Manual Welding Seam Grinding and Polishing Process

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Manual hand polishing is currently the primary way to finish products, although robotic polishing has gradually become more common. However, it's worth mentioning that robotic polishing requires significant floor space to accommodate the robotic arm and associated machinery. For small to medium-sized factories with limited space, the area occupied by a robotic arm may be equivalent to several workers' positions. As a result, smaller factories generally do not adopt automated polishing.

The process and corresponding tools for manual weld seam polishing and polishing can vary depending on the materials used. In general, the main material is a welded steel pipe, and the primary goal is to remove welding marks and achieve a smooth and flawless appearance. The subsequent polishing aims to create a mirror-like effect commonly seen in retail stores.

When it comes to grinding weld seams, angle grinders are commonly used, but the materials may differ. Here are a few examples:

Lamellar discs are made by cutting traditional sheet-like sandpaper into specific shapes and arranging them together. These discs are attached to angle grinders and rotate at high speeds, enabling rapid removal of welding marks. However, due to their sharp abrasive nature, inexperienced workers may risk over-grinding the product and causing damage. Therefore, lamellar discs are not recommended for novices or situations requiring deeper weld seam removal.

Nylon discs are made of a fiber composite material that is relatively soft and has abrasive particles coated on the surface. These discs provide effective results when used for grinding weld seams. Nylon discs are designed with a hook-and-loop fastening system and are compatible with sanding machines, offering excellent performance.

Aluminum oxide grinding discs: Also known as resin grinding discs, these discs are made of aluminum oxide and silicon carbide materials. They provide strong grinding power, but they tend to wear out quickly. These discs are suitable for use with angle grinders, where their high-speed rotation necessitates frequent disc replacement. Various other grinding tools, such as grinding wheels and sanding belts, are also available but not specifically discussed here.

Weld seam grinding is generally considered a challenging process. While there is a sensory aspect involved, the main purpose is to enhance aesthetics. The primary reason is to ensure proper compatibility between products by addressing the unevenness caused by weld seams. The tools commonly used for weld seam grinding are angle grinders, often referred to as polishing machines and sanders.

For curved surfaces, resin grinding wheels are typically used. The edges of the grinding wheels can be modified according to the inner bending angles to fit the internal weld seam of the material.

Next, a belt sander is employed to grind the surrounding area of the inner weld seam and the entire steel pipe, removing impurities and discoloration. This process aims to achieve a smooth and even surface.

In this case, a handheld belt sander is used, utilizing sanding belts with different grit sizes for preliminary and fine polishing processes. The selection of sanding belt grit sizes varies based on the material being polished, ranging from 60 to 3000 grit. In the case of steel pipes, four grit sizes are commonly used: 400, 600, 1200, and 2000. Starting with a coarser grit and progressing to a finer grit, the finest sanding belt helps achieve a preliminary mirror-like finish. However, the surface may still appear slightly hazy, with faint personal reflections. The next step involves the final polishing process.

Initially, a cloth wheel is used along with polishing compounds for initial polishing.

Finally, the belt sander is still required, with the choice of equipment depending on the material. For flat surfaces, a sanding machine is preferred, while for cylindrical materials like pipes, a belt sander with non-woven fabric belts and polishing compounds is utilized to continue the polishing process until the pipe.