How do I tell PP from ABS quickly?

Answer: Read the base first — the loop symbol and polymer code stand 4–6 mm tall. If worn, drop a 10 mm square in water: PP at 0.90–0.91 g/cm³ floats, ABS at 1.04–1.07 sinks, in 30 s.

How much metal comes out of one case?

Answer: It depends on the frame. A 90 L aluminium-frame case gives 1.8 kg of extrusion plus 0.8 kg of stainless, 2.6 kg; an all-plastic case gives 0.3–0.6 kg.

How much regrind can go into new parts?

Answer: Moulders hold 20–30%. Impact falls 10% at 20% loading and 15% at 30%, and white shells show ΔE 2 at 25%; push further and low-temperature drop fails.

Can a case that held chemicals go straight to the granulator?

Answer: No. Wash it, screen for residue, and confirm the disposal category with the local solid waste authority; a single-polymer shell is not a reason to skip that.

How long should disposal records be kept?

Answer: At least 3 years. Keep the despatch note, weighbridge ticket and receipt, and log quantity with weight.

End-of-Life Cases: Recycling and Compliance

Quick answer: End-of-Life Cases go by material first: water floats PP from ABS, regrind sells at 40–60% of virgin, and a 30% recyclate load costs 15% of impact.

Reading End-of-Life Cases: Density, Float and Flame
Teardown: How Much Metal Comes Out
Regrind: MFI and Recyclate Ratio
Three Routes: Refurbish, Regrind, Ship Out
Records and Paperwork
FAQ

1. Reading End-of-Life Cases: Density, Float and Flame

A 90 L case coming off service poses one question before any grinder is booked: which polymer it is. PP sits at 0.90–0.91 g/cm³, HDPE at 0.94–0.96, ABS at 1.04–1.07 and PC at 1.20. The spread matters: PP and ABS regrind differ enough in value that a mixed batch sells at the bottom grade.

A water float is the cheapest cut. PP and HDPE rise, ABS and PC sink, and a 20 L bucket settles it in 30 s. Swap the water for brine at 1.15 g/cm³ to lift ABS off the bottom; flame behaviour separates the rest.

Polymer	Density	Water	Brine	Flame
PP	0.90–0.91	Floats	Floats	Yellow over blue, wax
HDPE	0.94–0.96	Floats	Floats	Yellow, little smoke
ABS	1.04–1.07	Sinks	Floats	Orange, heavy smoke
PC	1.20	Sinks	Sinks	Black, sparks

Burn a sliver under 10 mm: PP burns yellow over blue with a wax smell, ABS orange with heavy black smoke and a styrene note, PC black and self-extinguishing.

The moulded mark on the base saves half the work: a triangular loop and polymer code, 4–6 mm tall, legible once the dust is wiped off.

2. Teardown: How Much Metal Comes Out

Hardware is the only part of an End-of-Life Case that sells by weight. A 90 L aluminium-frame case yields 1.8 kg of 6063 extrusion plus 0.8 kg of stainless pins and latches, 2.6 kg, against 0.3–0.6 kg of steel in an all-plastic shell — a fourfold gap for the same retirement.

End-of-Life Cases as a white moulded case seen front on, folding handle pressed flat, hinge seats, ribbed lid, pale grey backdrop

Teardown runs 3–5 min per case, and the clock stops at seized screws: moisture down the thread reddens steel in six months, and torque splits the boss. Warming it with 60 ℃ air for 60 s drops breakaway torque from 12 N·m to 5 N·m.

Sort into aluminium, stainless and plated steel: mixed, the buyer weighs the lot at the lowest rate and the loss per case equals 2 min of labour. Bag by stream, marked with polymer and weight.

An ultrasonic gauge then reads four corners and four edge midpoints: six of eight points above 0.5 mm with no through-crack means refurbishment, anything less goes to the grinder.

3. Regrind: MFI and Recyclate Ratio

Grade comes before granulation, because melt flow decides where regrind can go. Virgin PP sits at 3–5 g/10 min; one moulding cycle plus three to five years outdoors pushes regrind to 8–12, and shorter chains mean better flow with worse impact. Above 15 g/10 min it suits only low-end parts, under 40% of virgin price.

Run an 8 mm screen. At 12 mm melt time lengthens by 20% and energy climbs; at 5 mm fines pass 12% and bridge in the hopper. Flake bulks at 0.32–0.40 g/cm³, so a 30 m³ trailer carries 9–12 t — volume-limited, which is why the radius stops near 200 km.

End-of-Life Cases as a second white case, handle folded flush with the lid, rim groove, lower wall ribs and feet

Moulders hold recyclate at 20–30% of the blend. Notched impact drops 10% at 20% and 15% at 30%; beyond that, low-temperature drop leaves the specification. At 40% recyclate a case cracked at the corner in a −20 ℃ drop from 1.2 m, while the virgin control dented 1.5 mm.

White shells show colour first: at 25% recyclate the difference reaches ΔE 2 in daylight, while grey and black absorb 30% without a trace. Dry the regrind an hour at 90 ℃ to pull moisture from 0.3% to under 0.05%, or silver streaks cost 30 parts in 500.

4. Three Routes: Refurbish, Regrind, Ship Out

End-of-Life Cases leave by one of three doors: refurbish and reuse, granulate, or ship out as general industrial solid waste. The dividing line is not age but remaining wall and contamination history.

Refurbishment has the clearest gate: six of eight gauge points above 0.5 mm, no through-crack, hardware replaceable as a set. Two latches, two pins and a handle cost around 60 yuan and 25 min, and the unit must re-pass 20 kPa for 60 s with no more than a 2 kPa drop.

Granulating suits shells that are thin but single-polymer and clean: a 6.2 kg PP case yields 5.8 kg of flake, a 6% loss. An aluminium frame comes off first, because extrusion in the chamber damages rotor knives at 1,800 yuan a set.

Shipping out is for shells that held chemicals, carry residue, or mix polymers that will not separate. A case that held chemicals should be washed and screened for residue first, with the disposal category confirmed by the local solid waste authority. That is the only route of the three needing a third party.

Route	Precondition	Return	Risk
Refurbish	Wall over 0.5 mm	Cost down 50%	Aged gasket missed
Regrind	Single polymer	40–60% of virgin	Batch downgraded
Ship out	Residue or mixed resin	Fully cleared	Paperwork gaps

5. Records and Paperwork

Once a case leaves the gate its destination must be provable: keep the despatch note, weighbridge ticket and receiver acknowledgement, with counts and polymer codes agreeing across all three, for 3 years.

Eight fields cover it: batch number, quantity, polymer code, unit weight, total weight, disposal route, receiving party, operator. Quantity and weight go together, because count alone cannot reveal loss when walls differ.

Reconcile quarterly: pull 5% of records and compare weighed tonnage with the theoretical weight of the same model; a deviation above 5% means hardware went in un-stripped or polymers were mixed.

Conclusion

End-of-Life Cases follow a fixed order: material, remaining wall, destination. Mix PP at 0.90–0.91 with ABS at 1.04–1.07 and the load sells at the bottom grade; six of eight gauge points above 0.5 mm makes refurbishment worth half the replacement cost; a clean shell granulates at 40–60% of virgin; a contaminated one ships out with 3 years of paperwork. The test is whether the shell still holds pressure, and what it carried.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.