Automotion Components Sealing Screws
General Guidance
An ordinary screw lacks seal protection, allowing dirt, fluids, gases etc. to infiltrate and damage sensitive devices. Sealing screws provide bi-directional sealing protection to systems where screws are used, to protect them against dirt, chemicals, water or other contaminates, which (without the screw seal), may penetrate and damage or alternatively where gases and liquids may leak out.
The seal screws incorporate an O-ring underneath the screw, bolt etc. which forms a sealant layer. The seal provides bi-directional sealing. The screws are very easy to use and do not need any special preparation or re-tightening
Integral seal fasteners are designed and manufactured with a precision engineered groove beneath the head of the fastener. As the fastener is tightened, the O-ring is compressed, squeezing the O-ring between the groove and mating surface to complete the seal. The design of the groove controls the amount of compression of the O-ring and because O-rings retain theirelastic memory, the screws are reusable time after time.
There are a range of O-ring materials that can resist virtually all chemical and environmental conditions. We can also provide sealing screws (on request) to military specifications (MILSPEC).
The screws are widely used in military, medical and industrial devices. Each screw is equipped with a captive O-ring which provides a total barrier seal agaianst internal and external conditions (water, fluids, chemeicals, dirt, air, contaminates etc.) which colud otherwise penetre and damage systems.
When using self-sealing screws a high pressure seal is formed along the thread's contact surface when torqued.
If possible, and to ensure maximum sealing performance, we recommend a clearance hole. This creates room for the O ring to flow into.
The aim is to ensure full metal-to-metal contact between the underside of the fastener and the mounting surface.
If the counterbore cannot be applied, the O ring will still function as it will squeeze fit the gap between the male and female surfaces.
Features
Sealing Screw Heads
Ordering Options
P0170 - Pan head - Phillips® Security and Torx® options
P0174 - Button Hex-head Security and Torx® options
P0173 - Socket Head Security and Torx® options
P0178 - Hexagon Nut
| Schematic | Drive Types | Uses |
 | Hexagonal | Ideal for precision assembly. Most recommened where less surface area is available. |
 | Cross Drive (Phillips®) | Most recommended drive type. Provides good control in driving. Always use a driver bit of the proper size which is in good condition. |
 | Star Drive (Torx®) | Positive-engaging, fast-locating method which transmits drive torque with less required downward pressure. Good fastening appearance. |
 | Slotted | Accepts standard blade screwdriver. Requires less downward pressure to drive parts than those with recessed openings. Use proper fitting blade to minimize slippage. |
 | Hex flange | Accepts hex wrench. Slotted drive is added to make it easier to remove the fastener (if required). |
 | Security | These screws are impossible to remove without the special matching screwdriver. |
We can provide Torx® heads and security/tamper-proof screws, as well as special threads, grooves and cross holes for safety wires, and a further range of styles such as captive screws, anti-vibration strips on the threads etc (for extrene vibration applications).
Applications
Some of the typical applications for our sealing screws include:
- Motors
- Cabinets and enclosures
- Sensors and instrumentation
- Internal combustion engines
- Gear pumps
- Fuel tanks
- Transmissions
- Gear boxes
- Air cylinders
- Pressure gauges
- Computer disk drives
- Motion control valves
- Missle tanks
- Wet wings
Technical Specs
O ring selection
Standard O rings arered silicone,but a further five O ring material types are readily available. The main factor to consider when selecting an O ring type is the environment in which it will be placed, and the temperature range it will be subjected to.
| Material | Notes |
| Silicone (SI) | Our standard O ring type with a wide temperature range -60°C to +200°C. Resistant to moderate or oxidising chemical, but not generally oil or solvent resistant. |
| Fluorosilicone (FS) | Widely used in the automotive and aerospace industries as it has excellent resistance to fuel, oil and solvents. Standard temperature range -50°C to +180°C. |
| EPDM (EP) | These O rings are very suited for outdoor enviroments and are good for weather and water resistant applications having excellent ozone, steam and chemical resistance. Temperature range -50°C to +110°C. |
| Viton-fluorocarbon (VI) | These seals are widely used on aircraft engines and automotive fuel handling systems as they have excellent fuel, oil and solvent resistance. Standard temperature range -50°C to +100°C. |
| Nitrile (NI) | Widely used as highly resistant to petroleum based substances, water and alcohols. Temperature range -50°C to +110°C. |
Other O ring types can include Neoprene, Buna N, Teflon etc.
Installation Torque
| Thread Size | Standard Installation Torque |
| M3 | 0.6 Nm |
| M3.5 | 1.0 Nm |
| M4 | 2.2 Nm |
| M5 | 2.5 Nm |
| M6 | 8.5 Nm |
| M8 | 16 Nm |
| M10 | 30 Nm |
For optimal seal screw performance we recommend creating a clearnace gap in the panel into which the O ring can be fitted. This causes the O ring to create a complete seal, and the clearance hole thus prevents extrusion into the metal when the screw is under pressure.
We also have a range of sealing nuts to complement our range of sealing screws. These sealing nuts often eliminate the need for gaskets, compounds and surface preparation. They are widely usedin the hydraulic, pneumatic or fuel systems industries. They are invaluable when a vacuum needs to be created and provide a complete seal when gaseous or liquid pressure is a factor. Domed nuts are self-sealing and provide exceptional vibration resistance.
Clearance Hole Ø - recommended
| Nom. Size | M2 | M2.5 | M3 | M3.5 | M4 | M5 | M6 | M8 | M10 | M12 | M14 | M16 |
| Max | 2,437 | 2,946 | 3,454 | 3,656 | 4,546 | 5,562 | 6,655 | 9,041 | 11,048 | 14,048 | 16,051 | 18,057 |
Materials
Our standard screw material is stainless steel (A2, AISI 303). Other materials available are aluminium (non-magnetic and 1/3 weight of steel), brass (high electrical conductivity, non-magnetic and good corrosion resistance), titanium (low weight, very strong and highly corrosion resistant), Stainless steel (A4, AISI 316).
Fasteners can be supplied to MILSPEC standards (MIL-S-82496A) on request.
Finishes
Finishes are dependent on the material you are wishing to coat, but include:
| Finish | Notes |
| Black Chrome (MIL-C-1458B) | Black chrome is hard, non-reflective coating which is resistant to abrasion, heat and erosion. The black chrome surface is a dull, dark grey and may be waxed or oiled to darken surface. |
| Black Oxide Coating (MIL-C-13924B) | Black oxide is a uniform black coating for ferrous metals. Generally it is considered a decorative coating and provides only very limited corrosion protections under mild corrosion conditions. |
| Cadmium | Cadmium is a bright, silvery white plating. Supplementary treatments for type II can be golden, iridescent, amber, black or olive drab. |
| Passivate (QQ-P-35/MIL S-5OOSC) | Passivation is a process designed to remove foreign metals from the surface of stainless and corrosion resistant steels. |
| Phosphate Coating Light (TT-C-00490B) | Phosphate coating is a light coating for use as a base paint. |
| Gold (MIL-G-45204B) | Yellow to orange colour depending on a proprietary process used. Will range from matt to bright finish depending on base metal. Good corrosion resistance and high tarnish resistance. |
| Nickel | Nickel is a corrosion protective plating for steel, zinc and zinc alloys as well as copper and copper alloys. |
| Zinc (QQ-Z-325C) | The primary use of chromate finishes on zinc is to retard or prevent formation of white corrosion products on zinc surfaces. |
Shoulder Screws
Painted Heads
Captive Screws
Security Heads (Tamper Proof)
