Thermoforming Scrap Grinder — Inline Sheet Skeleton Recycling

More than in almost any other plastics process. The skeletal web left after parts are punched typically carries 30–50% of the sheet area away as scrap — round cups punched from rectangular sheet sit at the high end, tight-nested trays at the low end. Add sheet-line edge trims, start-up sheet and formed rejects and total scrap often approaches half the resin consumed. That is precisely why nearly every serious thermoforming plant grinds its skeleton and runs sheet with a regrind blend.

The skeleton is your own sheet, ground minutes after forming — it never left the plant or touched food, which is why sheet-to-sheet recycling of in-house skeleton is standard practice across the industry. Quality holds when the basics hold: one polymer and colour per stream, regrind stored covered and dry, and a consistent blend ratio at the extruder. For specific food-contact compliance on your product, confirm against the applicable FSSAI/IS norms for your sheet construction — multilayer and coated sheets need more care than mono-material PS or PP.

Yes, in one important way: moisture. PET is hygroscopic, and wet PET flake degrades sharply in the extruder — losing intrinsic viscosity and melt strength, which shows up as brittle sheet. PET regrind must be dried before re-extrusion, so plan drying capacity alongside the grinder. PS and PP are far more forgiving and need only clean, covered storage. The grinding step itself is identical for all three — the RE-series grinder handles PS, PP and PET sheet without changeover beyond a clean-down between materials.

Thin web needs steady feeding, not dumping. Fed continuously off the line — or in cut lengths if you wind skeleton onto rolls — the web draws into the rotor and cuts cleanly against the screen. Problems start when a whole compressed bundle is forced in at once. The overload-protection starter trips the motor on a jam rather than letting it damage anything, but disciplined feeding means it rarely has to. During a trial we will show you the feeding rhythm on your own web.

Calculate your scrap rate: sheet consumption per hour multiplied by your skeleton percentage. A line consuming 150 kg/hr of sheet at 40% skeleton generates 60 kg/hr of web — an RE12 at 80 kg/hr covers it with headroom; faster lines or lines with heavy reject loads step up to the RE16. Central grinding across multiple lines points to RE20–RE30. Our machine selection guide walks through the arithmetic, or send your line details for a free recommendation.

Every machine is quoted to the job. What moves the number is capacity, throat size, motor rating, MS or SS construction and the automation you add — a blower, a conveyor, a control panel. Our guide to what drives machine cost walks through each of those; send us your material and daily volume and we will size the machine and quote it, usually the same day.

Yes — bring rolls or bags of your actual skeleton, trims and rejects to our works at Andheri East, Mumbai, and we will grind them so you can verify flake size, throughput and feeding behaviour on your exact material and gauge. Outstation plants can request a video trial. Contact us to book a slot — Mon–Sat, 9 AM to 7 PM.