Cutting, Processing and Machining FRP, GFRP and CFRPs

Introduction

Uchida has been molding and processing composite materials (FRP) since its establishment in 1968. Our business centers on paving new pathways in next-generation mobility and weight reduction through the advancement of CFRP and its distinctive “lightweight, strong, and non-corrosive” characteristics. In this issue, we will discuss CFRP machining from a standpoint.

What is Carbon? Delving into CFRPs

While the term carbon fiber refers to thin strands of carbon, these fiber strands will not retain their form on their own. Thus, they are combined with a resin to retain the shape and maximize its distinct lightweight and strong characteristics.

Composite materials are substances composed of two or more constituents, such as carbon fiber and resin, to yield new functions. Carbon fiber reinforced plastic (CFRP) is the name given to a composite created from carbon fiber and resin.

The composite is named after the type of fiber employed. Carbon fiber composites are named carbon-fiber reinforced plastic (CFRP), glass fiber composites are referred to as GFRP, and aramid fiber composites are called AFRP.

The distinctive “lightweight, strong, non-corrosive” qualities of advanced CFRP has opened doorways for leading-edge development in various fields, such as aviation, satellites, automobiles, and sporting and leisure equipment industries. Unlike metals and other isotropic materials, with CFRP, the strength is determined by the orientation of the carbon fibers (anisotropic) and therefore necessitates product-specific material design. The high degree of design versatility, in terms of resin and carbon-fiber constitution and arrangement, means that is volatile and difficult-to-handle without expert technical knowledge of the material and its properties.

Challenges

Despite its numerous merits, CFRP is still succumbs to various challenges in productivity and cost-efficiency. These include the need for molds, high material costs, and complex production processes.

CFRP Molding Methods

Before delving into CFRP processing, let’s first look at molding methods. There is a wide variety of CFRP molding methods which are selected according to the desired application, shape/form, and production lot.

Autoclave Molding

RTM (Resin Transfer Molding) 

Va-RTM (Vacuum Assisted Resin Transfer Molding)

Press Molding

Hand Lay-up Molding

Filament Winding Molding

Sheet Winding Molding

Pultrusion

3D Printer

At Uchida, we use the fabrication methods shown in red.

Autoclave Molding Method: The Hallmark of High-quality CFRP Product Manufacturing

Despite the extensive range of molding methods, autoclave molding remains the hallmark method for design versatility and high-quality CFRP fabrication. High-quality CFRP created using the autoclave molding method is known as dry carbon. This method is suitable for prototyping and small-lot production as it does not require expensive metal molds. The diagram below illustrates the production process of CFRP products using the autoclave molding method.

Autoclave Internal Thermal Heating and Pressurization Processes

CFRP Cutting, Processing and Machining

There are some important points to note when machining CFRP.

(1)Knowledge of its Anisotropic Structure (Fiber Orientation)

As a review, CFRP is an anisotropic material whose strength depends on the direction of the fibers. Thus, machining requires a specific understanding of the fiber orientation, lamination structure, and properties of the resin used as the matrix. Proper machining paths cannot be created without unique know-how on CFRP (composite material) handling and property variances, such as differences in machining resistance depending on the amount and orientation of the fibers, laminate configuration, or differing thermal properties contingent on the resin.

(2)Dry Processing Prerequisites

Cutting oils are incompatible with CFRP machining due microscopic liquid-absorbing properties of the carbon fibers which soak up and retains the oils if immersed. Although moisture absorption is not visible on the exterior, as any soaked surfaces may delaminate after long-term use of the product, we must exercise caution when handling the material. If using the products in humid environments, we will specially treat the surface with paint or sealant after machining to prevent moisture absorption.

Uchida’s Dedication to CFRP Machining

– Uchida Tool and Jig Room

The Jig and Tool Room is the center (department) for CFRP processing. Here we design and manufacture molding dies, inspection or adhesive jigs, and other tools used for CFRP molding in our machining center, alongside secondary processing of CFRP products after molding. At Uchida, we offer one-stop services ranging from design and analysis to mold fabrication, laminate molding, secondary processing, coating, inspection, and testing. And our Jig and Tool Room oversees getting the entire manufacturing process rolling.

Commitment to Molding

For CFRP products, while mold processing is an important and quality-critical process, the most fundamental step is the designing of the mold. The mold determines the quality of the product.

At Uchida, our proficiency in large complex and monolithic molded products combined with extensive experience across diverse fields allows us to accommodate even the most difficult requests. We are further leveraging our strengths in one-stop manufacturing to produce “easy-to-use” molds that cater to downstream or post-processing processes. An easy-to-use mold is designed and processed to best match the production quantity and mold materials, based on an understanding of the product structure, while delivering effortless stacking, marginal temperature irregularities, minimal breakage during handling, and easy handling capacities. The most essential element in molding is an adept understanding of the entire manufacturing process.

Commitment to CFRP Machining

While we say CFRP machining, the item often employs a different internal material. Many of the CFRP products we manufacture are complex structural items with foam or metal inserts at the time of molding. In machining, we conduct prior investigations for (1) understanding CFRP anisotropy and resin, and (2) CFRP parts composited with metal, to determine the optimal machining method. Even the most complex composite product, such as the above, machine processing is generally performed dry. At Uchida, we possess vast experience in drilling, thread tapping, trimming, and 3D-shape machining, and employ a wide range of tools based on specific knowledge of CFRP’s characteristics.

UCHIDA Machining Center

Large, high-precision 5-axis machining center for meeting diverse needs and requests.

DMG MORI TVCM “Front Runner Vol.46 UCHIDA Co., Ltd.”

Summary

In this issue, we explored machining processes through an overview of CFRP manufacturing. CFRP manufacturing demands specialized knowledge and know-how of the material, and major problems can easily arise if machined without a thorough understanding of its structural properties. Moreover, as CFRP is generally dry processed, we cannot process it with metalworking machines that use cutting oils.

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ABOUT UCHIDA - 55 years since our founding

We leverage a wealth of technical expertise as a CFRP molding and processing manufacturer using FRP, GFRP, and CFRP materials. We offer a one-stop solution, encompassing design, analysis, manufacturing, secondary processing, assembly, painting, quality assurance, and testing.

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