BOMBARDIER AEROSPACE LEARJET ENGINEERING SPECIFICATION

Transcription

1 Page 1 of 11 BOMBARDIER AEROSPACE LEARJET ENGINEERING SPECIFICATION NO: TITLE: CHEMICAL CLEANING OF METALS Author: John Simon Ext Date Req d: 8/31/00 Release Date: Checked By/Group Engineer Kurt W. Holland APPROVED;8/8/00 Eng. Rep. Powerplant Eng. Rep. Interiors Eng. Rep. Structures Jan C. Jones APPROVED;8/9/00 Eng. Rep. Elec. Sys. Eng. Rep. Mech. Sys. Material & Processes Jay E. Thomas APPROVED;8/9/00 Quality Assurance Michael L. Cozad APPROVED;8/8/00 Methods Barbara S. Richardson APPROVED;9/1/00 LJL-508-K

2 PAGE REVISION RECORD REV LTR DATE DESCRIPTION AU 08/8/00 Revised entire specification to put into new electronic sign-off format. For revision AG thru AT see Rev. AT. Revised title of specification. Added Bombardier Aerospace Process Specifications. In 3.3 deleted Learjet specifications not currently used. In 4.0 deleted materials not currently used. Revised processing for Low Alloy Steels and Copper alloys. Revised contamination level of normal rinse tank from 750 ppm to 900 ppm. Reference DCP 31-L0065 and DCP60-L0081.

3 PAGE 3 TABLE OF CONTENTS 1.0 PURPOSE SCOPE REFERENCE Military Specifications Bombardier Aerospace Learjet MATERIALS AND OPERATIONAL LIMITS OPERATING PROCEDURES Processing Aluminum Alloys ALKALINE CLEANING DEOXIDIZING ALUMINUM ETCHING Processing Low Alloy Steels ALKALINE CLEANING PRIOR TO PLATING, WELDING, OR BRAZING PICKLING PRIOR TO PLATING, PAINTING, WELDING, AND BRAZING Processing of Corrosion Resisting Steels ALKALINE CLEANING PICKLING AND DESCALING 300 SERIES STAINLESS STEEL PICKLING OF 15-5PH,17-4PH,17-7PH,PH15-7MO AND PH13-8MO ALLOYS PASSIVATION Baking for Embrittlement Relief after Pickling Processing Copper Alloys ALKALINE CLEANING PRIOR TO PLATING PICKLE OR DEOXIDATION PRIOR TO PLATING Flux Removal for Steel or Copper Cadmium Plating Stripper Chromium Plating Stripper Zinc Plating Stripper Cleaning & Pickling of Titanium Alloys Heat Treat Scale Removal for Inconel Alloys RINSE TANK CONTROL QUALITY CONTROL REQUIREMENTS DEFINITIONS HEALTH AND SAFETY...11

4 PAGE PURPOSE.0 SCOPE This specification establishes the requirements and procedures applicable to the chemical cleaning of metals. This specification shall govern all chemical cleaning of metals at Learjet. Processes conforming to MIL-S-500 or Bombardier Aerospace Process Specifications may be used by sub-contractors. 3.0 REFERENCE 3.1 Military Specifications MIL-S-500 Surface Treatments and Inorganic Coatings for Metal Surfaces 3.1. TT-C-490 Cleaning Methods for Ferrous Surfaces and Pretreatments for Organic Coatings 3. Bombardier Aerospace 3..1 BAPS Baking of Steel for Relief of Hydrogen Embrittlement 3.. BAPS Alkaline Cleaning 3.3 Learjet LES 1044 Abrasive Cleaning of Metals 3.3. LES 139 Solvent Cleaning LES 1310 Hot Alkaline Cleaning LES 1311 Alkaline Etch of Aluminum Alloys LES 1313 Deoxidizing of Aluminum Alloys LES 1319 Determination of Contamination Level in Rinse Tanks LES 133 Passivation of Corrosion Resisting Steel

5 PAGE MATERIALS AND OPERATIONAL LIMITS 4.1 Acids Nitric, Technical Grade 4 Baume Hydrofluoric, Technical Grade, 5% HF by weight minimum Turco Nitradd - Turco Products, Inc. Elf Atochem North America Hydrochloric Technical Grade 31% HCl by weight minimum 4. Alkaline Cleaners for Aluminum, Stainless Steel, and Titanium Alloys For alkaline cleaning solution and operating conditions see LES Deoxidizer for Aluminum For deoxidizer solution and operating conditions see LES Etchant for Aluminum For alkaline etch solution and operating conditions see LES Degreasing Solvents See LES Ammonium Nitrate - Commercial Grade 5.0 OPERATING PROCEDURES 5.1 Parts may be reprocessed through any of the following procedures without Materials Review Action. This is applicable to those parts which are not satisfactorily processed on first treatment. 5. No processing shall be done on assemblies containing dissimilar metals, unless specifically approved in writing by Engineering Process Group. Parts containing crevices or pockets which will trap solutions and not allow adequate rinsing shall not be processed unless specifically allowed by the detail drawing. 5.3 Bonded assemblies, honeycomb assemblies, or mechanically fastened assemblies shall not be alkaline cleaned but shall be solvent cleaned per LES 139.

6 PAGE Processing Aluminum Alloys ALKALINE CLEANING Prior to anodizing, chemical film treatment, fusion welding, brazing, or penetrant inspection, parts shall be treated as follows: a. Soak parts in alkaline cleaning solution operated per LES 1310 until parts are clean followed by a thorough cold water rinse. b. Parts are clean when they show no water break when removed from rinse water DEOXIDIZING Deoxidizing prior to anodizing, chemical film treatment, fusion welding, or brazing, shall be done as follows: a. Soak parts in deoxidizer solution per LES Parts shall be thoroughly rinsed in cold water immediately upon removal from deoxidizer solution. b. Parts having any "Smut" shall be reprocessed ALUMINUM ETCHING Parts may be alkaline etched per a. to remove oxides, corrosion products, heat treat discoloration, or surface stains. a. Alkaline Etching (1) Soak parts in alkaline etch solution per LES 1311 for 1 to 5 minutes. () Rinse thoroughly in cold water. (3) Soak parts to deoxidizer solution per LES 1313 for 3 to 5 minutes. (4) Rinse thoroughly in cold water. 5.5 Processing Low Alloy Steels ALKALINE CLEANING PRIOR TO PLATING, WELDING, OR BRAZING Soak parts in solution until clean and rinse thoroughly in cold water. Clean parts will show no water break upon removal from the rinse tank. The parts may be anodically cleaned at 6 to 10 volts for 1 to 5 minutes to expedite cleaning. Solution shall be operated per BAMS , TT-C-490 Method III, or MIL-S-500.

7 PAGE PICKLING PRIOR TO PLATING, PAINTING, WELDING, AND BRAZING Parts shall be soaked in solution until oxides and scale are removed and then rinsed thoroughly in cold water. Solution shall be maintained MIL-S-500. Copper and ferrous alloys shall not be pickled in the same bath. Parts heat treated to 180 KSI. (Rc 40) or greater shall be baked per 5.7 of this specification following pickling. 5.6 Processing of Corrosion Resisting Steels ALKALINE CLEANING Soak parts in solution until clean and rinse thoroughly in cold water. Clean parts will show no water break upon removal from the rinse tank. Solution shall be operated per LES PICKLING AND DESCALING 300 SERIES STAINLESS STEEL Except as noted below, all 300 series stainless steel parts shall be pickled. All detail parts that are to be either welded, (fusion or spot), or brazed, shall be pickled prior to welding/brazing. All assemblies that have been swaged, spot welded, fusion welded, mechanically fastened, or silver brazed, or any other type of assembly having faying surfaces or other features which might trap processing solutions shall not be pickled. All parts machined from 303 or 316 stainless steel shall not be pickled but only passivated. Parts shall be vapor degreased or alkaline cleaned then soaked in pickling solution 10 to 0 minutes followed by a thorough cold water rinse. To prepare 100 gallons of this solution, take 51 gallons of water and add 35 gallons of 4 Baume nitric acid and mix well. Then add 14 gallons of Nitradd per and again mix well. Solution shall be operated at 40 F to 100 F. Except as stated above, pickling shall be done subsequent to welding, heat treating, machining, and forming. Thickness after pickling of sheet stock shall not be more than inch below the minimum thickness requirement for the material. All parts must meet the drawing requirements in all other respects. Solution concentration shall be checked periodically and maintained at 35 to 70 oz/gal. as HNO 3. Etch rate shall be checked periodically and maintained at to inch/hour/side on 31 SS. Add Nitradd or Hydrofluoric Acid to maintain etch rate.

8 PAGE PICKLING OF 15-5PH,17-4PH,17-7PH,PH15-7MO AND PH13-8MO ALLOYS Parts made of these materials will not normally be pickled. Parts made of these materials that have surface contamination resulting from contact with tools or equipment made of lead, zinc, or bismuth shall be alkaline cleaned or vapor degreased followed by a maximum of two () minute immersion in pickle solution per 5.6. followed by thorough hot or cold water rinse. Parts heat treated to 180 KSI. (Rc 40) or greater shall be baked per 5.7 of this specification following pickling. Scale on any parts resulting from either welding or heat treatment shall be removed using either 40 grit (or finer) abrasive or grit blasting per LES PASSIVATION 00 series, 300 series, 400 series, and precipitation hardening (PH) corrosion resisting steels shall be passivated per LES Baking for Embrittlement Relief after Pickling Low alloy steels (i.e. 4130, 4340), precipitation hardened (PH) stainless steels, and 400 series stainless steels heat treated to 180 KSI. (Rc 40) and greater shall be baked per BAPS after pickling. 5.8 Processing Copper Alloys ALKALINE CLEANING PRIOR TO PLATING Parts shall be cleaned per the alkaline cleaning procedure used for low alloy steels per of this Specification PICKLE OR DEOXIDATION PRIOR TO PLATING Parts shall be soaked in solution minimum amount of time necessary to brighten surface and rinsed thoroughly in cold water. Solution shall be maintained per MIL-S-500. Copper and ferrous alloys shall not be pickled in the same tanks. 5.9 Flux Removal for Steel or Copper Parts shall be immersed in hot water for minimum time necessary to remove flux. Scrubbing action may be used to aid in cleaning. Rinse thoroughly in cold or hot water.

9 PAGE Cadmium Plating Stripper Stripping Cadmium from Steel Parts Heat Treated up to 180 KSI Parts shall be immersed in the following solution until the plating is removed. Rinse thoroughly in cold water and replate per LES Solution shall be maintained at 10 to 5% hydrochloric acid by weight and operated at 60 to 100 F Solution shall be dumped when it fails to strip Stripping Cadmium from Steel Parts Heat Treated Over 180 KSI Parts shall be immersed in the following solution until plating is removed. Rinse thoroughly in cold water and replate per LES Solution shall be made up with 0 ounces per gallon of ammonium nitrate and operated at 60 to 100 F. Solution shall be dumped when it fails to strip Chromium Plating Stripper Parts shall be immersed in the following solution until plating is removed. Rinse thoroughly and replace with Chromium per LES Solution shall be maintained at 10 to 5% hydrochloric acid by weight and operated at 65 to 100 F Solution shall be dumped when it fails to strip plating. 5.1 Zinc Plating Stripper Stripping Zinc from Steel Parts Heat Treated up to 180 KSI Parts shall be immersed in the following solution until the plating is removed. Rinse thoroughly in cold water and replate per LES Solution shall be maintained at 10 to 5% hydrochloric acid by weight and operated at 60 to 100 F Solution shall be dumped when it fails to strip Stripping Zinc from Steel Parts Heat Treated Over 180 KSI Parts shall be immersed in the following solution until plating is removed. Rinse thoroughly in cold water and replate per LES Solution shall be made up with 0 ounces per gallon of ammonium nitrate and operated at 60 to 100 F. Solution shall be dumped when it fails to strip.

10 PAGE Stripping Zinc from Titanium Parts Parts shall be immersed in 4 Baume nitric acid until plating is removed. Rinse thoroughly in cold water and dry in a hot air circulating oven. Apply additional finish only if required by Engineering disposition. Nitric acid shall be dumped when it fails to strip Cleaning & Pickling of Titanium Alloys Prior to welding or penetrant inspection of welds, titanium parts shall be cleaned per the Alkaline Cleaning procedure used for aluminum alloys per of this specification Pickling of titanium tubes prior to orbital welding shall be performed per LES Decontamination of shot peened parts or pickling prior to penetrant inspection shall be accomplished by immersion in the following solution for 1 to minutes. Parts with faying surfaces shall not be pickled. The pickling solution shall be made as follows: 47 volumes of water, 47 volumes of 4 Baume nitric acid, and 6 volumes of Nitradd per Maintain pickle solution at 65 to 95 F with an etch rate of in/hr/side on commercially pure titanium. Solution concentration shall be checked periodically and maintained at 40 to 75 oz/gal. as HNO 3. Add Nitradd per or Hydrofluoric Acid per 4.1. to maintain etch rate. Maintain cold water rinse within 3-7 ph. Only titanium may be pickled in this solution, as contamination or pitting may result Heat Treat Scale Removal for Inconel Alloys Inconel parts which have been heat treated shall be glass bead blast cleaned per LES 1044 to remove visible oxide (heat treat scale), then pickled in solution per 5.6. for 0 to 30 minutes followed by a thorough cold water rinse. 6.0 RINSE TANK CONTROL All rinse tanks shall be maintained so that contaminants in the rinse tank are below 900 ppm. Contamination level shall be determined per LES 1319.

11 PAGE QUALITY CONTROL REQUIREMENTS Concentrations and activity of solution as required shall be checked periodically. Such tests shall be performed at regular intervals as determined by Statistical Process Control. Adjustments shall be made per inspection recommendations. Random spot checks shall be made on cleaning by the "water break" method. Parts as lifted from the rinse tank should present a smooth uniform film of water on the surface which does not disrupt as it drains. A break in the water film indicates improper cleaning. 8.0 DEFINITIONS 8.1 Cold Water Rinse 8. Smut A cold water rinse is a rinse in room temperature water (nominally 40 to 100 F). Smut is a chemical reaction product that discolors a metal surface after pickling, etching or deoxidizing. 9.0 HEALTH AND SAFETY WARNING Some of the materials used in this process may be toxic, flammable and/or irritating to the human body. At Learjet, consult Health and Safety Department for specific requirements related to facilities, equipment, ventilation and handling precautions. Outside Learjet, the user is solely responsible to consult with the appropriate health and safety authority for specific requirements related to facilities, equipment, ventilation and handling precautions.