Every machine before it separates on physical criteria: size, density, shape, magnetism. An optical sorter is the first machine in the line that separates on the basis of what the material actually is. It reads the chemical signature of every object and sends it where it belongs.
That is what makes the difference at the point of sale. A mixed plastic fraction fetches a low price. The same quantity separated into clear PET, coloured PET, HDPE and PP fetches several times more. Optical sorting is the machine that makes that jump possible at industrial throughput. See the full range of waste sorting equipment and where each machine sits in the flow.
Key Advantages of an NIR Optical Sorter
• It tells polymers apart, not just colours, the near-infrared sensor reads chemical composition, so it separates PET from PVC even when both are clear and look identical.
• Contact-free separation, individually controlled compressed air nozzles deflect the object from its path, so there are no mechanical parts to strike or dull.
• Throughput no human can match, it runs on continuous flows with a consistency manual sorting cannot hold across a whole shift.
• Configurable recipes, parameters are saved per target material, so you change the sorting objective from the panel rather than through mechanical adjustment.
• Data on your own flow, the system reports the real composition of the material passing through, valuable information when negotiating collection contracts.
• It raises the price of the fraction, purity sets value directly, and optical sorting is the difference between industrial-grade material and filler.
Technical Specifications, Optical Sorter
| Parameter | Configuration |
|---|---|
| Sensor type | Near-infrared (NIR) plus visible spectrum (VIS) |
| Recognition system | High-speed, high-resolution cameras |
| Sorting criteria | Polymer type, colour, shape, composition |
| Separation mechanism | Compressed air nozzles, individually controlled |
| Materials sorted | PET, HDPE, PVC, PP, paper, cardboard, glass, metals |
| Configuration | Recipes saved per material |
| Reporting | Data analytics on flow composition |
| Upstream requirement | Screened, 2D/3D separated flow, spread in a thin layer |
Working width and the number of modules are set from line throughput and from how many fractions you want separated at once. The optical and control components can be specified from recognised manufacturers, with Toshiba cameras, Phoenix optics and Schneider switchgear.
Applications for Optical Sorting
• Plastic recycling, separating PET, HDPE, PVC and PP by type and colour, the most valuable application.
• Municipal waste sorting plants, extracting recyclables from the mixed flow, as the fine sorting stage.
• Paper and cardboard, separating by grade, for a better price at the paper mills.
• Glass recycling, separating by colour and removing ceramics and stone.
• Metals, identifying and separating ferrous from non-ferrous fractions, as a check stage.
• Alternative fuel production, removing PVC from the combustible fraction, an environmental requirement for cement kilns.
How It Works
Material is spread in a thin layer on a fast belt that accelerates it to a constant speed. Above the belt, a near-infrared light source illuminates the material and a sensor reads the reflected or transmitted light. Every polymer has its own absorption spectrum, a chemical fingerprint, and the system compares it against a reference library. In parallel, a high-resolution camera records colour and shape. All this information is combined and, in milliseconds, the system decides whether the object belongs to the target fraction. At the end of the belt, a bank of compressed air nozzles, each individually controlled, receives the signal at the exact moment the object passes in front of it. The nozzle fires, the object is deflected from its natural falling path and crosses a splitter plate. Whatever is not blown continues to fall normally. Accuracy depends on three things: the material layer must be thin and free of overlaps, the belt speed must be constant, and the nozzles must be correctly calibrated.
Selection Guide
Before discussing models, check the preparation of the flow. An optical sorter needs screened material, separated into 2D and 3D, spread in a single-object layer. If objects overlap, the sensor only reads what is on top, and the nozzle deflects what is underneath as well. That is why optical sorting sits at the end of the mechanical line rather than the beginning. The second criterion is how many fractions you want separated: each additional fraction requires either an extra module or a second pass. The third is components: here it is worth specifying cameras, optics and switchgear from recognised manufacturers, because the machine's accuracy depends directly on sensor quality.
Frequently Asked Questions
Can it tell PET from PVC?
Yes, and that is the main argument for optical sorting. The two plastics are often both clear and impossible to tell apart by eye or with a colour camera. The near-infrared sensor, however, reads the absorption spectrum, which is entirely different, so the separation is reliable. It matters a great deal, because PVC contaminates a batch of PET and makes it unsellable.
What preparation does the flow need beforehand?
The material must be screened into a relatively uniform size fraction, separated into 2D and 3D, and spread on the belt in a single layer with no overlaps. If one object sits on another, the sensor only sees the one on top. That is why the optical sorter is the last machine in the mechanical chain, not the first.
How accurate is it?
Real accuracy depends on three factors you control: how thin the layer is, how constant the belt speed is, and how well the nozzles are calibrated. We do not quote a catalogue percentage, because a percentage that ignores flow preparation means nothing. It is established at commissioning, on your material.
Does an optical sorter replace manual sorting?
Largely, but not entirely. There remain objects the system cannot reliably distinguish, such as black plastics, which are hard to read in infrared, and composite packaging. That is why a manual sorting cabin remains useful as a final check, even in highly automated plants.
Is the equipment supplied new?
Yes. We supply new units only, made to order for your application, with complete technical documentation.
What maintenance does it need?
Periodic cleaning of the optical window and the lamps, checking and calibrating the air nozzles, checking the filters and the compressed air dryer, and verifying the tension of the acceleration belt. Clean, dry compressed air is the single most important condition for correct operation.
Why URSTAG?
URSTAG is a premium brand of recycling equipment, with over 15 years of experience. You don't just get a machine, you get a solution engineered by specialists, built from top-tier components and backed by a team that supports you from design through commissioning.
• European engineering, every machine and every complete line is designed by our engineering teams in Europe, with a focus on reliability, safety and energy efficiency.
• Premium components, we build on motors and automation from industry leaders: Siemens, Schneider Electric, ABB, WEG, SEW-Eurodrive, NORD Drivesystems and Bonfiglioli.
• Over 15 years of experience, we know how materials and machines behave in real-world operation, and we configure each solution for your flow and volume.
• New equipment, configured for you, we supply new units, made to order for your application, with complete technical documentation.
• Delivery, installation and training included, we handle transport, commissioning and operator training, with support throughout the equipment's life.
As a premium brand, URSTAG relies on European engineering, top-tier components and experience. You choose a partner that supports your production long term, with equipment built to run reliably in demanding industrial environments.
