Technical Informations

What should we do if the tap is broken when CNC machining the internal thread?

In the process of parts CNC Machining, the most common method for the internal thread processing structure of small holes is to tap the tap. However, in the process of using the tap, the operation of the tap is often caused by improper operation, the bottom of the hole is too small or the hole is too deep, and the breakage occurs. How to take out the broken part of the tap which is still in the tapping hole?

Method 1: You can use a small punch to slowly rush out, or break the tap, make a special tool with three claws and extend it into the chip pocket. The large tap can be piled out by electric welding, or use a flame bar tap. After the annealing, the electric drill is used to remove it, the electric spark is ablated, and two nuts are screwed with an eight tap, and then three steel wires are used to penetrate the chip flute, and the flutes of the tap inside the hole are aligned. If you can't turn it, if the workpiece is not big, put it in the fire and then turn it on.

Method 2: The material is a high-speed tool steel. If the wire picker cannot be taken out, it can be heated to 1200-1300 degrees with oxygen and then cooled by water to crack and then use the corresponding object to knock off the broken cone.

Under normal conditions, the taper of the cast iron piece is easily removed by the wire taker. This is because the brittle material is less deformed during the tapping process, and is directly cut to form a screw hole, and the steel piece is in the tapping process. Because of its good plasticity, a part of the material is plastically deformed to increase the thread height, and it also increases the frictional force of the tap and screw thread profile, which makes the tap difficult to remove. However, steel is still in the austenite solid phase zone at around 1200°C. Short-time heating does not cause grain growth and affects the mechanical properties of the material.

Method 3: According to the different machining holes, if it is a blind hole, it is better to leave a little more outside the broken tap. Clamp the broken tap directly with pliers, and then manually unscrew it by lifting the knife. It's more difficult if all the broken tap broken in, and you can only fight sparks, the cost is too high, you can do it yourself.

Method 4: If it is a through hole, and the normal tap is broken. Cut the wire in the cross direction with a wire cut. Generally, it can be down. If the screw is broken, it must be discharged the fine hole before cutting the wire.

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