Supply of captive PF21-M3.5-16.4 non-detachable spring screws, captive screws for cabinets.

Non-Detaching Screw
Applied to panels: Non-detaching screws, also known as spring screws. These screws can be riveted onto iron plates, allowing them to be freely screwed in and out. The entire assembly remains securely embedded in the panel without detaching, hence the name non-detaching screw. The outer hand-twist sleeve typically features straight knurling for easy manual tightening, so it is also referred to as a hand-tight screw or hand-twist screw.
Non-detaching panel screws (spring screws) can be used for installing PCB boards, occupying minimal space. The press-rivet sleeve of the hand-tight screw has knurled teeth and is pressed into the chassis or thin sheet hole (note: the drilled hole diameter of the thin sheet must meet specific requirements relative to the press-tooth diameter of the spring screw), forming an exposed spring screw that can be hand-twisted at the other end (the hand-twist end). Due to the internal spring, the screw can move in and out relative to the other end of the thin sheet. This solution addresses the challenge of frequently removing screws and is highly convenient and practical.

Name: Non-detaching screw, panel screw, spring hand-tight screw
Material: Combination of carbon steel screw, carbon steel press-rivet sleeve, and aluminum hand-twist sleeve; combination of stainless steel screw, stainless steel press-rivet sleeve, and aluminum hand-twist sleeve. The non-detaching panel screws produced by Yaoda Hardware*** are entirely manufactured and assembled in-house, with the exception of the spring, which is sourced externally. Strict quality control is maintained.
The panel spring screw (non-detaching screw) consists of several components:
1. Screw part (used to fasten the other end of the chassis thin sheet; typically made of carbon steel or stainless steel, with cross or slotted head for tool tightening)
2. Hand-twist sleeve (usually with straight knurling, typically made of aluminum, and sometimes anodized black as needed)
3. Press-rivet sleeve (used for riveting onto the panel)
4. Spring (facilitates the extension and retraction of the screw and prevents the entire assembly from detaching)
After each component is produced, they are assembled into one unit, and the hand-twist part is pressed to fit together with the press-rivet part via the spring, forming a complete non-detaching spring panel screw.