Flat panels are the easy case on a curing conveyor: every drop of adhesive faces the lamp at roughly the same distance. Three-dimensional parts break both assumptions. Some adhesive sits in shadow, and the rest sits at several different distances from the lamp at once.

Q: Can a UV curing conveyor cure tall or complex 3D parts?

A: Yes, if every bond line can see the lamp at a qualified distance — otherwise the part, the pass sequence, or the formulation has to change

UV cure needs line of sight: adhesive that receives no light receives no dose, no matter how slowly the belt runs. A 3D part on a conveyor therefore raises two separate questions. Can light reach every bond line from above as the part travels? And are those bond lines all within the working distance at which the process was qualified? When the answer to either is no, the fix lies in orientation, pass sequence, head choice, or chemistry — not in belt speed.

Problem 1: Height Spreads the Working Distance

Lamp intensity is published at a stated working distance — 2 inches for the UV LED heads on the Incure CDM™. A tall part puts its upper surfaces closer to the lamp than its lower ones. Consider a hypothetical part 1.5 inches tall riding under an LED head set 2 inches above the belt: its top sits 0.5 inch from the lamp (2.0 − 1.5), while a bond at its base sits the full 2 inches away. Those two bonds receive different irradiance in the same pass, and only one matches the qualified distance.

Practical responses:

• Qualify the process at the distance of the bond lines that matter, not the part’s top surface.
• Group parts of similar height on the same recipe rather than mixing tall and short parts.
• Where the geometry needs more clearance above the belt, the F400 and F500 arc heads offer a 3.0–6.5-inch curing height range, against 0.5–2.0 inches on the LED heads.

Problem 2: Shadowed Adhesive

Any feature taller than the bond line can block light arriving at an angle, and anything directly above the adhesive blocks it entirely. Typical shadow sources are overhanging components, deep recesses, and fixture walls. More dose from the same direction does not reach a shadow, so the options are geometric or chemical.

Email Us with a part drawing showing where the adhesive sits and Incure can help judge whether a single conveyor pass can reach every bond line.

Strategy 1: Reorient the Part

The cheapest fix is often to present the part so the bond line faces up. A carrier that tilts or rotates the part can turn a shadowed joint into an exposed one. If two joints face different directions, consider which orientation exposes the one that carries the most load, and handle the other separately.

Strategy 2: Use More Than One Pass

A part that cannot expose every joint in one orientation can make two passes in two orientations, re-seated in its carrier between them. Each pass is a separate dose event, so each orientation needs its own check against the data sheet. Dose per pass scales inversely with belt speed — the CDM™ F400x2AC delivers 2,630 mJ/cm² UVA at 6 ft/min and 1,320 mJ/cm² at 12 ft/min — so a two-pass recipe can sometimes run each pass faster if each joint only needs to be exposed once.

Strategy 3: Match the Beam to the Joint

When a 3D part carries one critical seam beside sensitive features, a focused beam can help. The CDM™ M51 exposes a 1-inch-wide strip and the M62 a 2-inch strip, so components outside the strip receive no UV. A flood head such as the 8″ × 8″ L88 suits parts whose bond lines are spread across the top surface and whose surroundings tolerate exposure.

Strategy 4: Choose a Formulation With a Secondary Cure

When a joint is truly hidden — inside a blind cavity or under an opaque component — a UV-only adhesive is the wrong tool. Dual-cure formulations use UV to fix the exposed adhesive in place quickly, then complete cure in shadowed regions through a second mechanism such as heat or moisture, according to the supplier’s data sheet. The conveyor then handles fixturing speed, and the secondary mechanism handles completeness.

Verifying a 3D Recipe

Measure irradiance at each bond location with a radiometer probe placed in the loaded carrier, not on the bare belt. Then section or test production parts at every joint, including the most shadowed one. Record orientation, pass count, curing height, and belt speed together so the recipe is reproducible.

Configuration data for every head is in the Incure CDM™ UV conveyor guide. The general overview of curing conveyor types is in the curing conveyor industrial guide, and for hidden joints that need a different cure path, Incure’s comparison of UV glue and epoxy for heavy-duty repairs covers the chemistry trade-offs.

Contact Our Team to work out a conveyor recipe for your 3D parts.

Visit www.incurelab.com for more information.