Npt Male Internal Hex Plug

The manufacturing process of Npt male internal hex plug involves the use of advanced molding technology combined with precise CNC machining. The main objective is to ensure the sealing performance of the thread and the reliability of the internal hexagonal drive.

（1）Softening raw materials

According to the characteristics of different materials, the long bar stock is subjected to soft annealing treatment. This process eliminates the internal stress in the steel, refines the grain structure, enhances the plasticity of the material, prepares it for the subsequent "cold forming" processing, and prevents cracking during the processing.

（2）Die casting of blanks

1.Standard production process (cold heading method): On the cold heading machine, the wire material is fed into the die. Through continuous stations such as cutting, pre-forming, and final forging, the punch of the equipment will directly shape it into an internal hexagon, and then an internal hexagon hole will be formed at the head.

2.High-precision process (CNC turning/milling method): The long bar material is fed into the CNC lathe. First, the shape is machined out, and then a special internal hexagonal tap (Broach) is used to process the internal hexagonal holes on the part.

（3）Precision turning & NPT thread forming

After the rough casting is completed, it is processed precisely using a high-precision CNC numerical control lathe.

The processing is carried out using a dedicated NPT forming thread milling cutter. After the processing is completed, the NPT thread ring gauge is used for inspection.

（4）Heat treatment & Hardening

In order for the Npt male internal hex plug to withstand high-pressure mechanical strength, the semi-finished products made of carbon steel or alloy steel need to undergo heat treatment. The core process is "tempering (quenching + high-temperature tempering)", which can make the hardness of the products meet even higher performance requirements.

（5）Surface treatment

The Npt male internal hex plug after heat treatment will undergo surface treatment according to the customer's requirements or the application environment.

（6）Quality inspection

Each batch of produced Npt male internal hex plug must undergo strict quality inspection before they can be packed and shipped.

1.Comprehensive dimension and thread inspection: including gauge block inspection, inner hexagon pitch measurement, to ensure dimensional consistency.

2.Strict appearance and performance inspection: Use XRF to verify the material, use a magnifying glass to look for defects, and conduct mechanical performance tests.

3.Factory inspection and final packaging: Before shipment, all products will undergo 100% factory inspection. After passing the inspection, the products will be cleaned and packaged.