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FASTENER TIPS: TESTING, TEST REPORTS, SUPPLIER

OVERSIGHT

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Fastener Testing 2

Topics

• Past Problems

• Quality Control

• Test Methods

• Test Variables

• Test Report Content

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Fastener Testing 3

Past Problems

– Lack of hydrogen embrittlement relief

– Wrong wedge angles

– Wrong gage lengths

– Sampling

– Process control of piercing diameter

– Concentricity of head and/or socket to shank

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Fastener Testing 4

Piercing Diameter

Minor Diameter Out of Tolerance

Minor Diameter Within Tolerance

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Fastener Testing 5

Concentricity

Socket is not centered in the head of the screwHead and shank are

not concentric

Socket is not centered in the head of the screw

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Fastener Testing 6

Topics

• Past Problems

• Quality Control

• Test Methods

• Test Variables

• Test Report Content

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Fastener Testing 7

Quality Control

Mil-I-45208 “Inspection System Requirement” Requires:

•Clear and concise procedures. (Para. 3.2.1)

•Use of calibrated equipment. (Para. 3.3)

•Providing and maintaining adequate records (i.e. Objective Quality Evidence (OQE)). (Para. 3.2.2)

Other quality standards may apply ,however the rules are basically the same (e.g. MIL-Q-9858, ISO 9001).

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Fastener Testing 8

Topics

• Past Problems

• Quality Control

• Test Methods

• Test Variables

• Test Report Content

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Fastener Testing 9

Test Methods

ASTM F606 Standard Testing Methods Are Typically Invoked

Unless Otherwise Specified

• Tensile / Yield / Elongation (Mach. specimens)• Axial Tension (Full Size fasteners)• Proof load (Full Size fasteners) • Wedge tension (Full Size fasteners)• Hardness

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Fastener Testing 10

Test Methods

Flat surface

•Hardness testing performed on a convex cylindrical surface

•Correction factors of ASTM E18 need to be applied

Cylindrical surface

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Fastener Testing 11

Test Methods

Determination Of Proper Wedge Angle For Wedge Testing

• ASTM F606 (Unless otherwise specified)

• ASTM A574 (Socket Head Cap Screws)

• MIL-S-1222H3 (Titanium, SC 10-122)

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Fastener Testing 12

Test Methods

Gage Lengths Are Different For Ferrous And Non-ferrous Fasteners

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Fastener Testing 13

Test Methods

Plated Steel Fasteners May Require Additional Processing And Testing

• The plating process can cause Hydrogen Embrittlement of steel fasteners.

• Post plate baking is normally required to drive off hydrogen introduced into the base material

• Hydrogen Embrittlement can cause delayed cracking.

• Stress Durability Testing may be required to determine the effectiveness of the post plate baking process.

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Fastener Testing 14

Test Methods

Determining Sample Size And Test Requirements

• The manufactured lot size is needed to determine the correct number of samples.

• Type of specimens.– Machined specimens– Full size fasteners

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Fastener Testing 15

Test MethodsDetermining sample size and test requirements

FF-S-86

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Fastener Testing 16

Determining sample size and test requirements

FF-S-86

Test Methods

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Fastener Testing 17

Determining sample size and test requirements

Mil-S-1222

Test Methods

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Fastener Testing 18

Determining sample size and test requirements

Mil-S-1222

Test Methods

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Fastener Testing 19

Topics

• Past Problems

• Quality Control

• Test Methods

• Test Variables

• Test Report Content

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Fastener Testing 20

Test Variables

Variables that can affect test results

• Fixturing, Alignment.

• Speed of applied load.

• Test Specimen preparation (Surface finish).

• Tool marks act as stress risers.

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Fastener Testing 21

Topics

• Past Problems

• Quality Control

• Test Methods

• Test Variables

• Test Report Content

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Fastener Testing 22

Test Reports

• Name of Testing Organization• Date of the test• Purchase Order number and Item number• Manufactured lot size• Material Spec. Alloy, Type, Class, Grade, Condition• Type of specimen tested (machined vs. full size)• Traceability to hardware (Lot Code)• Acceptance criteria.• Statement of acceptance or rejection• Units should be the same as those contained in the

acceptance spec. (lbs vs. psi)• Signature of test organization representative and date.

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Fastener Testing 23

Test ReportsC of C

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Fastener Testing 24

Test ReportsChemicals

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Fastener Testing 25

Test ReportsMechanicals

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Fastener Testing 26

Test ReportsMechanicals

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Fastener Testing 27

Test ReportsMechanicals

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Fastener Testing 28

Test ReportsNDT

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Fastener Testing 29

Test ReportsNDT

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Fastener Testing 30

Summary

• Past Problems

• Quality Control

• Test Methods

• Test Variables

• Test Report Content

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