SAE Finger Tightening Cap

An SAE 45°sealing cover that can be quickly installed and removed manually without tools and is designed for test ports and maintenance connections that require frequent operation or temporary closure. Finger pressure provides a reliable seal for quick service, pressure testing or system flushing scenarios.

 

 

Tool-less operation:
Hexagonal head design Wide non-slip knurling (knurling depth 0.5~1mm) provides sufficient friction to tighten or dismantle with fingers only.
Adaptable hand tightening torque range: 0.5~3 Nm, avoiding over-tightening and deformation of sealing surface.

 

Fast sealing:
45°tapered sealing face matches standard SAE 45°female fittings, metal-to-metal contact, no gaskets or lubricants required.
Sealing is accomplished with a single screw-in, with an operating time of ≤5 seconds.

 

Lightweight design:
Wall thickness optimized (20% thinner than conventional plugs), 30% lighter weight, easy to carry and quick operation.

 

 

1 Geometric design
Sealing taper:
45°internal taper (tolerance±0.5°), surface roughness Ra≤3.2um, sealing is realized by preloading and local plastic deformation.
Flexible transition zone at the root of the taper to accommodate slight misalignment (offset angle ≤2°).
Knurled head:
OD 1.5~2 times the thread diameter (e.g. 1/2"thread corresponds to OD 19mm), knurling pattern is cross diamond or straight groove.
Some models have integrated O-ring grooves (optional), which are compatible with elastomer seals to enhance low-pressure airtightness.
Thread design:
Short thread (effective length 1x diameter), thread type UNF fine thread (e.g. 1/2-20 UNF), to reduce manual screwing resistance.

 

2 Materials and Processes
Material:
C36000 free-cutting brass: hardness HRB 70~80, balancing strength and hand screwing operability.
Surface treatment: electrolytic polishing (EP) or nickel plating (optional) to reduce the risk of hand sweat corrosion.
Manufacturing Process:
Cold heading knurling: maintains the continuity of material fibers and avoids cracking of knurled edges.
CNC Precision Turning Taper: taper and thread coaxiality≤0.05mm to ensure uniformity of sealing.

 

Part#	Thread Size UNF	MAF
1709-D	1/4	10081
1709-E	3/8	10082

 

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