The project involved:

Component: Large EV Semi Truck Roof Fairing
Customer: Electric Vehicle OEM
Construction: One-Piece Composite Assembly
Manufacturing Process: Vacuum Infusion
Critical Tolerance: ±1 mm
Application: Roof Assembly Mounted to a Metallic Cab

The tight positioning requirement was central to the project. Internal supports and mounting hardware had to align with attachment points across a large composite structure.

EV Semi Truck Composite Fairing

Featured Project | One-Piece Composite Roof Fairing for an Electric Semi Truck

Performance Composites partnered with an electric vehicle OEM to develop a large, one-piece truck fairing using vacuum infusion manufacturing. The project required internal supports and mounting hardware to be positioned within ±1 mm to fit a metallic truck cab. PCI’s engineering and manufacturing capabilities supported the development of this custom composite roof assembly.

Project Overview: Custom EV Semi Truck Roof Fairing

Electric semi trucks require exterior components that meet specific structural, dimensional, and vehicle integration requirements. Large roof fairings present manufacturing challenges because their shape, mounting locations, and internal support structures must align with the vehicle.

The OEM worked with Performance Composites to develop a single-piece composite roof fairing.

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The Challenge: Tight Tolerances Across a Large Composite Structure

A semi truck roof fairing must fit the vehicle’s cab geometry while accommodating its internal mounting features. For this project, the OEM specified a positional tolerance of ±1 mm for the internal support structure and hardware.

Maintaining that tolerance across a large, one-piece component presented a significant manufacturing challenge. Unlike smaller molded parts, large composite assemblies require careful consideration of tooling geometry, material behavior, and component positioning. The challenge involved three connected requirements.

Maintaining the Roof Fairing Geometry

The exterior structure needed to match the intended roof design while maintaining its shape during manufacturing. Vacuum infusion provided the process for producing the large molded component.

Positioning Internal Supports

Internal structural elements needed to be located accurately within the roof assembly. Their placement was important because the composite roof would connect to a separate metallic structure.

Aligning Mounting Hardware

Mounting hardware had to correspond with the cab’s attachment points. Even relatively small positional differences could create difficulties when installing a large roof assembly.

The Solution: One-Piece Composite Construction

Performance Composites manufactured the roof fairing as a single composite structure using vacuum infusion. One-piece construction can reduce the need to join multiple exterior shell sections. It also allows complex curves and large surface areas to be formed within a common mold.

The approach was suited to the OEM’s roof fairing design, although the completed assembly still required accurate positioning of internal supports and mounting hardware.

Composite Manufacturing for Complex Geometry

Composite fabrication allows manufacturers to produce large, curved structures that may be difficult to manufacture using conventional sheet-metal methods. Reinforcement materials and resin systems can be selected according to structural, weight, and environmental requirements.

For this project, the documented manufacturing method was vacuum infusion. The exact reinforcement materials and resin system were not specified in the original project description.

Vacuum Infusion Manufacturing for Semi Truck Fairings

Vacuum infusion is a closed-mold manufacturing process used to produce fiberglass and advanced composite components. Dry reinforcement materials are placed into a mold and sealed beneath a vacuum bag. Resin is then drawn through the reinforcement under vacuum before the laminate cures.

This process is suitable for many large composite structures, including transportation body components.

Mold Preparation

The mold establishes the required exterior geometry of the roof fairing. Surface preparation, release materials, and mold condition affect the finished component’s appearance and dimensional quality.

Reinforcement Placement

Reinforcement materials are arranged according to the component’s laminate design. Depending on the application, composite structures may use fiberglass, carbon fiber, or other reinforcements.

Resin Infusion

Vacuum draws resin through the reinforcement materials.Resin flow must be planned to promote complete wet-out and minimize manufacturing defects.

Curing and Demolding

Once the laminate cures, the component can be removed from the mold. Further operations may involve trimming, machining, inspection, and hardware installation according to the approved manufacturing requirements.

Engineering a Semi Truck Fairing to Fit a Metallic Cab

The interface between the composite roof and the metallic cab was the defining engineering challenge. The fairing’s internal support structure and hardware needed to be positioned within the specified ±1 mm tolerance. For large assemblies, the relationship between the molded shell and the attachment points is critical.

Dimensional Requirements

A component’s exterior geometry and internal mounting locations must be evaluated together. An accurate exterior surface does not automatically guarantee that the internal hardware will align with the vehicle. The design must account for the required position of each critical feature.

Tooling and Fixture Considerations

Molds establish the component’s shape, while locating fixtures can support repeatable positioning during subsequent operations. CAD-based tooling and CNC-machined fixtures are among Performance Composites’ established manufacturing capabilities.

For projects requiring tight positional tolerances, fixture design can be an important part of the manufacturing approach.

Composite-to-Metal Assembly

Composite and metallic components have different manufacturing characteristics. The attachment design must account for dimensional requirements, loading conditions, and the intended installation method.In this project, the roof fairing needed to mate with a metallic cab, making accurate positioning of its internal features essential.

Weight and Material Considerations for EV Semi Truck Fairings

Weight is an important design consideration for electric commercial vehicles. Manufacturers must balance component weight with structural performance, durability, and vehicle requirements.

Composite materials can provide alternatives to conventional metal construction.

Potential advantages include:

Reduced Weight in Suitable Designs
Complex Molded Shapes
Tailored Structural Reinforcement
Corrosion Resistance
Integrated Structural Features
Consistent Exterior Surfaces

The actual benefits depend on the materials, laminate design, and finished component specifications.

For this EV project, the published information does not provide a finished fairing weight or a measured weight reduction compared with a metal alternative.

The documented achievement is the development of a large, one-piece composite assembly with a demanding positional tolerance.

Project Results and Manufacturing Specifications

Performance Composites developed the large composite roof fairing using vacuum infusion for the electric vehicle OEM.

The project demonstrates PCI’s ability to support specialized transportation components requiring complex geometry and close coordination between the molded structure and its mounting features.

Project specification Details

Industry	Electric Commercial Transportation
Customer	Electric Vehicle OEM
Component	Semi Truck Roof Fairing
Construction	Large One-Piece Composite Assembly
Manufacturing Method	Vacuum Infusion
Critical Requirement	±1 mm Internal Support and Hardware Positioning
Vehicle Interface	Metallic Truck Cab

The available project information establishes the manufacturing approach and required tolerance. It does not specify the final assembly weight, aerodynamic performance, production volume, or measured inspection results.

Custom Semi Truck Fairings and Transportation Components

Semi truck fairings are exterior structures designed to manage airflow around the vehicle. Roof fairings can help guide air over the cab and toward the trailer, depending on the vehicle’s configuration.

Composite manufacturing offers flexibility when developing these large exterior shapes. Performance Composites supports custom transportation projects involving molded structures, protective housings, and complex assemblies.

Semi Truck Roof Fairings

A semi truck roof fairing must match the cab geometry and accommodate the intended mounting arrangement. The shape and dimensions depend on the vehicle’s design and aerodynamic requirements.

Large Composite Body Panels

Large body panels require tooling that maintains the intended surface geometry. Manufacturing considerations include reinforcement placement, mold stability, trimming, and surface finishing.

Custom Transportation Enclosures

Composite enclosures can be designed around equipment dimensions, access requirements, and mounting features. These components may require additional machining and assembly operations before installation.

Transportation Composite Manufacturing in California and Nevada

Performance Composites manufactures custom composite components for transportation OEMs and industrial customers throughout the United States. Our manufacturing operations include a 53,000-square-foot facility in Compton, California, and a 51,000-square-foot facility in Reno, Nevada.

These locations support customers in Southern California, Northern California, Nevada, and other major transportation manufacturing markets. Our capabilities extend from prototype development through production, with engineering and manufacturing resources for specialized composite applications.

Why Transportation OEMs Work with Performance Composites

Large composite components require more than mold fabrication. Manufacturers must coordinate component geometry, production methods, dimensional requirements, and finishing operations.

Performance Composites brings more than 40 years of composite manufacturing experience to custom OEM projects.

Our capabilities include:

Engineering and Design Support
CAD-Based Tooling Development
In-House Mold and Fixture Manufacturing
Vacuum Infusion and Light RTM
Prepreg and Hand Layup Manufacturing
CNC Routing and Machining
Hardware Installation and Assembly
Dimensional Inspection
Surface Finishing and Painting
Prototype and Production Manufacturing

PCI is ISO 9001:2015 certified and provides American-made composite manufacturing services.

Discuss Your Custom Truck Fairing Project

Developing a semi truck roof fairing or another large transportation composite component? Performance Composites provides engineering, tooling, vacuum infusion, and production support for custom OEM applications.

EV Semi Truck Composite Fairing FAQs

Why are fiberglass enclosures used for telecommunications equipment?

Fiberglass offers corrosion resistance, electrical insulation, and the ability to form complex shapes. Its RF-transparent properties make it suitable for many antenna covers, radomes, and communications housings. Actual signal performance depends on the resin system, laminate thickness, and operating frequency.

Can Performance Composites manufacture custom fiberglass radomes?

Yes. Performance Composites manufactures custom fiberglass radomes and antenna covers according to customer drawings and technical requirements. Components can be developed around specific equipment dimensions, mounting features, and environmental conditions. Material selection must account for the required RF performance.

Are composite enclosures suitable for outdoor telecom equipment?

Composite enclosures can be designed for outdoor installations requiring corrosion resistance and structural protection. Appropriate materials and surface finishes must be selected for expected moisture, temperature, and UV exposure. Specific environmental ratings depend on the completed enclosure design and testing requirements.

Can Performance Composites provide finished telecom enclosures with mounting hardware?

Yes. Our capabilities include CNC machining, hardware installation, painting, finishing, and assembly. Components can be supplied with specified mounting features and installed hardware according to approved drawings and bills of materials. Final inspection requirements are established with the customer.

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