Custom-made O-ring
We manufacture O-rings to measure and according to your drawing. As an O-ring manufacturer with in-house tooling, we design the mold, select the appropriate mix, and press the O-ring to special specifications at our site in Munich. You receive an O-ring whose dimensions are tailored to your installation space and not to a standard series.
- Customised production
- Batch sizes 1 to 1 million units.
- Express production from 2 weeks
- 100% Reliability & proactivity
Bespoke O-rings according to your drawing
We do not carry catalogue items. All our special-order O-rings are made to your specifications: inner diameter, thread thickness, Shore Hardness, We coordinate the material and color with your application. If no final geometry is available yet, we advise you on the design during our engineering support.
Inner diameter and cord thickness outside the standard ranges, e.g. for installation spaces that are designed specifically and cannot be adjusted to a catalog size.
O-rings in special sizes
Micro-sized sealing rings from 0.01 g component weight with wall thicknesses under 0.3 mm for valve technology, sensors, and analysis equipment.
Micro O-rings
O-rings and sealing rings up to 650 mm diameter for container lids, manholes, filter housings and flange connections in plant construction.
Large-sized O-rings
Elastomer compounds adapted to your requirements for special applications and special certifications such as FDA, KTW-BWGL, WRAS etc.
O-rings in special materials
O-rings are suitable for mixed applications with defined leakage resistance for ESD-sensitive areas and applications with potential compensation via the sealing point.
Conductive & antistatic O-rings
We manufacture O-rings in small batches for retrofit projects, test benches, and to supply discontinued series of products for which no longer available catalog parts exist.
O-rings for small series
Color coding for the differentiation of materials or hardness levels during assembly; colored and not subsequently coated.
O-rings in special colors
If the sealing point needs to be reinforced or positioned, we vulcanize the elastomer directly onto a metal or plastic carrier.
O-rings with carrier
Advantages of a custom-made O-ring Compared to standard parts
An O-ring from the catalog forces the design to adapt the installation space to available dimensions. A custom-made version reverses this ratio.
- The size follows the component: you determine the nut diameter and nut depth; we supply the appropriate ring. Structural compromises due to the closest standard size are eliminated.
- Material according to medium: The mixture is selected according to your medium, temperature window, and pressure, not according to what is stocked as catalog items.
- Hardness level can be selected freely: Shore hardnesses of approximately 30 to 90 Shore A can be adjusted within a family of materials and adjusted for compression and gap size.
- Supply security: For an O-ring as per drawing, the tool is in our possession. Outdated catalog items or changed supplier assortments do not affect your spare parts supply.
- Reproducible quality: Each batch is produced from the same cavity with documented process parameters, which limits any variation between batches.
- A contact person: Tooling, mixing, shaping and testing are the responsibility of an O-ring manufacturer.
Custom-made O-rings -
individually tailored 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
Materials for your O-ring
made to measure
The appropriate Elastomer compound decides on the durability, temperature tolerance and lifespan of your special O-rings. We process all common Elastomers, We offer all available shore hardnesses and are open to discussing which material best meets your requirements in terms of cost-effectiveness.
Use in environments with mineral oil, grease and hydraulic fluids from approximately -30 °C to +110 °C, used in hydraulic cylinders, pump housings and fasteners for general machine construction.
Oil resistance of NBR at higher temperature and aging resistance up to about +150 °C, used in climate circuits, compressors and motor peripherals.
Resistant to hot water, hot steam, brake fluid, ozone and weather from approximately -50 °C to +130 °C, but not to mineral oils. EPDM O-rings are frequently used in drinking water and heating systems, in plumbing and in braking systems.
For aggressive chemicals, fuels and sustained temperatures of approximately -30 °C to +220 °C, used in fuel systems, chemical pumps and hot assemblies.
Temperature windows from -50°C to +220°C, physiologically harmless and FDA-compliant adjustable, used in medical technology, food processing plants and sterilization technology.
The low-temperature flexibility of the silicone up to -65 °C combined with resistance to fuels and non-polar media is used in aviation fuel systems and in low-temperature start-up testing rigs.
Chloroprene with resistance to weathering, ozone, refrigerants and moderate oil contact, used in refrigeration systems, in climate control systems and on components in outdoor applications.
Four sizes determine the sealing function one custom-made O-ring
Our individually manufactured O-ring seals not only by the size alone, but also by the interplay of thread thickness, groove geometry, and material hardness. We coordinate the following five dimensions together before the tool is created.
01 / 04
Level of enforcement
For static sealing, the recommended value is between 15 % and 30 % times the thread thickness; for dynamic loading, it % should be a maximum of 20. Too low compression leads to leakage as soon as the material sets. Too high compression creates a permanent residual compressive deformation and shortens the service life.
02 / 04
Nut filling level
In the crimped state, the groove should be filled to approximately 85 % %. The remaining volume increases due to expansion caused by heating and fluid swelling. If this reserve is not present, the internal pressure in the cross section increases and the ring is pressed over the groove edge.
03 / 04
Nut depth and width
The depth of the groove must be smaller than the thickness of the thread, and the width of the groove must be at least equal to the thickness of the thread. The edges should be rounded and insertion grooves should be provided to prevent the ring from being cut during assembly or damaged during operation.
04 / 04
Spalt dimensions and extrusion limit
With high pressure connection and a soft rubber compound, the O-ring can be pressed into the sealing gap to the required size and then trimmed over the groove edge. Three adjustment levers counteract this: higher Shore hardness, narrower tolerance of the gap size or a support ring.
At GUME, all steps are handled under one roof, from tool design to custom-made O-rings. This eliminates coordination loops between multiple suppliers, and you have a single point of contact.
O-Rine made to measure in 4 manufacturing steps
1. Design and layout definition
Based on your drawing and 3D model, we check dimensions and tolerances, advise on possible design optimizations, coordinate material, hardness, and quantity requirements with you, and prepare a free quote.
2. Mixing and toolmaking
In accordance with the application, we select or develop the rubber compound. At the same time, the mold is created in our own toolmaking department, made of aluminum or tool steel depending on the quantity and required service life.
3. Forming & Vulcanization
We manufacture large cross-sections and small batch sizes using the compression press process, fine cross-sections using the transfer press process, and high-volume production using injection molding. The raw rubber is vulcanized under pressure and temperature in the O-ring cavity.
4. Deburring, inspection & delivery
Depending on the component geometry, we deburr special O-rings using cryogenic deburring, trowalizing, or grinding. Upon request, we document the values in a preliminary sample test report. Only then will your batch be delivered.
You have questions about
custom-made O-rings
We have answers!
At what quantity is a custom-made product worth the cost compared to catalog products?
As soon as no standard size fits the installation space or the material is not available in stock, the custom-made product is the only option starting at 1 unit or the O-ring prototype is the only option. From a cost perspective, compared to catalog products, it usually becomes economical starting at a few thousand units per year, depending on the ring size and material.
What tolerances are achievable with an O-ring according to the drawing?
For inner diameters and thread thickness, we orient ourselves on ISO 3601-3 Class A or B. More precise tolerances are possible, but they increase the tooling and testing costs. Which class is appropriate is determined by the nut tolerance and the compression window.
What O-ring sizes are manufactured by GUME?
From micro-sized parts starting at 0.01 g to individually manufactured maxi-O-rings with a diameter of 650 mm. The maximum component dimensions in our presses are 650 × 750 mm.
What standards exist for O-rings?
For O-rings, there are two groups of standards: dimensional standards that order the inner diameter and thread thickness in fixed rows, and quality standards that regulate tolerances, surface condition, installation spaces, and material characteristics. The internationally leading standard is ISO 3601, which defines dimensions and tolerances, installation spaces, form and surface requirements, support rings, and material requirements. In addition, AS568 from the Anglo-American region is used primarily in inches. We manufacture according to each of these series, and also outside of them if no standard size fits your installation space.
How high can the pressure be at a moving sealing point?
For dynamic loading, the recommended value is a maximum of 20 % times the thickness of the wire rope; statically, 15 to 30 is % usual. Higher values increase friction, wear, and residual compressive deformation without improving the sealing effect.
Why can't the nut be completely filled when it is pressed in?
The fill level should % be about 85%. The remaining volume increases due to expansion caused by heating and fluid swelling. Without this reserve, the pressure in the cross section increases, the ring is pressed over the groove edge, and the service life decreases.
