Learn how to protect sensitive material surfaces during press brake bending. Discover techniques for preventing scratches, marks, and damage on stainless steel, aluminum, and coated materials.
Introduction
Surface damage during bending is common, particularly for stainless steel, aluminum, and pre-coated materials. At Fulei Metal, we serve clients with stringent surface finish requirements and have developed comprehensive protection strategies.
Why Surface Damage Occurs
Tool-material contact during bending transfers roughness and contamination. Material slides across die shoulders causing friction marks. Part handling causes scratches. Debris creates indentations.
Materials at Risk
Stainless steel (brushed or mirror), aluminum (soft and easily scratched), pre-painted and pre-coated materials, and pre-brushed materials with directional finishes.
Surface Protection Techniques
1. Protective Film
Most effective method. PE or PVC film applied before processing and left through bending. At Fulei Metal, we routinely apply protective film to sensitive materials.
2. Polished Tooling
Mirror-polished punches, polished die shoulders, chrome-plated tools reduce friction and marking.
3. Tool Inserts and Coatings
Nylon inserts prevent metal-to-metal contact. Urethane pads cushion material. Teflon tape provides low-friction barrier.
4. Die Lubrication
Dry film lubricants, stamping oils, or WD-40 reduce friction. Must be compatible with material and removed before coating.
5. Clean Tooling and Material
Clean tools before each job. Clean material surface. Keep work area clean. Use clean gloves.
6. Careful Handling
Protective separators between parts. Avoid direct stacking. Clean cotton gloves. Vacuum lifters. Clean, soft work surfaces.
7. Parameter Optimization
Wider die openings, air bending, reduced speed, proper alignment.
Material-Specific Protection
Stainless steel: always apply film, polished tools, dedicated tooling. Aluminum: apply film, nylon inserts, reduced force. Pre-painted: additional film, nylon inserts, air bending only. Pre-brushed: film in brushing direction, polished tools.
Conclusion
Surface protection adds cost but prevents expensive damage. At Fulei Metal, our protection strategies ensure parts meet stringent surface quality requirements for international clients.