THE BUSINESS OF VISCOSITY BLOG



The Necessity of Paint Temperature Control in Robotic Paint Finishing

Posted by Mike Bonner

Dec 10, 2017 5:01:31 PM

The rise of robots has revolutionized automotive and industrial finishing operations over the last several decades.  Robots are uniquely capable of handling those high-precision, repetitive tasks of which humans quickly grow tired.  They can repeat the same path, speed, angle and distance to the part time-after-time-after-time without ever growing tired or taking a sick day.

Automotive Paint Robots

Given that, you would think that robots offer increased efficiency, consistency, and throughput to finishing operations.

But maybe not…

For everything that robots offer to the painting process, there is one important factor that is often overlooked... 

Eye-hand coordination

There are subtle variations in the parameters of the painting process that can significantly affect the outcome.  One of the most critical is viscosity.  And as we’ve discussed in previous blogs, paint temperature is directly linked to paint viscosity.  In other words, as the temperature changes, so does the viscosity.  And this affects how the paint “behaves” during application.

An experienced human operator can see these changes as they occur and – through eye-hand coordination – can modify the speed, path, angle and distance to the part to correct for these changes in paint viscosity.  A robot, on the other hand, lacking this ability, will repeat the same errors over-and-over-and-over again!

The solution is to stabilize viscosity by controlling the temperature of the paint.

What is paint temperature control?

Viscosity increases as temperature falls, and increases as temperature rises.  Because of this change of viscosity, temperature directly affects the appearance and quality of the finished product.

This means that you can control all other variables in the painting process, but the quality of your finished parts may be seriously compromised unless you’re controlling your paint temperature.  Issues such as inconsistent color, uneven film build, orange peel, mottle, and other surface imperfections are all associated with viscosity variations and can contribute to unacceptable first-pass yields.

This is a problem because high-end customers demand consistent quality, often refusing to accept parts that are anything less than perfect.

So…

How do you add paint temperature control to your process?

Adding a paint temperature control system is a multi-step process.

First, a thermal analysis of your painting process must be completed.  Properly done, this will reveal the temperature variations (and therefore the viscosity variations) of the paint as it’s being applied.  Improperly done, this will just produce garbage data that will drive you further away from your goal – so be very careful about who you choose to help with this project.

It’s also important to track finish quality trends while temperature/viscosity data is being collected.  Devices like BYK Gardener’s WaveScan can objectively measure finish anomalies of completed parts.  Combining this temperature and finish quality data into a controlled analysis can help uncover the optimal temperature window to produce the ideal surface finish.  This window can be within just a few degrees, so it is important to make sure that your team includes consultants who are experienced in this kind of analysis.

Stabilizing your robotic process

The key to producing consistent quality in robotic painting applications is to maintain the temperature (and therefore the viscosity) of the paint within that narrow window.  A properly executed paint temperature control system can do just that, leading to increased first-pass quality and reduced costs with lower solvent and paint usage. 

There are many different options available, depending on your application, and your specific needs, but the best system will always provide temperature control at the most important point in your process – the point of application.

If you’d like more information about what a paint temperature control system can do for your application, contact Saint Clair Systems.

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Topics: Viscosity, automotive painting, industrial painting, Paint Temperature Control Series, robotic painting