Custom Linear Lighting Profile Manufacturing

What makes linear profiles different

A linear profile is judged along its length, not at a cross-section. The attributes that matter are the ones that accumulate: straightness, twist, colour consistency, and the continuity of the optical surface across joints. A profile that samples perfectly at 300 mm can fail at 3 metres.

The two-section construction

Most linear luminaires use two coextruded or assembled sections:

Co-extruding the body and the optical section removes an assembly step and guarantees alignment between them, which matters for optical consistency. It is usually the right answer above moderate volume. See custom lighting profiles and linear light profiles.

Designing the body

• LED board slot sized to the PCB tolerance – tight enough to locate, loose enough to slide.
• Screw channels or T-slots for fixing, with consistent geometry along the length.
• End-cap seats that are flat and continuous – the most common rework item.
• Enough section depth to span between fixings without visible sag.
• Thermal path consideration – the profile is often the heat sink for the LED board.

Designing the optical section

The optical section is specified by LED pitch, standoff distance and target appearance. For a diffuser, the question is the lowest haze that hides the dots at the intended viewing angles – because haze costs transmission, and transmission costs lumens per watt. See how to choose a material for LED diffusers.

Length, straightness and twist

Straightness and twist are controlled in calibration and cooling, not by tightening a drawing tolerance. Asymmetric sections – a heavy body with a thin flange, for example – cool unevenly and pull toward the thin side. The fixes are die balancing and symmetric cooling. State the required straightness against the run length so the line can be set up for it.

Joining long runs

Continuous runs longer than the transportable length need joins. Design considerations:

• Aligning features – a spline, pin or internal alignment rib that keeps two lengths coaxial.
• End-cap and joiner geometry defined on the drawing, not improvised at assembly.
• Optical continuity at the joint – a visible dark line at the join is the most common complaint on continuous runs.
• Colour consistency between batches – essential where two lengths meet on the same wall.

Thermal expansion

PC and PMMA both expand considerably more than aluminium or steel. On a long run, restrained fixings cause bowing between fixings in warm conditions. Allow movement: slotted fixing holes, sliding clips, or a defined expansion gap at joins. State the service temperature range on the drawing so the movement can be calculated.

Consistency across batches

For linear lighting, batch-to-batch consistency is a product requirement, not a nicety. The controls are a signed-off physical colour standard, a fixed masterbatch let-down ratio, recorded line parameters, and – for optical profiles – recorded transmission and haze measurements. Ask for these on repeat orders; they are the difference between a seamless extension and a visible mismatch.

Inspection for linear profiles

Send the cross-section with annual quantity and target run length: request a quote, or see the linear lighting applications page.