パウダーコーティングの厚みについて：適切な範囲とは？

How Thickness Affects Performance?

Powder coating thickness has a direct effect on a part’s performance. Getting it wrong can lead to poor protection, cracking, or a rough finish.

耐食性と保護

A proper thickness helps seal the surface, keeping out moisture, salt, and chemicals. Water or air can reach the metal if the coating is too thin and start corrosion.

Thicker coatings give better long-term protection in harsh environments, like coastal or industrial areas. But thickness alone isn’t enough. The coating must also cure well and bond tightly to the surface.

Impact on Flexibility and Adhesion

If a coating is too thick, it can become brittle. This makes it more likely to crack or chip when the part 屈曲 or flexes.

Thinner coatings are more flexible but may not offer enough coverage. The ideal thickness allows the part to flex slightly without breaking the coating. It also helps the powder stick better during curing.

Influence on Appearance and Finish Quality

Uneven or incorrect thickness can ruin the look of a finished part. Thin spots may appear dull or faded. Thick spots may lead to texture problems, like orange peel or drips.

Proper coating thickness gives a smooth, even, and glossy finish. It also helps colors look deeper and more consistent across the part.

Factors That Influence Final Coating Thickness

Several factors affect the thickness of the powder coating, including the method used, the powder itself, and how the surface is prepared.

申込方法

Electrostatic spray is the most common method. A spray gun charges the powder, which sticks to the grounded metal part. The amount of powder sprayed and the distance from the weapon affect the final thickness.

Fluidized bed coating involves dipping a heated part into a container of floating powder particles. The powder melts and sticks to the surface. This method usually creates thicker coatings and works well for heavy-duty parts.

Each method has a different range of typical thicknesses. Spray coating usually gives 1.5–5.0 mils, while fluidized bed coating can go 10 mils or more.

Powder Type and Particle Size

Not all powders behave the same. Some flow better, melt faster, or build up more quickly. The resin type (like epoxy or polyester) affects how thick the coating can be before issues appear.

Particle size matters too. Larger particles tend to create thicker coatings. Fine powders often produce smoother finishes but need more control to avoid thin spots.

Substrate Material and Surface Condition

The surface of the part changes how powder sticks. Smooth or glossy metals may also not hold powder, leading to thin spots. Rough or textured surfaces can trap more powder, making the coating thicker.

Surface prep—like サンドブラスト or using a chemical pretreatment—helps improve bonding. A clean, even surface also helps achieve consistent thickness across the part.

Operator Technique and Equipment Settings

How the powder is sprayed plays a significant role. The speed of the gun, distance from the part, and spray angle all affect how much powder builds up.

Equipment settings like voltage, air pressure, and powder flow rate must be adjusted based on the part shape and size. Even skilled operators can apply uneven coatings if the equipment isn’t set up right.

Measuring Powder Coat Thickness

Measuring coating thickness helps catch problems early. It ensures that the final finish meets both looks and performance standards. There are different ways to check thickness before and after curing.

Methods for Measuring Before Curing (DFT Prediction)

Before curing, you can estimate the final dry film thickness (DFT) by checking the powder buildup. This is usually done using:

• Comb gauges: Simple tools pressed into the powder to see how much has built up.
• Laser or ultrasonic sensors: Non-contact methods for more advanced setups.

These methods are only estimates. The powder melts and flows during curing, which can change the final thickness. Still, early checks help avoid over- or under-coating.

Post-Cure Thickness Measurement Tools

After curing, the coating becomes solid. This is when most inspections happen. Tools include:

• Magnetic gauges are used for coatings on steel or iron. They measure the distance between the surface and the metal underneath.
• Eddy current gauges: Work best on non-magnetic metals like aluminum. They detect coating thickness by measuring electrical resistance.

Both tools are fast, easy to use, and non-destructive. Most digital versions display thickness in mils or microns right away.

Common Challenges in Accurate Measurement

Getting an accurate reading isn’t always easy. Some common problems include:

• Rough or uneven surfaces: May lead to false readings.
• Edge effects: Thickness tends to be thinner at edges or corners.
• Operator error: Holding the gauge at the wrong angle or not zeroing it properly can skew results.
• 温度: Hot surfaces may affect readings if not appropriately cooled before testing.

To get the best results, use the right tool for the metal type, follow calibration steps, and test in several spots on the part.