MS troubleshooting

At MS we know there are a lot of issues that want to know what the cause is. Here we have added a selection of typical issues and corrections that may help

Grounding

Cause Correction
Poor conductive hose material, causing friction and charging of hoses (sparking)  Use manufacturer’s original powder hoses
At the injector due to insufficient grounding Ground injector
Between object and hose due to bad grounding Strip buckets and hoes of paint
At the handgun due to too little grounding Do not wear rubber soles or gloves

Decrease in System efficiency

Cause Correction
Too much powder accumulation in system components is often associated with leaks in the recovery system (absolute-filter, cyclone, hose connections, etc.) Check for leaks
In cyclone systems, peristalticfeed pumps or powder feed pumps can wear or clog Check powder recirculation system for function and leak-tightness
Clogged sieve mesh can substantially minimize separation Clean powder sieve regularly

Coating issues

Cause Correction
Particle size distribution too fine Consult with powder suppliers
Moisture in the powder due to improper storage Powder must stored dry at processing temperature
Sintering at the baffle plate and the nozzle due to excessive conveying air pressure Damage to nozzles by too high an air pressure of the feed air

Reduce conveying air

or

Check for wear on the injector - collecting nozzle

Poor fluidization in the powder tank due to moist compressed air or blocked fluid plate, fluid tubes Check compressed air for contamination, replace fluid plate or fluid pipes

Picture frame effect

Cause Correction
When using structure powder in Corona guns, the so-called picture frame effect may occur Effectively countered by the new MS controller with adjustable and variable amperage control.

Conductivity

Cause Correction
Poor conductive hose material, causing friction and charging of the hoses (sparking) Use manufacturer’s original powder hoses
Insufficient grounding at injector

Ground injector

Between object and hoe due to bad grounding Strip buckets and hoes of paint
At the handgun due to too little ground Do not wear rubber soles or gloves

Fluidization

Cause Correction
Powder fluidizability has a major impact on coating quality For difficult powder, additional vibration of the powder tank is recommended. Retrofitting with a vibration table is simple.
If lumps occur in the the fluidized powder, the powder was stored for too long or exposed to temperatures above 35°

Use new powder and check the storage of the powder

or

Sift powder

Poor fluidization of the powder can result from a fluid air pressure setting that is too low Check the fluid air pressure settings
Excessive fluidization can also significantly reduce powder output Reduce air supply pressure

Powder clumping

Cause Correction
Workpieces insufficiently grounded Clean buckets
Powder with insufficient resistance   Discuss with powder suppliers
Excessive field strength Change voltage and distance
Powder is blown out of the corners and recesses due to excessive air pressure Reduce air pressure, use proper nozzle
Too little penetration in the corners and niches due to excessive voltage or the use of an incorrect nozzle

Reduce voltage and use appropriate nozzles.

or

See also nozzles

Poor pre-treatment Discuss with  supplier
Poor oven setting (too high / too low temperature) Set oven temperature according to paint supplier
Inadequate powder quality Switch powder, change admixtures
Dirty base, oils etc. Check pretreatment

Brightness / gloss

Cause Correction
If powder emerges with dull / matt surface finish from the fcuring oven, specifications for powder curing have not been observed. The different curing temperatures of various powders must be observed.

Powder escape from booth enclosure

Cause Correction
If powder escapes from a properly configured booth, and the pressure monitor of the exhaust system displays normal values, the fault can usually be found in the external vicinity of the booth. The most common cause is drafts in the system building, through open doors or windows.  Watch for cross drafts from auxilliary equipment such as air conditioners or general ventillation systesm in vacinity of the booth.

Fat Edges

Cause Correction
Excessive powder cloud, distance between gun and workpiece too far. Minimize distance, use correct nozzles, or increase dosing air.
Excessive distances between the objects. Use automatic gap control, part recognition

Nozzle selection

In order to obtain an optimum coating result, the choice of the nozzle must be adapted to specific coating needs.  One size and type may not be applicable to all jobs.  

Round nozzles

The baffle plate produces a homogeneous powder cloud, which slowly approaches the grounded workpiece and therefore acts with good throwing power. The cloud can only be controlled under certain conditions and the penetration potential is small. It is used for flat parts, pipes and high surface services.

 

Flat nozzles

The flat nozzle generates an elliptical cross-section and can be  be well-aligned with the object. It is used for more complex parts (profiles) with wells.

 

Pinholing

Cause Correction
Often the use of silicone in the coating area is the reason for a dirty coating

Since all powder has an "allergic" reaction to silicone, it must never be used in the coating area

Level probe

Cause Correction
Sensor probe not adjusted properly Adjust immersion depth of probe to meet needs.

Orange peel effect

Cause Correction
If powder layer on the object is too thick, this results in an uneven surface.

Use the powder supplier’s settings for the powder coating

or

Use less electricity (µA)

Gun arrangement

Cause Correction
The ideal gun arrangement depends on the range of parts, booth configuration and exhaust system. A cabin with filter recovery is particularly suitable for the horizontal gun arrangement. Booths with central suction and quick color change systems should be built short as possible. In such cases, vertical arrangement is preferred.

Gun function

Cause Correction
An active powder gun not only produces voltage, but also draws current. Power increases at the work piece as the gun approaches. Too much power causes back-ionization and orange peel finish. The current can be reduced by configuring µA settings.

Gun powder surging

Cause Correction
Pulsation during powder supply results from incorrectly configured conveying air or an incorrect dosing ratio Check the conveying air setting and dosing ratio. For powder output of less than 80mg / min, a 10mm powder hose should be used.

Powder deposits on the object

Cause Correction
Too much powder output quantity per gun resulting in inefficient powder separation Reduce powder output quantity and reduce chain speed
Powder propulsion generally too high Increase powder hose diameters
Excessively long powder hoses Shorten powder hoses or increase diameter

Powder output irregular

Cause Correction
Powder air speed too low The ideal amount of air should be in the range from 4-5 Nm3
Fine powder/powder with poor flow properties Use a powder container with fluid air and vibration 
Short periods of high compressed air consumption can cause pressure fluctuations A compressed air reservoir before the powder plant solves this problem
Too small cross sections or too small radii in the powder hose routing The radii must be at minimum150-200mm
Incorrect ratio between fresh powder and recovered powder Use fresh powder
Excessively high/low emissions Adjusting the coating parameters
Contaminated injectors Injectors are often neglected during daily cleaning

Powder container

Cause Correction
The fluid air pressure or the amount of air are too high The fluidized powder should “boil” only slightly but evenly. Prolonged use may lead to the partial closure of the fluid plates, which must be compensated for with a high amount of fluid air. In this case the bottom must be replaced.

Recovery

Cause Correction
Clogged return feed system Clean
Clogged sieves Clean or replace

Back-ionization

Cause Correction
“Back-ionization” occurs when the powder layer is too thick.

Reducing powder flow often prevents back-ionization, but results in a reduction of the transfer efficiency. Back-ionization also depends on the temperature and humidity.

Very difficult powder materials may require air-conditioning of the coating zone. See also, orange peel effect. 

Sieve problems

Cause Correction
Sieve clogs quickly Sieve with larger mesh size
Insufficient sieve mesh size Replace sieve
Surface impurities Use a sieve with a smaller mesh size or use an ultrasonic sieving system

Striping / banding

Cause Correction
There is a fundamental mathematical relationship between powder feed speed, lgun motion velocity and number of moving guns to form and avoid banding on the workpiece. Determine manufacturers recommendations.  If the time of using a double stroke of the gun is less than the time it takes for the conveyor to pass through the width of the spray cloud, no banding or striping will occur.

Yellowing

Cause Correction
White powder reacts by yellowing excessively when exposed to high curing temperatures or excessive time. If pure white powder is used, the curing specifications of the powder manufacturer must be strictly observed.

Flow disruption

Cause Correction
Particle size distribution of the powder is too coarse. Contact powder suppliers.
Contamination. Contamination by foreign powder can be avoided by careful cleaning of the plant. In addition, different powders should not be mixed.
Too high or too low film thicknesses. Adjust powder output.
Too wet or too hot workpieces. Check drying and temperature of the workpieces.
Powder deposits accumulate on nozzles. Maintenance!
Drop formation occurs when the powder flow is too strong. Verification of the voltage and the distance to the workpiece, or the addition of thixotroping agents can help.

Contamination

Cause Correction
Inadequate sieve  machine. If a smaller mesh size is not sufficient, a sieve machine with ultrasound must be considered
If the conveyor is not cleaned regularly or inappropriate lubricants are used. Clean regularly, attach a cover if necessary
If powder is blown-off in the curing oven.

Check the air currents in the building

Powder residue in the oven. This can be prevented by regular cleaning
Poorly clean recovery. Regular cleaning
Dirty air is sucked into the booth. Here, the coating plant may need to be separated from production areas
If several booths are operated together, cleaning may cause an impairment may occur. In this case, the booths must be separated from each other

Degree of cyclone separation

Cause Correction
Squeeze valve running too slow or too fast Set the time according to the manual
Squeeze valve not open completely Check squeeze valve for fatigue and hose inserts for correct assembly, or replace.

Daily maintenance

  • Blow guns and check for sintering
  • Check the setting of the powder spray gun
  • Keep gun feed air low
  • Check the injectors (signs of caking or milling at collecting nozzle)
  • Blow injectors and hoses 
  • Blow suction pipe and check out for leaks
  • Clean facility, recovery and surrounding area
  • Check suction resistance of recovery -
  • Check fluidization
  • Check function of the level probe 
  • Check function of the flowmeter 
  • Check the setting of the air pistol 
  • Check high-voltage and current display
  • Check and empty waste containers at the final filter -
  • Check seal of filter/cyclone/piping 
  •  

Weekly maintenance

  • Check grounding inspection
  • Check whether the compressed air is clean, dry and free of oil
  • Check guns for voltage output
  • Check electrode for wear -
  • Check fan nozzle / baffle plate for wear 
  • Check powder hoses for sintering and kinks 
  • Check lifting and display 
  • Check filter systems

Economy

Cause Correction
Check squeeze valve for material fatigue and check hose inserts for correct assembly, or replace If new parts are integrated into the range, in most cases it is worth performing a review of the system parameters. If the objects are complex, a review of the gun assembly may also be worthwhile.