1、_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 arising theref
2、rom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, stabilized or cancelled. SAE invites your written comments and suggestions.Copyright 2012 SAE International All rights reserved. No part of this publ
3、ication 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: +1 724-776-4970 (
4、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/ARP4992BAEROSPACERECOMMENDEDPRACTICEARP4992 REV. B Issued 1996-08 Revised 2012-01Supe
5、rseding ARP4992A Periodic Test for Processing Solutions RATIONALEARP4992B results from a Five Year Review and update of this document. 1. SCOPE 1.1 ScopeThis SAE Aerospace Recommended Practice (ARP) describes a method for classifying the frequencies of analysis of solutions used in the processing of
6、 metals, such as electroplating, anodizing, and conversion coating and associated processes but usage is not limited to such applications. 1.2 Intent This document is intended to establish a periodic test plan that may be used by processors to satisfy the requirement of an Aerospace Material Specifi
7、cation (AMS) for a chemical processing solution periodic test plan as a control factor. 1.3 LimitationThis document does not fulfill the criteria for a formal statistical process control program. 2. APPLICABLE DOCUMENTS This section is not applicable to this document. 3. TECHNICAL REQUIREMENTS 3.1 T
8、he analysis of process solution constituents shall be performed at such a frequency as to ensure that the solution is not operated beyond the concentration limits authorized by the applicable specification or work instruction. SAE ARP4992B Page 2 of 4 3.2 Classes of test frequency used herein. TABLE
9、 1 CLASSES OF TEST FREQUENCY Class Frequency of Analysis Y Annually 2Y Semiannually 4Y Quarterly 6Y Bimonthly M Monthly 2M Biweekly W Weekly 2W Semiweekly 3W Three times each week D Daily SH Once each working shift BP Before processing each production load 3.3 Definitions 3.3.1 Specification Range:
10、The concentration range of a constituent in a solution required by the applicable process specification or work instruction. 3.3.2 Process Control Range: A concentration range that is 75% of the Specification Range. It is a tool used to aid in the establishment of a frequency of process control test
11、ing. 3.3.3 Work Instruction: A document that provides detailed processing or solution control instructions for fulfilling specified requirements.3.4 Calculation of Process Control Range 3.4.1 Subtract the lower permissible concentration limit to the Specification Range (A) for each constituent from
12、the higher permissible concentration limit to the Specification Range (B) and multiply by 0.25. 3.4.1.1 For those processes where a constituents concentration decreases with use, add this value to the lower permissible limit. The upper limit value remains as specified by the process specification or
13、 work instruction (B). Lower limit to Process Control Range = A + (B-A) x 0.25. 3.4.1.2 For those processes where a constituents concentration increases with use, subtract this value from the higher permissible limit. The lower limit value remains as specified by the process specification or work in
14、struction (A). Upper limit to Process Control Range = B - (B-A) x 0.25. 3.4.2 When there is no lower limit to the Specification Range, only a maximum limit, multiply this number by 0.75. Upper limit to Process Control Range = 0.75 x B. 3.4.3 When there is no upper limit to the Specification Range, o
15、nly a minimum limit, multiply this number by 1.33. Lower limit to Process Control Range = 1.33 x A. SAE ARP4992B Page 3 of 4 3.5 Example Calculations The following example applies to AMS2649, Etch Inspection of High Strength Steels. All these concentrations or values normally decrease with use. TABL
16、E 2 EXAMPLES OF PROCESS CONTROL RANGE ESTABLISHED FROM A SPECIFICATION RANGE Constituent Specification Range Process Control Range Nitric Acid 3 to 5% by volume 3.5 to 5% by volume Sodium Hydroxide 2 to 6% by weight 3 to 6% by weight Sodium Phosphate 0.5 to 1.0 oz/gal (3.7 to 7.5 g/L) 0.625 to 1.0 o
17、z/gal (4.7 to 7.5 g/L) 3.6 Adjustments to the concentration of any constituent shall be made whenever its concentration is found to be outside the Process Control Range in order to bring the concentration to within the Process Control Range. It is preferable to adjust the concentration to the opposi
18、te extreme of the Process Control Range (A or B). 3.7 Determination of Class 3.7.1 Initial Frequency Class: Sampling frequency rate for a solution for which there is no history-of-use should be analyzed at a frequency selected by the processor unless specified by the cognizant engineering or quality
19、 organization.3.7.2 Adjustment of Frequency: If three analyses for any individual constituent of a process solution out of the previous ten consecutive analyses show that constituent to be outside of the Process Control Range, the frequency of analysis for that constituent shall be increased by prog
20、ressing to the next more frequent analysis class stated in Table 1. If ten consecutive analyses show the constituent has been within the Process Control Range, the frequency of analysis may be decreased by selecting an adjacent (next less frequent analysis) class stated in Table 1. 3.7.2.1 Infrequen
21、tly Used Solutions: If a solution is not used regularly or has not been used since the last analysis, periodic testing may be suspended. However, this solution must be analyzed and shall be within the Specification Range prior to use. 3.8 Unspecified Concentrations When there is no Specification Ran
22、ge for any constituent contained in the applicable process specification or work instruction, or there is no requirement that an acceptable range must be established by the processor, the process solution need not be analyzed. The solution should be discarded and replaced on a periodic basis or subj
23、ected to periodic analysis. The frequency of replacement shall be selected by the processor unless specified by the cognizant engineering organization. 3.9 A freshly mixed solution shall be analyzed and all constituent concentrations shall be within the applicable Specification Range prior to using
24、the solution to process production parts. 3.10 Sampling Technique Prior to the removal of any aliquot (test sample) from a process tank: (1) the level of the solution in the tank should be brought to normal operating level, (2) the solution temperature shall be adjusted as necessary to ensure all co
25、nstituents are dissolved in the solution and (3) if the tank level needs to be adjusted by addition of water (or other diluent), the solution shall be mixed thoroughly.3.11 When the concentration of any constituent is not within the Process Control Range yet is still within the Specification Range,
26、the solution remains usable and parts processed through such a solution are fully acceptable (with respect to processing solutions) and equivalent to those processed in a solution which is within the Process Control Range. No solution shall be used to process parts if any constituent concentration i
27、s not within the applicable Specification Range unless otherwise authorized by the cognizant engineering organization. SAE ARP4992B Page 4 of 4 4. QUALITY ASSURANCE REQUIREMENTS 4.1 The processor shall be responsible for performing all required tests. 4.2 Records The processor shall be responsible f
28、or maintaining records for a minimum of 3 years. Changes to test frequencies and reasons for the changes shall be noted in the records. Records shall be maintained sequentially in writing or electronic media.4.3 Analytical procedures shall be performed in a manner acceptable to the cognizant enginee
29、ring or quality organization.4.4 When a constituents concentration is not within the Specification Range or the solution has not been analyzed on schedule or the operating temperature is not within the range required by the applicable process specification or work instruction, the processor shall ta
30、ke appropriate action to prevent the processing of parts. A solution that has been subjected to any circumstance that could result in an out-of specification-range condition such as an overflow shall be analyzed and concentrations adjusted to specification range prior to reuse. Use of a “Red Tag” on
31、 the tank or vessel is recommended. After a correction is made to restore all constituent concentrations to within the Specification Range, the solution shall be re-analyzed to establish that the constituents concentrations are within the Specification Range before processing of parts is allowed to
32、resume. 5. NOTES 5.1 A change bar (|) located in the left margin is for the convenience of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications nor in documents that contain editorial changes only. PREPARED BY AMS COMMITTEE “B”
