Threadless Plugs - Inch Buna O-Ring

Threadless cooling-circuit plugs are used inside injection molds to seal and cap pressure lines or drilled cooling passages without adding external threads to the tooling. The tensioned hex adjustment screw expands the Buna O-ring, making this option especially suitable for rough, oversized, or imperfectly drilled holes where conventional threaded fittings may leak.

• Automotive connector and housing molds: seal intermittent cooling-line penetrations and pressure coolant feeds, helping maintain consistent cooling performance under line pressure up to 72 psi.
• Medical device tooling: use the same sealing mechanism to prevent coolant migration in areas where surface finish and hole geometry can be challenging, improving fluid containment.
• General mold heating/cooling circuits: cap unused openings or correct minor drilling variation; the threadless form supports standard or oversize channel openings.

This variant’s built-in Buna O-ring and hex expansion feature are designed to restore sealing capability even when hole conditions are not tightly controlled.

The provided product data specifies an elastomeric Buna O-ring for sealing, but does not list a specific plug steel grade or measured hardness (HRC). As a result, material heat treatment, quench/temper, nitriding, and hardness/wear figures cannot be stated from the supplied specifications.

From a manufacturing standpoint, these threadless plugs rely on precision assembly of the O-ring and a hex adjustment mechanism that mechanically expands the seal against the bore wall to compensate for rough or oversized holes.

• Buna (NBR) O-ring sealing: selected for resilient sealing performance in pressure lines; the achievable pressure capacity is specified as up to 72 psi.
• Trade-off note: elastomer sealing performance depends on bore finish and compression uniformity; for rough holes, the hex expansion improves sealing contact.

Select the plug by Nominal Pipe Size (in): 1/8", 1/4", 3/8", or 1/2". Because this is a threadless design, sizing focuses on matching the plug to the drilled cooling opening size where you need a cap or seal, rather than threading into the bore.

• Core/cavity sealing: choose the nominal pipe size that corresponds to your cooling circuit opening so the plug can seat and expand the O-ring effectively.
• Rough or oversize holes: the hex adjustment screw expands the Buna O-ring to help stop leakage, which is beneficial when bore geometry is less than ideal.
• Pressure readiness: confirm that your line pressure is within the rated up to 72 psi range for this sealing approach.

Tolerance guidance (e.g., specific fit/clearance numbers) is not provided in the input data; however, the adjustable expansion is intended to accommodate practical variations in hole condition.