A fixture with several bond points and one single-output spot lamp forces an unpleasant choice: cure the joints one after another and accept the cycle time, or buy another controller. A multi-leg light guide offers a third option, with trade-offs that are worth understanding before the fixture is built around it.

Q: When Should a Multi-Leg UV Light Guide Be Used?

A: When Several Bond Points Must Cure Together and Can Share One Lamp

A multi-leg guide, also called a bifurcated, trifurcated, or multi-pole guide, splits one lamp’s output across two or more delivery tips. It fits when a part or fixture has several bonds that should cure in the same trigger, the tips can each be held at a fixed working distance, and the process can accept that every leg depends on the same source. It fits poorly when bond points need different doses, sit far apart, or must be cured at different moments in the cycle.

How Incure’s Spot Lamps Handle Multiple Points

Incure offers two routes to multi-point spot curing. The S20™ UV arc spot lamp pairs with 1-, 2-, 3-, or 4-pole liquid lightguides, where each additional pole splits the same mercury arc output across another simultaneous cure point. The L9000™ UV LED spot lamp supports up to four independent lightguides running from a single controller. Glass fiber guides can also be built as multi-pole guides from one source, or as line-to-circle converters that reshape a circular input into a linear output for a longer bond line.

Matching Leg Count to the Fixture

Pole count should follow the fixture layout, not the other way around. Incure’s S20™ configurations map to common layouts:

• S20-1P: a single joint, such as an individual connector or small component.
• S20-2P: symmetrical assemblies and dual-joint fixtures, curing both sides in one trigger instead of indexing the part between two cure steps.
• S20-3P: triangular fixture layouts and connector potting where three points should finish together.
• S20-4P: high-volume automated lines with four bonding positions per fixture, where a single-pole lamp would make the cure step the bottleneck.

Ordering more legs than the fixture uses does not help; unused tips still need capping and protection, and they still share the source.

Email Us with your fixture’s bond-point count and layout, and Incure can confirm a matching multi-pole or multi-guide configuration.

Trade-Off 1: Every Leg Shares the Source

Splitting a lamp across legs means each tip carries part of the source output rather than all of it. Before committing, confirm that each tip still delivers the dose the adhesive needs at its working distance, by measuring at every tip rather than at one. Sharing a source also means a lamp problem affects every leg at once, so lamp maintenance becomes more critical on a multi-leg station. On arc lamps, Incure’s replacement bulbs are commonly changed every 1,000–2,000 hours depending on duty cycle.

Trade-Off 2: Legs Age Independently

Each leg has its own tip window and its own routing. A leg that sits nearer a dispense point or bends harder around the fixture can lose transmission faster than the others. Over time, that turns a balanced multi-leg guide into an unbalanced one, and the weakest leg sets the station’s real capability. Measuring each leg against its own baseline, not just the strongest one, catches this drift. Contamination baked onto a tip under high-intensity light causes pitting, so tip protection matters on every leg equally.

Trade-Off 3: Every Tip Needs Its Own Working Distance

Spot-lamp irradiance falls steeply with distance. Incure’s L9000™ data shows 7,500 mW/cm² at a 9 mm focal point and 2,300 mW/cm² at 17 mm. On a multi-leg fixture, each tip must be located against its own hard stop at the qualified distance. A fixture that holds one tip precisely and the others loosely produces uneven cures even if the legs themselves are identical.

Adding Tip Hardware to Individual Legs

Not every bond on a fixture faces the same direction. Incure’s LGT-Series™ terminators redirect output at 90° (LGT-90-5, LGT-90-8) or 60° (LGT-60-5, LGT-60-8) and can be fitted to individual legs, so one leg cures a vertical side wall while another cures straight down. The terminator aperture must match each leg’s core diameter.

A Hypothetical Layout Decision

Consider a hypothetical fixture holding a part with two bonds on opposite sides, both using the same adhesive and dose. A 2-pole guide cures both in one trigger, removing an indexing step. Now consider a hypothetical part with one bond on a flat face and another deep in a cavity. The two need different working distances and possibly a terminator, so two independently mounted guides from a multi-guide controller give more control than a symmetrical split.

For how a single liquid guide carries light before it is split, see Incure’s liquid light guide explainer.

Contact Our Team to plan a multi-leg UV light guide configuration for your fixture.

Visit www.incurelab.com for more information.