How does travel case production choose between vacuum forming and injection?

Answer: By volume. Under 5,000 pieces an aluminium tool restyles faster and cheaper; past 30,000, injection wins once steel is amortised.

Is 8 mm of handle sway loose or tight?

Answer: It is the ceiling, read at full extension with 50 N of side load. Above it, clearance exceeds 0.25 mm or bolts fall short of 4 N·m.

Why wait 24 hours after trimming?

Answer: To let sheet stress bleed off. Drilling the same day lets holes drift past 0.3 mm, and brackets no longer share a centre line.

Where does the 45-second cycle time come from?

Answer: From the slowest station: lining takes 42 seconds, so 45 leaves three seconds of headroom.

Travel Case Production: Shell Forming, Wheels, Handle Test

Q: Why is the four-wheel height spread capped at 1 mm?

Answer: At 1.5 mm one wheel lifts off and the case rocks; at 3 mm the load sits on two brackets and they crack within months.

Quick answer: Travel case production runs in three stages: shell forming sets shape and wall, wheel assembly puts four wheels on one plane, and handle assembly fixes telescopic clearance. All three share four base pads held to 0.3 mm flat.

How Travel Case Production Starts
Trimming, Drilling and Datum Transfer
Wheel Assembly: Four Wheels, One Plane
Handle Assembly and the In-Line Pull Check
The Final Line and Its Cycle Time
FAQ

1. How Travel Case Production Starts

Shell forming opens every travel case production run, on one of two routes. Vacuum forming heats a 1.8 to 2.2 mm PC sheet to 170 C, pulls 0.08 MPa against an aluminium mould and demoulds in 90 seconds, at 3.5 minutes per shell. Injection runs a 60 to 80 C steel tool, cycles in 55 to 70 seconds and holds 2.2 to 2.8 mm walls.

Volume decides the route: aluminium pays from 500 to 5,000 pieces, steel past 30,000. Forming thins the sheet, so a corner under 1.2 mm cracks first; keep radii at 8 mm and parting-line mismatch under 0.3 mm.

Route	Material and wall	Cycle	Tool	Batch
Vacuum forming	PC sheet, 1.8–2.2 mm	3.5 min	Aluminium	500–5,000
Injection	PC/ABS, 2.2–2.8 mm	55–70 s	Steel	30,000+
Blow moulding	HDPE, 2.0–3.0 mm	4–6 min	Aluminium	2,000–20,000

2. Trimming, Drilling and Datum Transfer

A five-axis router leaves 0.5 mm and finishes in a second pass; all twelve holes are drilled in one clamp at plus or minus 0.2 mm. The base plane is datum A, wheel brackets B, handle holes C. Most disputes trace to B and C being drilled in different fixtures 0.4 mm apart, which tilts the handle. Rest the shell 24 hours first, or holes drift past 0.3 mm.

3. Wheel Assembly: Four Wheels, One Plane

Rims come in 50 and 60 mm: 50 mm turns easily indoors, 60 mm crosses kerbs. Each bracket sits on four M4 bolts at 2.5 N·m, retorqued one by one.

Four wheels level is the hard number: 1 mm of spread per case. At 1.5 mm one wheel hangs and the case rocks; at 3 mm the load sits on two brackets and they crack within three months. Fit the rear pair, index the front to them, then push 2 m straight and allow 10 mm of drift.

Item	Spec	Gauge	Pass
Rim diameter	50 or 60 mm	Vernier caliper	Four wheels, one size
Bracket torque	2.5 N·m	Torque wrench	No stripped thread
Height spread	1 mm max	Plate and feeler	No rock when empty

4. Handle Assembly and the In-Line Pull Check

The handle is three aluminium tubes, 22, 19 and 16 mm, with 1.0 to 1.2 mm walls. At 1.5 mm the assembly gains 200 g and feels dead, so the thinnest wall may not fall below 1.0 mm.

Telescopic clearance runs 0.15 to 0.25 mm. Below 0.15 mm sand jams the section; above 0.25 mm the grip sways, and past 8 mm the case feels twisted. Four M5 bolts hold the bracket at 4 N·m over a 2 mm steel plate. Every unit gets 20 full-stroke pulls; that is a self-check inside travel case production, not the durability test.

Item	Spec	Method	Pass
Tube wall	1.0–1.2 mm	Ultrasonic gauge	1.0 mm minimum
Telescopic clearance	0.15–0.25 mm	Feeler gauge	Free at full extension

5. The Final Line and Its Cycle Time

The line runs eight stations: wheels, handle, lining, latches, top grip, dust blow-off, open-close check and bagging. Cycle time is 45 seconds, or 600 pieces per ten-hour shift, taken from the slowest station, lining at 42 seconds, plus three seconds of headroom. Every unit gets three open-close cycles and a 5 m push. In travel case production rework data, crooked wheels and loose handles account for seven in ten rejects; cracked shells stay under one in ten.

Conclusion

Taken as a chain, travel case production runs from datum to torque: forming holds the base to 0.3 mm, drilling puts datums B and C in one fixture, wheels level four rims at 2.5 N·m, the handle keeps sway under 8 mm at 4 N·m, and the line ties it together at 45 seconds. Each stage answers only to the one before it, and that is how travel case production stays repeatable.

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.