Stamping is a formative processing method that applies external force to sheets, strips, tubes, and profiles using a press and a mold, causing them to deform plastically or separate, thereby obtaining workpieces of the required shape and size.
During the processing of metal stamping parts, sometimes burrs of different sizes are found on the stamped parts, which have a certain impact on product quality.
So, what are the reasons for the formation of burrs in metal stamping parts? Here are some common causes of burr formation:
I. Blunt Cutting Edge
Burr formation can result from a blunt or damaged cutting edge. Factors affecting the blunting of the cutting edge include:
1. Poor material and surface treatment of the mold’s male and female parts, leading to low wear resistance.
2. Poor mold structure with low rigidity, causing damage.
3. Fast wear due to lack of timely lubrication during operation.
4. Failure to timely sharpen the cutting edge.
Burrs can form if the die clearance is too large, too small, or uneven. Factors affecting large, small, or uneven clearances include:
1. Errors in mold manufacturing, such as non-compliance of die parts with drawings, poor parallelism of base plates, etc.
2. Assembly errors in the mold, large gaps in the guiding parts, misalignment of male and female molds, etc.
3. Poor precision of the press, like large gaps in the press guideways, poor parallelism between the slider bottom surface and the worktable surface, poor verticality of the slider stroke to the press table surface, poor rigidity of the worktable, etc., which can cause changes in clearance during punching.
4. Installation errors, such as not cleaning the upper and lower base plate surfaces during installation or improper fastening methods for large molds, misalignment of the upper and lower molds (especially for mold without guide posts) causing the working part to tilt.
5. Unreasonable mold structure, inadequate rigidity of the mold and working parts, unbalanced punching force, etc.
6. Large curvature of the steel plate, uneven steel plate.
III. Subpar Performance of Stamping Oil
Non-specialized oils such as rapeseed oil, mechanical oil, and recycled oil fail to meet the extreme pressure anti-wear, anti-corrosion, and cooling performance requirements of stamping processing.
Consequently, this can lead to issues like burring of workpieces, machine rusting, and worker skin allergies.
The specialized Yida Borun stamping oil, formulated with sulfurized lard and sulfurized fatty acid esters as the main additives, are suitable for stamping, punching, and drawing processes of various materials like copper, aluminum, carbon steel, stainless steel, and titanium alloys on different types of equipment.
IV. Incorrect Stamping State
Problems like burrs can occur when the blank (including intermediate workpieces) does not have proper contact with the male or female die, or when the positioning relative height is incorrect during edge cutting and punching.
This is because the height of the workpiece is lower than the positioning relative height, and the shape mismatch with the edge during stamping results in burring.
V. Poor Workability of Workpieces
Complex shapes with protrusions or sharp indentations are prone to rapid wear, leading to burr formation.
VI. Material Not in Compliance with Process Specification
Severe thickness deviations in the material or incorrect materials (such as incorrect steel grades) can cause an unreasonable relative gap, leading to workpiece burring.
The above points outline the causes of burr formation in metal stamping parts. It is understood that burrs in metal stamping parts are typically produced during sheet metal stamping. By improving the workability of the workpiece and enhancing the stamping conditions, burr formation can be effectively prevented.