10 Tough Questions: Part Two - Valve Troubleshooting

Part Two: Troubleshooting Your Dispense Valves

How you set up and adjust your dispense valve system can impact production throughput yields and the amount of waste and clean up on the factory floor.

This blog series sheds some light on common pitfalls encountered with typical valve system setup by providing answers to common questions.

Part one of the series answered the top two questions. In part two, we take a closer look at how to make your valve setup more efficient with higher performance to meet your production throughput goals.

We hope that you find this information helpful.

3. Is Your Dispensing Line Running as Fast as it Can?

There are several reasons why your line may be running slow. The first reason is that your valve control system may not be compatible with the dispense valve.

When faster cycle times and more precise control of deposit size are required, a dedicated valve controller with a fast-acting solenoid and a digital timer can be a simple and cost-effective way to achieve these objectives. The controller can also be interfaced with the Programmable Logic Controller (PLC) if desired.

Another thing to consider is that a PLC may or may not offer online programming of dispensing functions. But even if a PLC can program valve functions, the valve may not be within the line of sight of the engineer or operator trying to adjust it.

Solution: A dedicated controller mounted at the dispensing station will simplify initial setup, make it faster and easier to purge the valve after refilling the fluid reservoir, and allow adjustments to be made and checked “on the fly” without shutting down the production line.

Small details in the valve system can also make a big difference. A tapered polyethylene tip, for example, can shorten dispensing time by reducing resistance and providing a faster flow rate than a straight metal tip of the same size. Using a fluid line with a larger internal diameter is another way to reduce cycle time in certain applications.

The bottom line is in most situations, best results will be obtained with a valve style and configuration carefully matched to the specific properties of the fluid being dispensed.

4. Do Your Valves Leak and Drip?

Leaking is a common problem with valves that have complex designs or seals and O-rings that wear out over time. The most reliable diaphragm designs eliminate the need for seals and O-rings. The best valves will easily handle many different fluid applications and provide tens of millions of cycles without maintenance. Carefully choosing the valve seat materials will also prevent many problems.

5. Are Your Valves Mounted Close Enough to the Workpiece?

When valves are too large or heavy to be mounted at the dispensing station, extra time must be spent on design and fixturing. If extra lines and fittings must be added to transfer the fluid from the valve (where cutoff takes place) to the point of deposit, it increases the risk of dripping and drooling.

Using valves small enough to be mounted at the point of fluid application reduces the risk of dripping and drooling.

6. Is Your Current Valve Setup Trapping Air?

Be sure to purge all air and fluid lines whenever setting up a system, refilling the fluid tank, or performing maintenance. Other recommendations include:

• Keep air lines shorter than 5 feet.
• Tip selection can help prevent air entrapment. When using metal tips, use 21 gauge or larger, if applicable, as they will allow small air bubbles to purge through. Tapered polyethylene tips are a good choice in any size. They allow fluid to flow freely through the tip to purge and prevent air bubbles from collecting. Tapered tips typically range from 14 gauge to 27 gauge.
• Use a valve controller with a purge function that allows the user to bleed any air in the system quickly and easily.
• Use a fluid tank with a constant-bleed air regulator to prevent fluctuations in pressure and shot size.
• Install a filter/regulator between the plant air supply and the dispense valve to remove any residual moisture from the system. This is especially important when working with cyanoacrylates.
  
  

7. Is It Difficult to Produce Consistent Shots?

If your valves are taking too long to set up and you cannot obtain consistent results, a valve system with a dedicated controller is a more efficient approach to establish shot size and regulate valve operation.

Another advantage of using a controller is that settings can be recorded and saved for the next time that specific job is run, or after maintenance has been performed. With a digital valve controller, valve open time can be adjusted in increments as small as 0.001 seconds for exceptional control over the amount of material applied.

On production lines with multiple dispensing stations, using a dedicated valve controller at each station can make it simple to adjust each valve’s open time independently, and obtain an identical shot from each valve.

8. How Often Do Your Valves Require Maintenance?

All valves will eventually require maintenance, but some designs require more frequent repair than others. Here are some things to consider:

• How often is maintenance required?
• If valve maintenance is required, can it be performed on site or does the valve have to be returned to the manufacturer?
• If service can be performed on site, how complicated is it? Can you simply remove the fluid head without dismounting the valve? Or does the valve have to be removed from the mounting fixture and taken apart?
• Spare parts provided by local machine shops may not always be readily available. This delay could lead to line downtime when replacement parts are needed. Using engineered products that have an abundant supply of replacement parts can add significant value.

If you’re spending too much time and money keeping your valves up and running, it might be worth looking at a more reliable, low-maintenance design such as our xQR41 needle valve.

Next Up…Part Three: Should You Replace Your Current Dispense Valve System

In the final part of our series, we’ll look at how you can solve most dispensing issues with proper dispense tip selection. We’ll also cover whether you should ditch your current system and replace it with high-speed jetting or another valve system that would be a better fit for your application.

Do you have a valve setup question we didn’t cover in this blog post? Don’t hesitate to email us at [email protected]

 

 

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