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Designing a custom press brake mold is a delicate engineering process that has a direct influence on how quality, efficiency, and safety of metal forming processes. A well-crafted mold is essential whether it is a unique profile, specialized material or high volume production. The following are the key aspects to be considered.
Material Selection for the Mold
The basic decision is the material of the very mold. It has to be able to withstand great amounts of pressure, abrasion, and repetitive cycles without distorting or collapsing. Materials that are commonly used include tool steel, carbide and occasionally hardened steel. The choice will mainly depend on the volume of production and the workpiece material. In case of long-run production of abrasive materials such as stainless steel a material with high wear resistance such as carbide is desirable. A strong tool steel can be used and is less expensive in shorter running or softer materials. The aim is to align the hardness and durability of the mold to the application to prevent early wear and to maintain uniform bend quality.
Geometric Design and Specifications
The geometry of the mold determines the geometry of the bend. All this should be carefully planned.
The die opening or V-opening is the most important aspect. Its size dictates the shortest flange length that can be used and has impact on the bending tonnage that is needed. The greater the V-opening, the smaller the force needed but it can be less accurate. The shoulder style, acute or radiused influences the final part by reducing or adding markings. Likewise, the punch tip radius should be fashioned to form the required internal bend radius on the part without overstraining or cracking. Angles and clearances should be computed to obtain the desired target bend angle by considering springback..
Tolerance and Precision Engineering
In the design of molds, nothing has to be compromised. Tolerances of the mold are imparted onto the workpiece.
This entails maintaining very stringent tolerances on all critical dimensions such as die width, punch angle and geometry in general. It is important that uniformity exists throughout the entire length of the mold to facilitate uniform bends particularly with long parts. A single deviation may cause rejection of part. In addition, the design should take into account the press brake in which it shall be used, such that it fits perfectly with the tool holders in the machine to ensure no deflection and inaccuracies occur when bending the tool.
Surface Finish and Treatment
The surface state of the mold is a major factor in the life time of the tool, as well as, the quality of the bent part.
An excellent surface finish, which is a result of fine grinding and polishing, reduces friction in the course of the bending operation. This minimizes the amount of force needed and eliminates marring or scratching the workpiece surface which becomes essential when bending pre-finished or coated work. Other surface options include nitriding or chrome plating, which can add hardness, wear resistance, and additional friction reduction which lengthens the lifespan of the custom mold.
Safety and Operational Considerations
A bespoke design should have operator safety and ease of use as a priority.
This involves coming up with characteristics that do not cause pinching or kicking back of sheet metal during forming. Weight and handling considerations, e.g. use of lifting points so as to install easily and safely, should also be taken into account. The mold must be configured as foolproof as possible, with a minimum of risk of wrong configuration or operation which may result in damage of the machine or personal harm.
To sum up, an effective custom press braze mold can be achieved through a holistic approach in which material science, exact geometry, high tolerances and surface technology are all achieved, and safe operation has been ensured. A careful strategy in these areas would warrant high performance of the mold with high quality parts and provide the investment with a payback in terms of longevity and cost-effectiveness.
