永和工芸 Product Lineup

The film thickness varies every time it is measured. Do you think it's due to the operator's skill? The cause lies in the measurement and hanging methods. ────────────── ■Cause of Occurrence Variability in film thickness arises from differences in static electricity due to the shape of the material and inconsistencies in measurement points. Even with the same part, there can be up to a 2-fold difference in film thickness between recessed and flat areas. ■Truth If measurements are taken without determining specific points, half of the variability is measurement error. Temperature differences due to the position within the furnace also affect film thickness; a 5-degree difference inside the chamber can change fluidity. ■Improvement Measures Fix three or more measurement points on the drawing and record separately for flat and recessed areas. Check the electrical connection of the jig daily and regularly measure the temperature distribution inside the furnace. Please utilize the documentation summarizing the criteria for setting film thickness measurement points.

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Bending during assembly and temperature changes in winter cause fine cracks in the paint film. This is not an issue of the paint's flexibility, but rather a problem with the application method and curing process. When the film thickness exceeds 60 microns, the crack occurrence rate skyrockets. ────────────── ■ Causes of Occurrence Thick paint films cannot keep up with the expansion and contraction of the material, leading to cracking due to internal stress. If the curing is excessive, the resin's cross-linking progresses too far, making it hard and brittle. ■ The Truth The thick coating intended to prevent defects is causing further defects. There are many cases where increasing the film thickness for rust prevention results in a high incidence of cracks. ■ Improvement Measures Design the film thickness to be 30-50 microns according to the material and application. Keep the curing temperature and time within the paint specifications, and manage the temperature difference in the oven to within 10 degrees. Please utilize the materials that summarize the management standards for film thickness design and curing conditions.

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Only the inside of the box and the bottom of deep ribs do not receive powder no matter how much is blown. This is not a problem with the gun; it is caused by the nature of static electricity. When the depth of the recess exceeds 1.5 times its width, the powder cannot reach it. ────────────── ■ Cause of occurrence Electric field lines concentrate at the corners of the entrance of the recess and do not penetrate inside. Charged powder is attracted to the corners, leaving the back uncoated. ■ Truth Increasing the voltage has the opposite effect. At high voltage, adhesion at the entrance increases, further hindering access to the interior. ■ Improvement measures Lower the voltage and increase the air pressure to mechanically push the powder in. Depending on the shape, switching to solvent-based powder coating is reliable, and preliminary test coatings are effective. Please utilize the materials summarizing suitable shapes for powder coating.

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Although there is no problem with adhesion to the substrate, only the layered coats are peeling off. The complete curing of the primer, on the contrary, is causing the peeling. Repainting after complete curing results in adhesion strength being less than half. ────────────── ■ Cause of Occurrence The cured paint film has no reactive groups left, making it impossible to chemically bond with the topcoat. Due to the smooth surface, there is also no mechanical grip. ■ Truth The longer the waiting time, the easier it is to peel off. Oils or hand grease that adhere after baking create a thin film between the layers. ■ Improvement Measures Before repainting, perform surface sanding and degreasing before applying paint. If the condition is poor, it is more reliable to completely strip the paint film and repaint from the substrate. Please utilize the materials summarizing the management standards for repair painting and interlayer adhesion.

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Even though they have the same color number, they look different when placed next to the previous lot. It is not the paint, but the film thickness and curing conditions that affect the color. If the film thickness changes by 10 microns, the color difference becomes noticeable to the naked eye. ────────────── ■Cause of Occurrence Colors with low hiding power will show a change in brightness when the film thickness is thin, as the substrate becomes visible. The higher the curing temperature, the more the resin yellowes, and the difference is more pronounced in white shades. ■Truth Color matching done only by visual inspection creates variability among evaluators. When the type of lighting changes, the same painted panel can appear to have a different color. ■Improvement Measures Measure with a color difference meter and set the acceptance criteria numerically. Keep the film thickness within specified ranges and fix the curing temperature and time for each color. Please utilize the materials that summarize color management and film thickness standards.

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Only black and clear finish strangely turns out cloudy white. Before suspecting the paint lot, please check the humidity for that day. When humidity exceeds 70 percent, the risk of whitening rises sharply. ────────────── ■Cause of Occurrence When the solvent evaporates, the temperature of the paint surface drops, causing moisture in the air to condense. The tiny water droplets that are taken in scatter light and make the surface appear cloudy white. ■Truth Fast-drying thinners cause a greater drop in temperature during evaporation, leading to whitening. Managing humidity and the temperature of the material is more effective than managing temperature alone. ■Improvement Measures On days with high humidity, use 5-10 percent slow-drying thinner or retarders in combination. Keep the humidity in the painting booth below 60 percent and acclimate the materials to room temperature. Please utilize the materials summarizing the thinner selection criteria by season.

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The recurring issue in visual inspections is always the same contact point of the jig. It is not due to the painting conditions, but rather the design of the hanging method. Appearance defects caused by the jig account for 20-30% of rework labor. ────────────── ■ Cause of Occurrence The contact areas of the jig do not receive paint, resulting in exposed substrate and differences in film thickness. When paint builds up at the contact points, conductivity decreases, and the adhesion efficiency of electrostatic painting also drops. ■ Truth There is often a lack of awareness that jigs are consumables. Hangers that are used continuously without being stripped create foreign matter and defects in the next batch. ■ Improvement Measures Fix the contact points to non-functional or hidden surfaces and specify them in the drawings. Determine the stripping cycle of the jig based on usage frequency and conduct regular inspections of conductivity. Please utilize the materials that summarize jig design and appearance standards.

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The surface is clean, but only the edges and the rims of the holes rust first. It's not due to the corrosion resistance of the paint; it's that the film thickness is insufficient in those areas. The film thickness at the edges drops to 30-50 percent of that on the flat surfaces. ────────────── ■Cause of Occurrence The paint escapes from the corners due to surface tension and is pulled toward the flat surfaces. In powder coating, static electricity concentrates at the corners, leading to unstable adhesion. ■Truth The oversight is due to measuring the film thickness only on the flat surfaces. Even if it meets the standards, the corners fall below the corrosion resistance limit. ■Improvement Measures Request a chamfer of R0.5 or more during the design phase to reduce sharp edges. Paint the corners first, then coat the entire surface, and add corners as measurement points for film thickness. Please utilize the document summarizing the film thickness management standards by area.

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After removing from the oven, there are countless small bubbles on the painted surface. Before blaming the paint, please check the time before it was placed in the oven. Many issues arise from a lack of 3 minutes of setting time. ────────────── ■Cause of Occurrence When solvents enter high temperatures before fully evaporating, they vaporize and expand within the paint film. The trapped solvents break through the surface, creating bubble-like holes. ■Truth The combination of thick application and rapid temperature rise is the most dangerous. When the film thickness exceeds 40 microns, the surface hardens before the internal solvents can escape. ■Improvement Measures Ensure a setting time of 5-10 minutes after painting and gradually increase the temperature in the oven. Keep the film thickness below 30 microns in one application, and if necessary, apply in two layers. Please utilize the materials summarizing the management standards for film thickness and curing conditions.

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The finish waves like the skin of a mandarin orange. If it reoccurs in the next batch even after polishing, the cause is the painting conditions. The texture of a yuzu skin changes with a 5-second difference in paint viscosity. ────────────── ■ Cause of Occurrence If the paint's flow time is insufficient, fine unevenness remains during curing. This often occurs when there is insufficient dilution, inadequate film thickness, or if the spray gun distance is too far. ■ Truth As the temperature rises, the evaporation of the thinner accelerates, and even with the same mixture, it does not flow after application. In summer, the same viscosity settings as in winter lead to a sharp increase in yuzu skin texture. ■ Improvement Measures Use slow-drying thinners according to temperature ranges and measure viscosity with a Ford cup each time. Maintaining a gun distance of 20-25 centimeters and a film thickness of 25-35 microns stabilizes smoothness. Please utilize the materials summarizing viscosity management standards by season.

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The moment the paint is applied, it escapes and creates a round dent. If changing the paint doesn't fix it, the cause lies with the materials and equipment. Eighty percent of the sources of paint beading are oil and silicone. ────────────── ■ Causes of Occurrence If oil or silicone remains on the painted surface, the surface tension changes in that area. The paint cannot spread and results in circular dents with a diameter of 1-3 millimeters. ■ The Truth The real culprit is not the degreasing process but the airline. Oil contained in the compressor's drain adheres to the parts just before painting. Silicone-based release agents and hand creams can also be sources of contamination. ■ Improvement Measures Implement a two-stage air filter and perform daily drain discharge. Manage the oil concentration of the degreasing solution and prohibit handling with bare hands. Please utilize the materials summarizing the standards for pretreatment and equipment management.

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Chipping of the paint film occurs due to flying stones while driving. Chipping is a defect related to both film thickness and adhesion strength. ────────────── ■ Cause of Occurrence Chipping is a defect where the paint film partially peels off due to impact. If there is insufficient film thickness or poor adhesion to the substrate, resistance to impact decreases. ■ Truth Stainless steel has difficulty achieving adhesion due to the influence of the passive film, and in the case of thin films, it becomes particularly vulnerable to impact. If the substrate treatment is inadequate, this tendency is exacerbated. ■ Improvement Measures Ensure proper film thickness and avoid extreme thin films. Increase adhesion strength with blast treatment and specialized primers. Utilize documents that enhance impact resistance specifications.

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Although it should have been painted, the surface is sticky. Poor curing is a defect that is not easily noticeable visually. ────────────── ■ Cause of Occurrence Poor curing is a phenomenon where the paint film does not cure sufficiently due to low baking temperature or short baking time. Stainless steel has low thermal conductivity, making it difficult for heat to penetrate to the interior. ■ The Truth Even if the set temperature in the oven is correct, it takes time for heat to reach the interior of the material. If the time is shortened, only the surface will be cured. ■ Improvement Measures Adjust the baking time according to the thickness of the material. Regularly measure the temperature in the oven and check for discrepancies with the management values. Utilize materials that provide guidelines for baking conditions.

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Rust has appeared on stainless steel that is supposed to be "rust-free." If it recurs even after painting, there is another cause. ────────────── ■ Cause of Occurrence The recurrence of rust on stainless steel is mainly due to "rust transfer" from iron powder that adhered during processing. Insufficient coating thickness can also contribute to the recurrence of rust. ■ Truth Fine iron powder from tools used in polishing or cutting can adhere to the surface, leading to rust formation. If the coating is thin, it cannot suppress this rust. ■ Improvement Measures Please remove the iron powder through acid cleaning or passivation treatment. It is also important to stabilize the coating thickness at 8-15 microns. Utilize materials that explain the methods for pre-treatment and coating thickness management.

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Even though it is the same product, it appears to have different levels of gloss in certain areas. Gloss unevenness is a visual defect that detracts from the sense of luxury. ────────────── ■Cause of Occurrence Gloss unevenness occurs due to variations in drying temperature and wind speed during the curing process, which leads to differences in the hardening speed of the coating. Variations in film thickness also affect the appearance of gloss. ■Truth If the airflow inside the curing oven is not uniform, the drying speed will vary by area, resulting in differences in gloss. Since stainless steel is a material that easily shows gloss, even slight differences become more noticeable. ■Improvement Measures Regularly check the wind speed and temperature distribution inside the curing oven. Standardize spray conditions to minimize variations in film thickness. Please utilize materials that clarify the management points for gloss unevenness.

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There are small bumps on the painted surface. Contamination that directly leads to customer complaints originates from the worksite. ────────────── ■ Cause of Occurrence Contamination occurs when dust or grinding powder in the work environment adheres to the paint film. Stainless steel often involves a grinding process, making it prone to metal powder contamination. ■ Truth If the cleanliness of the painting booth is not maintained, airborne dust will adhere directly to the paint film. Dust adhesion due to static electricity is also a commonly overlooked cause. ■ Improvement Measures Thoroughly manage the filters and cleaning frequency of the painting booth. Separating the workflow of the grinding and painting processes is also effective. Please utilize materials that clarify the checklist for site management.

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Even though the same paint is used, the colors appear different. Color unevenness is not always caused by the paint itself. ────────────── ■ Causes Color unevenness occurs due to variations in baking temperature and uneven film thickness, which lead to differences in color development. Stainless steel is a material that tends to show color unevenness because the reflection of light changes depending on the direction of the hairline finish. ■ The Truth When there are temperature differences inside the baking oven, even within the same lot, the curing state can vary by area, resulting in changes in color development. Variations in film thickness also affect how the color appears. ■ Improvement Measures Regularly measure and manage the temperature distribution inside the baking oven. Standardize spray conditions to maintain uniform film thickness. Please utilize materials that explain the methods for managing temperature and film thickness.

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Vertical stripes of drips appear on the painted surface. Are you attributing it to "the worker's skill"? ────────────── ■Cause of Occurrence Drips occur when the paint viscosity is too low or when too much paint is applied at once. Stainless steel is a material with a smooth surface that allows paint to flow easily. ■Truth The viscosity of the paint changes with temperature and humidity. If you work without managing the viscosity consistently, the rate of drip occurrence will vary with the seasons. ■Improvement Measures Manage the dilution ratio numerically and maintain a consistent viscosity. Keep the film thickness per application low and paint in multiple passes. Please utilize materials that explain how to manage viscosity and film thickness.

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Blisters in the paint film after coating. They often occur months later, making the cause difficult to identify. ────────────── ■ Cause of Occurrence Blisters are a phenomenon where moisture or oil trapped within the paint film expands due to heat or humidity, pushing the film up. Insufficient degreasing and drying are the main causes. ■ The Truth Stainless steel has low thermal conductivity, and if the drying time is insufficient, the surface may dry while moisture remains inside. This residual moisture expands later, manifesting as defects. ■ Improvement Measures Ensure sufficient temperature and time during the drying process. It is also important to reliably remove oil during the degreasing process. Please utilize materials that allow you to review drying conditions.

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The stainless steel coating peels off immediately. If changing the paint doesn't stop it, the cause is in the pre-treatment. ────────────── ■ Cause of Occurrence The surface of stainless steel has a passive film known as an oxide layer, which has properties that make it difficult for general chemical treatments to be effective. This leads to poor adhesion and is the main cause of peeling. ■ The Truth If you paint without removing the film, an anchor effect does not occur between the coating and the material, and adhesion cannot be secured. Residual oil due to insufficient degreasing also worsens peeling. ■ Improvement Measures Create surface roughness through blasting treatment to enhance the anchor effect. Using a primer specifically for stainless steel is also effective. Please utilize materials that can confirm the pre-treatment conditions.

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Are there frequent pinholes in your stainless steel coating? Before giving up and blaming the material, please review your pre-treatment process. ────────────── ■ Causes of Occurrence Pinhole defects are tiny holes that form in the coating. The main causes are residual oil due to insufficient degreasing and moisture vaporization due to inadequate drying. Stainless steel is a material with a smooth surface that tends to retain oil. ■ The Truth If the temperature of the degreasing solution is low, oil cannot be sufficiently removed. If rinsing after chemical treatment is insufficient, moisture remains in the coating, which vaporizes during curing and causes pinholes. ■ Improvement Measures Maintain the temperature of the degreasing solution above 50 degrees to increase the oil removal rate. Ensure adequate rinsing and drying time after chemical treatment. Please utilize materials that allow you to review pre-treatment and drying conditions.

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Metal baking paint is a season where defects are likely to increase from the rainy season to summer. Both humidity and temperature management affect quality. ────────────── ■ Causes of Occurrence Defects unique to summer, such as pinholes, blisters, and rust reoccurrence due to high humidity, as well as uneven gloss and runs due to high temperatures, are likely to occur simultaneously. ■ Truth If we approach summer with the same management standards as winter, it may feel like there is an increase in unexplained defects. In reality, it is often just that the review of standards according to the season has not kept pace. ■ Improvement Measures Install hygrometers and thermometers in key processes and record daily data. Establish management standards for each season and switch conditions before the rainy season and during peak summer. Our company has established a quality management system for each season, providing stable painting quality. Please utilize the quality management materials for the summer.

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Since summer began, have you noticed an increase in blister formation? The cause may be the combination of moisture and high temperatures. In an environment with 80 percent humidity, the blister formation rate is twice that of normal. ────────────── ■ Causes of Occurrence Summer is a season when the moisture remaining in the material and the high temperatures during curing tend to act simultaneously. Moisture rapidly vaporizes during curing, pushing up the coating film and creating blisters. ■ The Truth There are cases where blisters occur only in summer, even though there were no issues under the same pre-treatment conditions in winter. This is often fundamentally due to seasonal differences in humidity. ■ Improvement Measures In summer, extend the drying time after pre-treatment and, if possible, add a pre-baking process. Gradually increasing the curing temperature instead of raising it sharply is also effective. Please utilize the materials for blister prevention during the summer.

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Are the materials before painting rusting just by being left out? The cause may be condensation during storage. It is said that condensation begins to occur with a temperature difference of 5 degrees. ────────────── ■Cause of Occurrence Condensation occurs on the surface of materials due to the temperature difference between air-conditioned indoor spaces and the outdoors or warehouses. Metals, in particular, have good thermal conductivity and quickly react to temperature differences, resulting in water droplets. ■Truth Even if there are no issues in the painting process, the quality can deteriorate solely due to condensation during storage. Special caution is needed during periods of significant temperature changes from night to morning. ■Improvement Measures Minimize the temperature difference in the storage area and protect the materials by sealing or covering them. Allow time for the materials to acclimate to the temperature before proceeding with pre-treatment after delivery. Please refer to the materials for summer storage management.

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Because it's summer, drying should be quick. This assumption can lead to pinholes and poor adhesion. Even if it looks dry on the surface, internal moisture can remain at 80 percent humidity, which is 30 percent more than expected. ────────────── ■Cause of Occurrence In summer, the surface appears to dry quickly, leading to a tendency to shorten drying time. However, when humidity is high, moisture remains inside and in crevices even if the surface is dry. ■Truth The appearance of dryness and the actual removal of moisture are two different things. If you proceed with the process based solely on surface judgment, it will manifest as pinholes or poor adhesion in later stages. ■Improvement Measures In summer, do not shorten drying time; instead, extend it according to humidity. If possible, check with a moisture meter and determine drying completion based on numerical values rather than time. Please utilize the materials for managing the degreasing process in summer.

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Metal baking paint tends to have an increased defect rate when humidity exceeds 70 percent. Special attention is required during the period from the rainy season to summer. ────────────── ■ Causes In high humidity environments, multiple defects such as insufficient drying after degreasing, condensation after pretreatment, and poor curing after painting are likely to occur simultaneously. ■ Truth Humidity is not visible, making it less consciously managed on-site compared to temperature. However, the root of many defects is often hidden in the effects of moisture due to humidity. ■ Improvement Measures Install a hygrometer in the factory and record daily data. Combine the use of dehumidifiers, extended drying times, and a review of storage conditions. Our company conducts seasonal management based on a humidity level of 70 percent or lower. Please refer to the materials for specific humidity management strategies.

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Has the amount of dripping increased since summer? The cause may be a decrease in viscosity due to temperature. With a 10-degree rise in temperature, the viscosity of the paint can decrease by up to 30 percent. ────────────── ■ Cause of occurrence When the temperature rises, the viscosity of the paint decreases, making it more prone to dripping on vertical surfaces and corners. If the discharge amount and film thickness settings remain the same as in winter, the risk of dripping increases in summer. ■ The truth If you continue working without realizing that the viscosity has decreased, dripping will occur repeatedly. Dripping tends to concentrate in the afternoon, during the time when temperatures are highest. ■ Improvement measures During summer, regularly check the viscosity with a viscometer and establish seasonal viscosity standards. Set the film thickness slightly thinner and adjust the spraying distance for vertical surfaces. Please refer to the materials for viscosity management during summer.

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During the summer, isn't there an increase in the variation of film thickness? The cause may be the temperature differences inside the curing oven. On days when the outside temperature is 35 degrees, the temperature difference inside the oven can expand to twice the normal range. ────────────── ■ Cause of Occurrence In summer, the high outside temperature can easily create a temperature difference between the entrance and the back of the oven. When the temperature is not uniform, the curing speed varies by area, leading to uneven film thickness. ■ The Truth It is not uncommon for temperature management inside the oven, which was not an issue in winter, to become unstable only in summer. The position of the ventilation openings that draw in outside air also affects this. ■ Improvement Measures Measure the temperature at multiple locations inside the oven and revise the settings specifically for summer. Adjust the timing of ventilation to keep the temperature difference inside the oven within plus or minus 5 degrees. Please utilize the materials for reviewing the curing conditions in summer.

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Right after the pretreatment, it is already rusting. The rust may be caused by condensation due to humidity. In an environment with 80 percent humidity, the recurrence of rust due to condensation doubles. ────────────── ■ Cause of Occurrence From the rainy season to summer, temperature differences within the factory can easily cause condensation on the surface of materials. The metal surface right after pretreatment is particularly prone to rust, and the condensed moisture directly turns into red rust. ■ The Truth Even if there is no problem with the pretreatment itself, rust can occur simply due to temperature differences in the storage location. Special caution is needed when moving items from an air-conditioned room to the outdoors due to the temperature difference. ■ Improvement Measures Shorten the time from pretreatment to painting, and manage the temperature and humidity of the storage location. If possible, use a dehumidifier to keep humidity below 80 percent. Please refer to the materials for managing pretreatment during the rainy season.

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In summer, have you noticed an increase in uneven gloss? The cause may be the rapid drying due to high temperatures. When temperatures exceed 30 degrees Celsius, the evaporation rate of solvents is 1.5 times that of winter. ────────────── ■ Cause of Occurrence When temperatures are high, the solvents in the paint evaporate faster than expected. The surface dries first, resulting in a difference in drying between the surface and the interior, which appears as uneven gloss. ■ The Truth If you continue to paint in summer under winter conditions, the drying will be too fast, leading to uneven gloss. This is especially true if the waiting time before entering the oven is long, as the surface drying will progress too much. ■ Improvement Measures In summer, it is effective to adjust the viscosity and dilution rate of the paint for the season. Shorten the waiting time and manage the oven temperature within plus or minus 5 degrees of the seasonal average. Please refer to the materials for seasonal painting conditions.

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■Cause of Occurrence: In metal coating, the shortage of manpower and the difficulty of skill transfer lead to quality defects. Experienced workers can notice residual oil, excessive film thickness, insufficient drying, and areas prone to dripping, but inexperienced workers may overlook these issues. Coating peeling, pinholes, poor curing, and blisters occur due to the accumulation of small variations in judgment. ■Truth: The danger of manpower shortages lies not only in the number of workers but also in the fact that judgment criteria can vary from person to person. If film thickness is judged by feel, curing conditions are not recorded, and drying conditions are assessed only visually, the same defects cannot be prevented. Clear standards that anyone can understand are necessary. ■Improvement Measures: Record degreasing conditions, drying times, film thickness measurements, curing temperatures, and inspection results, and standardize the three aspects of work procedures, inspection criteria, and defect confirmation procedures. Please utilize materials that allow you to verify pretreatment, film thickness, and curing conditions.

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■Cause of Occurrence: The importance of aluminum parts is increasing due to trends in weight reduction and cost management. Aluminum is lightweight and has excellent workability, but if painted with the same approach as iron, issues such as poor adhesion, paint peeling, pinholes, and blisters can occur. The three points to check are the residue of processing oil, the condition of the oxide film, and the drying after pretreatment. ■Truth: Peeling is not just a matter of paint selection. With weight reduction, shapes have become more complex, increasing ribs, holes, corners, and thin sections, making it easier for cleaning agents and moisture to remain. Even if the surface is clean at the time of shipment, peeling can become apparent during assembly or storage. ■Improvement Measures: Treat aluminum as a material where quality differences arise during pretreatment, managing degreasing, surface adjustment, and drying with numerical records. In the event of peeling, revert to check the pretreatment, film thickness, and curing conditions of the same lot. Please utilize documents that allow you to verify pretreatment, drying, and film thickness conditions.

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■Cause of Occurrence: In metal coating, invisible costs arise with every defect. Reusing paint, restarting drying ovens, re-inspections, and adjusting delivery dates. Repainting simultaneously increases losses in paint costs, electricity, gas, labor, and inspection man-hours. In an era of rising raw material costs, a single defect cuts into profits. ■Truth: The loss per item may seem small, but repainting 5 out of 100 items results in a defect rate of 5 percent. If this continues weekly, the burden accumulates across all processes. If it leads to delays in delivery or a lack of trust in quality, the losses exceed the numbers. ■Improvement Measures: Not only should defects be identified in the final inspection, but also the degreasing, surface preparation, drying, film thickness, and curing conditions should be checked at each stage to trace back the causes. Issues like pinholes, runs, poor curing, and paint peeling occur simultaneously due to inconsistencies in pretreatment or film thickness. Please utilize materials that can help organize pretreatment, film thickness, and curing conditions.

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■Cause of Occurrence: Poor adhesion of aluminum is often attributed to paint or curing conditions, but the surface condition before painting has a significant impact. The aluminum surface retains oil, oxide film, processing dirt, and moisture. In this state, the paint film cannot adhere properly. The three processes to check are degreasing, surface preparation, and drying. Weakness in any of these can lead to peeling or blistering. ■Truth: Surface preparation agents not only clean the surface but also play a crucial role in creating a state conducive to paint film adhesion. Even if visible dirt is removed, if the surface is not suitable for painting, quality will not be stable. Variability hides behind defects. ■Improvement Measures: Manage chemical concentration, treatment time, liquid temperature, and drying conditions numerically, and separate conditions by material type such as aluminum, iron, and zinc plating. Please utilize materials that allow you to verify the degreasing, surface preparation, and drying processes.

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■Cause of Occurrence: Poor adhesion of aluminum die casting is judged to be weak and easily peeling paint. The causes are not only the paint itself but also the residual oil from casting and processing, the presence of pores and gas escape on the material surface, and the surface condition after pretreatment. It is a material that tends to retain dirt and moisture in complex shapes, particularly around holes, corners, and ribs. ■Truth: It is difficult to detect at the time of shipment, and if oil or moisture remains under the paint film, it will peel off due to assembly or transport vibrations. In areas with pores, it can develop into pinholes or blisters. The quality of the paint is almost determined by the management before application. ■Improvement Measures: By confirming the three points of degreasing to remove oil, ensuring no moisture remains after cleaning, and checking for pores and roughness at each process, it can be recorded in the lot records to prevent recurrence. Please utilize materials that can confirm pretreatment, material condition, and film thickness conditions.

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■Cause of Occurrence: Drips are an appearance defect where traces of paint flow remain. Even a single line or a localized accumulation will stop the visual inspection. Common causes include decreased paint viscosity, excessive film thickness, close gun distance, and poor part orientation. Corners, areas around holes, and downward-facing surfaces are places where paint tends to accumulate and drip easily. ■Truth: It should not be resolved solely by the skill of the operator. Even if the viscosity is adjusted, if the discharge amount is too high, the film thickness will increase, and if the application method is poor, the paint will flow to the lower side. This is a warning that occurs when viscosity, film thickness, orientation, and drying time overlap. ■Improvement Measures: By checking and recording four points—areas where drips occurred, the number of occurrences, whether the film thickness is within standards, whether the viscosity is within the set range, and whether the part orientation is in a position that is less likely to flow—you can narrow down the causes. Please utilize materials that can confirm painting conditions, film thickness, and jig orientation.

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■Cause of Occurrence: Blisters are defects where the paint film swells like a balloon. Even if the product is good at the time of shipment, it may be discovered by the customer weeks or months later. The main causes are moisture retention after pretreatment, oil or rust on the surface of the material, and insufficient drying. Invisible residues foster defects beneath the paint film. ■Truth: No one notices the moment it occurs. Even if it passes visual inspection, if moisture or corrosion factors remain beneath the paint film, it will push the film up from the inside. This is a warning sign of adhesion failure, rust reoccurrence, and paint peeling. The risk for the entire lot is hidden behind a single blister. ■Improvement Measures: Check the drying time before painting, the overlap of parts, and any holes or edges where water may remain, as well as welds. Confirm during the process that no moisture remains on the parts, and also record cleaning, storage time, film thickness, and curing conditions. Please utilize materials that allow you to verify moisture retention, pretreatment, and drying conditions.

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■Cause of Occurrence: Paint peeling is a defect that tends to be discovered during the assembly process at the customer's site. Even if the surface is clean at the time of delivery, it can peel off due to bolt tightening or friction during transport. The three processes to check are whether the degreasing has effectively removed oil, whether there are any residues left after cleaning, and whether moisture has been eliminated during drying. If any one of these processes fails, the adhesion strength will decrease. ■Truth: Peeling is not an issue that occurs at the moment of painting, but rather a defect that surfaces later due to inadequate pretreatment. Changing the paint or curing conditions will not resolve the issue if oil or moisture remains. The adhesion conditions differ for aluminum, iron, and zinc plating. ■Improvement Measures: Instead of only addressing the areas that have peeled, it is important to revert to the state before painting and manage records of oil content, surface roughness, chemical conversion coating, drying conditions, and storage time. Treating pretreatment as the entry point for quality assurance is crucial. Please utilize documentation that allows you to verify pretreatment, film thickness, and curing conditions.

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■Cause of Occurrence: Poor curing that leaves stickiness on the surface is a defect that is difficult to judge visually. If a few pieces are mixed in one lot, it can lead to rubbing during assembly, sticking of packaging materials, scratches during transportation, and re-inspection. The three conditions to check are curing temperature, curing time, and film thickness. Even if the set temperature is reached, if the parts do not rise to the required temperature, they will not cure. ■Truth: At the time of shipment, they may appear slightly soft, but they can quickly deteriorate in the subsequent processes. If the film thickness is too thick, heat will not penetrate to the inside, and if the drying oven is unstable, curing will vary. This cannot be prevented by intuition alone. ■Improvement Measures: Confirm curing conditions based on part temperature, record film thickness with measured values, and check the temperature differences at the entrance, center, and exit of the drying oven. By including these three points as management items, the risk of recurrence will decrease. Please utilize materials that allow you to confirm curing conditions, film thickness, and drying management.

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■Cause of Occurrence: Pinholes are defects where small holes remain on the surface of the paint film. During visual inspection, even one instance is subject to selection. There are three main causes: oil residue on the surface of the material, moisture due to insufficient drying, and voids or unevenness in the material. These factors allow air or gas to escape during painting, creating holes. ■Truth: The areas with holes have interrupted paint films, leading to weaknesses in corrosion resistance and adhesion. In aluminum die casting and castings, internal cavities or gas escape in the material are also relevant. Simply repainting the surface will not prevent recurrence unless the pre-treatment and material condition are verified. ■Improvement Measures: By recording the three points of degreasing to remove oil, ensuring no moisture remains during drying, and checking for voids or roughness, you can narrow down the causes by cross-referencing with defective lots. Since pinholes can also lead to blistering and rust recurrence, please utilize materials that can help organize pre-treatment, drying, and material conditions.

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[Cause of Occurrence] One of the top causes of poor painting quality is "foreign matter contamination (dust and particles)" on the paint film. Many factories try to address this by increasing the frequency of replacing the intake and exhaust filters in the painting booth, but it is not uncommon for the expected results to not be achieved. [Truth] In fact, about 70% of the dust that adheres to the painted surface is caused by the workers' own "work clothes (dust generation)" and "static electricity" from parts brought in. Especially in winter, static electricity tends to occur, attracting fine dust in the air to the parts like a magnet, leading to frequent defects such as pinholes. [Improvement Measures] It is essential to ensure proper static elimination (installation of ionizers), thorough air showers before entering the booth, and wearing low-dust clean suits. A manual for dust prevention and static elimination measures to dramatically reduce foreign matter contamination can be downloaded for free from here. [Summary] The fundamental countermeasure against foreign matter contamination is not just the replacement of equipment filters, but also preventing dust generation from workers and implementing thorough static electricity measures. Eiwa Kogei Co., Ltd. conducts high-quality painting with foreign matter contamination minimized to the extreme under strict dust and static management.

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[Cause of Occurrence] In automotive interior and exterior parts, color unevenness (color variation) such as "the color appears different depending on the lighting" and "there are variations in shade between lots," despite being painted in the specified color, is a major factor that prevents meeting strict appearance standards. [Truth] Particularly with metallic and pearl-type paints, the arrangement of "aluminum pigments contained in the paint" determines the color tone. If the air pressure of the spray gun is unstable or the exhaust airflow in the painting booth is too strong, the pigments do not align uniformly, leading to color unevenness and worsening surface roughness. [Improvement Measures] To maintain a stable color tone, it is essential to stabilize the compressor pressure and optimize the airflow in the booth (approximately 0.3 to 0.5 m/s). A checklist for equipment inspection to prevent color variation and a guide for optimizing spraying conditions can be downloaded below. [Summary] Color unevenness is not due to defects in the paint itself, but occurs when disturbances in the airflow and air pressure of the painting environment disrupt the arrangement of pigments. Eiwa Kogei Co., Ltd. promises high-quality finishes by preventing color variation between lots through the maintenance and management of a stable painting environment.

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[Cause of Occurrence] "Dripping" defects are often seen in parts with vertical surfaces or complex shapes. Production managers on-site tend to blame "individual skill" factors, such as the operator's spray gun speed being too slow or the application amount being too high. [Truth] More than half of the causes of dripping are due to the mismatch between "paint viscosity" and "ambient temperature," rather than the operator's skill. Particularly during seasonal transitions, if painting is done at the same dilution ratio (excessive thinner) as in summer while the temperature is dropping, the paint becomes too runny and quickly drips off. [Improvement Measures] It is important to establish rules for selecting thinners (fast-drying or slow-drying) according to temperature and for strict time management using dedicated viscosity cups. A quick reference chart summarizing appropriate viscosity and dilution ratios for each season can be downloaded from this link and posted on-site. [Summary] Dripping in painting can be eradicated not by relying on individual skill but by quantifying paint viscosity management in accordance with temperature changes. Eiwa Kogei Co., Ltd. achieves a uniform and beautiful finish even on complex-shaped parts through thorough paint management.

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[Cause of Occurrence] There are many cases where, despite sanding off rusted areas on automotive undercarriage parts and repainting, rust reappears in the same spots within a short period, leading to serious reclaims. [Truth] Even if the surface red rust is removed, black rust, moisture, and salt remain in the fine pores of the metal in an "invisible state." When paint is applied over this, the oxygen and moisture trapped inside continue to react, breaking through the paint film (such as blisters) and causing rust to reappear. [Improvement Measures] Complete rust removal requires either physical stripping using blast treatment or chemical neutralization with a dedicated rust converter. You can download the process documentation for a robust anti-rust painting to help prevent recurrence from here. [Summary] Rust recurrence cannot be prevented by surface treatment alone. It is essential to completely remove and neutralize the corrosion factors lurking deep within. Eiwa Kogei Co., Ltd. possesses reliable technology to prevent recurrence, from fundamental rust removal to anti-rust painting.

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[Cause of Occurrence] There is a problem in the curing process after painting where "despite drying at the specified temperature and time, the hardness of the paint film is low, or there is a lingering solvent smell." This issue occurs frequently, especially with thick automotive parts. [Truth] Even if the displayed temperature in the drying oven is 180 degrees, the actual "product temperature" of the metal parts may not reach that level, which is the main cause. Thick parts have a large heat capacity, causing only the surface to dry rapidly while the internal solvent does not fully escape, leading to an uncured state that can induce pinholes. [Improvement Measures] It is essential to regularly use data loggers to attach thermocouples directly to the products and measure the actual "product temperature profile." A guide for setting optimal curing conditions, taking into account the heating time, is available for download as free technical documentation. [Summary] By managing based on "product temperature" rather than the oven temperature during the drying process, stable paint film hardness can be achieved. Eiwa Kogei Co., Ltd. assesses the heat capacity of each product and provides high-quality metal coatings under optimal curing conditions.

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