30 Experience Points of Stamping Die Design and Forming Process

1.Before designing the strip, make sure to understand the tolerance requirements of the part, material properties, punching tonnage, punching table, SPM (strokes per minute), feeding direction, feeding height, die thickness requirements, material utilization rate, and die life.

2.When designing the material belt, CAE analysis should be carried out simultaneously, mainly considering the thinning rate of the material, which should be below 25% in general. Especially deep-drawn stainless steel material can be annealed after pre-stretching; with a high-frequency annealing machine, the thinning rate can be accepted to 40%; in the design of the material belt must be more communication with the customer, it is best to ask the customer to provide the previous mold photos or structure drawings for reference, empty step is also very important, in the case of mold length allows, appropriate to leave empty step for the mold change after the mold test is very helpful.

3.The material belt design is the analysis of the product forming process, which decides whether the mold is successful or not.

4.In the continuous mold design, the design of the lifting material is very important; if the lifting bar can’t lift the whole material belt, it can’t carry out automatic continuous production.

5.In mold design, the selection of mold material and heat treatment and surface treatment (such as TD, TICN, TD time need 3-4 days), especially for tensile parts, if there is no TD, the surface of the mold will be easily pulled and burnt and hairy.

6. in the mold design, for the hole or tolerance requirements of the smaller surface, as far as possible to do adjustable inserts, easy to adjust in the test mold and production to easily reach the size of the part requirements, to do adjustable inserts when the upper and lower mold at the same time. For the word mark, the requirements in the punch can be removed; they do not need to be removed again under the mold and waste time.

 

7.the design of the hydrogen spring, according to the CAE analysis of the pressure to design, does not design too large a hydrogen spring to prevent product rupture. The usual situation is slight pressure, product wrinkling, immense pressure, and product rupture. To solve the wrinkling of the product, you can use the method of locally increasing the stretching bar, first fixing the bit sheet with the stretching bar and then stretching it to reduce wrinkling.

8.the first test mold, must slowly close the upper mold; for the stretching process, must use the fuse to test the thickness of the material and the material gap to reach the thickness of the material before trying the mold; the knife must be good first. Please use movable inserts to adjust the height of the stretching bar.

9.When testing the mold, the reference hole and reference surface must be matched with the mold and then put the product on the inspection tool for measurement or sent to CMM for a 3D report. Otherwise, it isn’t very sensible. 

10.Red Dan must be well matched, with a fit rate of 80% or more, before you can open the cutout and do the CMM report, or the benchmark hole benchmark surface has been matched, the product has been very stable and dense, the fit rate can be reduced. With red, Dan is a very important matter. Otherwise, the product is unstable, can not be later mould change judgment, and the size of the parts will not meet customer requirements. 

11.the customer sample office requirements: generally first laser office → shear mouth office → 100% OK office, in the laser office stage to match the red Dan, feed material adjustment, to solve the rupture wrinkle, size tolerance problems, in the opening of the shear mouth office change the main problem, followed by fine-tuning (mold local improvement). 

 

12.in the guest, must cut mouth office. Still, the process conditions are not mature; you can consider opening the soft material knife mouth (that is, directly opening the knife mouth with 45 steel, changing the cut mouth burned, and then opening the official hard material knife mouth after the size OK). 

13.For 3D complex products, 3D laser method can be used to laser, before 3D laser must do a good job of 3D graphics, use CNC to play a good reference point position before sending to 3D laser, 3D laser also has to do positioning sand type. 

14.For high-strength steel plates, the cutter should be made of carbide material such as A88 or V4.

15.in the test mold, to test the stretching effect, you can pad sandpaper on different positions on the material to test the effect after determining the effect in the corresponding position in the active stretching bar or active pockmark array (that is, a piece of plating grinding into pockmark), used to start the abrasion to hinder the material.

16. bending more parts and adjusting the mold step by step according to the process to adjust the bending. 

17.adjust the molding angle; you can close the small bending R angle or move the folding line benchmark to achieve the molding angle. 

18.most mold adjustment uses shims to adjust the height of the molding male or left and right to move the molding male; shims generally use stainless steel hard pieces. (If the customer is not allowed to use shims, wait until the mold is adjusted and then make a new workpiece for the customer) 

19. stainless steel material mold forming parts, can not use TD, to use (TICN) or called PVD.

20.To determine when the official material of the customer will arrive and when the mold is tested, use the material sparingly to avoid defective material. 

21.There are two kinds of sensors for continuous mold: the step sensor and the drop material sensor. 

22.The slope of the scrap hopper is at least 30 degrees, and for the low-angle scrap box (Scope box), the installation of pneumatic vibration (Pneumatic Vibration) can be used to solve. 

23.For the cutting edge line affected by the molding, we should choose to cut after the molding; the special position can be achieved using the cross-cut.

24.For more than one reference hole position, it is best to use a punching and forming method to avoid the impact of step-by-step punching and cutting accuracy. 

25 .For the analysis of the trial die, it is necessary to analyze the material strip after the trial dies step by step and to attach the red-dan material strip. 

26.For the product rupture, it can be taken to add package, squeeze material, increase the forming area of the piece of rod, open the hole, etc., in the preliminary stretching, and CAE analysis should be conducted before the mold change. 

27.The product material is divided into two kinds of coil material coil and sheet material sheet, some coil material needs to be slit again to the width of the strip after the factory, usually in the slit size for negative tolerance (negative 0.5mm), and the coil material inside diameter to meet the size of the feeding frame, to avoid too big or too small and too heavy.

28.mold processing, usually line cutting pin hole as a touch number of benchmarks, and CNC in the programming, the operator needs the coordinates of the two holes to the programmer, the programmer to find the angle, the program will be an angle after processing. Usually, in the first processing template, touch-edge processing does not require an angle.

29.The concept of fine blanking is to leave no blanking gap (or only 0.5%). The general blanking gap is 10% of the material thickness, the thicker the material, the larger the gap ratio. 

30.When the size of the hardware sample does not meet the requirements, it can be achieved by shaping, including plum pile, shooting flat again, simple punching and so on to repair the phi front.

The above is a summary of some experience in the actual stamping work; I hope it will be helpful to those who read this article to improve the on-time pass rate of the die and reduce the number of mould trials.