Common problems and processing methods in progressive die stamping -dgmf mold clamps co., ltd

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Common problems and processing methods in
progressive die stamping
Translated By Jasmine HL
In view of the common problems in the production of progressive molds, the causes are analyzed,
and the processing methods are proposed one by one, which can be used as a reference for
improving the design, manufacturing, and production of progressive molds.
1. Introduction
Stamping dies take high-precision, high-efficiency, long-life progressive die as an important
development direction. Progressive dies have the characteristics of the complex structure,
difficult manufacturing, and high cost. In the production of progressive die stamping, the causes
of common die failures and bad stamping phenomena must be analyzed in detail, and effective
treatment methods must be adopted to fundamentally solve the problems that occur, thereby
extending the life of the die and reducing the purpose of production costs.
Common problems and treatment methods in 2 progressive die stamping
2.1. Burrs on stamping parts
The burr of the stamping part refers to that the part of the stamping cut surface is higher than
the material and is generated along the direction of stamping or extrusion. The height of the burr
exceeds a certain limit, which will affect the quality and performance of the stamping part.
The cause:

(1). Cutting edge of the mold is worn and its fillet is formed at the cutting edge. When the punch
is worn, significant burrs will be generated on the upper end of the blanking part; when the
punch is worn, significant burrs will be generated on the lower end of the punching part; when
both the punch and the die are worn, burrs will be generated on both ends.
(2). Mating gap between the convex and concave dies is too large. The cracks in the material near
the cutting edge of the die are staggered inward during punching. The material is subject to a
large tensile force and the burr on the edge of the material is large.
(3). Edge collapses.
(4). Clearances of the convex and concave die are unreasonable, and the upper and lower sides
are offset or loose. When punching, the gap on one side is too large to produce burrs, and the
gap on the other side is too small.
(5). Mold is misaligned.
The Approach:
(1). When the cutting edges of the male and female die are worn, the working end faces of the
male and female die should be ground in time to keep the cutting edges sharp.
(2). Improve the machining accuracy of convex and concave dies, and design reasonable
clearances based on factors such as section quality, dimensional accuracy, die life and punching
pressure.
(3). Grind the cutting edge.
(4). Adjust the blanking clearance to confirm the wear of the template hole or the machining
accuracy of the formed part.
(5). Replace the guide or reassemble the mold.
2.2. Scrap up
Waste material jumping means that the waste material jumps out of the lower die edge and falls
to the lower die plate or other places. The jump of the scrap will cause the stamping parts to be
scrapped, and in severe cases, it will cause mold damage and threaten personal safety.
The cause:
(1). The outline shape of the stamping part is simpler than the complicated one, and the waste is
too light or in the surrounding open state, which will also cause the waste to jump up.
(2). There is no complete demagnetization treatment when grinding mold parts. When
processing magnetic materials, this micromagnetic force can absorb waste material to jump up.
(3). After lubricating, due to the reduced resistance of the waste material or stamping part in the
die, it is easy to cause the waste material to jump up. When the viscosity of the lubricant is too
high, due to the adhesive effect of the convex mold on the waste material, when the convex mold
rises rapidly, More likely to cause scrap to jump up.
(4). The punching gap is too small, resulting in the phenomenon of punching vacuum; the
punching gap is too large, the material is subject to tensile stress, and the size of the waste
material is smaller than the size of the die.
(5). Increased clearance caused by cutting edge wear or local wear varies, resulting in uneven
clearance.

(6). Depth of the male die entering the female die is too shallow.
The Approach:
(1). Design the structure of the card waste in the lower mold so that the waste is gradually
tightened when it is lowered; install a small ejector pin or compressed air in the punch.
(2).After repairing the punch, the punch and the corresponding template should be
demagnetized.
(3). Reduce the use of lubricating oil and choose a suitable viscosity lubricating oil.
(4). Design reasonable mold clearance.
(5). Sharpen convex and concave dies, and adjust die clearance.
(6). The Determine depth of the male dies entering the female die according to the thickness of
the strip, usually 0.5 ~ 1mm.
2.3. Leakage holes blocked by waste material
Because the leakage hole is not smooth, the waste is blocked in the leakage hole. The blockage of
scrap can cause the punch to break or the die edge to be damaged.
The cause:
(1). When the lubricating oil is too much and the viscosity is high, the waste material sticks into a
block shape, and it is not easy to fall in the leakage hole so that the waste material is blocked.
(2). Straight wall of the cutting edge of the die is too long or the slope design below the straight
wall of the cutting edge is not good.
(3). Excessively increasing the size of the blanking hole of the lower plate will cause the waste
material to flip inside the lower plate and prevent the waste material from falling into the lower
die seat.
The Approach:
(1). The most effective way to control the amount of lubricating oil, change the oil type, and solve
the blockage of waste is to adopt vacuum suction under the die.
(2). According to the thickness of the strip and the processing method, select the height of the
straight edge of the die and the slope of the blanking. Generally, the height of the straight edge
of the die is 3mm, and the slope of the leakage is 12.
(3). The size of the blanking hole of the lower plate is enlarged by about 1mm on one side
according to the size of the cutting edge of the die. The shape of the blanking hole of the lower
plate and the lower die seat should be as simple as possible. The oblique blowhole is processed
on the lower mold base, and the downward attraction force is generated when the air flows.
2.4. Large number of punches fractures
If punching breaks during punching, failure to find them in time will result in unqualified
stamping parts and even damage to the mold.
The cause:
(1). Scrap is stuck in the template, which causes the template to tilt and break the punch.
(2). Strength of the punch is insufficient.
(3). Diameters of several punches are greatly different, and they are very close to each other. The
small punches are prone to break or tilt due to the side pressure caused by the material flow.

(4). Inaccurate mold guiding.
The Approach:
(1). Solve problems such as chip jumping and scrap jamming.
(2). Modify the design, increase the overall strength of the punch, add a guide sheath outside the
punch, or use a discharge plate to directly guide.
(3). Use a step arrangement to make the length of the small punches shorter than that of the
large punches by about one material thickness.
(4). Replace the guide post and guide sleeve, pay attention to the daily maintenance of the mold.
2.5 Poorly sized stampings
Poor stamping size means that the size of the stamped part exceeds the size specified on the
drawing.
The cause:
(1). Defective mold design, processing or assembly, defective products appear in the first
production.
(2). Improper adjustment of mold clamping depth during assembly, mold work cannot be in place
during stamping, resulting in poor dimensions of stamping parts.
(3). Improper adjustment of feeding distance, pressing, and loose adjustment of the feeder will
cause the stamping parts to be off-positioned after stamping.
(4). When punching, the punching force stretches the material, which causes the dimensions of
the stamped parts to be poor.
The Approach:
(1). Modify the mold design to control the accuracy of mold processing and assembly.
(2). Select a punch suitable for the tonnage of the mold, check whether the mold height is within
the allowable range of the punch, and readjust the mold clamping depth.
(3). Readjust the feeder.
(4). Cut out the inclination or radian on the edge face of the punch to improve the force during
punching.
2.6. Poor flatness
When punching, there will be complex deformation. In addition to shearing, there are stretching,
bending, lateral extrusion, etc. The plane of the punched part and waste is uneven and often
warping.
The cause:
(1). Raw materials are not good, and the materials have not passed the leveler or the leveler has
not been adjusted properly.
(2). When punching, deformation occurs due to shearing or stretching, and the punching parts
are not shaped or the shaping effect is not good.
(3). Parallelism between the upper and lower dies is not high, resulting in that the stamping parts
cannot achieve the leveling effect.
(4). Uneven force of the upper die causes the arc of large structure stamping parts.
The Approach:

(1). Level the raw materials.
(2). Modify the mold structure and increase the shaping process.
(3). Improve mold manufacturing accuracy or reassemble molds.
(4). Setting elastic support blocks in the lower die can improve the surface flatness of the
stamping parts
2.7. Discharging of discharge plate is not smooth
The unloading board will not remove the strips that are sleeved on the punch after the punching
process, which will cause the punching work to continue.
The cause:
(1). Length of the mold equal sleeve is not equal, resulting in an unbalanced discharge plate.
(2). Distribution of the discharge spring is uneven, and the discharge force is insufficient in some
places.
The Approach:
(1). Install equal-length sleeves of equal length.
(2). Add a discharge spring at the position where the discharge is not smooth.
The Conclusion
The good and bad working conditions of the mold will have a great impact on the economic
benefits of the company. In the production practice process, the causes of the progressive die in
the stamping process are analyzed, the causes are generated, and the countermeasures are
proposed. Improving the quality of stamping parts has reference value.

Common problems and processing methods in progressive die stamping -dgmf mold clamps co., ltd

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