Fender Design

FENDER DESIGN REPORT

1. Introduction

The fender is a key component of a vehicle's body structure, primarily designed to prevent sand, mud, rocks, liquids, and other road spray from being thrown into the air by the rotating tires. Apart from aesthetics, the fender must also offer strength, support, and corrosion resistance.

2. Fender Design Overview

A well-designed fender integrates the following:

• Durability: To withstand impacts from debris.
• Aerodynamics: To reduce air drag and improve fuel efficiency.
• Fitment: To align perfectly with surrounding body panels.
• Manufacturability: To allow easy production and assembly.
• Mounting: Designed for secure attachment to the body using standard mount types.

3. Fender Mounting Points

Fender mounting points connect the fender to the vehicle chassis and nearby panels. Common mounting areas include:

• Sill Mount
• Bumper Mount
• Baffle (Splash Shield) Mount
• A-Pillar Mount
• Headlamp Bracket Mount (Optional)
• Drip Area Mount (Top Mount)

We will now focus on the four primary mounts, their custom design, and associated engineering practices.

4. Custom Mounting Designs

4.1. Sill Mount Design

Purpose: Supports the lower part of the fender and connects it to the car's rocker panel (sill).

Design Parameters:

• Material: Reinforced plastic or metal bracket
• Fastening Method: M6 bolt with embedded nut or U-clip
• Hole Clearance: Ø7 mm
• Corrosion Resistance: Zinc-plated metal

3D Design Concept:
(Custom-designed sill mount showing flange, fastener hole, and reinforcement ribs)

4.2. Bumper Mount Design

Purpose: Links the front lower edge of the fender to the bumper, allowing energy transfer and aesthetic alignment.

Design Parameters:

• Material: Glass-fiber-reinforced polymer (GFRP)
• Tolerances: ±0.5 mm for positioning
• Mounting System: Snap-fit + M5 screw (dual retention)
• Weather Sealing: Optional EPDM foam tape

3D Design Concept:
(Bumper interface with slide-lock and screw feature for strength and serviceability)

4.3. Baffle (Splash Shield) Mount Design

Purpose: Attaches the inner shield (baffle) to the fender, preventing water/mud ingress into engine bay.

Design Parameters:

• Material: Nylon 6 with 30% glass-fiber
• Mount Type: Push pin clip mount with reinforcement backing
• Hole Type: Slotted for thermal expansion
• Drainage: Slit opening for water run-off

3D Design Concept:
(Clip-in system design with flex ribs to support splash guard during off-road conditions)

4.4. A-Pillar Mount Design

Purpose: Connects fender to the A-pillar structure; critical for NVH (noise, vibration, harshness) performance.

Design Parameters:

• Fastening: Weld nut with bolt, threadlocker applied
• Location Precision: High – needs ±0.3 mm
• Vibration Control: Isolated with rubber washer
• Access: Must be serviceable from the engine bay side

3D Design Concept:

(Curved mounting bracket with weld nut and alignment ribs for correct positioning)

5. Manufacturing Process of Fender

Step-by-Step Process:

1. Material Selection:
• Sheet metal (steel or aluminum)
• Optional: Thermoplastic composites for lightweight applications
2. Stamping/Forming:
• Using large dies and presses
• Two or more draw operations for deep curves
3. Trimming and Piercing:
• CNC-controlled machines trim excess material and create mounting holes
4. Surface Treatment:
• Phosphate coating, followed by primer and paint layers
5. Assembly:
• Addition of mounting brackets, reinforcements, clips
6. Quality Check:
• Laser measurement systems verify dimensional accuracy

Parameter	Specification
Fender Thickness	0.75 mm – 1.2 mm (Steel)
Gap with Hood	3.0 ± 0.5 mm
Gap with Door	3.0 ± 0.5 mm
Fastener Torque	8–12 Nm (depending on mount)
Coating	E-coating + Topcoat
Weight (Average)	2–3 kg (depending on material)

6. Design Parameters for Fender

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7. Conclusion

Designing a fender involves a balance of aesthetic integration, mechanical strength, manufacturability, and serviceability. The custom-designed mounts for the sill, bumper, splash baffle, and A-pillar presented here follow standard engineering practices with appropriate tolerances, materials, and mounting strategies to ensure durability and performance under varying road conditions.