Summary of stamping die skills -dgmf mold clamps co., ltd

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Summary of stamping die skills
Written By Jasmine HL
1. What are the main points of continuous mold maintenance?
The maintenance of the continuous mold must be done carefully and patiently, step by step, and
must not be carried out blindly. Due to the failure of the mold repair, a material belt must be
attached to facilitate the inquiry of the problem. Open the mold, check the condition of the mold,
check the condition of the mold, identify the cause of the failure, find out the problem, and then
clean the mold before removing the mold. When removing the mold, the force should be uniform.
For the mold structure of the stripper spring between the fixed plate and the stripper plate and
the stripper spring directly on the inner guide bushing, the stripper plate should be removed to
ensure that the stripper plate pops out in balance. The inclination of the stripper plate may cause
a breakage of the punch in the mold.
(1) Maintenance of convex and concave dies
When disassembling the male and female mold, pay attention to the original condition of the
mold, so that it can be easily restored during subsequent mold loading. If padding or
displacement is required, the thickness of the gasket must be engraved on the part and a record
must be made. Whether the block die is smooth, and whether the gap between the insert and
the die is uniform, and the replacement of the die must also be tested to see if the gap between
the punch and the punch is uniform. For the shortening of the punch after repairing the punch, a

pad is required to reach the required length. Should check the effective length of the punch is
sufficient. Replace the broken punch to find out the reason, and at the same time, check whether
the corresponding punch has a chipped edge and whether it needs to grind the cutting edge. To
assemble the punch, check the punch and the fixed block or fix it. If there is enough clearance
between the plates, check if there is any margin for movement if there is a pressure block. The
assembly die should be placed horizontally, and then placed with a flat iron block, such as a
copper rod, and tapped into place with a copper rod. Tap diagonally and forcefully, and the
bottom of the die should be chamfered. After installation, check whether the die surface is flat
with the die surface. After the punch die and the core are assembled, make necessary checks
against the tape, and check whether the parts are installed incorrectly. Or reversely installed,
check whether the die and die block is reversed, whether the blanking hole is blocked, and
replace it with a new one. Whether the material needs to be stolen, whether the material needs
to be stolen, and whether the mold needs to be locked. Please pay attention to the locking of the
screw of the stripper plate. When locking, it should be locked from the inside to the outside with
a balanced force. Tighten one screw and then tighten the other screw, so as not to cause the
stripper plate to tilt and cause the punch to break or the precision of the mold to decrease.
(2) Maintenance of stripper plate
The removal of the stripper plate can be carried out by first using two screwdrivers to balance the
lever, and then using both hands to balance the force to take it out. When disassembly is difficult,
check whether the mold is cleaned up, whether all the locking screws are disassembled, and
whether the material should be caught. Mold damage, find out the cause and then deal with it
accordingly, do not handle it blindly. When assembling the stripper, clean the punch and stripper
first, add lubricant to the guide bushing and the punch, and put it in smoothly. Then press it in
place with both hands and repeat it several times. If it is too tight, find out the reason (whether
the guide post and guide sleeve are normal, whether there is any damage to the part, whether
the new punch can pass the position of the stripper plate correctly). If the reasons are clear, we
will deal with them accordingly. If there are pressure blocks on the fixed plate, check whether the
stealing on the backing plate is sufficient. The material contact surface between the stripping
plate and the die will cause indentation after a long time stamping (the stripping plate and the
die). The gap between the material and the material is generally reduced by 0.03-0.05mm.When
the indentation is serious, it will affect the pressing accuracy of the material, causing the
abnormal size of the product, etc., it is necessary to repair or regrind the stripping inserts and
stripping plates. The contoured sleeve should be checked for accuracy.When the height is not
equal, the stripper plate will tilt. Its precision-guided and stable spring-pressing function will be
damaged and must be maintained.
(3) Inspection of guide parts
Check the gap between the guide bushing and guide sleeve, whether there are burns or abrasion
marks, and whether the mold guide is in the normal state of oil supply, and it should be checked.
The wear of the guide and the destruction of the accuracy will reduce the accuracy of the mold,
and various parts of the mold will appear. Problems must be properly maintained and replaced

regularly. Check the accuracy of the material guide. If the guide pins are worn, they have lost the
expected accuracy and function of the belt guide and must be replaced. Check the condition of
the spring (discharge spring and Top material spring, etc.) See if it is broken or not broken for a
long time, but it has lost its original strength due to fatigue. It must be replaced regularly,
otherwise, it will cause damage to the mold or production will not be smooth.
(4) Adjustment of die clearance
The core positioning holes are worn due to the frequent and frequent combination of the cores,
resulting in large gaps after assembly (looseness after assembly) or uneven gaps (causing
positioning deviations) will cause the shape of the cross-section to become worse after punching,
and the convexity The die is easy to break, and burrs are generated. You can adjust the gap by
checking the cross-section condition after punching. When the gap is small, the cross-section is
small. When the gap is large, the cross-section is large and the burr is large. Reasonable clearance,
after adjustment, appropriate records should be made, and marks can also be marked on the side
of the die for subsequent maintenance operations. Daily production should pay attention to
collecting the tape when the original mold is in a better condition if the subsequent production is
not smooth When the mold is changed, it can be used as a reference for mold maintenance. In
addition, auxiliary systems such as whether the ejector pin is worn, whether the ejector can be
ejected, whether the guide pins and bushes are worn, should be checked and maintained.
2. What are the main reasons for mold burst?
Due to different stamping procedures and different working conditions, the causes of die burst
are various. The following is a comprehensive analysis of the causes of die burst in terms of
design, manufacture, and use of the die and find out the corresponding improvement measures.
(1) The mold material is not easy to be broken in the subsequent processing
The mold life of different materials is often different. For this reason, two basic requirements for
the material of the working parts of the die are proposed: ① The use performance of the
material should have high hardness (58 ~ 64HRC) and high strength and have high wear
resistance and sufficient toughness, heat treatment deformation is small, there is a certain Hot
hardness; ② good process performance. The manufacturing process of dying working parts is
generally more complicated. Therefore, it must have the adaptability to various processing
technologies, such as foreseeability, machinability, hardenability, hardenability, quench crack
sensitivity, and grinding processability. Generally, according to the material characteristics,
production batches, precision requirements of stamping parts, mold materials with good
performance are selected, while taking into account their processability and economy.
(2) Heat treatment: deformation caused by improper quenching and tempering process
The practice has proved that the thermal processing quality of the mold has a great impact on
the performance and service life of the mold. From the analysis of the reasons for the failure of
the mold, it can be known that the "accidents" of mold failure caused by improper heat
treatment account for more than 40%. The quenching deformation and cracking of the working
parts of the mold, and the early fracture of the use process are all related to the hot working
process of the mold.

1) Forging process:
This is an important link in the manufacturing process of mold working parts. For the molds of
high alloy tool steels, technical requirements are usually imposed on the metallographic structure
such as the carbide distribution of the material. In addition, the forging temperature range
should be strictly controlled, the correct heating specifications should be formulated, the correct
forging force method should be used, and slow cooling or timely annealing after forging should
be used.
2) Preliminary heat treatment:
Depending on the material and requirements of the working parts of the mold, preliminary heat
treatment processes such as annealing, normalizing or quenching and tempering are used to
improve the structure, eliminate the structural defects of the forging blank, and improve the
processing technology. High-carbon alloy mold steel can eliminate networked secondary
cementite or chain carbide through proper preliminary heat treatment, spheroid and refine the
carbide, and promote the uniformity of carbide distribution. This will help to ensure the quality
of quenching and tempering and improve the life of the mold.
3) Quenching and tempering:
This is the key link in mold heat treatment. If overheating occurs during quenching and heating,
not only will the workpiece cause greater brittleness, but it will easily cause deformation and
cracking during cooling, which will seriously affect the life of the mold. Special attention should
be paid to preventing oxidation and decarburization when the die is quenched and heated, and
the heat treatment process specifications should be strictly controlled. If conditions permit,
vacuum heat treatment can be used. After quenching, it should be tempered in time, and
different tempering processes should be adopted according to technical requirements.
4) Stress relief annealing:
Die roughing parts should be subjected to stress relief annealing after rough machining, with the
purpose of eliminating the internal stress caused by rough machining, so as to avoid excessive
deformation and cracking during quenching. For molds with high accuracy requirements, after
grinding or electrical processing, it is also necessary to undergo stress relief tempering treatment,
which is beneficial to stabilize the molding accuracy and improve the service life.
(3) The insufficient flatness of the mold grinding, resulting in deflection
The quality of the surface of the mold working parts is closely related to the wear resistance,
fracture resistance and adhesion resistance of the mold, which directly affects the service life of
the mold. In particular, the surface roughness value has a great impact on the life of the mold. If
the surface roughness value is too large, stress concentration will occur during work, and cracks
will easily occur between its peaks and valleys, which will affect the durability of the die and
affect the durability of the die. The corrosion resistance of the workpiece surface directly affects
the service life and accuracy of the die
To this end, the following should be noted:
1) During the processing of mold working parts, it is necessary to prevent the surface
phenomenon of grinding burned parts, and the grinding process conditions and methods (such as

parameters of grinding wheel hardness, particle size, coolant, feed rate, etc.) should be strictly
controlled;
2) During the processing, knife marks should be presented on the surface of the mold working
parts. Macro defects such as interlayers, cracks, and impact scars. The existence of these defects
will cause stress concentration, become the source of fracture, and cause early failure of the
mold;
3) The use of grinding, grinding and polishing and other fine processing and fine processing to
obtain a smaller surface roughness value and improve the service life of the mold.
(4) Design process: the mold strength is not enough, the blade edge distance is too close, the
mold structure is unreasonable, the number of template blocks is not enough, there are no pads
and feet, the mold guide is not accurate, and the gap is unreasonable.
1) Layout and edging.
Unreasonable reciprocating feeding and layout methods and too small overlap values will often
cause sharp wear of the mold or convex and concave mold damage. Therefore, while considering
the improvement of the material utilization rate, it is necessary to reasonably select the layout
method and the overlap value according to the processing batch, quality requirements of the
parts and the mold clearance, so as to improve the life of the mold.
2) The precision of the guide mechanism of the mold.
Accurate and reliable guidance has a great effect on reducing the wear of the working parts of
the mold and avoiding the damage of the convex and concave molds, especially the blanking and
small clearance punching dies, composite dies and multi-stage progressive dies are more
effective. In order to improve the life of the mold, it is necessary to correctly select the guidance
form and determine the accuracy of the guidance mechanism according to the requirements of
the process nature and part accuracy. In general, the accuracy of the guiding mechanism should
be higher than the mating degree of the convex and concave molds.
3) The geometric parameters of the cutting edge of the mold (convex, concave).
The shape, fit clearance and fillet radius of the convex and concave die not only to have a great
influence on the forming of the stamping parts but also have a great influence on the wear and
life of the dies. For example, the fit clearance of the mold directly affects the quality of the
blanking part and the life of the mold. For higher accuracy requirements, a smaller gap value
should be selected; otherwise, the gap can be appropriately increased to improve the mold life.
(5) Wire cutting process:
The man-made wire cutting and wire cutting gaps are not handled properly, and no clear angle
and the metamorphic layer of wire cutting is affected.
Die-cutting edges are mostly processed by wire cutting. Due to the thermal effect and electrolysis
of wire cutting processing, a certain thickness of the metamorphic layer is produced on the
surface of the die, which causes the surface hardness to decrease and microcracks, etc., which
causes early wear of the wire cutting die, which directly affects the die clearance gap. Keeping
and cutting edge is easy to chip and shorten the service life of the mold. Therefore, a reasonable
electrical standard should be selected in the online cutting process to minimize the depth of the

metamorphic layer.
(6) Selection of punching equipment: punch tonnage, insufficient punching force, too deep die
adjustment.
The impact of the precision and rigidity of stamping equipment (such as a press) on the die life is
extremely important. The stamping equipment has high precision, good rigidity, and greatly
improved die life. For example, the complex silicon steel sheet dies material is Crl2MoV, which is
used on ordinary open presses, and the average regrind life is 1-3 million times, while the new
precision presses, the die to regrind life is 60,000 to 120,000 times. In particular, small-gap or
gap-free dies, hard alloy dies and precision dies must be selected with high precision and good
rigidity. Otherwise, the die life will be reduced, and in serious cases, chess equipment will be
damaged.
(7) Stamping process:
Excessive thickness tolerances of raw materials for stamped parts, fluctuations in material
properties, poor surface quality (such as rust), or uncleanness (such as oil stains), etc., will cause
increased wear and tear on the working parts of the mold, and easy to break edges.
1) Use raw materials with good stamping technology as much as possible to reduce stamping
deformation force;
2) Before stamping, strictly check the brand, thickness and surface quality of the raw materials,
wipe the raw materials clean, and remove surface oxides and rust when necessary;
3) According to the stamping process and the type of raw materials, if necessary, softening and
surface treatment can be arranged, and the appropriate lubricant and lubrication process can be
selected.
(8) Correct use and reasonable maintenance of production operations.
1) Unsmooth material discharge: no demagnetization treatment and no material discharge tip
before production; there are stuck materials such as broken needles and springs in production.
2) Falling material is not smooth: There is no leakage of shit during assembly of the mold or
blocking of shit, and blocking of shit with feet.
3) Production awareness: Laminated stamping, positioning is not in place, no blow gun is used,
and the template continues to produce with cracks.
In order to protect normal production, improve the quality of stamping parts, reduce costs, and
extend the life of the die, the mold must be properly used and reasonably maintained, and the
"three inspections" system of the die must be strictly implemented (inspection before use,
inspection during use and inspection after use), and do Good die and maintenance work. Its main
work includes the correct installation and debugging of the mold; strict control of the depth of
the punch into the cavity; control of the bottom dead center of the upper mold in the process of
bending, cold extrusion, and shaping; grinding the cutting edge in time; attention to keeping the
mold clean and reasonable Lubrication, etc.
In short, in the entire process of mold design, manufacturing, use and maintenance, the
application of advanced manufacturing technology and the implementation of comprehensive
quality management is an effective guarantee to improve the life of the mold and is committed to

the development of professional production, strengthen the standardization of molds, in addition
to standardization of parts There are also standardization of design parameters, standardization
of combination forms, standardization of processing methods, etc., and constantly improve the
level of mold design and manufacturing, which is conducive to improving mold life.
3. What are the causes of burrs in die-stamping parts and what countermeasures should be
taken?
The causes of burrs in die-stamping parts and improvement measures are:
1) The knife-edge is worn or chipped, and the quenching hardness is low.
2) After the gap is too large, the effect is not obvious after studying the knife edge. It is necessary
to further control the machining accuracy of the convex and concave dies or modify the design
gap;
3) The gap is unreasonably shifted up or down, and the blanking gap needs to be further adjusted
to confirm the problems such as template hole wear or molding precision;
4) The mold is misaligned up and down, you need to replace the guide or reassemble the mold
4. What are the reasons for chipping and crushing caused by die-stamping parts, and what
countermeasures should be taken?
The reasons and corresponding countermeasures for chipping and crushing caused by
die-stamping parts are:
1) When the gap is too large, control the machining precision of the male and female die or
modify the design gap;
2) If it is improper feeding, trim the material belt and clean the mold in time;
3) The stamping oil drops are too fast and oily, control the amount of oil in the stamping oil drops
or change the oil type to reduce the viscosity;
4) The mold is not demagnetized, it must be demagnetized after training (more attention should
be paid to the iron material);
5) The punch is worn, and the scraps are pressed on the punch.
6) The punch is too short, and the length of the inserted die is insufficient. You need to adjust the
length of the punch into the die;
7) The material is hard and the punching shape is simple. It can be installed on the end face of
the punch blade to punch out or trim the bevel or arc, so as to reduce the bonding area between
the end face of the punch blade and the scrap.
Its emergency measures are:
Reduce the sharpness of the die edge, reduce the amount of training on the die edge, increase
the surface roughness (cover) of the straight edge of the die, use a vacuum cleaner to suck waste,
reduce the punching speed, and slow chipping.
5. What are the reasons for the blockage of the die-stamping parts and what countermeasures
should be taken?
The causes and corresponding countermeasures of chip blocking in stamping parts are:
1) The leakage hole is too small, which can increase the gap of the leakage hole;
2) The leak hole is too large, the scrap material is rolled, and the leak hole is modified again;

3) The cutting edge is worn and the burr is large.
4) The stamping oil drops are too fast and the oil is sticky, you can control the number of oil drops
and change the oil type;
5) The surface of the straight edge of the die is rough, and the powder is sintered and adhered to
the edge. The surface roughness can be reduced or the material can be changed by surface
treatment and polishing;
6) The material is soft, modify the blanking gap;
Its emergency measures are:
The edge of the punch is trimmed with a slope or arc (note the direction). Use a vacuum cleaner
to blow air at the blanking hole of the pad.
6. What are the reasons for the variation in the size of the blanking deviation during the die
stamping?
What countermeasures should be taken?
The main reasons and corresponding countermeasures for the deviation in the size of the feeding
offset are:
1) The knife-edge of the convex and concave die is worn, and burrs are generated (the shape is
too large and the inner hole is too small). The knife-edge needs to be studied;
2) Improper design clearance, modify design and control machining accuracy;
3) The blanking position of the convex mold and the concave mold inserts is uneven, and the gap
is uneven, and the position accuracy and blanking gap can be adjusted;
4) The guide pin is worn and the pin diameter is insufficient. You can replace the guide pin.
5) The guide is worn, and the guide bushing and guide sleeve can be replaced;
6) The feeding distance of the feeding machine is loosened and improperly adjusted, readjust the
feeding machine;
7) Improper adjustment of mold closing height, readjusting mold closing height;
8) The blanking position of the blanking insert is worn, and there is no blanking (strong pressing)
function or small punching caused by material pulling and turning.) You can grind or replace the
blanking insert, increase the strong pressing function and adjust the blanking
9) The pressure of the insert is too deep, and the punching is too large.
10) The mechanical properties of the stamping material are changed (the strength elongation is
unstable). The material needs to be replaced to control the quality of the feed.
11) The punching force causes the dimensional variation of the material traction. You can trim
the slope or arc on the end face of the punch blade to improve the force during punching or add
a guide function to the blanking part on the unloading insert.
7. What is the cause of the material jam during the die stamping, and what countermeasures
should be taken?
The main reasons and corresponding countermeasures for jamming during stamping are:
1) Improper adjustment of the feeding distance of the feeder to the press, which needs to be
readjusted;
2) The feed distance varies during production, and the feed distance of the feeder needs to be

adjusted;
3) The feeder is faulty and needs to be adjusted and repaired;
4) The material is curved and the width is too poor. When the burr is large, the material should
be replaced to control the quality of the feed;
5) The stamping of the mold is abnormal, causing a sickle bend, eliminating the sickle bend of the
material strip;
6) The hole diameter of the guide is insufficient, the upper die pulls the material, and the guide
hole is trained;
7) The upper and lower materials are not smooth in the bending or tearing position, and the
strength of the material spring is adjusted;
8) Improper setting of the material removal function of the material guide plate, modify the
material guide plate to prevent the material belt from being worn;
9) The material is thin, and the warpage occurs during feeding. It is necessary to add up and
down pressing between the feeder and the mold, and add up and down extrusion safety
switches;
10) Improper erection of the mold, which has a large deviation from the verticality of the feeder.
8. What is the reason for the sickle bending of the material belt when the die is stamped, and
what measures should be taken?
The main reasons and corresponding countermeasures for sickle bending of the material belt
during die stamping are:
1) Caused by punching burrs (especially on the carrier), the cutting edge needs to be studied;
2) Material burrs and molds need to be replaced when there is no cutting edge, and the mold is
equipped with a cutting edge device;
3) Improper punch depth (too deep or too shallow), readjust the punch depth;
4) The punch is crushed, and there is debris in the mold. The mold needs to be cleaned to solve
the problem of chip jumping and crush;
5) The partial pressing is too deep or the part is damaged, check and adjust the height and size of
each blank and die insert, and repair the damaged part;
6) The mold design structure is unreasonable and can be adjusted by the bending mechanism.
9. What is the cause of the breakage and chipping of the punch when the die is stamped, and
what countermeasures should be taken?
The main reasons for the breakage and chipping of the punch when the die is stamped and the
corresponding countermeasures are:
1) Jumping chips blocking the mold;
2) Improper feeding, cut in half, pay attention to feeding, trim the belt in time, and clean the
mold in time;
3) Insufficient strength of the punch, modify the design, increase the overall strength of the
punch, reduce the size of the straight edge of the punch, pay attention to the slope or arc of the
end face of the punch, and cut back the small part;
4) The small and large punches are too close to each other, and the material is pulled during

punching, which causes the break of the small punch. The length of the small punch can be
shortened by more than one material thickness of the large punch.
5) The convex mold and the concave mold are too sharp, and the design is modified;
6) The punching gap is too small. Control the machining accuracy of the convex and concave dies
or modify the design gap. The punching gap of the small part should be appropriately increased.
7) There is no stamping oil or the used stamping oil is highly volatile, you can adjust the amount
of stamping oil drip oil or change the oil type;
8) The blanking gap is unevenly shifted, the convex and concave dies interfere, check the
accuracy of each formed part, and adjust or replace it to control the processing accuracy;
9) The stripping insert has poor accuracy or wear, and loses the precision guide function, which
requires training or replacement;
10) The mold guide is not worn properly. You need to replace the guide post and guide bushing,
pay attention to daily maintenance;
11) The material of the male and female molds is improperly selected and the hardness is
improper. You need to change the material and use a suitable hardness;
12) The material guide (pin) is worn and needs to be replaced;
13) Improper installation of gaskets, which needs to be corrected. The number of gaskets should
be as small as possible and steel gaskets should be used.
10. What are the reasons for product deformation or dimensional variation during continuous die
bending, and what countermeasures should be taken?
The reasons and corresponding countermeasures for product deformation or dimensional
variation during continuous die bending are:
1) The guide pin is worn and the pin diameter is insufficient. Replace the guide pin.
2) The accuracy of the bending guide part is poor, and it must be reground or replaced.
3) Bending male and female die wear (pressure loss), regrind or replace;
4) Insufficient mold yield, check and correct;
5) The material slips, the bending convex die has no guide position function, and no preload is
applied during bending. You can modify the design and add guide and preload functions;
6) The mold structure and design size are not good. You can adopt measures such as modifying
the design size, disassembling the bending, and increasing the bending and shaping;
7) The burr of the punching part, when the cutting edge of the blank is required to be repaired
when the bending is not good;
8) There are many shims in the convex and concave dies of the bending part, which results in
dimensional instability. The overall steel shims need to be adjusted;
9) The material thickness or mechanical properties need to be changed to control the quality of
the material when the material changes;
11. What is the reason for the uneven surface of the product when there are multiple molds in a
continuous mold? What countermeasures should be taken?
The main causes of the uneven surface of the product and the corresponding countermeasures
are:

1) Punching the burrs, and cutting the cutting edge of the material;
2) The punching parts are crushed, and there is debris in the mold. Clean the mold to solve the
problem of debris floating.
3) The male or female die (bending position) is damaged or damaged, retraining or replacing with
new parts;
4) Turn material during punching and shearing, study punching blade, adjust or add strong
pressure function;
5) Wear and pressure loss of relevant pressure parts, inspection, maintenance or replacement;
6) The tearing dimensions of the relevant tearing positions are inconsistent, and the blade is
worn, repaired or replaced to ensure that the tearing conditions are consistent;
7) The pre-cut depth of the related easy-break position is inconsistent, the convex and concave
dies are worn or chipped, check the condition of the pre-cut convex and concave dies, and
perform maintenance or replacement;
8) The convex and concave molds of the relevant convex parts have chipped edges or are more
severely worn. Check the condition of the convex and concave molds and perform maintenance
or replacement;
9) Defects in mold design, modify the design, add height adjustment or add shaping stations.
12. What are the reasons for improper maintenance during die stamping, and what
countermeasures should be taken?
The main causes and countermeasures of improper mold maintenance are:
1) The mold does not have a fool-proof function. The negligence during the assembly of the mold
caused the misalignment in the opposite direction (referring to different stations). Modify the
mold to add a fool-proof function;
2) The inserts that have shifted the gap are not restored as they are, using the mark on the mold,
etc., and making necessary checks and confirmations on the material tape after the mold is
assembled, and making written records for the query.
In stamping production, the daily maintenance of the mold is very important, that is, daily check
whether the stamping machine and the mold are in a normal state, such as refueling of the
supply guide of the stamping oil. Inspection before the mold is placed on the machine, inspection
of the blade, Confirmation of part locking, etc., can avoid many sudden accidents. When you
repair the mold, you must think about it first, and carefully make records to accumulate
experience.
13. What are the main reasons for the repair of the blanking die?
There are many reasons for mold repair in production, mainly in the following aspects:
(1) The natural wear of the die parts, including the wear of the positioning and guide parts, the
loose shank of the die, the looseness of the punch on the fixed plate, the gap between the punch
and die becomes larger, and the cutting edge becomes blunt.
(2) Improper manufacturing process, mainly due to poor die material, insufficient quenching
hardness, an inverted cone of convex and concave dies, insufficient precision and rigidity of guide
parts, and eccentricity of the central axis of the convex and concave die after installation.

(3) Improper stamping operation: the bottom surface of the die is not parallel to the work
surface of the press, the work center of the press does not coincide with the work center of the
die, the punch enters the die edge too deeply, and the failure and the carelessness of the press
during the press operation are not in accordance with the rules The operation caused damage to
the mold.
14. What are the maintenance principles and steps of the punching die?
The basic principles of mold maintenance are:
1) The exchanged parts must meet the technical requirements of the drawings.
2) The fitting accuracy, dimensional accuracy, and intactness of each part of the mold must be
checked once.
3) After overhaul, try the mold, adjust and accept
4) The maintenance time of the mold should be adapted to the requirements of production.
The steps for mold maintenance are as follows:
1) The mold must be wiped clean before the inspection to remove oil and debris.
2) Check the reference positioning dimensions and clearance fit of each part of the mold, record
defects at any time and prepare a repair plan.
3) Determine the parts to be dismantled, and take out the repair card according to the scheme.
4) Reassemble, adjust and test the mold, if it fails to restore the original quality and accuracy, it
needs to be repaired.
15. What are the main contents of the temporary repair of the die?
Temporary repair of the die refers to the need to adjust the die on the machine without folding
the die or only the parts to be repaired. It mainly includes the following aspects:
(1) Replacement with spare parts
(2) Sharpen the blunt male and female die edges with a whetstone
(3) Replace the spring rubber and tighten the loose screws
(4) Tightened or welded loose die
(5) Adjusting die clearance and positioning device
(6) Replace with a new jacking device. 16 What are the common repairing methods for the
punching die?
The repair process of common characters for punching dies is as follows:
(1) Grinding dull convex and concave dies, one method is to grind with oil stone plus kerosene or
pneumatic wheel. The other method is to grind with a surface grinder.
(2) Repair the convex and concave molds with large gaps, first check the convex and concave
mold gaps with an appropriate size block gauge. If the clearance is not large, just sharpen the
cutting edge plane and then use oilstone to trim. If the clearance is too large, use oxygen first.
-The acetylene gas welding is heated and red, and the part is forged. The punching die should
strike the periphery of the die to ensure the size of the punch. After that, you can stop tapping,
but continue to heat for a few minutes to eliminate internal stress. After cooling, use the
embossing file repair method to readjust the gap, and quench with the flame surface.
(3) Convex and concave dies with uneven gaps,

In addition to natural wear, there are two cases:
1) The cylindrical pin is loose and loses the positioning ability, which causes the convex and
concave dies to be concentric and cause uneven gaps. The edge alignment of the convex and
concave dies should be restored to uniformity, and then tightened with screws, and the original
pinhole should be hinged 0.1 ~ 0.2mm larger. Non-standard cylindrical pins.
2) The guide device is worn, the accuracy is reduced, and the guide cannot be used so that the
convex and concave molds have relatively deviated. The surface of the guide post needs to be
chrome-plated, and then the grinding method and guide sleeve is used to match the original
clearance and accuracy level.
(4) Replace the small punching and blanking punches.

Summary of stamping die skills -dgmf mold clamps co., ltd

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Summary of stamping die skills -dgmf mold clamps co., ltd