The Cost of Prototyping CFRP and Carbon Vol.1 Autoclave Molding Method

Contents

Introduction
Overview
CFRP and Carbon Prototyping
Process
Process Explanation
Summary

Introduction

The lightweight and highly robust characteristics of carbon fiber reinforced plastic (CFRP) have affected huge traction and widespread application in diverse industries from aerospace and automobile fields to sports and leisure markets. However, the complex manufacturing processes and costs of CFRP products that arise from the need for specialized material design and product-specific manufacturing are often difficult to comprehend for people from outside industries.

Overview

Unlike metals and other isotropic materials, CFRP can assume different strengths and properties depending on the orientation of the carbon fibers (anisotropic). The distinct characteristics of the carbon fiber, combined with those of the resin used as the matrix, offer incredible design versatility and freedom. Despite such advantages, mainstream use of CFRP is still shadowed by high production costs due to the highly complex design and manufacturing processes involved. In this series (Vol.1 to Vol.4), we will discuss the key costs for prototyping CFRP.

CFRP and Carbon Prototyping

Autoclave Molding Method

First, we will introduce the autoclave molding method commonly used to create CFRP prototypes.

WORK FLOW

First, we will introduce the autoclave molding method commonly used to create CFRP prototypes.

Materials

CFRP molds are fabricated from either gypsum (plaster), metals, or CFRP depending on the final product design and production lot. Gypsum offers superb machinability combined with similar low thermal expansion efficient characteristics to that of CFRP, making it a highly compatible choice. In terms of materials, for autoclave molding we employ carbon fiber sheets pre-impregnated resin, known as a prepreg.

Process

First is the consultation stage. At Uchida, we welcome requests from any stage of product design, including the conceptual or pre-drawing stage. Next, we create a design that will bring the idea from the drawing board to actual production.

Process Explanation

In this section, we will detail the production process using a plaster mold.

First, is the modeling stage. This stage begins with a 3D model creation of the final product which is then used to fabricate the mold. To accomplish the final structural design of the product, modeling and mold fabrication must comply with the criteria and specifications of the mold and the constraints of the machining center (facility). After the post-processing inspection, the surface of the mold is coated with resin or a mold release agent to prevent the prepreg material from adhering to the mold during the molding stage. * Functions similar to the Teflon coating in a frypan.

Next, the prepreg is sliced from the roll using cutting data from the product design. Prepregs have a use-by date like food and, while it depends on the manufacturer, usually last for six months to a year in frozen storage. Prepregs that surpass the use-by-date are not covered by the manufacturer’s warranty and therefore discarded.

Once cut, the prepregs are laminated in a clean room. Each prepreg is stacked layer-by-layer forming a laminate stack accordant with the fiber orientation and design. The completed laminate stack is then wrapped in a vacuum bag (similar to vacuum-sealed bags used when traveling), in a process known as vacuum-bagging, and placed into the autoclave which molds the product under highly controlled temperatures and pressures.

Finally, the cured product is removed from the mold and the final finishing processes, such as trimming and removing excess edges, hole drilling/cut-outs, or adhesive assembly, take place using our machining centers and electric tools.

Summary

In Vol.1, we covered the CFRP and carbon prototyping from a manufacturing standpoint. In the upcoming Vol.2 and following, we will delve into the material, labor, and equipment costs alongside lead times and companies that handle CFRP projects.

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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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

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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