which can cause unwarranted retries. If
the BAILOUT line is printing occasionally, then vibration is most likely causing this. Increasing the
BAILOUT parameter should fix this.
A LAG time set too high may cause retries to overshoot their mark resulting in over dispensing.
2. Second, look at ACTUAL weight dispensed (DATA line 1).
Additive, for example, is a percentage of the natural. In the example above, Natural is 1538.4
grams, so additive, at 4 percent of Natural, is targeted to be 61.5 grams. In fact, if 62.8 were
dispensed, the error would be 1.3 grams, well within the expected accuracy of a 1” auger feeder.
The actual GRAM error of a dispense is more meaningful then the percentage error. Mechanical
devices and material flow are not perfect. The most we can expect from them is to operate within a
reasonable range of accuracy. This range is better defined by an error expressed in grams, rather
them percentage.
3. Third, look at the dispense TIME (DATA line 3).
Very short times (40, 50, 60 milliseconds) indicate dispense devices not well matched to the task.