FAQ's

SFC KOENIG® is a global provider of products and solutions for sealing and flow control. Our core applications are in the transportation sector, in fluid control technology and precision engineering. To increase availability to our customers, we have three branches in the United States, China and Germany, and our headquarters is located in Switzerland. With two production sites – in Switzerland and in the US – we are able to provide the highest level of service and efficiency. In addition, we have numerous distribution partners around the globe.

The origins of SFC KOENIG® lie in a flexible and innovative company, which was founded by Dr. Max Koenig, who received his PhD in Engineering in 1927. The company was originally focused on sheet metal processing, though throughout the years its capabilities and products expanded. In 1985, it was renamed KVT-Koenig AG. In 2014, the company again changed its name and brand to SFC KOENIG®, to better reflect its position as a provider of the world’s leading sealing and flow control solutions. The company is proud of its successful and innovative past and is excited about the future.

Our contact form can be found in the upper section of this website. In addition to standard information, please provide as many details as possible regarding your project so one of our engineers can assist you.

SFC KOENIG® is the new identity of KVT-Koenig. Even though we have changed our name and logo, our focus and our commitment to providing superior engineering solutions for sealing technology and control systems remains the same. Our new name supports our position as the world’s leading supplier of sealing and flow control solutions.

Compared to other expander seal options, KOENIG EXPANDER® plugs provide unmatched reliability and a track record of superior performance, helping customers improve the total value of their sealing solution. The original inventor of the one-piece expander seal design, SFC KOENIG® utilizes advanced, automatic manufacturing technology to produce parts with precise capabilities. With over 5 billion parts installed, KOENIGEXPANDER® plug products are proven to successfully perform even in installations with vibration, pressure spikes, contaminants, and harsh operating environments. KOENIG EXPANDER® plugs support temperature tolerances which surpass many other seal options, with operating temp ranges from -40°C to 150°C (-40°F to 302°F). Our seals are also available in a wide variety of standard material options and plug sizes, and can also be custom-developed to meet your specific application requirements.

Expander plugs feature a serrated sleeve that expands into port walls during installation, forming a secure metal-to-metal seal without the use of chemical sealants or compounds. As the inventor of the one-piece expander seal solution, SFC KOENIG® offers two styles of expander plugs: push-style expander plugs and pull-style expander plugs. Push-style plugs utilize an integrated ball to expand the serrated walls of the plug into the base material and require a counter-bore drilled hole. Pull-style plugs utilize an integrated mandrel, and are ideal for angled channels, deep-hole installations, and do not require a counter-bore. While each expander plug design offers distinct benefits based on installation location and system configuration, both provide unmatched reliability, with failure rates less than 1 PPM, flexible tolerance allowances, and proven performance in a wide variety of critical applications.

All SFC sealing & flow control components and tooling equipment are RoHS compliant. The plating applied on the carbon steel plugs is zinc-iron, clear trivalent chrome.

SFC products are standard commercially available catalog items. If DFAR is absolutely necessary, further investigation would be required based on the part number.

The installation force of the product varies by the size and materials, and other factors such as tolerance stack up, etc. SFC does not recommend installing by force but rather by distance, install force can be provided on a case-by-case bases for reference in sourcing adequate installation equipment.

With hard base materials like steel, titanium, cast iron, the drilling roughness should be from Rz = 10 – 30 microns. A normal drilling process with no secondary process of reaming or finishing of the hole is recommended.

The holes must be round within t = 0.05 mm or t = 0.002 inches. See catalog under design guidelines.

1. The drilled hole must be within the specified tolerance.

2. The counter bore hole for the ball style plugs must be properly sized for the through hole (d2/d3) according to the dimensional sheet in the catalog.

3. Holes must be round within t = 0.05 mm or t = 0.002 in

4. For hard materials, the bore roughness should be from Rz = 10 – 30 microns for best results, especially in harder materials.

5. Longitudinal rifles and spiral grooves should be avoided. This may affect sealing.

6. The bore must be free of oil, grease, and chips.

No, secondary sealants of any type are not recommended. SFC EXPANDER plugs achieve sealing through metal-to-metal contact and hence the part and the hole must be free of any substance, including sealants or machining oils.

SFC recommends controlling the stroke of the EXPANDER element while pressing. There is, of course, a much larger variation in the force, and the stroke provides the most consistent method for controlling the installation of the plug.

As a part of the qualification process, the products undergo a temperature-pressure cycle test. SFC products are tested and rated for -40°C to 150°C. For higher temperatures please contact SFC KOENIG®.

The EXPANDERs are designed & rated for sealing fluids, but they have been used in various applications to seal gases. Inquire with our application engineering team to review your requirements for sealing gases.

We recommend installing the EXPANDER plugs after the heat treatment of the housing. It’s also recommended to mask the port where the EXPANDERs will be installed before heat treatment.

The EXPANDERs are based on the metal-to-metal sealing principle. The outside surface of the EXPANDERs must be free of any sealants, adhesives, or compounds. Applying any compounds reduces the sealing performance of the plug.

Occasionally within hydraulic systems, there are pressure spikes due to system variations. The proof pressure rating of the product indicates the maximum acceptable pressure spikes.

The working pressure rating of the plug indicates the continuous pressure that the EXPANDER product can withstand over the long term. The EXPANDER component can also withstand higher pressure spikes over the course of its lifetime, provided these spikes are temporary and not frequent.

It’s recommended to use the pull-style EXPANDER plug (SK/SKC or LK series). If for other reasons you have to use the push-style EXPANDER then it’s recommended to use a pin or provide some fixture from the bottom to support the forces acting on the product during the installation and insertion of the EXPANDER element.

The EXPANDER products can be used in softer materials like aluminum. During the expansion of the body, the grooves on the outside surface bite into the softer material to create a mechanical seal and provide anchorage. See catalog anchorage principle.

The EXPANDER products can be used in hard base materials like steel, cast iron. It is recommended to have a surface finish of Rz 10 – 30 microns. During the expansion of the body, the grooves on the outside surface create mechanical locks with the rough base material at the microscopic level to create a mechanical seal and provide anchorage. See catalog anchorage principle.

It is not recommended to remove reuse expanded component. The entire component (EXPANDER element & body) should be removed together. The bore should be inspected and drilled to the next larger size if necessary, and then install a new EXPANDER component. Plug removal is under the installation instructions (see comments above).

There are several advantages:

1. Using the EXPANDER plug eliminates the thread cutting operation in manufacturing. The EXPANDER plug is installed in an as-drilled counter bore and does not require any special finishing process of the hole.

2. Contamination from screwing in or cleanliness issues from thread locking adhesive or sealant are eliminated. The EXPANDER plug anchors in the base material and provides a metal to metal seal.

3. The expansion principle of the plugs prevents any back-out or loosening even in high temperature and high vibration environments.

4. The installation of the EXPANDER plug is suitable for high volume production. There are issues with thread misalignment or cross-threading.

5. EXPANDER plugs take up less space than typical threaded devices, especially o-ring screw plugs. Designers save space, weight, and also process costs in the creation of the bore.

6. Further processing of the component after assembly of the EXPANDER sealing plug can take place immediately. No drying time is required for adhesives or sealants.

You can find helpful videos on our website here.

It’s recommended to mask the hole during the anodizing process and then install the EXPANDER product. The sealing could be compromised if the EXPANDER is installed in the anodized hole, due to the risk the hard anodized surface will crack under the stress of expansion.

It depends on the specific SFC location. You can find our certs here.

1. In the US, SFC KOENIG LLC is certified for IATF 16949 and ISO 9001.

2. In Switzerland, SFC KOENIG AG is certified to IATF 16949, ISO 9001 and ISO 14001

3. In Germany, SFC KOENIG GmbH is certified to ISO 9001 and ISO 14001.

4. In China, SFC KOENIG® Flow Control is certified to IATF 16949 and ISO 9001.

The EXPANDER element must be pressed until the top surface of the element is flush or slightly below the top surface of the body/sleeve. Please refer to ‘x’ dimension in the SFC KOENIG® product information under the mounting guidelines.

All EXPANDER products are designed to be a slip fit. The EXPANDER product can be simply placed into the hole with no effort.

The hole must be round within t = 0.05 mm (t = 0.002 in). Click here to view.

We can send you the 3D CAD files for SFC products. Please contact SFC KOENIG®.

SFC products are delivered ready for installation. However, if the product is already in an open package in a relatively dirty environment cleaning may be advisable. It is recommended to only spray clean and air dry. Do not submerge in any solution or vacuum dry, which could affect the integrity of the assembly.

The plug can be drilled out with a carbide tipped drill of a high-speed drill. After removal of the plug always re-inspect the hole to be sure it is within technical specifications and drill out to the next larger size plug if necessary. Plug removal is under the installation instructions (see comments above).

The drilling roughness requirement is Rz 10-30 microns.

1. At a roughness greater than Rz=30 microns leakage might occur.

2. If the roughness is less than Rz = 10 µm, the EXPANDER sealing plug may not be anchored sufficiently (especially in the hard base material).

See catalog anchorage principle.

Ra measures the average roughness (mean value), while Rz describes the sum of the largest profile peak and the depth of the largest profile valley within the measurement section. Since peaks within a certain range are desirable for a mechanical seal, we specify the bore roughness in Rz.

Please refer to the SFC KOENIG® catalog or website for a simple formula to calculate the minimum wall thickness. The minimum wall thickness is dependent on the base material, plug style, and diameter of the plug.

There are two types of tests that SFC KOENIG® carries out regularly:

1. Test A: Static pressure test. The plugs are subjected to continuous increasing pressure until failure. The recorded failure pressures should be above the threshold. This blowout pressures has a factor of safety from the rated working pressure of the plug. Each batch of the plugs go through this verification testing.

2. Test B: Temperature/Pressure Cyclic test. The plugs are subjected to cyclic temperature (-40°C to 150°C @ 2-hour frequency) and cyclic pressure (0 bar to rated proof pressure @ 2 min frequency) for a total of 168 hours. The plugs are expected to withstand these conditions without any leakage or blowout. This long-term test simulates the application conditions.

Click here to view.

Technical details can be found on the SFC website under the following link.

Type III, Clear Trivalent Chromate per ASTM B633.

The plating thickness is between 2-7 microns.

We can provide the IMDS certificate for all products. We will need your company IMDS code to send it through the system.

All SFC Sealing & Flow Control components are REACH compliant. Corresponding REACH declaration is available upon request.

SFC does have some applications in plastics and reinforced fiber-glass materials. Such applications require special consideration and can be developed upon request. Inquire with our application engineering team to review your requirement.

SFC does have some applications in brass materials. It’s recommended to use plugs with a stainless-steel sleeve due to potential galvanic corrosion. Such applications require special consideration and can be developed upon request. Inquire with our application engineering team to review your requirements.

Small quantities or single parts can be installed with a hammer and a setting tool. For series production, it’s recommended to use a press.

The MB punch can be used for the installation of CV products and vice versa (see catalogue specification).

It’s always recommended to use original SFC tooling. SFC does not accept any liability for incorrectly processed EXPANDER products by using non SFC tooling.

Passivated acc. to ASTM A967M-17