The polishing process for metal coil nails requires systematic process control and detailed optimization to ensure a uniform, scratch-free surface. The key lies in the coordinated coordination of material selection, equipment debugging, operational procedures, and quality inspection.
Surface pretreatment before polishing is fundamental. Coil nail surfaces may retain processing burrs, oxide layers, or oil stains, requiring multiple cleaning steps. First, mechanical rust removal or chemical cleaning removes the oxide scale. Then, sandpaper or a fiber wheel is used to polish the surface, eliminating noticeable protrusions. For minor burrs, ultrasonic cleaning equipment with a neutral detergent can be used to remove impurities through high-frequency vibration. The pretreatment stage must ensure surface cleanliness to prevent impurities from scratching the workpiece during subsequent polishing.
The choice of polishing tools and materials directly affects surface quality. For the metal material of the coil nails, a dedicated polishing wheel and abrasive media are required. For example, stainless steel coil nails are suitable for fiber wheels or damping cloth wheels, whose softness reduces over-cutting; carbon steel coil nails can be polished with white corundum or alumina polishing paste, gradually smoothing the surface through micro-cutting action. The particle size of the polishing compound should be gradually increased, transitioning from coarse to fine (e.g., 400 mesh) to avoid scratches caused by residual coarse particles.
Parameter adjustment of the polishing machine is a core control point. Excessive speed can cause metal overheating and deformation, while insufficient speed will affect polishing efficiency. In actual operation, the speed needs to be adjusted according to the size and material of the coil nails. For example, small coil nails can use medium speed (approximately 1500-2000 rpm), while large coil nails require a reduced speed (approximately 800-1200 rpm) to control the cutting force. Polishing pressure must be applied evenly, which can be achieved through pneumatic or hydraulic devices to maintain constant pressure output and avoid excessive local pressure that can cause scratches.
The standardization of operating techniques and motion trajectory is crucial. During polishing, the relative movement between the workpiece and the polishing wheel should be kept smooth, avoiding sudden speed changes or stops. For the cylindrical surface of coil nails, a combination of axial movement and rotation should be used to ensure comprehensive polishing coverage. Operators must wear protective gloves to avoid contaminating the surface with hand oils and regularly clean residue from the polishing wheel to prevent impurities from embedding and causing secondary scratches.
A multi-stage polishing process can progressively improve surface precision. The coarse polishing stage uses larger-grained abrasive media to quickly remove surface defects; the medium polishing stage switches to medium grit to smooth out coarse polishing marks; the fine polishing stage uses ultra-fine polishing paste to achieve a mirror finish. After each stage of polishing, the surface must be wiped with a clean cloth and the scratches checked. If residual defects are found, the process must be repeated from the previous stage.
Cooling and lubrication measures prevent overheating during polishing. High temperatures generated during metal polishing due to friction can lead to surface oxidation or ablation. Temperature can be reduced by spraying coolant or applying lubricant, while also reducing the adhesion between the polishing paste and the metal. The coolant must be compatible with the metal material to avoid chemical reactions that could cause surface discoloration.
Final inspection and quality assessment are crucial to ensuring a scratch-free finish. After polishing, the surface should be visually inspected under bright light, paying particular attention to edges and curved transition areas. For products requiring high precision, a microscope or roughness tester can be used for quantitative testing to ensure that the surface roughness meets design standards. In addition, samples should be subjected to salt spray tests or abrasion tests to verify the corrosion resistance and adhesion of the polished layer, avoiding problems in subsequent use due to process defects.
