Sheet Lamination — formally Laminated Object Manufacturing (LOM) — is an additive process that builds parts by bonding successive sheets of material together and cutting each layer to shape with a laser or knife before the next sheet is added. Unlike powder-bed or extrusion methods, the feedstock arrives as a continuous roll or stack of sheets, making it one of the cheapest and fastest ways to produce large, low-detail prototypes.

How the process works:

• A sheet (paper, plastic film, metal foil, or composite prepreg) is rolled over the build platform.
• A heated roller activates an adhesive backing — or in metal variants, ultrasonic vibration welds the sheet to the layer below.
• A laser or drag knife traces the layer outline, then crosshatches the surrounding scrap into small squares (called cubing) so it can be picked away later.
• The platform drops by one sheet thickness (typically 0.07–0.2 mm), a fresh sheet feeds in, and the cycle repeats.

Two flavors worth knowing:

• Paper-based LOM (Helisys, Mcor): cheap, wood-like parts good for visual mockups, architectural models, and foundry patterns. Parts must be sealed against humidity.
• Ultrasonic Additive Manufacturing (UAM): aluminum, copper, or titanium foils solid-state welded under ultrasonic vibration. Because no melting occurs, dissimilar metals and embedded fiber optics or sensors can be sandwiched mid-build — impossible with DMLS or EBM.

Real-world example: Fabrisonic uses UAM to build aluminum heat exchangers with copper cooling channels embedded inside — a single monolithic part that would otherwise require brazing two materials with mismatched thermal expansion. NASA has also used UAM to embed fiber-optic strain sensors directly inside structural aluminum panels.

Rule of thumb — build time estimate:

Because cutting time scales with perimeter, not volume, LOM is fastest for chunky parts. Estimate:

Time ≈ (Part height / Sheet thickness) × (Perimeter cut time + Sheet feed time)

A 100 mm tall block with 0.1 mm sheets needs 1,000 layers. If each layer takes 6 seconds to cut and feed, that's ~100 minutes — regardless of whether the cross-section is 10 cm² or 200 cm². Compare to FDM, where doubling the cross-section doubles print time.

Limitations: stair-stepping on sloped surfaces, anisotropic strength (weakest in the Z-direction along bond lines), poor internal feature access (trapped scrap is hard to remove), and limited material selection compared to powder-bed processes.