To install a wire thread insert (also known as a helical coil insert), you'll need to tap the hole with an STI (Screw Thread Insert) tap, and then use an installation tool to thread the insert into the tapped hole. Ensure the tang (the small piece that helps drive the insert) is centered in the middle of the slot on the installation tool, and apply light downward pressure while threading.
Here's a breakdown of the typical process:
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Prepare the Hole:
- Clean the existing hole thoroughly. Remove any debris or damaged threads.
- If necessary, drill out the existing hole to the correct size for the STI tap. Consult a tap drill size chart to determine the appropriate drill size.
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Tap the Hole:
- Use an STI tap to create threads specifically designed for accepting the wire thread insert. This is a crucial step as standard taps will not work.
- Apply cutting oil to the tap to lubricate it and help remove chips.
- Turn the tap slowly and carefully, ensuring it is aligned correctly. Back the tap out periodically to break chips and prevent binding.
- Tap to the full depth required for the insert.
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Install the Insert:
- Place the wire thread insert onto the installation tool. These tools often have an adjustable stop to control the insertion depth.
- Position the insert over the tapped hole, ensuring the tang is correctly aligned with the notch on the installation tool.
- Apply gentle downward pressure while rotating the installation tool to thread the insert into the hole. Do not force it.
- Continue threading the insert until it is slightly below the surface of the part. The installation tool stop, if properly set, will help prevent over-insertion.
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Remove the Tang (if applicable):
- Many wire thread inserts have a tang that needs to be removed after installation.
- Use a tang break-off tool, a sharp pick, or needle-nose pliers to break and remove the tang.
- Ensure the tang is completely removed and that no fragments remain in the threads.
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Inspect:
- Inspect the installed insert to ensure it is properly seated and that there are no defects.
- Verify that the insert is flush or slightly below the surface of the part.
Key Considerations:
- Tap Selection: Using the correct STI tap is vital. Consult the insert manufacturer's specifications for the appropriate tap size and type.
- Installation Tool: Using the correct installation tool makes the process easier and helps prevent damage to the insert.
- Lubrication: Cutting oil improves the tapping process and the installation of the insert.
- Proper Depth: Correctly setting the installation tool's stop or carefully monitoring the insertion depth ensures optimal insert performance.
