Optimizing Transfer Efficiency With a Robotic Cell

Industrial-scale operations require industrial-scale solutions. One of these comes with powder and other forms of coating where transfer efficiency is key.

Transfer efficiency is usually defined as a ratio between coating material that sticks to an object vs the total weight of coating used in a process interval. This is generally expressed as a percentage. For example, if only half the coating makes it onto the part being processed, that could be considered a transfer efficiency of 50%. The more that makes it onto the part, the higher that percentage.

Where Transfer Efficiency Is Important

For a few reasons, powder coating transfer efficiency may not need to be particularly high. Some powder coating booths allow for the recovery of material, although color changes can lead to contamination that ultimately compromises the whole endeavor of material recovery.

This is where the challenge becomes impactful. For even an average powder coating shop, spending $1 million or more per year on powder is not uncommon. If within this expense, 50% or more of the material is wasted, this can be incredibly burdensome for a small or medium-sized business. 

When we consider larger shops which may be running 2 or 3 shifts on multiple lines, 6 or even 7 days per week throughout the year — these enterprise-grade production environments can be spending tens of millions or more coating complex part shapes where faraday caging and unique targeting challenges make powder waste a huge cost. Often the biggest cost in powder is simply in finding enough skilled labor to get enough material on the part. 

What Is a Good Transfer Efficiency

Good transfer efficiency is generally considered to be 65% and up. This is because of a few things, including the need to overspray faraday caging areas in order to ensure that sufficient coating can adhere to the part. Generally, powder as a material can be a little cheaper than paint — particularly specialized industrial paints — so those using powder coating in manufacturing are able to spray more liberally and less accurately than they might for conventional paint.

That being said, high transfer efficiency is always more desirable in the sense that more powder on target is better. The challenge again becomes that if too much powder is deposited on the target parts, then money is wasted for every pound of powder that is in excess of what is required by the customer or the overall production process. 

Transfer efficiency overall can be improved by increasing voltage or improving the grounding of your operation as well as overall design or “batch run” improvements that optimize how your coating process works according to the shape of your parts, but these specific improvements can vary according to the specifics of a certain production. For more on how to improve the fundamentals of your powder coating booth, the Powder Coating Institute can be one of the best resources out there!

How Is Powder Coating Done Today

Powder coating is done today through two primary means: handheld, pressure pot-driven systems and automated booths utilizing overhead conveyors, reciprocating arms and quick color change or rapid recovery additions.

For manual coating, the process can be challenging in that workers must wear protective equipment since inhaling powder coating is essentially toxic, while said equipment can also reduce the desirability or accuracy in doing a manual powder coating job. Secondly, the equipment used has to be safe within the bounds of human presence and then essentially relies on lower pressure and volume of coating with a higher need to rest over trouble spots or faraday cages.

When it comes to automated systems, higher volume and broader distribution of coatings are achievable through automated arms that have a consistent 24/7 output. Maintenance on these systems is minimal, but accuracy according to uniquely-shaped parts or parts with varied cavities can be a challenge. In this context, many vendors still provide systems with light screens or other vision components that can overcome the limitations of some part nuances, and while these can work within specific scopes or for most manufacturers’ needs, many may still find themselves returning to manual coating or touch up for trouble parts. 

How a Robotic System Can Help

A robotic system can help improve powder coating in both transfer efficiency and in reducing unnecessary overcoat by better targeting coating according to the shape of a part. If, for instance, 35% of coating is lost due to mixing and another 15 or 20% to overcoat, the savings of reducing these losses by even 50% respectively can amount to hundreds of thousands of dollars per year for even the smallest powder coating production. 

The challenge in incorporating robotics, however, is that each robot needs specific programming and jigging in order to be effective for individual parts. For mass manufacturers or those working with highly specialized, expensive coatings with very low part mix, this could allow some to benefit from robotics. However, the real challenge here is that most coaters who use A LOT of coating have a lot of different parts to process, meaning traditional robotics may not really have the answer they’re looking for. 

Why Autonomous Robotics Is the Next Step

Autonomous robotics is different because it’s based on the concept that a robot can be programmed automatically, in real-time, based on simple instructions or parameters driven by the manufacturer. In these circumstances, autonomous robots are able to adapt to the variations in part shapes that most need without compromising the consistency, reliability, or precise output that robots are generally known for.

With this in mind, it’s important for coaters to consider what the real scale of their needs is. If it’s simply one or two robots on a single production line, the autonomy to power them and save those hundreds of thousands (or more) per year may actually be cheaper than you think. 

Omnirobotic provides autonomous robotics technology for spray and finishing processes. Its revolutionary Shape-to-Motion™ approach can SEE parts, PLAN a unique program and EXECUTE it in real-time with existing industrial robot brands. Check out our payback calculator to find out if an autonomous robotic cell could be right for you.

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