BSP Male Captive Hollow Hex Plug

production process 

【1】Billet Forming

To transform bar or wire materials into blanks that are close to the final shape, there are two main methods:

【2】Precision Machining

（1）Turning: Using a CNC lathe, the key parts of the blank are finely machined to prepare for the subsequent processes. For instance, the sealing surface for installing the sealing ring is turned, and chamfers are machined.

（2）Drilling: For threaded BSP Male Captive Hollow Hex Plug that require oil channels and other structures, drilling operations will be carried out.

（3）Internal Hexagon Machining: This is the key process for creating the internal hexagonal drive groove.

①Cold heading forming: For large-scale products, the hexagonal holes can be directly formed during the cold heading process, which is extremely efficient.

②Punching: For certain processes, a hexagonal prism punch is used to press an internal hexagon onto the head of the workpiece.

③CNC milling: For small quantities or orders with specific requirements, a CNC milling machine can be used to precisely machine out hexagonal holes.

（4）Thread Processing: The fine machining of BSP threads is a crucial step in the entire production process and is of vital importance to the final performance.

①Main method: The part is formed in one piece through the thread turning process using a CNC lathe. During the turning process, a special 55° thread cutting tool is required.

②Dimension control: The dimensional accuracy of the thread is the core. During the production process, gauge blocks and stop gauges will be used for strict inspection to ensure that the parameters such as the pitch and the mean diameter of the thread are all qualified.

【3】Heat Treatment

Quenching & Tempering: We do a heat treatment process – first quenching, then high‑temperature tempering. The result of this is that the material of the BSP Male Captive Hollow Hex Plug becomes stronger and less prone to breaking.

【4】Surface Finishing

(1) Zinc Plating – This is the most common and cheapest option. It gives basic rust protection. You'll often see it in white, blue, or yellow finishes.

(2) Nickel Plating – This lasts longer against rust than zinc and has a shinier look.

(3) Dacrotizing – This is a zinc‑aluminum coating without chromium. It's very good at resisting rust and can survive salt spray tests much longer than regular zinc plating. It works well in really harsh, corrosive environments.

(4) Black Oxide – This creates a black finish on the surface. It helps a bit with rust and looks nice, but it scratches easily.

【5】Seal Assembly

(1)Assembly method – We use automated or semi‑automated machines to put the sealing ring exactly into the groove on the end face of the BSP Male Captive Hollow Hex Plug.

(2) Anti‑detachment design – The groove is sized precisely so the sealing ring stays firmly in place. It won't fall off during shipping, installation, or later when you're using the plug.