The most commonly used, and the most commonly specified, machineable plastics are difficult or impossible to fasten to themselves with one-part adhesives.
Delrin in particular cannot be glued to itself with any sort of significant bond strength with a one-part. By saying Delrin I am referring to both acetal homopolymer and acetal copolymer.
The reason for thisis that one-part solvent based adhesives do not dissolve the surface of Delrin plastic shapes properly. Solvent based adhesives work by making the two surfaces a material to be bonded “sticky”. Once the two sticky pieces are clamped together and allowed to dry (i.e. the solvent evaporates) they become one bonded piece.
There are some uncommon pretreatment steps, like low-pressure plasma treatment that have been reported to improve the strength of Delrin to Delrin solvent bonds.
3M also sells several two-part adhesives like their formulas DP8010 and DP8010NS that can be used to bond polyolefins like polypropylene and polyethylene to themselves.
If you have any questions about bonding machineable plastics to themselves, please get in touch with us here at Colorado Plastics.