What advantages does roller leveling have over other methods?

Other methods are time consuming and do not release as much stress. Roller leveling is an easy and fast way to obtain flat parts, sheets or strips with the highest precision. Manual flattening, for example, was once reserved for workers with the most extensive and longest experience, as it requires a lot of skill. Today anyone can learn quickly and easily how to level sheet metal parts with roller levelers.

Why is leveling necessary after lasering or plasma-cutting or after stamping?

Thermal manufacturing processes such as laser, oxy-fuel or plasma cutting  introduce a great deal of heat into the material.  The resulting temperature gradient within the material leads to stresses and edge hardening. Parts and sheets cut by such methods are distorted. As for stamping and perforating internal stresses in the material are released in addition to the parts being deformed by the punching operation.

Can all materials be leveled?

It is possible to level all metals with an ultimate elongation of at least five percent and a distinct yield strength. If these values are unknown, a material's suitability for leveling can be determined by leveling tests. As a rule of thumb we say: “if you can bend it, you can level it”. 

Can hardened materials be leveled?

Yes and no. If the material has an elongation at fracture after hardening, you can assume it can be leveled to a certain degree. However, high forces combined with small roll diameters are necessary to work such material. If the material has no elongation at fracture, there is a risk of initiating cracks or even fractures. Only leveling tests can indicate whether leveling is possible and what the results will be.

Does roller leveling change the material properties?

No changes to mechanical properties such as tensile strength or dimensions occur in ferrous metals under normal circumstances. Stainless steels differ, tend to harden after being leveled several times. This -is not necessarily valid for non-ferrous metals. Particularly soft metals such as aluminum and magnesium have a risk of material abrasion or lowering the yield point. 

What needs to be set on a leveler in addition to the entry and exit values?

In principle nothing, because modern leveling machines work with bank adjustment. The leveling rollers are summarized in the upper and lower roller mill and no longer need to be adjusted individually. The operator only has to modify values for the inlet and the outlet of the machine. Exceptions are high capacity levelers, where even the deflection of the leveling rollers can be adjusted.

How do I find the correct setting values?

The most important setting parameter is the material thickness . For example, to level a one centimeter thick steel plate, the entry is closed deeper than one centimeter  and the exit value is set approximately equal to the plate thickness of one centimeter. This is only a rough guideline. Advanced levelers are equipped with a setting database helping the operator by recommending specific settings and new settings can be added to the database as well.

What should a sheet-metal fabricator consider when buying a leveler?

The machine's design depends on the materials to be leveled. The key parameters of a leveling machine include the diameter, the roller pitch and the number of leveling rollers.  Basically: the closer the roller pitch and the smaller the leveling roller diameter, the better the result. Essential is a sufficient support of the leveling rollers against deflection. To cope with daily production, the leveler should also be equipped with a quick-change system for the leveling rollers. This enables easy changing of the leveling rollers and thorough cleaning of the leveling unit. Dirt or material residues in the machine can degrade the leveling results and cause more wear on parts in the leveling unit.

Does the number of leveling rollers affect the quality of the results?

The process material is subjected to mechanical alternating bends in the machine. The intensity of the alternating bends is reduced towards the leveling unit outlet. The higher the number of leveling rollers, the higher the number of alternating bends. General speaking: the more alternating bends, the better the leveling result. At least five rollers are required to trigger any effect at all. However, with five rollers you can achieve only a rough level of flatness. For thin material you tend to need more leveling rollers than for thick material. Experience indicates that at least 11 to 13 rolls are needed on parts leveling machines in order to achieve good tolerances.  

After leveling the sheet metal it is still not flat – What can be done?

Three possible main causes are: If the sheet-metal part is still bent in the same direction as before leveling, then the levelers entry setting was set too soft The sheet-metal part is under-leveled. This can be fixed with a second pass through the leveler and a tighter entry setting. If the sheet-metal part is bent in the opposite direction than before leveling, the leveler was set too tight at the entry. The sheet-metal part is over-leveled. The operator should check if the exit value is set to the sheet-metal thickness and if necessary  open up the entry setting. It is also possible that the sheet-metal part simply cannot be leveled on this leveler type or size. The next thing to do check is whether the material can be leveled on a different leveler or whether the material cannot be leveled at all.