Mold Cooling Plugs
Aluminum, brass, and steel mold cooling plugs with O-ring, pressure, threadless, and screw-type sealing — including 150°C heat-resistant options — for sealing unused waterline ports and cross-drilling exits.
All Products (13)
mold cooling plugs - Aluminum, One-Piece
Aluminum · One-piece design · Economy
mold cooling plugs - Brass, O-Ring
Brass · O-Ring seal · Reusable
mold cooling plugs - Metal Bar Tapped
Metal bar stock · Tapped thread
mold cooling plugs - 150°C Heat Resistant
FKM O-Ring · High-temp rated
Screw Plugs with O-Ring - Hex Socket Flange
Hex socket · Flange · O-Ring seal
Plug Material & Seal Type Selection
Choose your plug based on material requirements, mechanical sealing pressure, and temperature limits.
| Dimension | Aluminum One-Piece | Brass O-Ring | Steel Pressure (PFPE) | Threadless (PLGT) |
|---|---|---|---|---|
| Seal Mechanism | Interference thread deformation | Captive elastic O-Ring squeeze | Mechanical expansion sleeves | Press-fit friction on unthreaded bore |
| Removability & Reuse | Removable; prone to thread stripping | Easily removable; highly reusable | Non-removable (permanent locking) | Removable only with puller rod |
| Max Temperature | $\le 80^\circ\text{C}$ (thermal deformation limits) | $\le 200^\circ\text{C}$ (FKM-sealed variant) | $250^\circ\text{C}+$ (metal-to-metal contact) | $\le 80^\circ\text{C}$ (limited by friction shear) |
| Pressure Limit | 3 - 6 bar (standard waterline) | Up to 8 bar (high-pressure seal) | 15+ bar (high-integrity seal) | 3 - 5 bar |
| Port Preparation | Requires tapped metric thread M/Rc | Requires tapped parallel G/Rp thread | Requires straight drilled blind hole | Requires straight reamed bore |
| Relative Cost | $ (lowest, economy block) | $$ (moderate, reusable) | $$$ (higher cost, heavy-duty) | $ (economical speed install) |
| Best For | Standard plates, low-temp economy | Zone maintenance, core inspection | Cross-drilling exits, permanent plugs | Unthreaded thin walls, space-limited cores |
Selection rule: For routine cooling channel plugging with future access needs, brass O-ring plugs are the best balance of reliability and serviceability. For permanent sealing of cross-drilling exits, pressure plugs are preferred. See our Plug Selection Guide.
Choose Your Plug in 3 Steps
Installation note: Proper torque is critical — over-tightened plugs crack mold plates, under-tightened plugs leak. Use a torque wrench and follow manufacturer specifications. See our Plug Installation Guide.
Compatible Accessories
Ensure correct sizing and thread standards when selecting plug installation tools and replacement seals:
Plug ↔ Replacement O-Rings
Replace elastomer seals at every maintenance cycle to prevent seal set leakage:
- M6 / M8 Plugs $\rightarrow$ ORSO 4.8 (NBR) / ORSO 4.8-V (FKM)
- M10 / M12 / PT1/8 Plugs $\rightarrow$ ORSO 6.8 (NBR) / ORSO 6.8-V (FKM)
- PT1/4 Plugs $\rightarrow$ ORSO 9.8 (NBR) / ORSO 9.8-V (FKM)
Threadless Plugs & Drivers
Threadless plugs (PLGT Series) must be driven into the bore using dedicated alignment tools to prevent bore scoring.
E.g., PLGT ø8 plugs require the PLGT-8 installation tool.Threaded Plugs & Anaerobic Sealants
Tapered pipe threads (Rc/NPT) without O-rings require liquid anaerobic sealant to seal micro-gaps. Use Loctite 567 (rated up to $204^\circ\text{C}$) to prevent leaks under cyclic expansion.
About Mold Cooling Plugs
mold cooling plugs seal unused waterline ports, cross-drilling exits, and backup cooling channels in injection molds. Every mold has multiple points where cooling channels intersect or exit the mold surface — each one requires a reliable plug to prevent coolant leaks during operation. Our range spans 13 products covering aluminum, brass, and steel materials in O-ring, pressure, threadless, and screw-type sealing methods, plus a specialized 150°C heat-resistant variant for high-temperature applications.
Application Scenarios
Cross-Drilling Exit Sealing
Every cross-drilled cooling channel creates two exit points on the mold surface that must be permanently sealed. These are the most common plug application in any mold.
Steel pressure plugs provide a permanent, high-pressure seal for cross-drilling exits. The expansion fit ensures no loosening over millions of cycles — critical because these plugs are never meant to be removed.
Recommended → Pressure Plug - Steel
Serviceable Cooling Channel Ports
Cooling channel access points that need periodic removal for descaling, inspection, or cooling circuit reconfiguration during mold maintenance.
Brass O-ring plugs install and remove cleanly without damaging threads. The captive O-ring provides reliable sealing through multiple install/remove cycles. Simply replace the O-ring at each service interval.
Recommended → Cooling Circuit Plug - Brass, O-Ring
High-Temperature Mold Cooling
Engineering plastic molds (PC, PA, POM) running at 80-150°C where standard NBR-sealed plugs degrade within weeks, causing persistent coolant weeping.
The 150°C heat-resistant plug variant uses FKM (Viton) O-rings that maintain elasticity at elevated temperatures. Combined with heat-treated body construction, these plugs provide reliable sealing for 2+ years in high-temperature environments.
Recommended → Cooling Circuit Plug - 150°C Heat Resistant
Frequently Asked Questions
What is the difference between O-ring plugs, pressure plugs, and threadless plugs?+
What material should I choose for mold cooling plugs?+
Can mold cooling plugs withstand temperatures above 150°C?+
Do I need a special tool to install mold cooling plugs?+
Are mold cooling plugs available in both metric and inch sizes?+
Engineering Resources
Need a Custom Quote?
Specify your bore diameter, thread type (metric/NPT/none), material (aluminum/brass/steel), and temperature requirement. Non-standard sizes and special sealing configurations available.