Making robotic paint automation pay.  GUARANTEED!

 

North American Paint Applications

Specializing in Industrial Paint Robot Automation

 

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Products & Services

  - Paint Process Optimization

  - Paint System Audit

  - Paint System Specification

    a Paint Color Change Efficiency

    a Paint Shop Throughput

    a Paint Overspray Reduction

    a Paint Robot Integration

    a Paint Finish Quality

    a Paint System Troubleshooting

    a Painting System Automation

  - Paint Supply & Delivery Systems

    a Dead Head Paint Supply

    a Recirculating Paint Supply

    a Flexible Colors Paint Delivery

    a Piggable Paint Supply System

    a Self-Flushing Paint Systems

    a Oil Free Paint Supply

    a Paint Sheer Reduction

    a Spray Booth Waste Collection

  - RoboGuide PaintPro Simulation 

  - Paint Robot Program Conversion

  - ABB RobotStudio for Paint

  - 2 or 3K Paint Dispensing Systems

   

  

  

  

Since 2008, our customers have created over a thousand jobs in paint finishing, opened new facilities, expanded existing ones, and brought millions in production back to the USA.  Improved paint finishing operations have added greater than $300 million to their businesses.  The average NAPaint project ROI is less than 5 months.  Annual benefit can exceed tens of millions.

 

  

       

 

  

 

 

       

 

PAINT FINISH QUALITY

 

Consistent quality finishing can be achieved and sustained at a high level of efficiency.  But, complex high volume production paint lines are insufficient by themselves to do it.  It is not enough to spray expensive paint, to use a ridiculously expensive applicator or even more expensive robot.  Without a special knowledge of the equipment, integration, process and application, paint finishing might feel like a crap shoot.  A few days you win . . . most days you lose.

 

To start, just about anything and everything in and around the paint shop can affect the quality of the finished product.  The following discussion and analysis covers some of the more common defects found in paint application systems and those that are responsible for producing the greatest proportion of  imperfections.  We hope you will find this helpful when analyzing and troubleshooting finish quality issues.

 

 

PAINT DEFECT ANALYSIS

 

NA Paint offers true turn-key services for paint defect analysis and correction.  We identify paint defect root cause.  And we fix it.  It is that simple.  

See More NAPaintShop Benefit Examples

Our working knowledge of industrial paint processes, electrostatics, 1K, 2K, and 3K basecoats, clearcoats and tri-coats, solvent and waterborne chemistry, AdPro, conductive primers, E-Coat, steel, plastics, SMC and carbon fiber, conveyors, washers, air houses, ovens, flash tunnels, air flow, sludge systems, waste recovery and treatment, system controls and integration, robot automation, spray guns, bells, flow control systems, paint supply and distribution, compressed air systems, contaminants, and overall good paintshop practices are extremely beneficial for fast, efficient, and absolute problem solving.

 

For the person who has spent a few days around production paint operations, it should be no trouble to point out dirt, fibers, craters, solvent pop, or even a paint spit.  But the elimination of these may be a greater challenge.  NA Paint offers turn-key services for paint defect analysis and correction. We identify paint defect root cause.  We eliminate the cause and the defect.  

 

We fully understand the importance of high yields and efficient paint operations to your business  We understand that you may have already invested substantial resources and time chasing paint problems.  Give me a call, Joe @ (708) 663-8705.  

  

 

UNEVEN FILM BUILD DISTRIBUTION

 

Variations in paint thickness across the part are not uncommon in electrostatic or conventional spray applications.  In some cases, these varying builds do not noticeably affect the quality of the finished part.  Sometimes though, heavy and light film builds do regularly and significantly contribute to runs, drips, sagging, mottling, striping, color mismatch, crazing, blistering, solvent pop, craters, fish eyes, peeling, and surface roughness.  If you cannot well control the paint distribution across your finished part, then it is likely you cannot well control the quality of finish on your product.

 

There is a real dollar cost in lost productivity and increased operating costs that are associated with uneven paint distribution.  If the robot paint program builds areas of high film on the part, you may see pops and sagging in this area that result in increased levels of costly rework and scrap.  Global overrides may fix the pops and sagging but create other problems such as light areas, mottling, and color mismatch.  Light areas left by the robot may require manual touch-up, which can open another can of worms.  

SMC Outgassing Thru Base/Clear.

 

The process control window shrinks, the operator has less control, yields fall, rework, scrap and finesse labor go up, production schedules are not met, and life in paint can quickly become unbearable and even expose the business.

 

Uneven film builds have many causes but are most commonly created by robot programs.  Spray patterns, atomizer positioning, speeds, and pathing must be adjusted for uniform application.  If paint process parameters such as flow control, air pressure, conveyor speed, part location, etc., are controllable and repeatable, then the proper application of equipment can correct the problem.

 

 

DIRT

 

Regardless of the method of application, dirt is the most generic and the most common defect found in paint finishes.  It can enter the finishing process at any stage prior to, during, or after painting.  For example, the target substrate can be contaminated prior to paint.  It is also possible that the paint can be contaminated.  The application process can even create the contamination.  And, anytime in the wet, dirt can impinge upon the wet finish and create a blemish.  

 

Dirt comes in many forms and it is the painters good fortune that it is usually visible.  A careful, methodical inspection of the painting process should reveal at which stage dirt is introduced into the painting process.  Once the source and type of dirt are identified, corrective action can be taken.  

 

 

PAINT SPITS

 

When spray guns or bells fail to adequately atomize paint, spitting can occur.  Paint spits show up in the final finish in different ways including as bumps, globs, splatter, and off-color spotting.  

 

Spitting can occur because of dirty nozzles or bell cups, partially plugged paint feed tubes, surging paint, defective trigger hardware, when atomizing air pressures are too low, by incorrect process control, or other causes.  

 

 

RUNS, DRIPS, AND SAGS

 

This category of blemishes can also be present in almost any system, regardless of the method of application.  These defects are also visible, either in the wet, or during and after curing.  Runs drips and sags are almost always caused by the application on the target of too much paint, either generally or locally.  Fortunately, there are a number of effective and efficient ways to control both the rate and total of paint build-up on the part.

 

Paint Spits and Sanding Marks In Conductive Primer on SMC.

Accurate and repeatable control of paint application rates can significantly improve this problem.  All aspects of the applicator including size, head to target distance, bell speed, spray pattern size and distribution, voltage levels, dwell time, and angle of application can and ought to be used to control finish quality.  The composition, shape, motion, and orientation of the target ought to lend itself to the process in the most accommodating way.  Booth conditions can be a contributing factor.  Finally, the applied material must be suitable for the process.

 

 

MOTTLING, STRIPING, AND COLOR MISMATCH

 

Mottling, striping, and color mismatch are all terms used to describe color variations on the finished part.  The term mottling is generally used when referring to color variations across a single part.  Often these variations in shades of color are random.  Sometimes, however, there is a distinct pattern and repetition to the color variations.  These can be described as striping or checkerboarding.  The term color mismatch is generally applied when comparing the color of two whole parts such as a car door to the body panels.

 

The level of pigmentation in paint affects color.

 

On parts painted with solid color paints from the same tote or batch and have consistent solids suspension, any color variation is almost always caused by film builds that are below the level at which 100% hiding is achieved.

 

On parts painted with metallic paints from the same tote or batch, film builds that are below the level at which 100% hiding is achieved is but one possible cause of color variations across a single part, or among different parts.  Possible causes of color variation with metallic paints include variations in film build, inconsistent fluid delivery, spray pattern non-uniformity, paint impact speed, improper atomization, electrostatic effects, and metallic flake damage.

 

To help understand the cause of color variation in metallic paints, it is convenient to visualize the metallic flakes as tiny strips of aluminum foil.  When these strips are laid flat on a surface they reflect light.  When these strips are perpendicular to the surface, standing on end, they reflect very little light.  If part of a surface has the strips standing on end, and another part has them lying flat, there will be a noticeable difference in color.  In other words, variations in the orientation of the metal flakes relative to the surface is a cause of color mismatch in metallic paints.

 

Generally, the most desired appearance of metallic finishes is when all the flakes are lying somewhat flat, some tri-coats the possible exception.

  

So, variations in film build affect the metallic flakes by providing 'deeper pools' of wet material in which the flakes can reorientate, by electrostatic or other forces.  Metallic applications generally require a sufficient paint impact velocity to flatten out the flakes on the surface.  This is why air-atomized guns, which apply paint at higher speeds, have traditionally been used.  Metallic flake damage is often caused by the paint supply and recirculation system and is discussed more fully in the chapter on paint supply sytem sheer.

  

 

CRAZING

 

Crazing describes small cracks that appear in the finish.  Generally, these cracks are quite numerous and have random axis, resembling a dry lake bed.  They are akin to the crazing seen in pottery glazes.

 

Crazing is caused when two materials bonded together expand or contract at different rates causing lateral surface forces greater than the strength of bond.  The expansion and contraction can be caused by thermal, chemical, or mechanical forces.  Crazing can appear at any adhesion interface including that between substrate and primer, between primer and basecoat, or between basecoat and clear coat.

 

It is often easy to determine which adhesion point cracks and whether or not the cause is thermal.  If it is thermal related, as usually is the case, it is often easy to determine the conditions under which the crazing occurs, e.g. which stage of heating or cooling.  Usually, thermally induced crazing is controllable, either by less abrupt temperature changes or by using materials with more closely matched coefficient of expansions.

 

 

BLISTERING, SOLVENT POP, CRATERS, and FISH EYES

 

These terms are often used to describe relatively small circular blemishes in the finished surface with a void of paint.  Although they are sometimes interchanged, the following definitions are widely accepted.

 

A blister is a raised area in the dry paint finish with a hollow center that is crusted over, or was crusted over with paint.  Foreign materials painted over on the substrate can cause blistering by evaporation during curing.  Solvent pop is closely scattered small blistering caused by solvent evaporation during curing.  This occurs when conditions do not permit adequate flashing of solvents, either locally or across the finished part.  Craters are spots where the paint on the surface, once coated, has receded, often concentrically, to leave a spot with no paint.  Cratering is caused by incompatible foreign materials either in the paint or on the substrate.  Fish eyes are craters that have a bit of material remaining in the center.  

 

 

PEELING

 

Paint peeling refers to paint that does not adhere to the surface.  It can appear in a wide range of geometries.  It is usually caused by incompatible foreign materials either in the paint or on the substrate, but can also be caused by incompatible substrate material, and occasionally improper paint application process control.

 

 

ORANGE PEEL

 

Orange peel refers to texture in the finished painted surface similar to that of an orange skin.  Excessive orange peel is commonly caused by a paint process in which the paint does not sufficiently ‘flow out’ on the part in either the application, flash, or curing phases.  Paint properties, substrate properties, part orientation and geometry, booth conditions, flash and cure cycles, film builds, and application parameters are determining factors controlling the level of orange peel in the final product. Orange peel is tightly controlled on Class A automotive finishes.

Orange Peel In Conductive Primer on SMC.

 

 

    

 


 

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