qu01. What is the purpose of tempering the guillotine knives?
Tempering consists of steel capacity to suffer martensitic transformation (hardening) after being cooled rapidly in a given environment from the austenitic field. For cutting knives, aims to:
- Increasing the hardness
- Increase the tensile strength
- Reduction in tenacity
02. What is Annealing?
It is a heat treatment step of hardened steels which have fragility reduced or tenacity addition, as its major objective.
What determines the annealing conditions for a given application of the material is the balance between hardness (or Resistance) and tenacity required in service.
Estampar use as standard triple Annealing for its cutting knives, thus ensuring that all internal tempered microstructure is transformed.
This way, minimizing the possibility of stress points, consequently, cracks originated in tempering.
03. What are the types of Local Heat Treatment?
- Tempering by flame
In this process the surface to be hardened is heated quickly by an oxyacetylene flame, above the critical temperature. Being the heating just by fire, its process is irregular, not maintaining uniform hardness and a constant depth.
- Tempering by laser
Light source with which it can be applied a pre-determined amount of energy at specific areas of a component. Its penetration is superficial, reaching an average depth of 1.5 mm.
- Tempering by magnetic induction
Method used by Estampar Profasa, where the steel is heated by a magnetic field generated by a medium-frequency alternate current passing through or over an inductor (copper coil).
With a unique system of surface copier, our treatment achieves a uniform penetration of 4-5 mm, ensuring constant resistance and hardness along the entire length of the parts.
The great advantage of this process is to maximize longevity in future maintenances. Because in eventual sharpening, the hardness depth will represent more than double the tool lifetime compared, for example, to laser treatment.
04. Full or Local Tempering for Press Brake Tools?
As the tools of press brake machines work open, the local tempering was taken as a safety standard, where only the contact areas with the plate should be treated. In this way, if some error or carelessness happens in the process, the tool absorbs the pressure and there is no breakage or chipping of parts that can cause a serious work accident.
Depending on the tool deformation, it can be recovered.
For cases that require greater rigidity in the tool structure, raw materials pre-hardened at 22-30HRc added to local tempering 54-60HRc is used.
05. What is the difference between the Tools for Conventional X CNC Press Brake?
The difference lies in the tool finishing, tolerance, and surface roughness.
The CNC tool, after the machining and heat treatment, is rectified. Both in the fixation system, as along the bending track.
Thus ensuring dimensional precision and parallelism (0.03 mm) and low roughness (N6-0,8μm).
Regarding Conventional Tools, they follow a tolerance of decimals and milled finishing. Thus, the surface roughness is higher (3.2 μm (N8)).
As advantages, the CNC tool, or the tool designed to be used in CNC Press Brakes gives greater speed of assembly with quick and accurate replacements without the need for adjustments by shimming. Very useful for anyone working with small lots of parts.
By presenting dimensional warranty, all parts can be assembled together, ensuring perfect fit, thus, being modulated to different daily situations. In addition to offering the operator a better working ergonomy with respect to handling operation. Thereby, adapting to the NR12 requirements.
With a smoother finishing minimizes any flow signals and marks on the sheet, and increases the tool longevity by also minimizing friction during the bending process.
As the CNC Press Brake is also designed to give accuracy, speed and versatility, the tool as an extension has to ensure that everything that has been set up happens! As it is not to make manual adjustments but by the control panel, we must ensure that what we have entered on the panel corresponds to reality, otherwise, production speed will get lost. And this is not exactly what the modern companies seek.
Regarding the conventional tools and because they are only milled, they work with a more open tolerance. After the heat treatment, it also has to be fixed in alignment and this correction is manual.
For conventional ones, these points are minimized in one-piece tools. If fractionation is necessary, small mismatches in segments will be evident in the bent profiles. Therefore, compromising the final product. In relation to the roughness of milled tools, they generate more flow friction, accelerating tool wear as well as stamping more the bent profile.
06. When is the use of Matrix inserted channels with steel-tool indicated?
Basically, when the material to be bent is very aggressive. We consider in this situation: plates with holes close to a bending area, plates with cutting burrs (guillotine or plasma), uneven edges, wire mesh, welded plates, etc.
As the rulers are made of special steel alloy C-Cr and high hardness, they ensure the original properties of the channel up to 3X compared to the conventional system. Another advantage is that they are interchangeable,
At any moment, it is possible to get the tool with the original factory characteristics. All this combined with considerable improvement in reducing fold marks for the best flow of the plate.