Marks and scratches that appear on part surfaces after press brake bending create a serious quality issue, especially for parts intended for visible surfaces. In this article, we look at the causes of post-bending surface marks and how to prevent them.
Causes of Bend Marks
Contact Between Die Surface and Material
During bending, the material comes into direct contact with the upper and lower die surfaces. Scratches, rust, or debris on the die surface transfer to the material surface, leaving marks.
Excessive Bending Force
Applying more bending force than necessary presses the material harder against the die surface, which can leave noticeable marks, especially on soft or glossy-surfaced materials.
Foreign Particles on the Material Surface
Metal chips or dust particles stuck to the material surface during cutting or handling can get trapped between the die and material during bending, causing scratches.
Methods to Prevent Surface Marks
Protective Die Coatings
Polyurethane or specialty polymer-coated dies create a soft interface between the material and the metal die surface, significantly reducing mark formation. These types of dies are preferred especially for sensitive materials such as stainless steel and polished-surface aluminum.
Using Protective Film
Protective PE film applied to the material surface beforehand prevents direct metal contact during bending, protecting the surface from scratches and marks. This method has become a standard practice, especially for aesthetically sensitive products.
Die Cleaning and Maintenance
Regularly cleaning dies and removing debris or rust from their surfaces is the most fundamental step in preventing mark formation. Replacing worn or damaged dies in a timely manner is also important.
Correct Bending Force Setting
Setting bending force appropriately for material thickness and type preserves surface quality by preventing unnecessary pressure.
Which Materials Are More Sensitive?
Stainless steel, aluminum, and color-coated sheet are particularly sensitive to surface marks. Taking protective measures is more critical when working with these materials compared to standard carbon steel.
The Cost Impact of Surface Marks
Marks appearing on visible surfaces can lead to part rejection or the need for additional surface processing (polishing, repainting). This means both material and labor loss. Taking preventive measures from the start significantly reduces these costs.
DMK Makina's Approach to Surface Quality
DMK Makina preserves post-bending surface quality on sensitive-surface materials through protective die coatings and protective film applications. With regular die maintenance and correct force settings, the company minimizes the risk of marks and scratches on parts intended for visible surfaces.
Serving manufacturers across the Thrace and Marmara regions, DMK Makina delivers reliable solutions for aesthetically sensitive press brake bending projects, evaluating each project's surface quality requirements together with its technical team.
