Plate rolls form sheet metal into shells, half-shells, arcs or cones: the plate passes between the rolls and every pass reduces the radius. This is how tank and silo bodies, large-diameter pipe, casings, cyclones and canopies are made. The catalog carries our own LUNA Nebula machines and Italian MG ones: working widths from 550 to 6100 mm, plate from 1.2 to 195 mm thick and drives from 1.1 to 380 kW.

Two, three or four rolls

Type	How it works	Best for	In the catalog
Two-roll plate benders	the steel top roll presses the plate into the elastic polyurethane bottom roll, so the cylinder is formed in a single pass	thin plate and batches of identical cylinders	LUNA Nebula 2R and 2R-A: 600–2050 mm, up to 4 mm
Three-roll plate rolls	the top roll presses while two lower rolls drive the plate; the edges are pre-bent as a separate operation	general work, from a job shop to heavy engineering	MG G-GE-GL: 1250–3100 mm, up to 195 mm
Four-roll plate rolls	the plate is clamped between the central rolls and the radius is set by the side rolls, so both edges are pre-bent without re-setting	batch work, accuracy, less handling	LUNA Nebula 4R-S, 4R and 4R-H, MG M-ME-ML: 550–6100 mm, up to 160 mm

What to compare

Thickness and width go together. The maximum thickness in the catalog is given for a particular steel grade and for the full roll width. The same machine will take thicker material in a narrower plate and thinner material in a higher-strength steel. That is why every card carries a note that the final figures are confirmed by calculation.
Minimum shell diameter. It is always larger than the top roll diameter, and by how much depends on thickness and yield strength. In the catalog the top roll ranges from 52 mm on the compact LUNA Nebula 4R-S 1050/1.2 to 1100 mm on the heavy MG machines. Small diameters need a smaller roll, thick plate a larger one.
Pre-bending the edges. The straight end of the plate is not gripped by the rolls and stays flat, so it is pre-bent separately. In the data this is a separate figure: the MG G-GE-GL 1204 L takes plate up to 4 mm but pre-bends up to 2.5 mm. Four-roll machines pre-bend both edges without removing the plate.
Control. Hydraulic with a digital readout suits one-off and varied parts. NC or a Siemens PLC with a touch screen suits repeat shells: the LUNA Nebula 2R-A 600/2 stores up to 100 programs, and the 4R-S series runs on servo drives with the same control.
Supports and tooling. A long or heavy shell has to be supported as it comes out, a cone needs a conical bending device, and the finished part is removed over the top roll through a drop end. These are separate items in the configuration and are worth agreeing together with the machine.

Common mistakes

Choosing rolls by the maximum thickness in the table without checking your steel grade, plate width and the shell diameter you need.
Forgetting about pre-bending: without it the shell keeps flat sections that then have to be straightened or cut off.
Not planning the unloading: a finished shell comes off over the top roll, and a heavy one needs a support and a crane.
Costing the machine alone, without supports, a cone device and tooling for your part.

Send the material grade, the plate thickness and width, the shell diameter you need and the number of parts — we will select the type, the model and the tooling and cost delivery, commissioning and training. If the part is bent to an angle rather than into a cylinder, see press brakes; for tube and profile there are profile bending machines; and the plate can be cut beforehand on laser machines or guillotine shears.

Two things are settled before the machine is even chosen: the blank length and what happens to the ends of the plate. The length is calculated from the neutral layer — π × (outside diameter − thickness) — otherwise the shell falls short by exactly πS. And the edges stay flat, because the plate is not gripped right from the edge, while the machine pre-bends at a smaller thickness than it rolls. Both calculations, with examples, are in the article on rolled shells and their development.

Questions and answers

How many rolls do I need?

Two for batches of thin-walled cylinders: the shell is formed in one pass. Three is the universal choice for varied parts and thick plate, although the edges are pre-bent as a separate operation. Four when parts repeat and accuracy matters: the plate stays clamped and both edges are pre-bent without re-setting.

What is pre-bending and why is its thickness lower?

It is bending the straight end of the plate before rolling so that the shell has no flat section. The operation loads the rolls more heavily than rolling itself, so the permissible thickness for pre-bending is always lower than the maximum: 4 and 2.5 mm on the MG G-GE-GL 1204 L, for example.

Do you have manual plate rolls?

The catalog has only hydraulic machines and programmable ones: manual rolls are made for thin sheet and do not give repeatability in batch work. The lightest models here are the MG M-ME-ML 0501 L for 1.5 mm plate 550 mm wide and the LUNA Nebula 4R-S for 1.2 mm.

How much do plate rolls cost?

The price depends on the width, thickness, number of rolls, control and tooling, and on delivery terms, so it is not listed on the site. Send a request and we will prepare a quotation including delivery, commissioning and training.

What should I send for a selection?

The material grade and yield strength, the plate thickness and width, the inside diameter of the shell, the length of the part, the monthly quantity and whether you need cones. From this we calculate the loads and select a model with its tooling.

Not sure which model fits?

Send your part parameters — we'll select and quote.

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