Hardware mold several common skip waste solutions

In the process of hardware mold design and manufacturing for many years, it was found that the floating phenomenon is a common bad phenomenon in the metal stamping mold, which can easily lead to serious defects or even scrap of the metal stamping parts. The causes of flotation are various, so the solutions are also diverse. Some floats are caused by poor hardware mold design, some floats are caused by mold processing errors that are not found in time, some are caused by poor incoming raw materials, and some are caused by careless operation of stamping workers. For this specific problem, when it is necessary to make an effective and quick solution, it is necessary to carefully study its types and reasons. The following is the company's experience in the design and manufacturing of hardware mold to share and exchange with friends:


First, the type of hardware mold float
Today, let's talk about the types of float, for float, I divided it into three types according to its size and formation factors
1, the rising phenomenon of stamping waste
Scrap refers to the part of the product that is removed in a single punching (forming) process. Its size is generally the same as the shape of the lower die edge. Its area and harm are the largest among the three phenomena. When this phenomenon occurs, it is possible to crack or even break the punch or knife edge, it is possible to break the guide pin of the product, and it is possible to crack the template and blow the mold.
2, the rising phenomenon of stamping waste
Scrap refers to the non-integral product or non-integral waste produced in a single process. Its size is relatively small, like the product's raw edge (burr) fall off to form; Blanking scrap filaments, etc. This is reflected in the appearance of scrapes, scratches, pits or dents in the product. This situation is mainly bad for the product, but this situation is the most common and relatively hidden in mold production.
3, the rising phenomenon of stamping waste powder
Waste powder refers to the fine powder produced by the friction between the punch and the product in a single process. This phenomenon in the early stage of production is generally difficult to find the naked eye, only when the accumulation of a degree, the punch and into the color change is easy to identify. When the waste powder reaches a certain degree, it is easy to cause the punch fracture or the crack of the die. It is most likely to occur in brass and aluminum substrates.

Second, the cause of hardware mold float
1. Rising float of stamping waste
The reason for the waste to rise first of all to analyze the source of the force, because the waste is generally the same shape as the punch or the lower die edge, therefore, the waste should have a certain amount of friction in the metal mold, from the principle of punching, the waste will recover the organizational structure due to the plastic or elastic deformation of the material after cutting. In other words, its actual shape should be larger than the shape of the lower die edge without constraint, which is why the waste can no longer be easily filled back into the lower die after the waste is removed from the inside. If you push the scrap upward there should be an upward force greater than the sum of the friction and tension. This force may come from two directions, one is the tension or elasticity of the waste material itself, because the waste in the process of punching bending (simply put) molding deformation, so when the punch is out of it, its internal tension will have a rebound force, perhaps downward or upward; The second is the force from the outside, which also has two aspects, when the punch and the lower die are cut away, the punch surface is closely attached to the raw material (and waste)


Together with the lower die to form a closed space to produce a vacuum state, when the punch rises, the destruction of this vacuum state, so the effect of the negative pressure in the air induces the waste and the punch to rise together, resulting in the phenomenon of waste rising; Secondly, in the general stamping process, there is a waste overlap inside the lower die, and when the latest piece of waste is added, the internal force (reaction force) of the other waste itself will also promote the new waste. Therefore, when the stamping speed is very low, and there is no waste accumulation phenomenon, the waste float phenomenon rarely occurs. This is one of the reasons.
2, the floating material of stamping waste
How is waste produced? It has several cases, one is the product or waste of the burr (or hair) off; First, the punch or other parts of the metal mold and the raw materials of the abnormal scratch or collision caused by small waste, mainly because the punch in the need to make excessive effects on raw materials when there is no corresponding structure; Third, because the raw material has been surface treated before stamping, and there is still a certain non-structural integration between the surface treatment layer and the material itself, the edge of the material will be separated and fall off; Another is due to the unreasonable mold design, there is a secondary punching (heavy cutting) or too small waste cutting, generally speaking, the width of punching should not be less than 1/3 of the thickness of the material, these too small cutting waste is easy to be separated from the main body of large waste or due to hardening collapse to form scrap.
3, the reason for the rise of stamping waste powder
Waste powder is caused by structural reasons of raw materials, and it has been said before that aluminum and brass based materials are prone to this situation. There is no way for raw materials, and the reason for this is that there is roughness on the surface of the punch or the insert, that is, there are pits on the surface at a certain degree of amplification. When the punch or punch touches the raw material, it will rub the raw material (like a file filing iron) to produce waste powder.

Third, hardware mold floating countermeasures
1. Countermeasure of stamping waste float
Through the above two phenomena and causes of formation, we can analyze the countermeasures of hardware mold. First of all, the method of each waste float is explained.
A. Float caused by improper discharge design
This kind of float mainly appears in the process of discharging material, most of which produce a relatively simple punching shape. Such as square, smaller edge shaped scrap.
At this time, the process gap should be deliberately made at the time of design, such as trapezoid and dovetail. Make the simple punching shape complex, increase the friction of the waste to prevent the waste rebound and vacuum suction.
B, punching hole itself is simple shape
Such as round hole, square hole, etc. In this case, starting from the formation of waste float, one is to change the rebound direction, and the other is to reduce the vacuum area. Common methods such as, 1, grinding the punch into a unilateral bevel or a bilateral bevel, so that one can deform the material, reduce the internal and external rebound of the material, and reduce the vacuum area. 2, can also be in the round hole punching in the center of the round punch grinding a small boss, its role is the same as the inclined surface, but this method is more effective for the round hole. 3, when the cutting edge is three or two sides, it is not necessary to cut the punch edge to make a certain step, so that when stamping, you can first do a little bending action to make the waste downward deformation conducive to the waste blanking. 4, the cutting surface of the punch is made into a corrugated or rough surface, which can be processed with a file or electric mill to increase the amount of air and reduce the amount of vacuum.
C, for all punching shapes that are likely to produce float
The above B method (most of which are processed by fitters) is sometimes not able to completely solve the problem, which should be solved by considering the design


1. Add top needle to punching punch
The ejector needle and spring are installed in the punch that is prone to float, and the ejector needle is used to push the waste into the lower die when parting the die. This method is suitable for the occasion where the punching shape is relatively large and the raw material is relatively thick.


2, the lower die into the child and punch to do sharp Angle pits
That is, the normal step distance of the punch should be equal to the shape surface of the punch, but the shape surface of the punch near the feeding end is deliberately made into a shaped pit such as a triangle, and the other cutting edge is designed according to the normal edge, so that in a step of punching, the need to cut the edge due to the pits will have more small triangle convex than (actually is beyond) the other cutting edge. In this way, the corresponding punch is rounded and does not form a punching effect, and the extra triangle edge will be pulled into the lower die and strongly resist the lower die and increase the friction force to prevent rebound or prevent the vacuum suction.


3, the lower die into the hole side for symmetric extrusion point
Usually in the design of the lower die will be matched with the equivalent gap of the punch, and in order to prevent floating, the lower die to make 1 or 2 pairs of symmetric points are less than the stamping gap about 1/2, so that when punching the waste due to small gap stamping and the waste stuck in the lower die into the child, this grammar can be and discharge plus a bump or line cutting method to complete.


4, the lower mold into the child to make no straight edge shape
This method is more suitable for thin materials. Generally, a straight edge of 3-5mm is left when the die is inserted (knife edge) in the design. This method is not a straight edge directly made 8-15' slope, so the higher the waste is the smaller the gap, and the lower the gap is larger it is not easy to run up the rebound.


5, the lower die into the remaining part of 3mm cut away from the straight edge with the discharge method to increase the blanking part of the waste without accumulation, lengthening the length of the punching punch. Each punch washes the waste away from the blanking area, making it impossible for the waste to float upward.


6, the punch is equipped with the same blow hole and blowing device as the thimble. Because the blowing device can be linked with the punch to control the blowing time, it can be applied to thinner materials, which is incomparable to the thimble anti-float material.


7, the lower die or the lower die plate plus blowing groove
This is similar to and different from the principle of punch blowing, the specific approach is to make an airway from the lower die plate, and then drill a diagonal hole down 45 through the blanking hole in the need to blow air, and the airway is blocked from the blanking hole (remember this point), and use the air to form a negative pressure space when blowing down the waste. This method is suitable for thin materials.


8, the use of external suction waste
The method is to add a lower die auxiliary plate under the die base and make a large blanking frame on the auxiliary plate with all possible and even all blanking holes in the punching parts, weld a material tube similar to a funnel, and then connect it to the material tube with the industrial suction device. All the waste material is sucked into the industrial suction through the suction of the suction; Whatever scrap scrap goes in, the insurance is reliable. The waste suction device can be purchased, the cost of a set is roughly four or five thousand yuan, and Changdong Mold has ordered in 2016.


9, extremely thin material 0.10 simple shape anti-float
Due to the small stamping gap of the extremely thin material, some of the above methods to prevent waste float are not very suitable, such as the thimble top, the lower die to do the bump, the industrial suction device.
For this material, the lower die is generally designed to be 8-12' without straight body, and then tested by the test die which lower die is easy to jump chips. Then remove the mold, use a long fine thimble plus diamond powder (diamond plaster) carefully into the lower mold to make several symmetrical rough points. This method works well, but it requires a very skilled fitter.


[Hardware mold waste debris float countermeasure]
The waste float is mainly caused by the unreasonable design or the material itself.
1. Unreasonable design
Try to avoid the phenomenon of recutting and overcutting during the layout of the punching process. Because the hardware mold is generally designed with CAD, the previous process is not taken care of when doing some processes.