Harlacher, Grunig, Q-Lux
In general, the most common issue with coating machines is recalibration. Over time, there are a number of connections that become loose and wear points that must be accounted for in order to maintain tight tolerances. Depending on the volume of screens per day (25+), a good rule of thumb is to have the machine recalibrated and tuned-up once a year.
The Harlacher, Grunig and Q-Lux coating machines all have similar issues that develop over time. Whether connections are loose, parts worn, etc., the result is a substandard product.
- The deposit may be heavy on one side.
- It may be too thick in a corner.
- The coating carriage may develop chatter over time.
- There may be a squeak originating from a bearing, pulley or belt.
- Erratic coating trough movement.
- Problems with the clamping system.
- Water in the airline.
- Recalibration Tuneup.
There are 5 main areas of recalibration
Cleanliness, loose connections, frame position within the machine, front and back coating trough position relative to the screen and lastly trough speed towards and away from the screen. Any one of these or a combination of these can cause the resulting emulsion thickness to be out of spec.
1. Cleaning: In particular, where the frame touches the frame holding system, there should be no emulsion between the clamp and the frame. That would adversely affect the home position of the frame and certainly affect accuracy.
2. Connection Calibration: The main machine frame supports should be checked for level and square. If the frame is not good, the carriage will not track correctly. Then the coating carriage pull plates on either side should be checked. If the plate screws are loose there will be a roll to the carriage. Good results would be jeopardized particularly when coating one side only. The force on one side would cause the carriage to roll to the non forced side potentially causing a thicker deposit than desired.
The next connection is between the carriage pull plates and the track it rides on. There should only be limited play when gently lifting up on the carriage. Excessive play will also cause carriage roll.
After ensuring the machine frame and the carriage frame are stable, all shoulder bolts in the carriage cylinder assembly need to be looked at. Excessively tight bolts limit smooth coating trough travel. Too loose allows for “slop” and can dramatically affect the calibration.
3. Frame position: As with all these models, the screen sits in the machine against a clamp back stop in each corner of the frame and is held securely with a pneumatic arm pushing it against the back stop. It is crucial that the back stops are all in alignment with each other. If one If one is not aligned with the others, it’s like a table with a short leg. The frame can wobble as the coating is being applied. The result could be a heavy deposit in one corner of the frame.
4. Front a back coating trough positioning: Once a good frame position has been established (Home Position), the final coating trough position against the screen needs to be evaluated so each of the coating troughs come into the screen to the same degree on the left and right sides. If the coating trough position is not adjusted properly you will see a heavy deposit on one side of the frame.
5. Trough speed towards and away from the screen: Speed does not technically affect the calibration, however, if the travel speed is different between the left and right side of the coating trough, it will begin to wear the shoulder bolts and cylinders unnecessarily.