Surface spraying (also known as spray coating) is a versatile surface treatment for stamped parts, involving the application of a liquid coating material (such as polymers, ceramics, metals, or composites) onto the part’s surface using a spray gun or automated spraying system. This process creates a protective, decorative, or functional layer that enhances the part’s performance—including resistance to corrosion, abrasion, UV radiation, or chemical exposure—while also improving its aesthetic appeal. Stamped parts used in outdoor equipment, automotive undercarriages, industrial machinery, or consumer goods often rely on surface spraying to meet durability and design requirements.

The surface spraying process for stamped parts consists of three main phases: pre-treatment, coating application, and curing. Pre-treatment is critical to ensure adhesion between the coating and the stamped part’s surface, as oils, oxides, or contaminants from stamping can cause coating failure. Common pre-treatment steps include degreasing (using solvents or alkaline cleaners to remove machining oils),  (to eliminate rust or oxide layers, especially for ferrous metals), and surface activation (such as sandblasting or chemical etching to create a micro-rough surface that improves coating grip). For example, stamped steel brackets used in construction equipment undergo sandblasting to achieve a roughness Ra of 2-5 μm, ensuring the spray coating adheres firmly.

The coating application phase involves selecting the appropriate coating material and spraying method based on the part’s function and environment. Polymeric coatings (such as epoxy, polyurethane, or acrylic) are widely used for their corrosion resistance and flexibility—epoxy coatings, for instance, are applied to stamped aluminum electrical enclosures to protect against moisture and chemicals. Ceramic coatings, known for their high-temperature resistance, are used on stamped steel parts in engine components or industrial furnaces. Metal coatings (e.g., zinc-rich primers or aluminum sprays) provide sacrificial protection, preventing the underlying metal from corroding. Spraying methods include airless spraying (using high pressure to atomize the coating, ideal for large parts like stamped truck frames), HVLP (High-Volume Low-Pressure) spraying (reducing overspray, suitable for precision parts like electronic housings), and electrostatic spraying (charging the coating particles to attract them to the grounded part, ensuring uniform coverage even on complex geometries).

The curing phase hardens the coating into a durable film. Curing methods depend on the coating type: solvent-based coatings cure through evaporation of solvents (at room temperature or with mild heating), while thermosetting coatings (like epoxy or polyester) require heating to 120-200°C in an oven to trigger chemical cross-linking. For example, stamped plastic parts (e.g., ABS casings for power tools) are often spray-coated with acrylics and cured at 80-100°C for 30-60 minutes to achieve a scratch-resistant finish. Post-curing inspections include adhesion tests (using tape or cross-cut methods), thickness measurements (with a coating gauge, typically 20-100 μm for protective coatings), and visual checks for defects like pinholes, runs, or uneven coverage. Surface spraying offers flexibility in color, texture (matte, glossy, or textured), and performance, making it adaptable to diverse industries. It also allows for cost-effective customization—for instance, automotive manufacturers use spray coating to match stamped body panels to the vehicle’s color, while industrial equipment makers apply textured spray coatings to stamped handles for improved grip.