CFRP inspection and Quality Assurance

Contents

Introduction
What is Carbon? Delving into CFRPs
- Challenges
CFRP Molding Methods
Autoclave Molding Method: The Hallmark of High-quality CFRP Product Manufacturing
Uchida CFRP Testing
- CFRP Quality Assurance
Uchida’s Commitment to CFRP Inspection and Quality Assurance
Summary

Introduction

Uchida has been molding and processing composite materials (FRP) since establishment in 1968. Our operations focus on leveraging the distinctive “lightweight, strong, and non-corrosive” characteristics of CFRP to deliver new potential in next-generation mobility and weight reduction. In this issue, we aim to offer a specialist manufacturer perspective on CFRP inspection and quality assurance.

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.

Uchida CFRP Testing

There are several precautions that need be taken when handling CFRP.

CFRP Quality Assurance

1. Knowledge of its Anisotropic Structure (Fiber Orientation)

As a review, CFRP is an anisotropic material whereby the strength is determined by direction of the fibers. It therefore requires expert understanding of the internal structures of the manufactured product, including how the fibers are orientated, the lamination configuration, what types of resins are used as the matrix, and what specific properties each of these exhibits.

2.Thorough Engineering Management and Control

Commitment to Engineering Management and Controls

The CFRP sheets (prepregs) processed in the Lamination Room have a use-by-date like that of food, and generally requires storage in temperatures of 18℃ or below. The handling of prepregs drastically impacts the quality, requiring meticulous management and traceability of material exposure times and temperature/humidity levels from the time of removal from the freezer to cutting, lamination, vacuum-bagging, and autoclaving. Regardless of how proficiently our technicians perform the work, if the proper engineering management and controls aren’t put in place, then major defects may arise down the track after molding.

The lamination process involves layering ultra-fine carbon sheets of 0.2mm, to form a laminate stack, and is a key determining factor for strength and rigidity. Thus, any shortcomings in engineering controls risk impacting the structural integrity, causing internal defects which are not detectable with external inspection. Such processes whereby defects cannot be detected down the track are referred to as “focused processes.” During lamination, multiple cross-checks are performed by technicians and inspectors to confirm the correct fiber orientation and ensure against human errors such as failure to remove protective films, preventing defects before they occur.

Uchida’s Commitment to CFRP Inspection and Quality Assurance

Uchida Inspection Room

The Inspection Room oversees in-process mold inspection and primary/final inspections of molded CFRP products. It is the end-of-the-line before delivery in our one-stop manufacturing which starts from design and analysis through to mold fabrication, lamination, molding, secondary processing, painting/coating, final inspection, and testing.

Commitment to “Measurement Customized to the Site.”

With our business focus on prototype development and high-mix low-volume production, the degree of precision and quality required varies by customer and product. Prototype development attracts numerous requests for short turnarounds, in which case, each section coordinates what is needed for the job and commences production before the specifications have been 100% finalized. As the primary and final inspections are performed according to manufacturing flow, measurements cannot be taken according to the predetermined schedule. For this reason, the Inspection Room works to maintain flexible measurements in tune with the manufacturing (flow of work site).

Commitment to Enhanced Facilities

We house a range of testing devices including non-contact coordinate measuring machines (CMM), constant temperature bath-equipped static universal testing machines (UTM), ultrasonic testing (UT) equipment, and inverted microscopes.

Inspection Equipment Introduction

INSTRON　Static Universal Testing Machine 5985

ESPEC CORP.　Temperature & Humidity Chamber

Olympus Corp.　Inverted Microscopes

AMETEK CREAFORM MetraSCAN750 Elite

Toshiba Matrixeye EX　(Ultrasonic flaw detector)　Matrix-Arrey : 32

Summary

In this issue, we covered inspection and quality assurance through an overview of CFRP manufacturing. We hope this provided some insight into the variety of non-destructive inspection and testing involved in “focused processes.”

If considering manufacturing CFRP products, we suggest that you seek a manufacturer that is well-versed in CFRP and has a proven track record in the field.

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.

See Details

UCHIDA's equipment

We have cutting-edge equipment to ensure that we can address even the most advanced challenges of our customers.

DMG森精機 - VS1000/40/2050
X軸：2,050mm（ストローク）／ Y軸：1,000mm ／ Z軸：600mm ／テーブル作業面：2,250×1,000mm

ASHIDA MFG Co., Ltd.
Autoclave Oven 2
Size : Ø1,150x1,000mm / Operating temperature : at normal temperature - 400℃ / Design pressure : 2.0Mpa (maximum working pressure) / Vacuum system : back suction system / Vacuum units : 5

ASHIDA MFG Co., Ltd.
Autoclave Oven 3
Size : Ø3,000x6,000mm / Operating temperature : at normal temperature - 200℃ / Distribution accuracy : ±2.5℃less / Heating rate : 4.0℃/min. (empty furnace) / Cooling rate : 4.0℃/min. (empty furnace) / Design pressure : 0.99Mpa (maximum working pressure) / Working pressure : 0.7Mpa less (if no specification from the manufacuturer 0.3Mpa around) / Pressure accuracy : ±0.02Mpa（for pressure setting of ０ - 0.99Mpa/cm²） / Boost pressure accuracy : 0 - 0.03Mpa/min / Pressure source : compressed air (regular use) / Vacuum system : back suction system / Vacuum units : 10

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

Oven
Size : W1,000xH1,000xD1,000mm / Temperature range : Environmental Temperature +20 - 300℃ / Temperature elevation capability : Environmental Temperature (20 - 40℃) - 300℃ / 45min less / Vacuum system : back suction system / Vacuum units : 10

ESPEC CORP.
Temperature & Humidity Chamber

INSTRON
Static Universal Testing Machine 5985

Oven
Size : W7,000xH3,000xD2,000mm / Temperature range : Environmental Temperature +20 - 300℃ (Max) / Temperature elevation capability : Environmental Temperature (20 - 40℃) - 300℃ / 60min less / Vacuum system : back suction system / Vacuum units : 10

NEO
X axis : 4,000mm (stroke) / Y axis : 2,000mm / Z axis : 1,200mm / C axis : 0° - ±270° / B axis : 0° - ±110° / Table working place : 4,000x2,000mm

【開発】
3Dプリンター | Markforged

Painting booth
Various painting, and clear finish is done in dedicated painting booth

Adhesion, Finishing, Coating Room
Finishing process, such as trimming, drilling, and bonding, surface treatment of the molded product type and is done in a private booth

Toshiba Matrixeye EX (Ultrasonic flaw detector)
Matrix-Arrey : 32

AMETEK CREAFORM Metra
SCAN750 Elite (3D scan)

Olympus Corp.
Inverted Microscopes

Oven
Size : W450xH450xD450mm / Temperature range : Environmental Temperature +20 - 650℃ / Temperature elevation capability : Environmental Temperature+50 - 650℃/120min less

Cutting Plotter Table working place : W1,500xL3,500mm

SHIMA SEIKI MFG., LTD
Cutting Plotter

KUKA
Robot

Krauss Maffei
Epoxy resin injection machine Resin 60L ／ Hardener 25L

Krauss Maffei
630t Press machine Height total 5,200mm ／ Length max 1,500mm ／ Width max 1,200mm ／ Whole cycle time per component part 240sec

DMG森精機 - NV5000B/40
X軸：1,020mm（ストローク）／ Y軸：510mm ／ Z軸：510mm ／テーブル作業面：1,320×600mm

Big sized clean room
JIS B 9920 cleanliness class maximum concentration (Pcs/m³） / Class 5 : 100,000m³ / Capacity : m² (16,000x16,000mm) 760m² (16,000x16,000x3,000mm) / Temperature and humidity condition : Temperature : 23℃±3℃, Humidity 65% less / Ambient conditions : Temperature 35℃ during summer, Humidity 70% less / Ambient conditions : Temperature 35℃ during summer, Humidity 70% less / Temperature -5℃ during winter, Humidity 40% less