Simple composite bonding instructions
Choose the adhesive according to your needs - use our cheat sheet (Adhesives Table) and consider the following:
- Work Life – How much time before the mixed adhesive becomes non-workable? Typical ranges are from 5 minutes (fast) to 120 minutes (long).
- Fixture Time – How much time to hold/fixture the assembly in its non-cured state? This refers to the amount of time required until you can let go, when the adhesive has cured to a tacky enough state to hold your assembly in its own place. Typical ranges are from 15 minutes to well over 240 minutes.
- Cure Time – How much time until you can use the bonded assembly in its intended application?
- Shear Strength – How much pressure can the adhesive hold until it fails? Typical values of the adhesives we offer are between 2000 and 5000 pounds per square inch (psi). Crazy Glue or Super Glue has a shear strength of ~1000psi.
- Temperature Resistance – Typical values do not exceed 250F, however, we offer some that can reach 300F.
Basic instructions follow below. For more thorough instructions, scroll further.
- Surface Preparation – Be sure to prepare both surfaces by roughing or sanding. To sand the inner diameter of a carbon fiber tube (or other material) use a properly sized abrasive flex hone or 120 grit sandpaper.
- Degreasing – Follow this by degreasing the part with isopropyl alcohol or acetone and cleaning thoroughly. It is most common to bond to the ID of our carbon tubes rather than the OD given the tighter dimensional tolerances (+/-0.004” vs. +/-0.012”). Allow parts to dry.
- Determine Bond Line and Bond Line Controller (optional but recommended) – Whether bonding Carbon+Carbon or Carbon+Metals you may wish to use Bond Line Controller (BLC), which is made of glass spheres or beads. This minimizes galvanic corrosion between two dissimilar materials (general metals including aluminum). BLC also helps to ensure your parts retain a concentric bond. We offer BLC in various diameters that are intended to be added into the adhesive/epoxy during mixing. Choose the correct size based upon the gap between your two parts. If you are specifying this gap to a machinist, we would typically recommend a bond line (gap) of around 0.008” to 0.013” which would use SKU 1031 and SKU 1030. It is recommended for every 3oz. of adhesive you use 2g of BLC. *Note - Some parts may be forced into position if the bond line bead matches the bond gap identically. This is not always necessary to ensure concentricity.
- Mix Adhesive and Apply - Our cartridge style adhesives are by far the simplest to use, however, they do require special applicators (mixing guns) and mix nozzles. If titled "Dual Cartridge," both a mixing gun and dispensing nozzles will be required. Apply adhesive to both parts and slide parts together, trying to ensure there is near 100% mating surface coverage of adhesive. Quickly clean adhesive overrun using disposable rags.
- Fixture and Cure - Allow assembled parts to cure for the necessary time required. Refer to your chosen adhesive's "Fixture Time" before removing fixture equipment / tape holding the parts in place.