what epoxy do you use to join delrin parts?

Dupont Delrin design guide:

[ Adhesive Joining

The adhesive joining of Delrin acetal resin is generally limited to prototype models with low shear forces. This is because the shear strength achieved with most adhesives is only 2 to 10% of the available shear strength of Delrin acetal resin.

The best adhesion requires a special roughening step such as sanding with 280 grit emery cloth.

A number of adhesives have been evaluated for bonding surfaces treated with sanded surfaces of Delrin acetal resin to other materials. See Table 17 for adhesives, suppliers, procedures, and bond strengths. ]

Table 17 on page 61

Delrin to Delrin? I think it's very difficult as Tom says.

I have a regular job which is a vintage car part (Radiator Cap) see "

" Which involves bonding a brass threaded insert into a Delrin Cap. I use Polyurethane WOOD GLUE, the stuff that foams up. The two parts are screwcut left hand interrupted thread cut deliberately loose to increase surface area and improve security of the bond.

We tried over adhesives, but found this works a treat.

Not one has ever come apart.

Wayne....

Mike:

Background info: ==================================================================

Polyoxymethylene (POM), in the USA also commonly known under DuPont's brand name Delrin, is an engineering plastic, a polymer with the chemical formula -(-O-CH2-)n-. It is often marketed and used as a metal substitute. Delrin is a lightweight, low-friction, and wear-resistant thermoplastic with good physical and processing properties and capable of operating in temperatures in excess of 90 degrees celsius (approximately 200 degrees fahrenheit). According to the material safety data sheet from DuPont, the material has a slight odor of formaldehyde.[1]

It is also known as polyacetal, acetal resin, polytrioxane, polyformaldehyde, and paraformaldehyde (the latter term is usually restricted to the short-chained polymer).

Bonding:

Acetal polymers are typically very difficult to bond. Special processes and treatments have been developed to improve bonding of acetal. Typically these processes involve surface etching, flame treatment or mechanical abrasion. Typical etching processes involve chromic acid at elevated temperatures. DuPont has a patented process for treating acetal homopolymer called satinizing which creates anchor points on the surface, giving an adhesive something to grab. There are also processes involving oxygen plasma and corona discharge[4].

Once the surface is prepared, a number of adhesives can be used for bonding. These include epoxies, polyurethanes, and cyanoacrylates. Epoxies have shown 150-500 psi shear strength on mechanically abraded surfaces and 500-1000 psi on chemically treated surfaces. Cyanoacrylates are useful for bonding to metal, leather, rubber and other plastics. ==================================================================

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One of the properties of Delrin® that makes it difficult to bond to is its low friction properties which are the result of the manufacturing process. Delrin® can be bonded to but it requires careful preparation and BONDiTTM brand adhesives manufactured by RELTEK LLC. BONDiTTM products are among the few available that can be used to bond Delrin® to itself, and to other substrates for harsh environments and long term deployment without debonding. ==================================================================

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Metal, vinyl, nylon, plastic, delrin, ==================================================================

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Great for gluing Delrin track or hand-laid rail to ties. ==================================================================

I haven't used these items myself, so can't attest to the amount of advertising hype they may contain.

Loctite make a cyanoacrylate (super glue) that works if you also use their primer. 406, 410 IIRC are the two glues I have used. I think the

410 works better as it is thick.

It is not the adhesive that makes teh major difference, but the surface prep. Although the Loctites are the purest off the shelf that I have found.

ca

mike wrote: