3.20
PROBLEM # 2, for automatic models with a shuttle.
Inaccurate lengths in AUTO mode.
POSSIBLE CAUSES
1. Encoder
a. Pinion not engaging rack all the way from front to back; mechanical interference, pinion loose on encoder
shaft.
2. Encoder Cable
a. Bad connection at encoder or at PLC
b. Intermittent open in one or more signal wires
3. Improper programmed information
a. Existing parameter(s) incorrect
b. Incorrect blade kerf
4. PLC
a. Faulty PLC unit (not repairable in the eld)
GENERAL RULES - Normally, three types of length inaccuracies may occur.
1. Inconsistent
a. Lengths cut are not consistent, error changes. It doesn’t matter how long the part required is the error is never the
same.
Cause:
b. Most likely a defective electrical, hydraulic or mechanical component.
2. Consistent
a. Lengths cut are consistent and the error is also consistent. The error always stays the same regardless of
part length.
Cause:
b. Kerf value
3. Linear
a. Lengths cut are consistent but the error increases as the part length increases. The longer the part the greater
the error.
Cause:
b. When self-calibration is executed, incorrect “Act Lth” value entered
DIAGNOSIS
1. Check and record existing parameters. Also check for proper blade kerf.
By making a cut part way into a piece of material and measuring the width of the cut, the operator can check
blade kerf.
pinion gear is securely fastened to the encoder shaft and that it can rotate along the rack as the shuttle moves.
If all mechanical components are functioning correctly then the encoder is defective.
If all tests check positive, the problem is in the PLC unit.
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