1、 INCH POUNDMIL-STD-866C (USAF) 01 March 2007 SUPERSEDING MIL-STD-866B 28 June 1978 DEPARTMENT OF DEFENSE STANDARD PRACTICE GRINDING OF CHROME PLATED STEEL AND STEEL PARTS HEAT TREATED TO 180,000 PSI OR OVER This document is inactive for new design. AMSC: N/A AREA: MFP Provided by IHSNot for ResaleNo
2、 reproduction or networking permitted without license from IHS-,-,-MIL-STD-866C FOREWORD 1. This military standard is approved for use by 309MXSG/MXRL, Department of the Air Force, and is available for use by all departments and agencies of the Department of Defense. 2. This standard establishes the
3、 requirements for grinding of martensitic high strength steel, heat treated to 180,000 pounds per square inch, ultimate tensile strength and above and for grinding of chromium plating applied to such steel when such parts are intended for use in components for man-rated flight hardware. 3. Beneficia
4、l comments, recommendations, additions, deletions, and any pertinent data, which may be of use in improving this document, should be addressed to 309MXSG/MXRL, Hill AFB, UT 84056-2609 or 309MXSG/MXRLhill.af.mil. Since contact information can change, you may want to verify the currency of this addres
5、s information using the ASSIST Online database at http:/assist.daps.dla.mil. ii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-866C CONTENTS PARAGRAPHS PAGE FOREWORD i 1. SCOPE 1 1.1 Scope 2. APPLICABLE DOCUMENTS 1 2.1 General 2.2 Government
6、 documents 1 2.2.1 Specifications, standards, and handbooks 1 2.3 Non-Government standards and publication 1 2.4 Order of precedence 2 3. DEFINITIONS (Not Applicable) 2 4. GENERAL REQUIREMENTS 2 4.1 Materials and equipment 4.1.1 Materials 2 4.1.2 Equipment 4.2 Processing 2 4.2.1 Grinding process 2 T
7、able I 3 4.2.2 Cleaning 4 5. DETAILED REQUIREMENTS 4 5.1 General 5.2 Responsibility for inspection 4 5.3 Inspection requirements and procedures 4 5.3.1 Ground surface inspection 4 5.3.2 Magnetic particle inspection 5.3.3 Nital etch inspection 4 5.3.4 Ground holes 5.3.5 Chromium plate 4 5.3.6 Penetra
8、nt inspection 5 5.3.7 Magnetic particle inspection 5.4 Grinding practices 5 5.4.1 In-house control document 5.4.2 Parametric studies 5 5.4.3 Grinding practice guidelines 5.4.3.1 Grinding equipment 5 5.4.3.2 Grinding wheel characteristics 5.4.3.3 Coolants 6 5.4.3.4 Wheel dressing 5.4.3.5 Wheel speed
9、6 5.4.3.6 Work speed iii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-866C CONTENTS PARAGRAPHS PAGE 5.4.3.7 Cross-feed 6 5.4.3.8 Down-feed/in-feed 5.4.3.9 Grinding with side of the wheel 6 5.4.3.10 Chrome plate 6. NOTES 6 6.1 Intended use
10、6.2 Subject term (key word) listing 6 6.3 Changes from previous issue 7 CONCLUDING MATERIAL 7 iv Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-866C 1. SCOPE 1.1 Scope. This standard establishes the requirements for grinding of martensitic h
11、igh strength steel heat-treated to 180,000 pounds per square inch (psi), ultimate tensile strength (uts) and above, and the grinding of chromium plating applied to such high strength steel, when such parts are intended for use in components for man-rated flight hardware. 2. APPLICABLE DOCUMENTS 2.1
12、General. The documents listed in this section are specified in sections 4 and 5 of this standard. This section does not include documents cited in other sections of this standard or recommended for additional information or as examples. While every effort has been made to ensure the completeness of
13、this list, document users are cautioned that they must meet all the specified requirements of the documents cited in this standard, whether or not they are listed. 2.2 Government documents.2.2.1 Specifications, standards and handbooks. The following specifications, standards and handbooks form a par
14、t of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract. DEPARTMENT OF DEFENSE STANDARDS MIL-STD-867 Temper Etch Inspection (Inactive) (Copies of these documents are available online at http:/assist.
15、daps.dla.mil.online/start/ or from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 19111-5094.) 2.3 Non-Government standards and publications. The following documents form a part of this document to the extent specified herein. Unless otherwise specified, t
16、he issues of these documents are those cited in the solicitation or contract. SOCIETY OF AUTOMOTIVE ENGINEERS INTERNATIONAL (SAE) SAE-AMS-H-6875 Heat Treatment of Steel Raw Materials SAE-AMS-2644 Inspection Materials, Penetrant (Copies of these documents are available online at www.sae.org or from t
17、he Society of Automotive Engineers International, 400 Commonwealth Drive, Warrendale, PA 15096-1001.) AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM) ASTM E-1444 Standard Practices for Magnetic Particle Inspection 1 Provided by IHSNot for ResaleNo reproduction or networking permitted without licen
18、se from IHS-,-,-MIL-STD-866C ASTM E-1417 Practice for Liquid Penetrant Examination (Copies of these documents are available at ww.astm.org or ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Comshohocken, PA 19428-2959.) 2.4 Order of precedence. In the event of a conflict between the t
19、ext of this document and the references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 3. DEFINITIONS Not applicable. 4. GENERAL REQUIREMENTS 4.1 Material and equip
20、ment 4.1.1 Materials.a. Grinding Coolant. A suitable coolant shall be used, which does not have an adverse effect on the part being ground. Re-circulated coolants shall be either gravity separated or contaminants or continuously filtered to minimize re-cycling grinding residue. A coolant nozzle suff
21、iciently wide to flood the entire width of the wheel interface area shall be used. b. Grinding wheel. Grinding wheels shall be labeled or numbered as to abrasive type, grit size, grade, structure, bond type, and maximum operating speed. Unless otherwise specified, aluminum oxide vitrified bonded, gr
22、inding wheels shall be used. 4.1.2 Equipment.a. Grinding equipment. Grinding equipment shall be capable of maintaining grinding speed, work speed (spindle or traverse), cross feed and down feed in increments necessary to avoid surface degradation of the part. Provisions shall be made to supply a con
23、stant application of coolant to the working surface of the wheel. b. Ovens. Ovens used for baking and stress relieving shall be controlled in accordance with SAE-AMS-H-6875. 4.2 Processing.4.2.1 Grinding process. The grinding process shall be performed in accordance with Table I to result in metallu
24、rgical sound parts. All feeds, speeds, and stock removal parameters are actual and not necessarily machine or indicator readings. 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-866C 3 Provided by IHSNot for ResaleNo reproduction or network
25、ing permitted without license from IHS-,-,-MIL-STD-866C 4.2.2 Cleaning. Protective coatings and other foreign materials shall be removed from parts prior to grinding to preclude contamination of coolant and wheels. Coolant and grinding residuals that have a deleterious effect on the part shall be re
26、moved after grinding. Cleaning materials shall not corrode or otherwise degrade the surfaces of the part. Where process delay time is such that corrosion might occur, parts shall be adequately protected after cleaning. 5. DETAILED REQUIREMENTS 5.1 General. The contractor shall maintain in-house docu
27、ments designed to establish control of inspection procedures to assure that parts produced are within acceptable design criteria. The contractor shall be able to demonstrate that he is applying such controls. 5.2 Responsibility for inspection. Unless otherwise specified in the contract, the contract
28、or is responsible for the performance of all inspection requirements as specific herein. Except as otherwise specified in the contract, the contractor may utilize his own or any other facilities suitable for performance of the inspection requirements specified herein, unless disapproved by the Gover
29、nment. The Government reserves the right to perform any of the inspections set forth in this standard where such inspections are deemed necessary to assure supplies and services conform to prescribed requirements. 5.3 Inspection requirements and procedures.5.3.1 Ground surface inspection. All ground
30、 surfaces shall be visually inspected without magnification for evidence of overheating, cracks, tears and cold flow. Ground surfaces shall be checked for surface finish. 5.3.2 Magnetic particle inspection. All ground surfaces (excluding ground holes) shall be inspected by magnetic particle in accor
31、dance with ASME E-1444 or approved alternate procedure (see 5.3.4). 5.3.3 Nital etch inspection. All ground surfaces (excluding ground holes and chromium plate) shall be inspected by nital etches in accordance with MIL-STD-867 or approved alternated procedure (see 5.3.4 and 5.3.5). Water may be used
32、 as an alternate solvent for the nital etch solution. After nital etching, parts shall be baked at 375F for four (4) hours. 5.3.4 Ground holes. All ground holes shall be treated as ground surfaces unless engineering requirements, size, shape or location make magnetic particle or nital etch impossibl
33、e or impracticable. When ground holes are not inspectable by magnetic particles or nital etch, approved alternate procedures or parametric study data shall be used to establish that the surface has not been degraded (see 5.4.2). 5.3.5 Chromium plate. After final grinding of chromium plated parts, th
34、e parts shall be inspected for grinding induced damage to the chromium plate and base metal as well as base metal cracking. Penetrant inspection shall be used for the detection of plate and base metal damage and magnetic particle inspection will be used for the detection of base metal cracking for c
35、hromium plate thicknesses less than 0.004 inch per surface, penetrant inspection shall be used for detection of plate and base metal 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-866C damage. Parts shall be stripped if evidence of plate o
36、r base metal damage is found during the penetrant inspection. Re-inspect base metal in accordance with 5.3.2 and 5.3.3. 5.3.6 Penetrant inspection. Penetrant materials with SAE-AMS-2644, Level 3 sensitivity shall be used in accordance with ASTM E1417. Penetrant, emulsifier (if used) and developer dw
37、ell time shall be used that produce light background fluorescence from the chromium plate micro-cracking. Anodic etching of the chromium plate (0.0001 inch plate removal) is recommended as the preparation of the surface for inspection. Indications of damage include spiraling, chattering and coarse “
38、mud-flat” cracking. The inspection procedures developed shall include photographs for inspection reference of all rejectable conditions as well as acceptable conditions. 5.3.7 Magnetic particle inspection. Wet, continuous, fluorescent methods in accordance with ASTM E-1444 shall be used. Magnetizing
39、 currents and methods shall be used that provide adequate field strength in the part, yet do not cause burning. Because of the poor adherence of particle indications to the smooth chromium surface, the procedures developed shall minimize the chances of indication “wash-off.” 5.4 Grinding practices.
40、The grinding practices set forth in these paragraphs are recommended for optimum results under variety of, but not all, conditions. Such practices are not intended to restrict the contractor from developing technology or methodology other that described herein provided the resulting part meets presc
41、ribed criteria. 5.4.1 In-house control document. In-house control documents are those documents used by each contractor to control part configuration and quality. They include engineering drawings, engineering process specifications, manufacturing process specifications, inspection procedures and an
42、y other documents designed to control manufacturing and inspection techniques. Such documents are to be based upon proven techniques derived from parametric studies, experience, and tests. 5.4.2 Parametric studies. Parametric studies refer to the techniques used by the contractor for the purpose of
43、the initial establishment of grinding practices and inspection procedures that will consistently produce parts within the design criteria. The equipment, grinding wheels, coolant, material, heat treat, and prior processing, feeds, speeds, shall simulate the production techniques used as closely as i
44、s reasonably possible. The number of samples used shall be a matter of the contractors judgment but shall be sufficient to prove the practice and inspection procedure. 5.4.3 Grinding practice guidelines. Grinding practices include control of all the following factors. Lack of control or improper sel
45、ection of any of these factors can cause decrease in structural integrity. 5.4.3.1 Grinding equipment. The grinding equipment shall be capable of operating in the required wheel speed, feed rate, and work speed ranges, and shall have adequate horsepower to maintain required wheel speed and shall be
46、in good mechanical condition (spindle and bearings). 5.4.3.2 Grinding wheel characteristics. Grinding wheel (normally friable or semi-friable aluminum oxide) in a relatively soft grade normal to open structure, and 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without licens
47、e from IHS-,-,-MIL-STD-866C vitrified bond are recommended in the largest grit size that will produce the required finish. Hard, dense wheels in fine grit size are most likely to cause problems and their use should be avoided. This same philosophy also applies to coated abrasives. 5.4.3.3 Coolants.
48、Copious quantity should be delivered to the part at the working surface of the grinding wheel. Dry grinding should be avoided whenever possible. 5.4.3.4 Wheel dressing. Wheels should be dressed frequently and before the start of final grinding passes to prevent grinding with a dull or loaded wheel. Dressing should p
