How To Install A HeliCoil Screw Thread Insert

Drill - Drill out the damaged threads using the drill size specified in the catalog. Drill to sufficient depth to accommodate the insert length and bolt or screw being used.
Tap - Use the Heil-Coil Tap specified in the catalog. Check the size on your shank to make sure you have the right one. Tap the hole to sufficient depth to accommodate the insert length and bolt or screw being used.
Install - Use the specified installation tool. Just wind the insert into the hole until the top coil is 1/4-1/2 turn into the tapped thread.

Note: Remove tang with the appropriate tool specified.

Drilling And Countersinking

The suggested drill sizes for aluminum Iisted in the catalog are within the minor diameter Iimits for HELI-COIL tapped holes. Alternate drill sizes are suggested in many instances for magnesium, steel and plastics to provide for maximum tap wear life. In the case of magnesium, the larger size is recommended to allow for material close-in. The MINOR DIAMETER AFTER TAPPING should be within the limits shown.

Depth
Minimum drilling depth allows one pitch chip clearance between the point of the plug tap and the bottom of the drilled hole. Minimum drilling depths for bottoming taps which have a shorter chamfer and no male centers are given separately.

THESE DRILLING DEPTHS ARE MINIMUM AND SHOULD BE INCREASED WHERE POSSIBLE PARTICULARLY FOR SPIRAL POINT TAPS.

Countersinking
To prevent the feather edge at the start of the hole, a 120o +-5o countersink to diameter is recommended BEFORE TAPPING. The minimum depth of the full tapped thread takes into consideration 0.5 pitch for depth of countersink.

Drawing Callout - Example
Here is a typical drawing callout for HELI-COIL Screw-Lock Insert M8xl.25 1.5 diameters long, for Tolerances Class 5H. This can be abbreviated by using a production process sheet to provide the operational steps thus limiting the drawing to dimensional data only.

8.3mm Drill maintaining 8.271/8.483 Hole Diameter to 23.5 minus 0 plus your standard drilling depth tolerance.

Countersink 120o ± 5o @ to 9.50/10.10 Diameter

Tap with HELI-COIL STI Tap No. 2087-8 (Tolerance Class 5H) to 13.3 Min. Full Thread Depth

Gage with HELI-COIL Gage No. 1324-8 according to your sampling plan. P.D. 8.812/8.911.

InstalI HELI-COIL Screw-Lock Insert 4184-8CN12.0 with HELI-COIL Inserting Tool No. 7751-8.

Break off driving tang with HELI-COIL Tang Break-Off Tool No. 4238-8.


Extraction Tools

TooIs to remove HELI-COIL Inserts are Iisted below. This is done by applying the tool to the insert, striking the head of the tool a light blow and turning it counterclockwise, maintaining steady downward pressure.

NOMINAL EXTRACTING
DIAMETER TOOL

2.2mm, #2 1227-02
2.5 - 4.5mm, #3 - #8 1227-06
5 - 10mm, #10 - 3/8" 1227-6
11 - 24mm, 7/16" - 1" 1227-16
27 - 39mm, 1-1/8" - 1-1/2" 1227-24


Hand Inserting Tools

Hand tools are designed with threaded mandrel and patented driving contour to install HELI-COIL Inserts correctly and efficiently. Complete instructions are furnished with each tool.