Achieving the Perfect Lamination Bond
07/24/2024
When you’re building high-performance electric motors, the mechanical bond between individual laminations is just as critical as the electrical steel itself. A strong adhesive layer keeps cores rigid during high-speed rotation, minimizes eddy-current losses by maintaining insulation integrity, and prevents the chatter and vibration that shorten service life. Yet the adhesive process is far from “one size fits all.” Material thickness, part geometry, and the ever-present “squeeze-out” of adhesive each add their own layer of complexity. Here are some practical guidelines for engineers, buyers, and quality managers.
Thin Laminations Demand Special Handling & Stronger Adhesives
At the extreme end of the spectrum, 0.004" laminations behave more like foil than sheet metal. They flex, buckle, and can even tack themselves to press rollers if operators aren’t vigilant in handling. Because these ultra-thin parts lack the inherent stiffness to resist roll coating application, Laser Technologies often recommends high-strength, high-tack epoxies. Different application techniques are used taking into considerations the lamination’s low rigidity, ensuring a uniform bond that survives post-assembly handling and secondary machining operations.
In contrast, 26-29 ga (≈0.014 - 0.019") steel offers enough backbone to tolerate a broader menu of application methods. Acrylics, modified phenolics, or lower-viscosity epoxies can all perform well, giving designers more latitude to optimize design without a major impact on cost or risk of damage to the lamination.
Geometry Can Affect Coverage
Finger slots, thin back iron, and complex OD/ID geometry may optimize magnetic efficiency but could create challenges where adhesive can thin out or skip entirely. Lasertech’s team counters this with a three-step strategy. First, application parameters are determined by our engineering team, then torque models are evaluated to predict how much pressure to apply to the lamination stack for curing while minimizing “squeeze out.” Lastly, our bonding process is verified for acceptable adhesive strength before sending to the customer. For OEMs, that translates into predictable stacking variables and less fallout on received assemblies.
Stamped vs. Laser-Cut: Adhesive Choice Isn’t the Limiting Factor
The same epoxy families that excel on stamped laminations bond flawlessly to laser-cut parts. Surface texture and oxide layer differences can be addressed with minor tweaks to application processing or adhesive selection.
The Myth of Zero Squeeze-Out
Every buyer loves the idea of perfectly flush slots and immaculate OD edges, but the physics of adhesive flow say otherwise. When pressure and temperature climbs, some resin must move somewhere. If you never see a hint of “squeeze Out” , you’re probably leaving micro-voids and bond strength on the table. Lasertech targets nearly nominal squeeze-out: After cure and cool-down, light clean up on the OD, ID, and slot faces is performed so that liner insertion and winding slots remain effortless.
Turning Best Practices into Competitive Advantage
By aligning adhesive chemistry with lamination thickness and rigorously managing squeeze-out, manufacturers gain three strategic wins:
- Higher power density - tighter stacks with minimal air gaps improve magnetic flux.
- Longer service life - robust bonds resist thermal cycling and vibration.
- Faster assembly - clean slot edges reduce scrap and rework on winding lines.
Lasertech’s process engineers integrate these principles into every new project, from prototype through production, ensuring your motor cores perform exactly as modeled with no surprises on the test stand.
Ready to audit your lamination bonding process? Contact Lasertech for a free application review and discover how optimized adhesive strategy can unlock the next tier of efficiency and reliability in your motors.
