- Expansion plugs are an inexpensive and effective way to seal holes in a wide range of metal products.
- Expansion plugs provide a metal-to-metal seal with performance characteristics detailed below.
- The classic use case is sealing core holes in machined castings.
- We manufacture all our expansion plugs at our facility in Oxford, Michigan, USA.
Hubbard Spring is the original patent holder and manufacturer of expansion plugs since 1913.
Cup Plugs
Cup Plugs – burnished edge ENGLISH spring lock
Cup Plugs – burnished edge METRIC DIN443
Cup Plugs – burnished edge FORD WM104 + WM901
- Burnished edge Cup Plugs are engineered to seal holes ranging from [8mm – 40mm] and [0.312” – 2.250”].
- High-pressure retention combined with simple hole preparation and installation.
- Cup plugs have the least overall cost of all expansion plugs when considering hole preparation and installation.
SEALING DYNAMICS
- The seal is created by the tapered and burnished sealing surface compressed into a machined through hole.
- Retains up to 60 bar pressure on 25mm or 1” diameter plugs.
- Requires a machined through hole with lead-in as detailed above and on the part print available on the item page.
- Requires a shouldered installation tool as detailed above and on the part print available on the item page.
Cup Plugs – burnished edge PRECISION series
- Precision series Cup Plugs are engineered to seal holes ranging from [3mm – 8mm] and [0.118” – 0.312”].
- Good-pressure retention combined with simple hole preparation and installation.
- Cup plugs have the least overall cost of all expansion plugs when considering hole preparation and installation.
SEALING DYNAMICS
- The seal is created by the tapered and burnished sealing surface compressed into a machined through hole.
- Retains up to 30 bar pressure on 6mm or 1/4” diameter plugs.
- Requires a machined through hole with lead-in as detailed above and on the part print available on the item page.
- Requires a shouldered installation tool as detailed above and on the part print available on the item page.
Welch Plugs
Welch Plugs – blanked edge ENGLISH
Welch Plugs – blanked edge METRIC DIN470
- Blanked edge Welch Plugs are engineered to seal holes ranging from [3mm – 100mm] and [0.125” – 4.500”].
- Good for limited depth and low-pressure applications.
- Best used as cover or to retain liquid at low or no pressure.
- Blanked edge Welch Plugs are the least expensive expansion plug but require a machined counterbore.
SEALING DYNAMICS
- The seal is created by the sharp corner of the blanked edge expanding into the sharp corner of the counterbore wall.
- Retains up to 3 bar pressure on 25mm or 1” diameter plugs.
- Requires a machined counter bore as detailed above and on the part print available on the item page.
- Requires an installation tool as detailed above and on the part print available on the item page.
Welch Plugs – ground edge ENGLISH
Welch Plugs – ground edge METRIC DIN470
- Ground edge Welch Plugs are engineered to seal holes ranging from [8mm – 63mm] and [0.312” – 2.500”].
- Good for limited depth and high-pressure applications.
- Meet or exceed the pressure retention of cup plugs.
- Ground edge Welch Plugs are usually more expensive than cup plugs and require a machined counterbore.
SEALING DYNAMICS
- The seal is created by the sharp corner of the ground edge expanding into the sharp corner of the counterbore wall.
- Retains up to 100 bar pressure on 25mm or 1” diameter plugs.
- Requires a machined counter bore as detailed above and on the part print available on the item page.
- Requires an installation tool as detailed above and on the part print available on the item page.