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Fastener Engineering Test Procedure

Document Number: FST-10

Issue Date: January 21, 1999

Originator: METS Fastener Engineering Test Laboratory

Registered Holder: METS Fastener Engineering Test Laboratory

Revision Date: February 6, 2012

Authorized by: Section Supervisor

Title: FST-10 Torque-Angle-Failure

(For Assembly Torque Spec Development)

Important:

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•

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Table of Contents

1) Purpose

2) General Instructions for Sample Submission

3) Instrumentation

4) Equipment and Facilities

5) Initialization Procedure Sample Preparation

6) Test Operation

7) Standard Operating Procedure -One Stage

8) Presentation of Data

9) Header Information

10) Post-Test Sample Review

11) Sample Disposal

12) References

Appendix

1. Purpose

The purpose of this test is to produce torque-angle data (angular rotation) which can be used to determine an

appropriate assembly torque specification for a threaded joint as well as the joint failure mode. The test is run

with a slightly oversized power tool in order to drive the fastener to failure. A Torque-Angle plot is generated

to show joint behavior during assembly. Typical data generated include Threshold (b1_Yield 1), YIELD

(b2_Yield) and ULTIMATE (a1_Ult) torque data to determine the limits for setting the assembly torque

specification.

A Drive to Strip test is performed for self tapping screws to determine the +4σ drive torque and the -4σ strip

2

torque as the limits for fitting an assembly torque specification.

Printed copies of this document are UNCONTROLLED.

Be certain that you are using the correct revision of this document.

All obsolete versions must be destroyed or properly identified per the Corporate Records Retention Manual.

Fastener Engineering and Testing 1 of 11 FST-10 Torque-Angle-Failure Test

Date Printed: 3/17/2014

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2. General Instructions for Sample Submission

Please refer to the Fastener Engineering Lab Process Guide for complete instructions on generating a

Testnet Request, sample requirements and submission process.

(/)

Sample Preparation

Sample parts should be in production-level condition (i.e. unused and with appropriate surface finish such

as e-coat, paint, etc…)

.

In addition, large components should be sectioned to a size and weight which

can easily handled by the test technologist. Caution should be exercised to make sure that the

joint is

not structurally altered from the application state

.

Sample size

Minimum of 15 test samples + 3 additional samples for test set-up.

3. Instrumentation

Suitably-sized calibrated Torque Transducer

MC900 Transient Recording Analyzer.

4. Equipment And Facilities

Select the smallest power tool with the capability of tightening the joint to failure at the rundown. Use an

appropriate fixture for securing the assembly firmly so parts do not rotate during testing.

5. Initialization Procedure

6. Test Operation

Parts are assembled according to design intent. During the test, the fastener is torqued to failure as the

analyzer records data for RPM, Torque and Angle. Based on the observed failure mode, the Torque-Angle

plot is identified as an Yield-Ultimate or Drive-Strip.

Before beginning sample testing for each test request, a test initialization procedure shall be run according to

the FST- 01 Joint Test Equipment Initialization Procedure.

Fastener Engineering and Testing 2 of 11 FST-10 Torque-Angle-Failure Test

Date Printed: 3/17/2014