LORD 7545-A/F Structural Urethane Adhesive

LORD 7545-A/F structural urethane adhesive is the slowest and most forgiving grade of the LORD 7545 series, mixed 1:1 by volume and offered in a 400ml cartridge. It bonds FRP, SMC and other plastics with little surface preparation, plus primed metals and dissimilar substrate combinations. Two numbers define it: 45 to 65 minutes of work time, the longest in the family by a wide margin, and 145% cured elongation against 70% on the faster grades. Pair that with the largest cartridge and you get the combination built for one job in particular, bonding a long panel seam in a single continuous pass. Mixed, it is an off-white non-sag paste. Made in the USA.

Key Product Details

An Hour of Work Time and 41 Feet of Bead

Every other grade in this family makes you choose. A 400ml of A/C holds 41 feet of quarter-inch bead but gives you 6 to 8 minutes, so you dispense a section, set it, and come back. A/F is the one where the cartridge and the clock actually match: 45 to 65 minutes is enough to lay a long seam end to end, position the panel, check it against a reference edge and adjust, all before anything starts to skin.

The 45 minute purge time reinforces it. On the fast grades a pause means a scrapped mixer. Here you can stop, deal with something else and come back to the same tip inside the window.

The price is fixture time, and it is the steepest in the series. 4 to 5 hours to handling strength means one fixture turn per shift. Modest heat, up to 250°F (121°C), will shorten that, and on a grade this slow it is worth considering rather than treating as optional. If your parts are short and your bottleneck is fixtures, the faster grades give you identical bond strength without tying a jig up all afternoon.

Cured Properties

Parker publishes the following cured properties for the LORD 7545 system. The technical data sheet does not break them out by individual curative, so treat them as series-level and test your own joint before production. Elongation is the exception and appears grade-specific in the table above.

Bond Performance by Substrate

Lap shear in psi, with failure mode in parentheses. SF is stock failure, meaning the substrate broke before the bond did. COH is cohesive failure, the adhesive itself split. ADH is adhesive failure, the bond released from the surface. Parker publishes this data for the LORD 7545 system without breaking it out by curative.

Test specimens: CFRP was 2×2 twill in an epoxy resin matrix, 3 mm thick. ABS and PC/ABS were both 5 mm thick. E-coated steel was 1008 steel, 8 mm thick, coated with PPG E6060C. Your substrate, joint geometry and surface prep will move these numbers, so run your own bond trial.

Performance in Production

• 45 to 65 minutes of work time is roughly ten times what A/B gives you. On a long panel seam you lay the whole bead, position the part and adjust it without racing anything.
• 145% cured elongation is more than double the 70% on A/B, A/C and A/G. On a plastic-to-metal joint that cycles through a temperature swing, the bond line moves with the parts instead of fighting them.
• The 400ml cartridge and the work time fit each other. You have time to actually use a full cartridge’s worth of bead in one continuous pass, which is not true of a 400ml on any faster grade.
• Fixture time is the steepest cost in the series. 4 to 5 hours to handling strength is one turn per shift on a single fixture. Heat up to 250°F (121°C) is worth planning for rather than treating as a fallback.
• 45 minute purge time means a pause mid-job is unlikely to cost you a mixer, which is a real workflow difference from the fast grades where any interruption scraps a tip.
• Stock failure on CFRP at 2900 psi and on ABS across nearly every aged condition means the part gives up before the joint does. The slow cure costs nothing in ultimate strength.
• At 230,000 to 650,000 cP the curative is a heavy paste, so the bead holds position on vertical and overhead work. That matters most on this grade, because the bead sits unsupported for hours before it sets.
• 7545-A resin is moisture sensitive. Keep cartridges in the Mylar bag with the desiccant and leave the used mixer in place on a partial as a plug, or the next bead cures short.

Common Applications

• Long continuous panel seams bonded in a single pass
• Sidewall, roof and front panel bonding on truck, trailer and service bodies
• Cross bonding plastics and composites to primed, painted or e-coated metal where thermal expansion differs
• Large panels that need positioning, checking and adjustment before the adhesive sets
• Marine and recreational vehicle composite panel bonding
• Assemblies seeing vibration, road shock or repeated impact
• Outdoor assemblies cycling through seasonal temperature swings
• Multi-joint assemblies where many parts come off one cartridge load

How to Dispense LORD 7545-A/F

On this grade almost nothing goes wrong from running out of time. What goes wrong is disturbing a joint that has not set, or pulling a fixture early. Clamp the part and leave it for the full 4 to 5 hours. Parker’s instruction still applies: discard the part if working time is exceeded, because a bead that has begun to skin will not wet the mating surface.

• Prep both surfaces. Plastics and composites get a dry rag wipe or a solvent-dampened rag to pull loose debris and processing fluids. Metals get primed, painted or grit blasted, then solvent washed.
• Load the cartridge in a 1:1 gun built for 400ml cartridges and pull the end caps. Level the plungers by expelling a little material with no mixer installed, until both sides dispense evenly.
• Fit a static mixer with at least 24 elements, Parker’s minimum for 400 mL dispense. Purge a mixer’s length to waste before the first bead.
• Consider the pneumatic gun. Pushing 400ml of 230,000 to 650,000 cP curative by hand over a long seam is real effort, and hand fatigue shows up as an inconsistent bead.
• Lay the bead, mate the parts and clamp inside the 45 to 65 minute work time. Target a 0.010 to 0.040 in bondline. Larger gaps can be filled where mating surfaces are irregular.
• Hold the part fixtured 4 to 5 hours at 75°F, then handle. Full strength is 24 hours. Modest heat up to 250°F (121°C) will shorten the fixture window, which on this grade is usually worth doing.
• Clean tools with acetone or MEK before cure. Do not use alcohol. Cured adhesive softens at 300°F (149°C) and above if parts have to come apart.

Substrates the process runs on: FRP, GRP, SMC, carbon fiber, ABS, polycarbonate, PC/ABS blends, other engineered plastics, HDU urethane foam, wood, and primed, painted, powder-coated or e-coated metals. Glass, non-porous ceramic and stone need LORD AP-134 first. Vulcanized rubber and elastomers need LORD 7701. TPE and TPO need LORD 459X. Bare aluminum and bare steel are not urethane substrates, so prime them or move to an acrylic.

LORD 7545 Series Grades Compared

Every grade runs the same 7545-A resin at the same 1:1 volume ratio. The curative letter changes speed, mixed color and cured elasticity, not the chemistry. Parker states the full range of work times all provide the same bond strength, so pick by how long your assembly takes and how much the joint has to move.

A/F is the slowest grade and the second most elastic. A/E edges it on elongation at 160% and comes in a 200ml cartridge if you need a smaller package. Everything from A/D down cures roughly half as stretchy and sets far faster.

Available Size and Part Number

The 400ml cartridge is the only size currently offered in this grade. At a 1/8 in bead it runs about 165.5 ft and at 3/8 in about 18.4 ft, minus a mixer’s length of purge. If you need a smaller package with similar flexibility, 7545-A/E cures at 160% elongation in a 200ml cartridge with a 22 to 38 minute work time.

Dispensing Equipment

• Albion B26T400 manual applicator, 1:1 for 400ml cartridges
• Mixpac DP2X 400 pneumatic dispensing gun, worth it if you run these regularly
• Medmix MCQ 08-24T static mixer, 24 elements, which meets Parker’s minimum for this size

Related Products

Surface modifiers, used when the substrate needs priming before bonding:

• LORD AP-134 adhesion enhancer for glass, non-porous ceramic, stone and concrete
• LORD 459X adhesion enhancer for TPE and TPO
• LORD 7701 surface treatment for vulcanized rubber and elastomers

Frequently Asked Questions

What is LORD 7545-A/F used for?

LORD 7545-A/F is a two-part structural urethane adhesive used to bond FRP, SMC and other plastics with minimal surface preparation, plus primed metals and dissimilar substrate combinations. It is the slowest grade in the 7545 family at 45 to 65 minutes work time, built for long panel seams and large assemblies that need positioning time. Urethane adhesive, polyurethane adhesive and PU adhesive all describe the same chemistry.

Why choose A/F over a faster grade?

Because you need the whole seam laid and the part positioned before anything sets. 45 to 65 minutes is roughly ten times what A/B gives you, and paired with the 400ml cartridge it means a long bond line in one continuous pass. It also cures at 145% elongation against 70% on the faster grades. The trade is 4 to 5 hours to handling strength, which is one fixture turn per shift.

What size does LORD 7545-A/F come in?

The 400ml cartridge, which is the only size currently offered in this grade. It runs about 41.4 linear feet at a 1/4 in bead. If you need a smaller package, 7545-A/E comes in a 200ml with 160% elongation and a 22 to 38 minute work time, which is the closest alternative.

What color is LORD 7545-A/F?

Off-white. The 7545-A resin is a brown paste and the 7545-F curative is off-white. A/F is not offered with a black curative. For a visible unpainted bond line on a dark part, look at 7545-A/B or 7545-A/D in black, though both cure at lower elongation and set much faster.

What gun and mixing tip does the 400ml need?

A 1:1 gun built for 400ml cartridges plus a static mixer of at least 24 elements. We stock the Albion B26T400 manual applicator, the Mixpac DP2X 400 pneumatic, and the Medmix MCQ 08-24T mixer. Under-mixing matters more on this grade than any other, because with a 4 to 5 hour fixture window you will not find out until the fixture comes off.

How long until I can handle the part?

4 to 5 hours at 75°F, with full cure at 24 hours. That is the longest fixture window in the family. Modest heat up to 250°F (121°C) will shorten it and on this grade is usually worth planning for. A cooler shop will lengthen it further.

Should I use the manual or the pneumatic gun?

Manual is fine for occasional use. Go pneumatic if you run 400ml cartridges regularly, because the 7545-F curative is a heavy paste at 230,000 to 650,000 cP and hand fatigue across a 40 foot bead turns into an uneven bond line.

What is the shelf life, and how should cartridges be stored?

8 months from date of manufacture in the original unopened container stored at 65 to 85°F (18 to 30°C). The resin is moisture sensitive, so keep cartridges in the Mylar bag with the desiccant until you need them, and protect a partial by leaving the used mixer in place as a seal. Run inventory first in, first out.

Questions on fit for your bonding application? Call (800) 220-1966 or email [email protected].