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Paint treatment

Table of Contents

Definition

General grinding, also called ordinary sanding or rough grinding, is a basic mechanical surface finishing process that uses abrasive sandpaper, grinding belts and grinding wheels to grind off excess material, burrs, deep tool marks, pits and oxidation layers on raw workpieces. It is the preliminary processing step before fine polishing, sandblasting, coating or anodizing.

Working Principle

Different grit abrasive tools (from coarse grit #80 / #120 to medium #240 / #400) rotate or rub against the workpiece surface. The abrasive grains cut away uneven surface layers to level the base, without pursuing high gloss or mirror effect.

Two Main Types

  1. Dry Grinding Direct grinding with sandpaper/belts without liquid coolant, simple operation for most metal, composite and plastic parts.
  2. Wet Grinding Grind with water or grinding fluid to reduce dust, avoid overheating and get finer uniform base surface.

Core Purposes

  • Remove sharp burrs, flashes and rough edges after CNC machining, casting or stamping
  • Eliminate deep machining lines, casting pores, rust and oxide skin
  • Level uneven surfaces to prepare a clean base for follow-up surface treatments
  • Achieve simple uniform matte rough surface for low-demand decorative parts

Material Compatibility

Aluminum alloy, steel, stainless steel, copper, zinc die castings, carbon fiber composites, hard engineering plastics.

Standard Process Flow

Raw machined part → Coarse general grinding (#80–#180 grit) → Medium general grinding (#240–#400 grit) → Next process (polishing / sandblasting / powder coating / anodizing)

Advantages & Limitations

Advantages

  • Low cost and high processing efficiency for mass workpieces
  • Effectively remove heavy surface defects that fine polishing cannot handle quickly
  • Simple equipment, suitable for complex curved and irregular parts

Limitations

  • Will leave uniform fine grinding lines on the surface, low gloss
  • Cannot reach mirror or ultra-smooth satin finish; fine polishing is required for high-reflection appearance
  • Excessive coarse grinding may change workpiece dimensional tolerance

Surface treatment resources

Frequently Asked Questions

  To shorten the delivery cycle of CNC workpieces, we start with the documents submitted by customers. Please provide complete and clear 2D drawings, 3D models, dimensional tolerances, surface requirements, and processing specifications, and specify special materials, surface treatments, and assembly standards. Avoid incomplete drawings, ambiguous markings, and version confusion.
Complete documents enable direct programming, order splitting, and production scheduling, cutting down repeated confirmation and supplementary work. Customers are also advised to finalize order quantity, delivery schedule, and special requirements in advance. Eliminating repeated communication and rework risks at the source accelerates the whole process and effectively shortens the overall lead time.

  With 12 years of expertise in CNC machining, YUEYI stands out from other manufacturers and middlemen. Our factory covers an area of 4,000 mu and is equipped with over 100 processing machines. We achieve a machining precision up to 0.001 mm, capable of producing high-precision components. Backed by standardized production management, our on-time delivery rate reaches 98%. As a direct manufacturer with full in-house production capacity, we control every production link without outsourcing. We deliver consistent quality, outstanding precision and reliable lead time, making us your trustworthy partner for CNC precision machining.

  Fast delivery is one of our key strengths. For 3D printing orders, we support delivery within 3 days, ideal for rapid prototyping and urgent sample requests. For regular CNC machining projects, the standard lead time is around 3 weeks.
We manage the whole process in-house, from drawing review and process planning to production, quality inspection, and shipment, with no intermediate links. Equipped with complete facilities and an experienced team, we reliably fulfill both urgent sample orders and mass production. We guarantee stable lead time and consistent quality to keep your projects on track.

  We offer a full range of surface treatments with rich color options. Our services include anodizing, powder coating, spray painting, electroplating, wire drawing, sandblasting, and polishing. Anodizing features various colors and strong anti-corrosion performance for aluminum parts. Powder coating and spray painting come with extensive color selections and durable coatings. Electroplating enhances luster and rust resistance. Wire drawing creates fine linear textures, while sandblasting delivers a matte finish. Polishing achieves a bright and smooth surface. All finishes can be customized in colors and styles to match your application needs.

  Yes, we fully provide complete material certificates and relevant test reports for all CNC-machined parts. All raw materials are sourced from qualified suppliers with authentic documentation. We can offer material certifications, dimension inspection reports, and quality test records upon request. Every product is strictly inspected before delivery. These official documents fully guarantee material compliance and product quality, supporting your quality audit and project requirements.

  We take strict quality control measures in advance to prevent non-conforming products. Every workpiece is fully inspected dimensionally and visually during and after production to ensure full compliance with design drawings and specifications.
In the rare case of non-compliant items, we will take immediate responsibility. We will promptly confirm the issues with you, then arrange free rework or remanufacturing as required. All related costs will be borne by us. We will also analyze the root cause to optimize our processes and avoid similar problems recurring. Our goal is to deliver qualified products steadily and safeguard your project progress.

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