High Pressure Rinse and Air Dry Not Working on Wide Web Anilox Unit

Welcome to my column where I will share best practices for Flexo Wash technology and common flexo challenges. I want to answer your real world questions, so be sure to send them to me at: service@flexowashus.com and we will feature them in an upcoming column. As your partner, I look forward to handling all your issues as soon as possible and offer lessons learned.

If you’re troubleshooting a narrow web anilox unit, head over to this article: HP Rinse and Air Dry Not Working on Narrow Web Anilox Unit

Question: Why is High Pressure Rinse and Air Dry not working?

Answer:

Have you ever been in the situation where the high-pressure rinse and air-dry passes are not working on your anilox unit?  We have run into this situation a number of times over the years.  Let’s take a look at what might be causing the issue. 

When Should the Rinse and Air Dry Actually Start? 

First of all, it is important to remember that the HP rinse and Air Dry do not actually come on until the drain cycle is complete.   

An anilox cleaning unit functions in the following order: 

• Wash
• Drain
• HP rinse
• Air dry

So, when you hit start, the unit goes into the wash cycle, and the high-pressure pump is not supposed to come on until after the drain cycle finishes. 

Most Common Issue: Return Proximity Sensor is Stuck On 

If your HP rinse does not come on after the drain cycle, the number one culprit is that the return proximity sensor is stuck on. Meaning, this sensor is sending a faulty signal to the circuit board or microcontroller.   

Troubleshooting the Proximity Sensor by Unit Type 

Mid-2008 and Earlier Narrow Web Units (Microcontroller Units) 

On mid-2008 and earlier narrow web units, there is a microcontroller that handles the programming. The proximity sensors in these units are normally open.  

When the spray head is in the home position, the home proximity sensor is illuminated. This tells the programming that “I’m at home” so I can start the high-pressure rinse after the drain cycle. 

If the return proximity sensor is also illuminated, that tells the programming “I’m at the end and I need to go back to home”.  

Well, what we have here is 2 sensor inputs at the same time. This causes the programming to shut down and then you don’t get your HP rinse or air-dry passes. The cycle shuts off and then the unit is ready to start again.  

It is important to note that the return proximity sensor does not have to be illuminated to send that false signal. The light on the sensor may be burned out or there may be a hole in the sensor cord which is causing that signal to jump across wires and go to the programming.  

You can check the microcontroller to see if you are receiving a faulty input from the return sensor.  If the lid is closed, the screen on the microcontroller will display the inputs (I) on the top row and outputs (O) on the bottom row.  If you see the circle for input 7 is illuminated, the return sensor is bad. 

Mid-2008 to Late 2019 Narrow Web Units (Circuit Board Units) 

Narrow web anilox cleaners built from mid-2008 to late 2019 have a display screen and circuit board. These units also normally have open sensors so identifying a bad return sensor follows the same process as previously mentioned.  

However, if the return sensor is not illuminated, you can check the input via the screen on these narrow web circuit board units.  

• Arrow up until “check inputs” is displayed on the screen and press the program button.
• Enter password 9936 by holding the up arrow.  
• When 9936 is on the screen, press the program button again.  
• At this point, you can arrow up to #35, slide end.
• If this input says “on” and there is nothing in front of the sensor flagging it, then the return sensor is bad.  

Late 2019 and On: NXT Narrow Web Units 

Narrow web units built from late 2019 onward are classified as NXT units. These have different circuit boards and display screens from earlier models. 

Understanding NXT Sensor Behavior 

• NXT units use normally closed sensors.
• When flagged, the sensor’s light is off.
• If the return sensor light is off when it shouldn't be, the sensor is likely bad. 

How to Check Sensor Inputs on NXT Units 

1. Press the gear icon on the display.
2. Arrow up to “Check Inputs”.
3. Press the check button.
4. Arrow up until “Slide End” is displayed.
5. If the input reads “On” and nothing is flagging it, the return sensor is bad. 

Even if the return sensor light is on, it may still be sending a faulty signal. Always confirm via the input screen. 

If your return sensor is good and the unit is going into the rinse cycle but the spray arm isn’t moving or you don’t see any rinse water, then something else is going.  There may be a bad traverse motor, traverse coupling, broken timing belt/pulley, dropped output, water inlet solenoid valve, etc. that might be causing the problem.  Give us a call at the shop and we can help you troubleshoot the issue. 

As always, if you need immediate assistance, call us at Toll Free: 888-493-5396 | F: 888-543-5396

Flexo Wash US

2010 Plantside Drive
Louisville, KY 40299
1-888-493-5396
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