PC or ABS for a hard shell suitcase?

A: Match temperature and budget. City travel favours PC or a blend, which springs back and does not whiten; short trips on a budget are fine in ABS.

Is PC always tougher than ABS?

A: At room temperature yes, and the gap widens in cold. ABS keeps a third of its impact strength below minus ten.

Why are PP shells so plain?

A: Low surface energy stops ink bonding, so the shell needs a film or corona treatment; both cost money.

How do I spot a PC/ABS blend?

A: Look for flow lines under strong light, and compare weight: heavier than pure PC per litre, lighter than ABS.

Does a 2.5 mm wall mean the same everywhere?

A: No. Thermoforming quotes sheet thickness, moulding quotes nominal wall, and a corner may be 1.8 mm. ---

Hard Shell Suitcase Materials: PC, ABS and PP Compared

Quick answer: The three materials divide by forming route and failure temperature, not hardness. PC trades weight for toughness, ABS toughness for cost, PP surface for impact. City travel suits PC or a blend; cold regions and budget carriers suit PP.

Forming sets the ceiling
PC: best rebound, poor scratch resistance
ABS: stiff, brittle when cold
PP: toughest, hardest to finish
Cost and life
FAQ

1. Forming sets the ceiling

Start with the process: it decides what shape the material can take. Hard shell suitcases follow three routes: PC sheet thermoforming, ABS injection moulding, PP thermoforming.

Thermoforming gives even walls from the sheet, but ribs can only be pre-formed and stay shallow. Moulding builds ribs, wheel mounts and lock pockets in one shot, yet flow length thins the corners: a 2.5 mm nominal wall often measures 1.8 mm where it bends.

Hard Shell Suitcase: cream case closed on a pale floor, two cam latches clamped, a round pressure valve beside the grip

Material	Forming	Wall	Thinnest corner
PC	sheet thermoforming	1.5–2.0 mm	near nominal
ABS	injection moulding	2.2–3.0 mm	20–30% thinner
PP	thermoforming	2.0–3.0 mm	near nominal

2. PC: best rebound, poor scratch resistance

PC reaches 600–900 J/m notched impact and 60 MPa tensile, with a Vicat point near 145 °C: a dent springs back and cold does not crack it.

Scratch resistance is poor: PC yields instead of fracturing, and the flowed surface changes refractive index, leaving a white line. Sunscreen esters, petrol and alkali craze it.

Pale PC needs a UV coating or it yellows within eighteen months; most cases die of appearance, not fracture.

3. ABS: stiff, brittle when cold

ABS sits near 40 MPa and 150–300 J/m notched at a density of 1.05. It moulds flat and glossy without paint, and reproduces grain and metallic flake.

Cold is the weakness: below about minus ten the butadiene phase stops toughening and impact strength falls to a third. A winter drop splits the corner where the wheel mount meets the shell.

Weathering is the second cost: chalking within two or three years. PC/ABS blends at 6:4 or 7:3 land at 400–500 J/m.

Hard Shell Suitcase: the cream case on a timber bench at an airport, grey scuffs along a corner and a latch edge

Property	PC	ABS	PP
Density	1.20	1.05	0.90
Tensile	60 MPa	40 MPa	30 MPa
Notched impact	600–900 J/m	150–300 J/m	40–60 J/m
Cold	good	poor	good
Surface	whitens	moulds glossy	needs film

4. PP: toughest, hardest to finish

PP is lightest at 0.90. Notched impact is only 40–60 J/m, yet unnotched impact is high, because the part deforms as a whole: a PP case can be stood on and recover, then split from a knife point.

Surface is the limit. At 31 mN/m ink barely holds, so printing peels and the shell needs a BOPP film or corona treatment, which fades. PP shells carry the fewest graphics.

Shrinkage of 1.5–2.0%, unequal along and across the shell, misaligns lid and base.

Hard Shell Suitcase: close-up of a cream lid corner, grip, two latches and the lid lip, fine sand-textured surface

5. Cost and life

PC costs 1.8–2.2 times ABS per kilo; PP is cheapest. Resin is not the whole case: an injection tool runs 150,000–400,000 yuan against 30,000–80,000 for thermoforming.

Below 3,000 pieces the cheaper tool outweighs the resin gap; above 20,000, moulding amortises.

Life follows use: PC gives five or six years with scratches and coating going first, ABS two or three in cold, PP four or five with film lift as the usual end.

Hard Shell Suitcase: silver-grey shell side-on, a three-dial combination lock between the ribs, side grip above the wheel housing

Item	PC	ABS	PP
Resin index	100	50	45
Tool cost	30–80k	150–400k	30–80k
Economic batch	under 3,000	over 20,000	3,000–10,000
Main failure	scratches	cold cracks	film lift

Conclusion

Hard shell suitcase material reduces to three questions: the lowest temperature in use, the surface requirement, and the batch size. Temperature separates PC from ABS, surface decides whether PP is viable, batch decides between thermoforming and moulding. Then the hard shell suitcase has one material left.

This article covers container-side specifications and design implications only, not the handling, loading or use of the contents.