F-F101_REV_E__DOC_8__approved_OEMimages.pdf

2017-07-17

PCO LETTER REQUEST

A-10 TLPS

Legacy VI 7/17/2017

Contract/Delivery Order Number: FA8202-15-D-0001

Program Manager: Edie Messina

Letter Number: A10-CDM-0001-E-17-0041

Date of Letter: 6/15/2017

CDRL Number: A129

Document Title:

A-10 Process Specification Steel, 180 KSI Tensile and Above - Maching of

Document/ Drawing Number: F-F101 Rev E

NOT APPROVED (See comment below)

X APPROVED

APPROVED Subject to inclusion of attached comments

OTHER (please identify below)

Notes:

Program Manager Signature and Date:

X

MESSINA.CARRIE.E

.1023771388

Digitally signed by MESSINA.CARRIE.E.1023771388 DN: c=US, o=U.S. Government, ou=DoD, ou=PKI, ou=USAF, cn=MESSINA.CARRIE.E.1023771388 Date: 2017.07.17 12:29:46 -06'00'

77751 F-F101 Revision E

06 April 2017

Data contained on this sheet is subject to the restrictions on the title page of this document.

ii

REVISION DESCRIPTION

REV. CHANGES APPROVED

C

4/11/86 Para 2.0 Comply with COR req’ts

Para 3.0 Use current applicable specifications

Para 4.0, 6.0, 7.0 To current manufacturing processes

Para 8.0 Syntactical revisions

Para 9.0 Alternate permitted specification

REV. CHANGES REASON FOR CHANGE APPROVED

D

11/01/16 Incorporated EO 93C0523. Specification requirement. M. Kassinger

In Paragraph 1.1, changed “heat treated to above Rc39 (180 KSI),…” to “heat treated to 180 KSI (Rc39) and above,…”

To encompass heat treatment to 180 KSI.

In Paragraph 1.2, added “water jet cutting” to list of machining methods;

replaced “Quality Assurance” with “the A-10 SPO”.

To include water jet machining; to properly assign approval responsibility.

Updated Section 2.0, Applicable Documents, and all references and callouts throughout. Renumbered subsequent sections and paragraphs accordingly.

Specification requirement.

Clarity; consistency.

Designated previously unnumbered table of recommended speeds and feeds as Table I.

Clarity.

Replaced obsolete Problem Action Report (PAR) with Materials Review Board (MRB) throughout.

Currently applicable entity.

iii

REV. CHANGES REASON FOR CHANGE APPROVED

D (Continued)

In Paragraph 3.1, provided specific means of dealing with areas likely to entrap lubricants. Added CAUTION requiring use of lubricants that are compatible with high strength steel.

Clarity. To ensure use of proper lubricants.

In Section 4.0, changed definition of kip: is: 1,000 pounds force, lbf; was:

1,000 psi.

To correct error.

In Paragraph 7.2.2, rewrote second sentence to make certain that only surfaces machined by hand do not require temper etch inspection.

Clarity.

Made minor grammatical corrections throughout.

Clarity.

E 04/06/17

In Paragraph 3.1, reworded first part of first sentence, as follows: is:

“Cutting fluids directed at the cutting interface or solid lubricants shall be used in all machining operations...”;

was: “Cutting fluids or solid lubricants directed at the cutting interface shall be used in all machining operations...”.

To comply with AF PM Response Letter 03/14/2017 Comment Incorporation

M. Kassinger

In Paragraph 7.2.2, added Note beneath paragraph, as follows:

“NOTE: Powered hand-held tools are not to be considered hand-powered tools.”

To comply with AF PM Response Letter 03/14/2017 Comment Incorporation iv

TABLE OF CONTENTS

REVISION DESCRIPTION ............................................................................................... i

LIST OF TABLES ......................................................................................................... v

1.0 SCOPE

2.0 APPLICABLE DOCUMENTS

2.1 Government

2.2 Industry

2.3 A-10 Program

3.0 GENERAL REQUIREMENTS

4.0 ABBREVIATIONS

5.0 HOLE PREPARATION

6.0 SURFACE MACHINING

7.0 POST-HEAT TREATMENT MACHINING REQUIREMENTS AND INSPECTION.. 11

8.0 QUALITY ASSURANCE

v

LIST OF TABLES

Table I: Recommended Speeds, Feeds and Drill Materials

1.0 SCOPE

1.1 This specification, when called out on Engineering drawings, provides recommendations for machining and hole preparation for alloy steels heat treated to 180 KSI (Rc39) and above, in order to prevent, or minimize, surface damage, overheating, deleterious residual stresses and temper softening.

1.2 Other uncommon machining/drilling methods not described herein, such as ECM, EDM, ultrasonic drilling, water jet cutting and laser cutting require specific approval, prior to usage, by the A-10 SPO, and shall meet the Quality Assurance requirements of this specification subsequent to approval.

2.0 APPLICABLE DOCUMENTS

The following documents of the issue in effect on the effective date of contract shall form part of this specification. In the event of conflict between the contractual documents referenced herein and the requirements of this specification, the contractual documents referenced herein shall govern.

2.1 Government

MIL-C-15074 Corrosive Preventive, Fingerprint Remover

MIL-STD-866 Grinding of Chrome Plated Steel and Steel Parts Heat Treated to 180,000 PSI or Over

MIL-STD-867 Temper Etch Inspection

2.2 Industry

ASTM E1444 Standard Practice for Magnetic Particle Inspection

2.3 A-10 Program

PW220T0037 Post-Production A-10 Magnetic Particle Inspection of Class 1A Critical Parts

QATB M-45 Magnetic Particle Inspection, General Practice

NOTE: PW220T0045 will be released to replace QATB M-45 once approved by the A-10 SPO.

3.0 GENERAL REQUIREMENTS

3.1 Cutting fluids directed at the cutting interface or solid lubricants shall be used in all machining operations, in accordance with their respective manufacturer’s technical data sheets. Do not use silicones. In parts or assemblies where there is a possibility of fluid entrapment, this shall be prevented using masking techniques. Only maskants approved by the lubricant manufacturer shall be used. A non-contaminating coolant that leaves no residue also may be used in these areas. Fay sealed structure shall be fully cured prior to application of lubricants to help prevent entrapment.

CAUTION: Only lubricants that have documented evidence/data that they are not deleterious to high strength steels shall be used.

3.1.1 Cutting fluids containing chlorine or free sulfur may be used only if parts are solvent cleaned after separate machining operations (e.g., turning, grinding, drilling). These fluids shall not be used on parts machined on assembly.

3.2. All metal removal operations shall be performed with screw or other positive power feed equipment, except for hole chamfering, honing, burr removal, and where hand-powered tools or controlled power rotation are used.

3.3 During processing, parts should be coated with an oil per MIL-C-15074, or equivalent, if succeeding operations are delayed more than eight hours.

3.4 Surface finish, including holes, shall be 125 RHR maximum, unless otherwise noted on drawings, after all finish machining operations described within this specification.

3.5 After all finish machining operations per this specification, all cutting fluids and abrasive grit shall be removed.

4.0 ABBREVIATIONS

HSS high speed steel ipr inch per revolution ipt inch per tooth KSI kips per square inch (1 kip = 1,000 pounds force, lbf) MRB Materials Review Board psi pounds per square inch Rc Rockwell hardness ‘C’ RHR roughness height rating RPM revolutions per minute SFM surface feet per minute

5.0 HOLE PREPARATION

5.1 All holes in alloy steels within the scope of this specification should be prepared as outlined herein unless otherwise noted on Engineering drawings.

5.1.1 Hole preparation or finishing techniques other than those covered in this specification are not permitted, except where approved in accordance with Paragraph 1.2.

5.1.2 Broaching or hole grinding shall not be used as hole finishing techniques.

5.2 Drilling

5.2.1 Drilling shall not be used as a hole finishing process.

5.2.2 Drill fixtures, bushings, or piloted center drills should be used on holes 1/4 inch in diameter or larger.

5.2.3 Oil hole drills are recommended for drilling holes 3/8 inch in diameter and larger and are over four drill diameters in depth, to supply adequate cutting fluid to the cutting interfaces.

5.2.4 Drill bits should be replaced or sharpened at the first sign of chipping, discoloration, or impaired cutting action as indicated by chattering or change in noise level.

5.2.5 Tool materials and tool configurations shall be selected by Manufacturing to meet requirements of this specification and/or the applicable drawing.

5.2.6 Speeds and Feeds, Drill Materials

5.2.6.1 Recommended speeds, feeds and drill materials – see Table I

Table I: Recommended Speeds, Feeds and Drill Materials

Strength Level and Material Hardness Drill Material Cutting

Speed, SFM Feed, ipr Drill

Diamater, in.

180–200 KSI

(40–43 Rc)

Tungsten HSS 25 max. 0.002–0.004 0.12–0.50

Cobalt HSS 25–75 0.004–0.008 0.50–0.75

C-2 Carbide 75–150 0.008–0.010 0.75–2.00

200–240 KSI

(43–50 Rc)

Tungsten HSS 10 max. 0.0005–0.001 0.12–0.25

Cobalt HSS 20–40 0.001–0.003 0.25–1.00

C-2 Carbide 60–100 0.003–0.004 1.00–2.00

260–300 KSI

(53–61 Rc)

Brazed Carbide Tip or Solid Carbide 40–60 0.0015 max. Up to 4.00

5.3 Reaming

5.3.1 Holes finished larger than 3/4 inch in diameter shall be double reamed to final diameter.

5.3.2 A minimum of 1/64 inch in diameter should be removed when reaming holes to less than 3/4 inch in diameter and 3/64 inch in diameter should be removed in holes finished to 3/4 inch and larger in diameter.

5.3.3 Reamers should be replaced at the first sign of chipping, discoloration or change in cutting action that affects the hole finish.

5.3.4 Recommended Reamer Material and Recommended Cutting Speeds

a. For 180–220 KSI (40–46 Rc) steels – Cobalt or tungsten HSS at 10–30 SFM and carbide or brazed carbide insert at 5–20 SFM low range or 100–120 SFM high range.

If chatter develops at high speed, use low range.

b. For steels above 220 KSI – Cobalt or tungsten HSS at 5–20 SFM and carbide or brazed carbide insert at 5–20 SFM low range or 75–100 SFM high range. If chatter develops at high speed, use low range.

5.3.5 Reamer feed recommended is 0.001 ipr maximum, except that a maximum of 0.0005 ipr feed should be used in holes reamed in areas where coolant is not used (see Paragraph 3.1).

5.3.6 Use a flood of coolant during all reaming operations with exceptions noted in Paragraphs 3.1 and 3.1.1.

5.3.7 Where power feed equipment cannot be adapted, hand reaming (without power rotation of the reamer) or maximum 500 rpm controlled power rotation of reamer (e.g., air drill) is permitted.

5.4 Boring

5.4.1 Boring, although not recommended, may be used as a hole finishing operation if the requirements of Section 7.0 are met.

5.4.2 Boring can be used to prepare a hole for any finishing technique outlined in this specification. If boring is used to prepare a hole, it is recommended that:

a. Cutting speeds should be 90–125 SFM for carbide tools and 20 SFM for HSS tools.

b. Feed should be 0.004 ipr during final pass.

c. Depth of cut should be 0.060 inch maximum during final pass.

5.4.3 Use a flood of coolant during all boring operations with exceptions as noted in Paragraphs 3.1 and 3.1.1.

5.5 Honing

5.5.1 Honing may be used as a hole finishing process.

5.5.2 Honing should not be used as a finish improvement operation on holes with surface roughness greater than 125 RHR.

5.5.3 Multi-stone heads are preferred for honing. Heads with steel shoes or steel wipers are not recommended.

5.5.4 Medium hard bond abrasive stones with 150 to 350 aluminum oxide grit, operating at 200 SFM maximum, and 60 strokes per minute, maximum, are recommended for honing.

Any equivalent procedure can be used as long as a minimum of 0.006 inch is removed from a hole diameter having a surface roughness between 125 and 63 RHR.

5.5.5 Use a flood of coolant during honing operations with exceptions as noted in Paragraphs

3.1 and 3.1.1.

5.6 Hole Edge Refinement

5.6.1 Techniques used for hole edge refinement shall leave the surfaces free of scratches, nicks, gouges, machine tears, and cracks.

5.6.2 Any hand-powered tool (file, emery paper, etc.) can be used to hand radius or break edges of holes.

5.6.3 Chamfering of holes can be by any technique that removes more than 0.010 inch of material and is produced by rough cutting to within 0.005 and 0.010 inch of finish dimension;

then finish cut to size.

5.6.3.1 Tools and chamfered surfaces should be inspected after each cut, and tools replaced at the first evidence of wear that will create any of the imperfections described in Paragraph 7.1.

6.0 SURFACE MACHINING

6.1 Surface machining procedures described herein are recommendations or prohibitions.

6.1.1 Other equivalent procedures that meet the inspection requirements in Section 7.0 can be used if approved in accordance with Paragraph 1.2.

6.2. Grinding

6.2.1 Side wheel grinding is prohibited.

6.2.2 A flood of filtered coolant from a nozzle, sufficiently wide to flood the entire width of the wheel, should be directed at the cutting interface during all grinding operations.

6.2.3 Grinding wheel type recommended is 45 to 60 aluminum oxide abrasive with G to K hardness, vitrified bond, and 8 to 12 structure density.

6.2.3.1 Wheel speed of 2,000 to 6,000 SFM, work speed of 30 to 60 SFM, and crossfeed of 1/8 to 1/2 the wheel width are recommended.

6.2.3.2 During downfeed or infeed, rough grinding should be 0.001 inch per pass to within

0.005 inch of finish size for surface grinding and 0.001 inch per pass to within 0.008 inch of finish size for cylindrical grinding. Finish grind to final dimension using recommended feed of

0.0005 inch per pass on all grinding operations.

6.3 Turning

6.3.1 Any tool that produces an acceptable surface when inspected per Section 7.2 can be used.

6.3.2 Turning speeds of 90–180 SFM and feeds of 0.002–0.004 ipr are recommended.

6.3.3 A depth of cut on the final pass should be 0.030 inch maximum on the diameter.

6.3.4 Use a flood of coolant directed at the cutting interface.

6.4 Milling

6.4.1 End Milling

6.4.1.1 HSS tools with 35° helix (axial rake) angle, 15° radial rake angle, 5° peripheral relief angle; and C-2 or C-6 carbide tools with 0° radial and axial rakes, 5° end clearance angle, 10°–15° peripheral clearance angle are recommended.

6.4.1.2 Feed of 0.001–0.003 ipr with a maximum 0.200 inch depth of cut is recommended.

6.4.1.3 Use a flood of coolant directed at the cutting interface.

6.4.2 Face Milling

6.4.2.1 C-6 carbide tool with 0° axial rake, minimum 15° radial rake, 8° primary clearance angle, and 45° chamfer is recommended.

6.4.2.2 Cutting speeds of 100–125 SFM for steels heat treated up to 240 KSI and 65–85 SFM for steels heat treated above 240 KSI are recommended.

6.4.2.3 A maximum 0.010-inch depth of cut is recommended on the final pass, with a feed of 0.002–0.004 ipr.

6.4.2.4 Use a flood of coolant directed at the cutting interface.

6.4.3 Side or Slot Milling

6.4.3.1 C-2 or C-6 carbide tool with 5°–10° (bi-negative) axial rake, minus 10° radial rake, and 8° peripheral relief angle is recommended.

6.4.3.2 Cutting speeds should be 100–125 SFM for steels heat treated up to 240 KSI and 60–90 SFM for steels heat treated above 240 KSI.

6.4.3.3 A maximum 0.200-inch depth of cut with a feed rate of 0.002–0.004 ipt is recommended.

6.4.3.4 Use a flood of coolant directed at the cutting interface.

7.0 POST-HEAT TREATMENT MACHINING REQUIREMENTS AND INSPECTION

7.1 Machined Holes

7.1.1 All holes, whether machined before or after heat treatment, shall be visually inspected for evidence of overheating, surface roughness and discrepancies shown in Paragraphs

7.1.2 and 7.1.3. Parts containing any of the discrepancies shown in Paragraphs 7.1.2 or

7.1.3 shall be considered unacceptable and shall be submitted for MRB action.

7.1.2 Holes (and chamfers) showing evidence of nicks, gouges, scratches or chatter marks and holes with surface roughness greater than 125 RHR, unless otherwise noted on the Engineering drawing, shall be cause for rejection.

7.1.3 Evidence of discoloration due to overheating in or around holes or parts with holes (and chamfers) containing machining tears and cracks, regardless of surface roughness, shall be subject to MRB action.

7.2 Machined Surfaces

7.2.1 All surfaces, whether machined before or after heat treatment, shall be visually inspected for evidence of nicks, gouges, scratches, chatter marks, cracks or tears. Parts having evidence of any of the above discrepancies shall be considered unacceptable and shall be submitted for MRB action.

7.2.2 Any surface machined after final heat treatment shall be inspected to the requirements of Paragraph 7.2.1 and then followed by temper etch inspection per MIL-STD-867. Surfaces from which material was removed using only hand-powered tools (i.e., filing, emery paper, etc.) do not require temper etch inspection.

NOTE: Powered hand-held tools are not to be considered hand-powered tools.

7.2.3 Parts found to have evidence of overheating (e.g., re-hardening or tempering, softening, burns), after temper etch inspection, shall be stress relieved at 50°F below the final tempering temperature indicated by the applicable drawing heat treat specification.

7.2.3.1 Magnetic particle inspect stress relieved parts per ASTM E1444 (see Paragraph 8.2).

7.2.4 Parts found to have evidence of re-hardening after temper etch inspection (see Paragraph 7.2.6) shall be processed per Paragraph 7.2.4.1.

7.2.4.1 Parts below 220 KSI heat treat shall be re-tempered per the applicable drawing heat treat specification and hardness requirements. Parts above 220 KSI heat treatment shall be re-double tempered per the applicable drawing specification. Temper etch inspect re-tempered parts. Failure to meet drawing requirements shall require parts to be submitted for MRB review.

7.2.4.2 Magnetic particle inspect acceptable parts per ASTM E1444 (see Paragraph 8.2).

7.2.5 Parts found to have softening—below drawing requirements—after temper etch inspection (see Paragraph 7.2.6) shall be submitted for MRB action.

7.2.5.1 When required by MRB action, soft parts shall be re-hardened and tempered per the applicable drawings’ heat treat specification. After complete reheat treatment, parts shall be temper etch inspected. Failure of parts to meet temper etch requirements shall require MRB action.

7.2.5.2 Magnetic particle inspect acceptable parts per ASTM E1444 (see Paragraph 8.2).

7.2.6 When testing suspected re-hardened (Paragraph 7.2.4) or softened (Paragraph 7.2.5) areas, use 15N Rockwell superficial hardness scale. If the readings taken in the suspected areas do not fall within the hardness range of the base material, the parts shall be cycled as applicable per Paragraphs 7.2.4.1 and 7.2.5.1.

8.0 QUALITY ASSURANCE

8.1 Quality Assurance shall enforce the requirements of this specification.

8.2 Indications found during magnetic particle inspection shall be evaluated to the requirements of QATB M-45 or PW220T0037, as applicable. Parts not meeting the requirements of QATB M-45 or PW220T0037, as applicable, shall be submitted for MRB action.

NOTES: For information purposes only.

1. Grinding of chrome plated parts whose basis (substrate) metal is heat treated from 270 KSI and above is not permitted.

2. Grinding of chrome plated parts whose basis metal is heat treated to below 270 KSI is permitted when specified by the applicable drawing or if MIL-STD-866 is specified.

3. MIL-STD-866 – Grinding of chrome plated steel parts heat treated to 180 KSI or over.