Rubber bung
We manufacture bespoke rubber and silicone sealing plugs to your drawing. As a sealing plug manufacturer with our own toolmaking shop, we produce not only the components, but also the necessary moulds at our site near Rosenheim.
- Customised production
- Batch sizes 1 to 1 million units.
- Express production from 2 weeks
- 100% Reliability & proactivity
Custom-made sealing plug matching your bore
A expansion plug seals a bore both internally and externally. Unlike a fitted cap, the plug sits within the bore diameter and exerts its sealing effect via the radial preload of the rubber against the bore wall. Diameter, oversize, taper, Shore Hardness, We adapt the seal geometry and material to suit your specific opening. We manufacture all sealing plugs to measure based on your drawing and do not carry off-the-shelf products.
The tapered shape centres itself when inserted and compensates for bore diameter tolerances along the insertion depth.
Conical plug
The defined outside diameter fits with even pressure in calibrated bores and keeps insertion and extraction forces close together.
Cylindrical sealing plug
Multiple circumferential sealing lips compensate for bore tolerances without increasing the insertion force beyond that of a solid wall.
Slotted sealing plug
An integral pull tab allows for tool-free removal on closures that are repeatedly opened for maintenance, filling or inspection.
Plug with pull tab
A moulded or vulcanised external thread seals tapped holes with a defined preload and withstands higher internal pressures than a pure press fit.
Threaded plug
A vulcanised-in metal or plastic insert stiffens the plug, absorbs compressive forces or provides a connection interface.
Composite sealing plug
Benefits of custom-made Industrial sealing plugs
A custom-made sealing plug is tailored to your bore, medium and assembly process. In addition, properties emerge that a catalogue plug with a fixed geometry and standard compound does not cover.
- Tight sealing without an additional seal: the radial pre-load of the elastomer provides the seal, eliminating the need for a separate O-ring.
- Tolerance compensation: Conical shape and sealing lamellae compensate for dimensional variation in the bore and maintain a constant sealing effect over a tolerance range.
- Defined insertion and removal force: By means of hardness, allowance and geometry, the assembly force can be tailored to your process, ranging from smooth manual assembly to a tight press fit.
- Resistance to media and temperature: The choice of material depends on the media and temperature range of your application, ranging from water and oil to aggressive chemicals.
- Reusability: Plugs with a pull tab can be removed without tools and used multiple times.
- Non-marking compounds: For contact with painted or coated surfaces, we supply compounds without migratable constituents.
Custom-made rubber sealing plugs -
Custom-made by GUME
- In-house toolmaking: moulds are created internally, with no external waiting times
- Express production possible: first samples already available in 2–3 weeks
- Flexible sizes and quantities
- Custom production from single items to large-scale series
The right rubber band
for your sealing plug
We process all standard Elastomers, to meet the requirements for your sealing plug regarding media resistance, temperature range and recovery behaviour. A softer compound (from 30 Shore A) increases tolerance compensation and reduces the insertion force. A harder compound (up to max. 85 Shore A) increases dimensional stability and pressure absorption.
Seals oil-bearing boreholes in gears, hydraulics and drive technology that come into contact with mineral oil, grease or fuel, in the range of -30 to +110 °C.
Used when NBR sealing plugs reach their limits in hot, oil-bearing boreholes due to high continuous operating temperatures of up to 150 °C.
Seals openings in water-bearing systems and for outdoor use, is resistant to ozone, hot water and steam at -50 to +130 °C, but unsuitable for contact with mineral oil.
Withstands high mechanical stress fasteners with frequent dismantling in the range of -55 to +70 °C, away from oil and ozone exposure.
Seals gaps in food processing and medical technology as well as during rapid temperature changes from -50 to +220 °C, available in food-compliant compounds.
Secures boreholes in chemically contaminated plants against aggressive media and fuels at temperatures up to +220 °C.
Applications of Sealing plugs
made of rubber
Not every application can be covered with a standard plug. Custom-made rubber sealing plugs are used wherever geometry, material properties or approvals have to meet specific requirements.
01
Coachwork
In body construction, sealing plugs are often designed specifically for a particular opening. In the case of high production volumes, custom-made parts enable an optimal fit and cost-effective series production.
02
Switchboard manufacturing
In control cabinet manufacturing, mounting openings that do not correspond to standard dimensions frequently need to be closed. Custom-made solutions fit the respective geometry precisely and ensure a secure seal.
03
Food industry
In the food industry, sealing plugs are tailored to the requirements of the respective process. The main priorities here are media resistance as well as food-safe materials and certifications.
You have questions about
Rubber sealing plug?
We have answers!
What is a sealing plug?
A sealing plug is a component made of rubber or silicone that seals a bore or opening from the inside. The sealing effect is achieved through the radial preload of the rubber against the bore wall, without an additional seal.
What is the difference between a sealing plug and a blanking cap?
The plug fits inside the inside diameter of the opening and seals radially, whereas a cover cap is pushed over a component or a projection and protects from the outside. For sealing bores, pipes and threads, the plug is the correct design.
From what quantity does GUME manufacture custom sealing plugs according to drawing?
We manufacture custom-made sealing plugs starting from batch size 1 up to rubber sealing or blanking plugs in annual quantities of up to 1 million pieces. We rely on compression moulding presses for small quantities with large-volume geometry, and on injection moulding for high quantities.
Are sealing plugs available for the food industry or medical technology?
Yes. For hygiene-sensitive applications, we manufacture stoppers from FDA-compliant silicone or other suitable compounds and, upon request, supply declarations of conformity in accordance with EC 1935/2004 and the FDA. Metal-detectable compounds are also possible.
How are the insertion and withdrawal forces determined?
The interference fit with the bore, the Shore hardness and the contact length determine the retention. We help you design these parameters so that the plug holds securely and can still be fitted or removed with the intended force.
Can sealing plugs withstand internal pressure or a vacuum?
Yes. Through oversizing, sealing lips, a collar or a vulcanised-in support element, plugs can also withstand overpressure or underpressure.
What component sizes are possible?
We manufacture sealing plugs ranging from micro-parts starting at 0.01 g with wall thicknesses of less than 0.4 mm up to large-volume designs. We produce small diameters using injection moulding, and high-volume plugs with thick walls using compression moulding. The maximum component size is 650 by 750 mm.
How does the bore influence the design of a rubber sealing plug?
A chamfer or rounded bore edge facilitates assembly and protects the sealing edge against damage during insertion. Surface roughness and bore tolerance therefore also influence the design of the interference fit and sealing geometry so that the plug seals across the entire dimensional variation.
