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FastenerTorquingStakingProcedure.md

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Fastener Torquing and Staking Procedure

The procedure describes the process of torquing and staking a fastener. It shall be performed only by someone trained and certified for this operation.

Parts List

Part Description Part Number Quantity
Torque Driver
3M 2216 A/B Gray a/r
Scale 1
Dental Pick 1
Syringe 5ml 1
Ethyl Alcohol a/r
Mixing cup a/r

Reference Documents

Nasa Std 5020A Requirements for Threaded Fastening Systems in Spaceflight Hardware

Procedure

Fastener Cleaning

All fasteners to be installed shall be cleaned until they pass the wipe test. This test uses a clean room wipe which is pressed down into the thread and the screw turned out of the wipe. The wipe should come out clean without showing any coloration from contamination.

Verify Calibrations

  1. Verify Torque Wrench Calibration
  • Record Torque Wrench S/N: _____________________
  • Record Torque Wrench Calibration Date: _____________________
  1. Verify Scale Calibration
  • Record Scale S/N: _____________________
  • Record Scale Calibration Date: _____________________

Mix epoxy

  1. Toque to the level stated in the build procedure. The torque wrench should not be used below 20% of is full scale range. Use a lower range toque wrench. If the torque wrench is a beam type, it should be braced with the other hand so only a torque is applied to the fastener, not the lateral force. The torqueing should be witness by QA. The operator should have passed the fastener torquing course. Note: there should be no running torque prior to the screw tightening up. There are some self-locking nuts that are used and they will have a running torque. This running torque should be measured and recorded on the build log. Then the torque requested should be in addition to the running torque. For example: if the running torque is 1 in-lb, and 4 in-lb torque is requested, the final torque should be 5 in-lb.

  2. After tightening the fastener. Inspect the area for metal fragments or staking compound, clean with alcohol if needed.

  3. Clean the head of each fastener and the area around the head with ethyl acohol to ensure the head staking compound will stick. Blow dry with N2.

  4. Clean a mixing cup with alcohol before adding the head staking compound. Mix up a small quantity of 3m 2216 A/B epoxy, weighing each component in a gram scale. Stir until the mixture is well mixed.

  • Record Mass of Part A: _____________________
  • Record Mass of Part B: _____________________
  • Record start time: _____________________
  1. Fill a syringe with the epoxy and apply a small bead of epoxy at two places on the head of each fastener. This is the second locking method. If there is a washer under the head of the screw, the epoxy should span the washer and connect the head with the substrate. WA should witness the staking process.
  2. Allow to cure. After the curing period, inspect each of the mix cups to ensure the material has cured properly. ID each cup and store for later inspection if required.