Friday, May 15, 2020

How to reduce part marking at the press brake?

3 ways to avoid rejected parts  

It’s not uncommon for some jobs to require a finished part to be free from marks or aesthetic imperfections. If part marking occurs during the bending process, in the form of marking or creasing the bend line, a good part can quickly be turned to scrap metal, resulting in rejection and increased production costs. Here are three ways to minimize or eliminate part markings:

1 – Use clean press brake tools 
Clean the press brake tool(s) before and after use and always check for damage before bending a new product. If you’re bending galvanized material, you may start to notice scratches on the surfaces of the bottom tool, known as galling. Read more to learn how to prevent galling.  

2 – Choose the right press brake tool
The correct shoulder- and tip radius contribute to damage free bending. For example, a larger shoulder radius creates less friction, which greatly reduces the marking on the outside of the workpiece. Too small of a punch tip radius can crease the bend line. This can be easily avoided by choosing an appropriately sized punch tip radius. For galvanized material, consider using specially coated tools to prevent zinc deposits on shoulder radii, which can eventually lead to work pieces getting stuck in the groove.

3 – Protect the sheet material
By properly protecting the sheet material with cloth or foil, you ensure that the bottom tools do not come into direct contact with the workpiece. Lay the cloth or foil between the bottom tool and the workpiece during bending to minimize or eliminate part-marking. Another option involves applying foil to the sheet material itself, such as laser foil on stainless steel. In combination with the right tools this can also minimize part marking.

WILA’s advice

Which solution suits you best, of course, depends on your situation. At WILA we offer various options to minimize part marking. We recommend a liquid spray wax  for cleaning. It has been specially developed for cleaning, maintaining and protecting press brake tools. When choosing the right press brake tool, pay close attention to the punch tip radius and shoulder radius. WILA’s New Standard Premium tools have a working height linked to the shoulder radius. At working height of 100mm, for example, there is an increased shoulder radius of approximately 20% of the V-groove width. We also offer various tools that are specially made to reduce marking, such as RotaBend tools and tools with plastic inserts. 

Do you bend galvanized sheet material often? Then the OZU-ZN coating can be a solution. This protective layer on the tools prevents zinc deposits on the bending radii. Finally, you can protect the sheet material with WILA K-005 cloth or foil  (K-003 / K-004) by placing it between the sheet and the press brake tool. 

Do you want to know which solution for mark-free bending best suits your bending application?

Our Technical Sales Engineers are happy to help you. We will examine your application and determine where there may be risks of part marking. Based on this, we will provide a custom solution for your specific applications and quality standards. You can reach us at or + 31 (0)573 289 850.

How to reduce part marking at the press brake?

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