Gasket Dispensing

Gasket dispensing describes the extrusion of a viscous fluid that, upon curing, creates a seal with elastomeric (rubber-like) qualities.  After cure, when a mating surface is applied, the joined parts typically meet some requirement for a barrier against liquids or gasses.

If the parts have been assembled prior to the compound curing, the gasket is more appropriately considered a seal and is by nature a one-time-use application.  If the gasket compound is cured prior to assembly, that assembly in theory can be disassembled and reassembled throughout the life of the product.

Some common gasket compounds are RTV silicones, UV cure silicones, UV cure acrylates, UV cure polybutadienes, two component polyurethanes, two component silicones, and solvent cure systems.

Form In Place Gasketing

Using a robotic dispensing system to form such gaskets is commonly referred to as Form In Place gasketing (FIP), this process avoids the cumbersome aspects of handling and placing cut gaskets and affords the flexibility of many variations without having to inventory cut gaskets.

Classical gasket dispensing solutions include key process control elements such as needle tip calibration to ensure dispense tip location, height measurement (tactile, laser, or ultrasonic) to rule out part height errors, temperature control to lock in consistency, vision for part location and quality verification, and the software tools that make these elements work together effectively.

Standoff Foot Dispensing

New Precision Technology has developed a new standoff foot dispensing technique designed to deal with part height variation as a production issue. With standoff foot dispensing, we rotate the part, preventing potentially messy dispense valves from being complicated with rotational hardware. This technique lends itself to precision gasket formation for fuel cells, LCD screens, display terminals, and any flat structures requiring precision gaskets or adhesive seals.

Adhesion and Bonding

Adhesion promotion, resistance, and control is a crucial element of successful bonding, sealing, and gasketing operations.  There are occasions where an application needs the most aggressive bond possible and other applications that require less aggressive techniques.  Ultimately, the bond strength only needs to be as strong as the weakest bonded surface.  There are many methods of adhesion promotion and all of them have their strengths and weaknesses:

Over the last two decades of dealing with adhesive, sealant, and gasket applications, New Precision Technology has implemented all of these processes and more, including:

  • Flame treatment
  • Corona or plasma treatment
  • Solvent etch treatment
  • UV “bedding” materials
  • Soda or Sandblast etc
  • Adhesion promotion chemistries

New Precision Technology, Inc. is a leader in affordable standard and semi-custom automated systems. To learn more, give us a call at 412-596-5948, or visit our Contact Us today.

High Speed Hotmelt

At 24 inches per second of travel, this CP24 yields terrific throughput! The head dispenses "pats" of hotmelt PSA adhesive to help fixture products on a plastic sheet. The sheets are held on with a vacuum system that detects when a sheet has been removed and when a new sheet has been placed on the pallet. The high speed and the vacuum system combine to yield a throughput rate of less than eight seconds per sheet!

Vertical Wall Gasket Dispensing

With a theta mounted on the Z axis, it becomes possible to accurately dispense gaskets along the vertical walls of objects. In this example we have machined sockets which require a seal at the entry point. By itself this is not a difficult concept. The difficulty in doing this kind of thing in production lies with the issue of tip calibration. Using a unique calibration process that definitively locates the dispense tip no matter the tip angle or length of arm from center of rotation, New Precision Technology has simplified this technique, making it a production-friendly process.

Moisture cure RTV gasket dispensing

Moisture cure RTV materials have certain strengths that make them an important player in the gasketing world. Unlike UV cure gasket compounds that cure virtually instantly upon exposure to UV, moisture cures can take several hours before they can be handled and they require a little more maintenance than UV cure materials as well - it's more difficult to keep humidity away from a moisture cure than it is to keep UV away from a UV cure! On the plus side, they do not have to be translucent like many UV cures (unless you have a dual UV/moisture cure like Loctite 5950) and this allows some unique properties - ones that enable silicones to survive in the engine compartment with high heat and oil contact. Also on the plus side: they tend to be far less costly than their UV cure counterparts!

Two Component Cartridge Dispensing

New Precision Technology equipment can be outfitted to handle larger meter-mix heads for 2-part dispensing applications. A stronger z-axis stage, geared x-axis stage, and larger gantry shafts enable the use of heavier dispense hardware. A recommended needle tip calibrator will ensure that the necessary meter-mix tube replacements will stay on the mark every time. Dual-pack cartridge dispensing is a dispensing technique that avoids the breakdown and clean-up time of dedicated material lines.

Conductive inks and adhesives

Conductive ink, gasketting, and shielding applications benefit a great deal from the synergy of motion, sensing, and software. IMAGE ONE below shows traces formed with conductive inks on polyester with an LED placed directly on the ink to form the circuit. Subsequent application of a conformal coat serves to secure the assembly. Note the soldered wires on the polyester. Video one shows resistance traces precisely formed with the benefit of accurate height measurement. Video two shows sprayed RF shielding applied with minimal waste of material. Video three shows a silicone RTV filled with silver used as an EMI shield compound on cell phone housings.

Precision Gaskets For Fuel Cell Plates

Fuel cells can present interesting challenges when it comes to gasketing and sealing the spaces between plates. Stackup problems can become quite pronounced when multiplied by the number of plates in the stack. Well-defined specifications for fuel cells can simplify the process requirements.