1、 AEROSPACE INFORMATION REPORT Repair Tooling Issued 2004-12 AIR5431 TABLE OF CONTENTS 1. SCOPE 2 2. REFERENCES.2 3. GENERAL3 4. MATERIALS.4 5. TOOLS (EXAMPLES) 9 6. PREPARATION OF TOOL SURFACES 13 7. MAINTENANCE AND STORAGE15 8. INSPECTION OF TOOLING15 APPENDIX A TOOL MANUFACTURING METHOD (ONE SPECI
2、FIC EXAMPLE)16 SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement
3、arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2011 SAE International All rights reserved. No pa
4、rt of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1
5、 724-776-4970 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR5431Reaffirmed 2011-11RATIONALEThis document has been reaffirmed to
6、 comply with the SAE five-year review policy. SAE AIR5431 - 2 - 1. SCOPE: This SAE Aerospace Information Report (AIR) offers information about the use of support tooling for composite repair processes, as well as descriptions of some of the different tooling materials used and their applications. If
7、 the repair document requires the use of tooling, refer to this AIR for additional information. 1.1 Purpose: The purpose of this AIR is to provide a general information and guidance in selecting materials and provide an example of a manufacturing technique for tooling used in the repair of thermoset
8、ting composite components. 2. REFERENCES: 2.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. ARP4916 Masking and Cleaning of Epoxy and Polyester Matrix Thermosetting Composite Materials ARP5143 Vacuum Bagging of Thermosetting Composite Repairs ARP5144 Heat A
9、pplication for Thermosetting Resin Curing ARP5319 Impregnation of Dry Fabric and Ply Lay Up 2.2 OEM Manuals 2.3 Other References: Composites Volume 1 Engineered Materials Handbook ASM International METALS PARK , OHIO 44073 SAE AIR5431 - 3 - 3. GENERAL: As the use of the composite material has increa
10、sed over the past years, the size and the number of the components has also increased, as has the geometrical contour complexity. Also the wider use of complex composite components has increased the need for repair tooling.The need for performance of larger repairs and the geometric complexity neces
11、sary leads to the situation that these repairs cannot be performed without any aid of tooling in order to support the total shape of the component and/or to restore and retain the geometric contour in the repair area. In particular , large area repairs done without tooling, often led to scrapping th
12、e component due to distortion. The tooling/mold must be manufactured to sustain the specific curing cycle load without deformation, leakage or other damage. To achieve an effective and economical repair it is essential that the most appropriate tooling material and process is used. The factors influ
13、encing the material and process must be investigated; especially the materials thermal characteristics. To choose the most appropriate tooling material, tooling manufacturing technique and repair tool type, the following options and factors must be considered: a. The geometric contour, the complexit
14、y of the repair part, and the required dimensional tolerances (including spring back). b. Coefficient of Thermal Expansion (CTE) - An important factor is the coefficient of thermal expansion of the component material and the repair tool material. Selecting an inappropriate factor can result in subse
15、quent distortion of the component. c. Schedule - The time available to complete the repair. d. Required Tool Life e. Cure Temperature, Pressure and Repair Size f. Dimensional stability and resistance to creep at the cure temperature, especially if the tool will be used many times. SAE AIR5431 - 4 -
16、4. MATERIALS: The component to be repaired is the reference for the dimension and the geometric contour of the tool. If the tool is not totally enclosed in the vacuum bag, the tool must be vacuum tight. All repair tools must sustain the pressure and the temperature used for the repair. The thermal m
17、ass and conductivity of the tooling material should be compatible with the selected repair process. In most cases, the repairs will be performed at elevated temperatures. Tool durability is influenced by the different maximum operating temperatures of the materials. When selecting tooling materials
18、consider the following characteristics: - Thermal expansion coefficient compatible with the component materials to prevent distortion of the component during the repair cure cycle. - Low thermal mass with high thermal conductivity for autoclave and oven processing. The thermal mass of a given toolin
19、g material, shown in the figure 3, is found by multiplying its specific heat by its density for a given volume. - Low thermal conductivity for heat blanket or lamp cure. - Low weight for ease of handling. - Ability to maintain contour at the repair cure temperature. The following repair tooling mate
20、rials should be considered: - composite tooling Carbon Fiber Reinforced Plastic (CFRP) (Made from Wet lay up or Prepregs) Glass Fiber Reinforced Plastic (GFRP) (made from Wet lay up or Prepregs) - metallic tooling materials Aluminum SteelElectroformed Nickel- elastomer tooling material Rubber room t
21、emperature vulcanizing (RTV) Elastomer Silicone Rubber Sheet (for surfacing or caul sheet) - non metallic castable compounds Plastics Plaster, Gypsum or Cast Ceramic - can be reinforced with glass fibers SAE AIR5431 - 5 - 4. (Continued): The specific properties of these materials are: TABLE 1 Toolin
22、g Mat. Tooling Properties Comments CFRP - low density - low CTE - low thermal conductivity - low heat mass - preferred material for repair tools for CFRP parts- high cost GFRP - low density - low CTE (similar to steel and nickel) - low thermal conductivity - medium heat mass - preferred material for
23、 repair tools for GFRP parts and acceptable for AFRP(Aramid Fiber Reinforced Plastic) parts - difficult for CFRP parts - low cost Aluminum - medium density - high CTE - very high thermal conductivity - medium heat mass - very difficult for CFRP/AFRP parts due to high CTE.- can be used for flat surfa
24、ces and single curvatures- low cost Steel - high density - medium CTE - high thermal conductivity - high heat mass - acceptable material for repair tools for CFRP/ AFRP/GFRP parts due to CTE - medium cost Nickel(electroformed)- high density - medium CTE - high thermal conductivity - high heat mass -
25、 acceptable material for repair tools for GFRP/ CFRP/AFRP parts when total tool mass is low - high cost SiliconeRubber- ability to cast intricate shapes - ability to reproduce the surface finish it is cast from - used for consolidation of complex shapes - used to impart a required surface finish - P
26、ossible contamination of bonding surfaces from uncured material SAE AIR5431 - 6 - Plaster,Gypsum- high accuracy - low thermal conductivity - low CTE - easy to handle - limited in temp. to 110 C (230 F) - often used as an intermediate plug/ splash to make tool - needs to be sealed before use - low co
27、st Ceramic - high accuracy - low thermal conductivity - low CTE - high temp. resistance - high cost 4. (Continued): Tooling Material for Repair Application - Summary a. CFRP tooling material is preferable for all CFRP-parts. b. GFRP tooling material is preferable for GFRP-parts and acceptable for AF
28、RP parts. c. Steel tooling material is preferable for large GFRP and CFRP parts, when the differential CTE can be calculated and compensated. d. Nickel (electroformed) tooling material is primarily only used during original production. e. Aluminum tooling material: CTE must be calculated during tool
29、 dimensioning. The following charts compare the different properties of the possible materials, which can be selected for the tooling manufacture. NOTE: Nickel refers to electroformed nickel tooling material. SAE AIR5431 - 7 - FIGURE 1 FIGURE 2 SAE AIR5431 - 8 - FIGURE 3 FIGURE 4 SAE AIR5431 - 9 - 5
30、. TOOLS (EXAMPLES): a. Plate for repair of flat surfaces of carbon fiber componentsFIGURE 5 A slip sheet is used when the entire component will be vacuum bagged and heated. Slip sheets are highly recommended for aluminum plate to allow the part and the slip sheet to move relative to the support tool
31、. This prevents distortion of the component during cure that would result from differences in CTEs between the part and the support tool. For small repairs a PTFE sheet is sufficient if a heat blanket cure is performed. If tooling plate has a similar CTE to the part being repaired no slip sheet is r
32、equired. SAE AIR5431 - 10 - 5. (Continued): b. Full contour support tool to support geometrical profiles FIGURE 6 Elevated temperature repairs cured at or near the original component cure temperature require full support of the whole contour. Some parts with high dimensional tolerances may have low
33、curvature but may still require tooling with a compatible CTE. Other parts with low dimensional tolerances may have greater curvature and can use tooling with a less compatible CTE. A general consideration for high temperature part is to provide full support for the whole contour when the cure tempe
34、rature is within 50oC below the original cure temperature of the component. In certain repair cases, such as large area repairs or very complex geometry, the tooling to be used should be similar to the manufacturing tooling. This figure shows typical tooling, that would be used for an autoclave or o
35、ven application with a surface vacuum bag. If the tool is intended to be used inside an envelope vacuum bag the support structure would be changed to prevent distortion of the tool. Consult the OEM to determine if envelope bagging of part is acceptable. Consult the repair document or the OEM to dete
36、rmine original component cure temperatures.SAE AIR5431 - 11 - 5. (Continued): c. Local contour support tool FIGURE 7 d. Support Block - Support block must be designed to be removable without damaging the repaired component.- When fabricating the block using casting materials, apply release agent or
37、parting film to the spar cavity before filling. SAE AIR5431 - 12 - FIGURE 8 5. (Continued): e. Alignment fixture An alignment fixture is used to: - Align fittings during reinstallation after a repair - Check fitting locations and alignment - Alignment of bonded - in fittings during cold bonding inst
38、allation process SAE AIR5431 - 13 - FIGURE 9 6. PREPARATION OF TOOL SURFACES: This section describes surface preparations that are used to provide release of the tool from the master model or the repaired component from the tool. Master models are typically painted with a polyurethane coating which
39、can be coated with liquid release agents.Liquid release agents should not be used on un-aged (not fully cured) polyurethane coated surfaces because the chemical interaction will prevent the release of the component from the tool. SAE AIR5431 - 14 - 6. (Continued): Possible release materials are bond
40、able films, release films, wax, liquid agent, etc. Before applying the release material, an epoxy paste can be applied onto the surface to fill any surface irregularities. This layer can be sanded to provide a smooth surface. Many release materials can transfer contaminants to the part surface. Ensu
41、re the contamination is removed from the surface prior to secondary bonding operation. Following materials can be applied as release layers: a. ONE SIDE Bondable PTFE Film advantages: seals tool surface against vacuum. easy to apply. some can provide for release for multiple cure cycles. disadvantag
42、es: component curvatures require the material to be cut into gores. When used with high CTE tools wrinkles in the film may occur. b. Liquid Release Agents advantages: easy to apply to complex components with curvature provides release for multiple cure cycles disadvantages does not seal surfaces for
43、 vacuum integrity potential release agent transfer c. Wax Release Agent advantages: excellent surface finisher disadvantages: only good for one cycle requires polishing potential release agent transfer only good for low temperature cure SAE AIR5431 - 15 - 6. (Continued): d. Release Film advantages:
44、can be quickly applied applicable for all temperatures disadvantages: can only be used on single curved parts due to the possibility of wrinkles on complex curvature parts low quality surface finish, particularly for use on master models 7. MAINTENANCE AND STORAGE: After using the tool, remove any r
45、esidual release agent and clean thoroughly. Make sure, that the repair tool is used and stored carefully in order to avoid any damage. Check smoothness, if necessary fill existing voids and perform necessary repairs to restore the tool. Store the tool safely in a dry environment preferably at room t
46、emperature. For prolonged storage it is recommended that tooling is covered with a protective sheet. Avoid placing loads on the tool during storage. Identify the tool with a part number for record keeping and which provides a link to the applicable component. 8. INSPECTION OF TOOLING: A tooling insp
47、ection plan is required to make sure that each tool is fit for use prior to using the tool to perform a repair. Make sure, that tool is free from damages. Check measurement of geometrical contour. Check the surface quality. Before using the tool, check vacuum integrity, if necessary, perform repair
48、to achieve its desired level. If using a commercial tooling system follow the manufacturers instructions. PREPARED UNDER THE JURISDICTION OF AMS COMMITTEE “CACRC“ SAE AIR5431 - 16 - APPENDIX A TOOL MANUFACTURING METHOD (ONE SPECIFIC EXAMPLE) This appendix gives an example for making a durable tool f
49、or autoclave or oven application. As detailed in previous sections, several manufacturing concepts and tool materials can be chosen. This example describes the manufacturing of a CFRP mold tool. The following ARPs may be used for general reference in tooling manufacture ARP4916 Masking and Cleaning of Epoxy and Polyester Matrix Thermosetting Composite MaterialARP5143 Vacuum Bagging of Thermosetting Composite Repairs ARP5144 Heat Application for Thermosetting Resin Curing ARP5319 Impregnation of Dry Fabric and Ply Lay Up The preferred mold tool material for repa
