Powder Coating Thickness Is Uneven – Troubleshooting with UNI-T UT343E Malaysia

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Published: 1 October 2026

Uneven powder-coating thickness may appear as low readings at edges and recessed areas, with excessive build-up on flat surfaces or corners.

The UNI-T UT343E Coating Thickness Gauge helps production and quality-control teams map these differences across compatible steel and aluminium components. The reading pattern can then be used to investigate the coating process.

Common Signs of Uneven Coating

A component may require further investigation if:

Readings vary significantly across the same surface
Edges are consistently thinner than flat areas
Corners show excessive coating build-up
Recessed areas fall below the required minimum
One side of the component is thicker than the other
Different rack positions produce different results
Readings change after a shift or operator change
Repeated batches show inconsistent averages
Touch-up areas are substantially thicker
Similar components produce different results

Repeat the measurements before adjusting the production process.

First Confirm the Gauge

Before assuming that the coating process is faulty:

Clean the UT343E probe.
Select the correct ferrous or non-ferrous reference plate.
Check the instrument with a standard coating film.
Confirm stable repeated readings.
Verify the FE or NFE mode.
Check the component surface for contamination.
Repeat the measurement at the same point.

If the gauge is unstable on a clean reference plate, the instrument may require further inspection.

Create a Measurement Map

Random readings may not reveal the true coating pattern.

Divide the component into consistent inspection areas:

Upper section
Lower section
Left and right sides
Flat centre
Corners
Edges
Recesses
Welded areas
Areas facing the spray gun
Areas facing away from the spray gun

Use the same locations on several components. This makes it easier to identify repeated process problems.

Poor Grounding

Electrostatic powder application depends on effective grounding.

Poor grounding may contribute to:

Uneven powder attraction
Thin areas
Inconsistent coverage
Excessive operator adjustment
Variation between rack positions

Check:

Rack contact points
Hooks and fixtures
Paint or powder build-up on hangers
Contact between the component and grounding system
Maintenance condition of the conveyor fixtures

The UT343E identifies the resulting thickness variation but does not test the electrical grounding itself.

Incorrect Gun Distance

Holding the spray gun too close or too far from the component can affect powder distribution.

Possible signs include:

Heavy build-up in easily reached areas
Thin coverage in other sections
Uneven appearance
Greater variation between operators
High readings in the centre and low readings around edges

Compare readings across several components produced by the same operator and spray setting.

Inconsistent Gun Speed or Spray Pattern

Manual spraying may produce uneven coating if the gun movement changes across the product.

Possible causes include:

Gun movement too slow
Gun movement too fast
Unequal overlap between passes
Inconsistent angle
Irregular distance
Missed areas
Repeated spraying over the same section

A grid of thickness readings can reveal whether the problem follows the operator’s spray path.

Difficult Component Geometry

Corners, channels, recesses and internal angles may receive less powder because of component shape and electrostatic effects.

Inspect:

Deep recesses
Inside corners
Narrow channels
Areas behind flanges
Sections near holes
Welded joints
Complex profile transitions

Do not compare a difficult recessed area directly with a large flat surface unless the specification treats them equally.

Coating Build-Up at Edges or Corners

Some parts may show thicker readings around external corners or spray-overlap areas.

Possible causes include:

Multiple spray passes
Slow gun movement
Repeated touch-up
Poor spray planning
Operator focusing on visible edges
Excessive powder output

Record the exact location of high readings to determine whether the pattern repeats across the batch.

Rack Position and Part Orientation

Components positioned differently on the rack may receive different powder coverage.

Compare readings from:

Upper and lower rack levels
Front and rear positions
Parts closest to the gun
Parts partly blocked by other components
Different hanging orientations

If one rack position repeatedly produces low readings, the issue may be related to line layout rather than the powder itself.

Powder Flow and Equipment Settings

Inconsistent powder delivery may result from:

Irregular powder flow
Blocked or worn equipment
Incorrect air settings
Unstable voltage or current settings
Poor powder circulation
Inconsistent recovery-system performance
Maintenance problems

Review the equipment settings and maintenance condition whenever the measurement trend changes unexpectedly.

Line Speed and Production Changes

If the line moves too quickly, components may receive insufficient coating.

If the process slows or a component remains in the spray area longer, excessive coating may result.

Record whether the thickness problem started after:

Line-speed adjustment
New production batch
Product changeover
Operator change
Equipment maintenance
Powder change
Rack modification

The timing of the problem can help identify the cause.

Surface Preparation

Contaminated or poorly prepared surfaces may affect coating behaviour and quality.

Check for:

Oil
Dust
Moisture
Rust
Incomplete cleaning
Pretreatment problems
Residue from handling
Uneven substrate condition

The UT343E measures thickness but does not confirm adhesion, surface cleanliness or curing quality.

Use Minimum Maximum and Average Values

Review the UT343E results as a group:

Minimum: Identifies the thinnest measured point
Maximum: Identifies excessive local build-up
Average: Shows the general coating level
Range between minimum and maximum: Indicates variation

A satisfactory average can hide a critical thin spot. Always review the individual locations.

Use Limits to Identify Out-of-Range Areas

Enter the approved upper and lower thickness limits into the UT343E.

The LED and audio alarm can help operators identify areas outside the selected range during repeated inspection.

Do not use the alarm as the only quality record. Store or record the actual values and locations.

Confirm the Improvement After Adjustment

After changing the process:

Produce a controlled sample.
Measure the same inspection points.
Compare the new minimum, maximum and average values.
Check several components.
Confirm that the improvement continues across the batch.
Record the process change.
Continue monitoring subsequent production.

One improved sample is not enough to confirm that the process is stable.

When the Problem May Be the Instrument

Arrange further UT343E inspection if:

Readings fluctuate on a clean reference plate
The gauge repeatedly fails the reference check
FE or NFE identification is incorrect
The probe is damaged
The instrument was dropped
Results remain abnormal after restarting
The gauge differs significantly from a verified reference

Do not use an unstable instrument to adjust the production line.

Powder-Coating Support in Malaysia

Powder-coating factories and metal fabricators in Selangor, Kuala Lumpur, Johor and Penang can use the UT343E to map coating variation and maintain digital inspection records.

For an initial assessment, WhatsApp MTM Precision a photo of the component, coating type, substrate, UT343E display and the locations producing inconsistent readings.

MTM Precision Sdn Bhd
Showroom & Service Centre: No. 29-1 & 29-2, Jalan Bandar 18, Pusat Bandar Puchong, 47160 Puchong, Selangor, Malaysia
Tel: 03-8080 7172
WhatsApp: +6016-660 7346
Email: mtmpre@yahoo.com
Website: www.mtmpre.com.my

Powder Coating Thickness Is Uneven – Troubleshooting with UNI-T UT343E Malaysia