Metal Parts For Cargo Trucks

A metal part typically undergoes the following main stages from raw material to finished product:

Raw Material Preparation → Blank Manufacturing → Machining → Connection and Assembly → Surface Treatment → Inspection and Packaging

Below, we will elaborate on each stage according to this process.

• 1. Raw Material Preparation

Material Types:

Steel: The most commonly used material. Includes:

Ordinary Hot-Rolled Steel Plate/Section Steel: Used for structural components such as vehicle frames and floor panels that require high strength but not high surface finish.

High-Strength Steel: Used for critical load-bearing structures to reduce weight.

Cold-Rolled Steel Plate: Good surface quality, used for cab covers, doors, etc.

Alloy Steel: Used for wear-resistant, high-strength parts in key components such as engines and transmissions.

Aluminum Alloy: Mainly used for fuel tanks, wheel hubs, and cab panels to reduce vehicle weight and improve fuel economy.

Cast Iron: Used for brake drums, some brackets, and other complex-shaped components requiring vibration damping.

Preparation Process: According to the product design, large coils of steel plates or long strips of profile are prepared into blanks of the required dimensions through uncoiling, leveling, shearing, or sawing.

• 2. Blank Manufacturing

This is the process of giving the parts their basic shape, mainly using the following methods:

Stamping:

Applicable to: Thin sheet metal parts such as cab covers, doors, and body panels.

Process: Using large presses and molds, steel plates are punched, drawn, and bent to form complex shapes in one or multiple steps. This is one of the most automated and efficient methods.

Forging:

Applicable to: Key safety components requiring high strength and toughness, such as engine connecting rods, steering knuckles, and ball joints.

Process: After heating the metal blank, it is subjected to enormous pressure through a mold on a forging press, shaping it in a plastic state. Forging refines the metal grains and improves mechanical properties.

Casting:

Applicable to: Parts with complex structures that are difficult to forge, such as gearbox housings, engine mounts, and brake drums.

Process: Molten metal is poured into a pre-made sand mold or metal mold, and after cooling and solidification, a blank is obtained. Common processes include sand casting and die casting.

Cutting and Blanking:

Applicable Objects: Thick plate parts such as longitudinal beams and crossbeams of vehicle frames.

Process: Using plasma cutting, laser cutting, or high-pressure water jet cutting, the steel plate is precisely cut into the required shape according to digital drawings. Laser cutting has the highest precision and is the most widely used.

• 3. Machining

After the blank is manufactured, its dimensional accuracy and surface finish do not meet the assembly requirements, so machining is required.

Main Processes:

Turning: Machining the outer diameter, inner hole, and end face of rotating parts (such as shafts and sleeves).

Milling: Machining planes, grooves, and complex curved surfaces.

Drilling/Reaming/Boiling: Machining and finishing mounting holes, positioning holes, etc.

Tapping: Machining internal threads.

Equipment: CNC machine tools, machining centers, special combination machine tools, etc. Modern manufacturing widely employs CNC technology to ensure high precision and efficiency.

• 4. Connection and Assembly Assembling multiple machined parts into components or assemblies.

Welding:

Spot welding: Primarily used for joining thin sheet metal parts, such as cabs.

Gas shielded welding: The most widely used welding method, used for joining most structural components such as frames and bodies.

Arc welding/laser welding: Used in applications requiring higher weld quality and strength.

Riveting: Still used in heavy-duty truck frames, offering advantages such as good impact resistance and fatigue resistance.

Bolted connections: Used for connecting detachable components, such as suspension systems and engine mounts.

• 5. Surface Treatment This is a crucial step in preventing metal corrosion and improving the product's appearance.

Pre-treatment: Includes degreasing (removing oil stains), washing, surface conditioning, and phosphating. Phosphating forms a protective phosphate film on the metal surface, significantly improving the adhesion and rust prevention of subsequent coatings.

Coating:

Electrophoretic Coating: The entire workpiece is immersed in an electrophoretic paint tank, and an electric current is applied to evenly adhere the paint film to the inner and outer surfaces of the workpiece. This is the most important primer anti-corrosion process.

Spray Coating: Includes powder coating and liquid coating. Powder coating is environmentally friendly, produces a thick coating, and has good corrosion resistance; it is commonly used for vehicle bodies and frames. Liquid coating is used for cabs and other areas where appearance is critical.

Baking: After spraying, the workpiece enters an oven to cure the paint film.

Electroplating: Such as zinc plating and chrome plating, used for small parts such as screws and nuts, providing corrosion protection and decorative effects.

Hot-Dip Galvanizing: The workpiece is immersed in molten zinc to form a thick and dense zinc layer, providing extremely strong corrosion resistance; it is commonly used for structural components in outdoor environments.

• 6. Inspection and Packaging

Inspection: Throughout the entire production process.

Incoming Material Inspection: Checking the quality of raw materials.

In-Process Inspection: Checking dimensions and appearance after each process.

Final Inspection: A comprehensive inspection of the finished product is conducted, including dimensional, performance (e.g., hardness), non-destructive testing (e.g., magnetic particle testing for cracks), and assembly quality checks.

Packaging: Depending on the characteristics of the components, rust-preventive oil, rust-preventive paper, bubble wrap, wooden crates, etc., are used for packaging to prevent damage or rusting during transportation and storage.

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