Five Precautions for Using Double Screw Extruder Thread Inserts

Double screw extruder thread inserts are commonly used in angular threaded workpieces. Besides mechanical machining, the threads can also be obtained using tapping and threading methods. Tapping involves using a tap to machine internal threads on the inner cylindrical surface of the workpiece; threading involves using a die to machine external threads on a cylindrical rod.

Five precautions for using double screw extruder thread inserts:
1. Drilling for Double Screw Thread Inserts
Drill holes using the standard drill bits listed in the table. The drilling depth should be greater than or equal to the installation depth of the wire thread insert; be careful not to drill a tapered hole, and prevent chips from falling in. After drilling, the hole depth should not exceed 0.4 times the thread pitch, as an oversized hole is detrimental to the insertion of the wire thread insert.

2. Tapping for Double Screw Thread Inserts
Use a wire thread insert tap with the specified thread specifications for tapping. The tapping length must exceed the length of the wire thread insert. For through holes, tap the entire length; the accuracy of the tapping determines the tolerance zone of the final standard internal thread. Users should appropriately select the tapping method and lubrication. For blind holes, apply appropriate force to prevent tap breakage. After tapping, the threaded hole should be cleaned, generally by blowing with a compressed air gun. For blind holes, a long nozzle with a diameter similar to the hole should be used to clean from bottom to top. Cleaning methods can also be used to clean the threaded hole. When high accuracy is required for the threaded hole, a wire thread insert bottom hole plug gauge should be used for inspection.

3. Installation of Double Screw Thread Inserts
Under normal circumstances, a manual installation tool should be used for installing wire thread inserts. Place the wire thread insert into the installation tool, insert the installation handle into the guide rod groove, and rotate the installation tool handle to screw the wire thread insert into the threaded hole, leaving 0.25-0.75 turns of thread above the surface. When installing a small number of wire thread inserts or coarse-pitch wire thread inserts larger than M14*2, a "T"-shaped slotted or threaded head simple tool can be used for installation. Care should be taken not to apply excessive axial force to the wire thread insert installation handle to prevent cross-threading. After installation, the accuracy grade of the resulting standard internal thread hole can be checked with a corresponding gauge.

4. Removing the installation tang of double-ended wire thread inserts
For wire thread inserts with a break-off groove, the installation tang should be removed after screwing it into the threaded hole using a tang removal tool. For through holes, the wire thread insert installation tang should be broken off. Generally, a punch is used to align with the installation tang, and a sharp blow with a hammer weighing about 200g will remove it. For coarse-pitch wire thread inserts larger than M18*2.5 and fine-pitch wire thread inserts larger than M14*1.25, the installation tang can be broken off by bending it up and down with needle-nose pliers. Then, the broken-off installation tang can be removed from the threaded hole.

5. If using an automatic tang removal tool, simply apply appropriate force with the punch of the automatic tang removal tool to the wire thread insert installed in the bottom hole to break off the installation tang.