How much side clearance does a plastic case holder need?

15 mm a side, 30 mm total. Tighter and fingers will not fit; wider and the case slides into the uprights.

Can level height simply match case height?

No. A 150 mm case reaches 355 mm with the lid open, so the level needs 400 mm.

Does a 1250 mm span always need a centre post?

Not with 1.5 mm shelving, which sags about 2 mm. With 1.0 mm shelving the sag reaches 6 mm and cases drift inwards.

Should the frame be fixed to the wall?

Above 3 to 1, always. A 2000 by 1250 mm frame is 1.6 to 1, so anchoring is still advised once it is loaded.

Can castors be added to a plastic case holder?

Yes, but count the set at 300 kg rather than 400 kg. Castors add 130 mm of height, so the top pick height changes.

How to Choose a Plastic Case Holder: Five Criteria

Quick answer: Choose a plastic case holder in reverse order: measure the case, size the frame, then check the span. Work to 430 mm clear width for a 400 mm case, a 400 mm level height for a 150 mm case with the lid open, and a 900 mm span on 1.0 mm shelving.

Five Criteria for a Plastic Case Holder
Criterion One: Clear Width and Depth from the Case Outline
Criterion Two: Level Height from the Open Lid
Criterion Three: Picking Method and Latch Clearance
Criteria Four and Five: Load, Span and Stability
FAQ

1. Five Criteria for a Plastic Case Holder

Measure the case, size the frame, then check the span. A 400 mm case with 3 mm side ribs measures 406 mm and will not enter a 400 mm opening.

Criterion	Driven by	Typical value
Clear width, depth	Outline with ribs	Outline plus 30 mm
Level height	Case height, lid swing	Height plus 250 mm
Picking method	Picks per day	Flat, tilt, side open
Load and span	Case weight times cases per level	80 kg distributed
Stability	Height, aspect ratio	Anchor above 3 to 1

2. Criterion One: Clear Width and Depth from the Case Outline

Measure the outline, not the nominal size. A 400 mm case gains 3 mm from each rib but loses 12 mm into the handle recess, occupying 406 mm; a 430 mm clear width leaves 15 mm a side for fingers.

plastic case holder: close-up of a white moulded case side, two triangular ribs either side of a recessed handle, fine grain texture on the wall

Depth needs 20 mm over the case. A 15 mm lip at the shelf edge stops it sliding out when pulled, kept low so it does not block the handle. Against a wall, put the whole allowance on the picking side.

3. Criterion Two: Level Height from the Open Lid

Level height is case height plus lid swing. A 150 mm case reaches 355 mm with the lid up, so that level needs 400 mm; set it at 200 mm and the lid stops halfway.

Uprights are punched at 50 mm centres, so levels land on 350, 400 or 450 mm, and a 2000 mm plastic case holder takes four levels at 400 mm with 400 mm left on top. Allow another 30 mm wherever the lid swings towards a wall.

4. Criterion Three: Picking Method and Latch Clearance

Picking method follows the pick rate. Above 20 picks a day, a 15-degree tilt or a side-opening frame saves lifting the case out; below 5 picks a day, a flat stack uses space best.

plastic case holder: close-up of a translucent case latch on a lab bench, the catch engaged, three glass dishes alongside and instruments blurred behind

In a plastic case holder, latches need side clearance: each takes 30 mm to trip, and a case wedged between uprights forces a screwdriver under the catch, chipping the base. A 15-degree tilt costs depth instead, adding 60 mm and narrowing a 900 mm aisle to 840 mm.

5. Criteria Four and Five: Load, Span and Stability

Load is case weight times cases per level, times 1.5. Three 2.4 kg cases weigh 7.2 kg, far below 80 kg, so deflection over the span limits the choice.

Span, mm	Shelf thickness, mm	Distributed load, kg	Mid-span sag, mm
900	1.0	80	3
1250	1.5	100	2
1500	1.5	100	4
1800	2.0	120	5

A 1.0 mm folded shelf sags 3 mm at 900 mm and 6 mm at 1250 mm, so cases drift; 1.5 mm brings the 1250 mm sag to 2 mm. Past 1500 mm, add a centre post.

Stability in a plastic case holder is an aspect-ratio question. A 2000 mm frame at 1250 mm wide is 1.6 to 1, and a full load lifts the centre of gravity, so anchor anything above 3 to 1 with M8 expansion bolts at 1200 mm centres. Castors rated 100 kg count as 300 kg a set, and 2 mm per metre of floor error lifts one of four.

Conclusion

Measure the case, size the frame, then check the span: 30 mm clear over the outline, a level height from the open lid, a picking method matched to daily picks, and load and stability at the worst case. Those five numbers in the enquiry bring back a drawing that matches. Get width, height and span right, and a plastic case holder runs five years without a structural change.

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.