There is a definite advantage to using an injection molded lens vs a thermoformed lens.  SLP injection molds lenses for Citadel Enclosures as well as the housing for the CircLED and Remote Box Enclosure in our facility in Sullivan, MO.

Thermoforming/Vacuum forming is a manufacturing process in which:

• plastic sheet is heated to a pliable forming temperature
• formed to a specific shape in a mold
• then trimmed to create the finished part

Injection Molding is a manufacturing process in which:

• plastic material is heated to a fluid state
• injected into a mold

On finished thermoformed parts there is a trimming operation that introduces micro-fractures into the edges of the part. Injection molded parts do not require trimming or routing and have a uniform material strength throughout.

Thermoformed part micro-fractures on the edge

Injection Molded part smooth edge

Due to nature of plastic, expanding and contracting due to weather and humidity, the micro-fractures from routing turn to full cracks.  Injection Molded parts under pressure or stress remain intact.

Another advantage of injection molding is the option to create what SLP had patented as the Guardian Seal on Citadel Lenses.  This small nub of plastic that runs around the top edge of the lens creates 34% more contact between the lens and the gasket of the enclosure creating a better seal.

SLP’s Guardian Seal