Design and manufacture of 2k mold for automotive lamps and precautions

 1. The flat ejector pins on the welding ribs need to be arranged more densely, preferably every 50mm. In addition, because the mold temperature is required to reach 90 degrees, the flat ejector pins are easy to pull, so the flat ejector pins need to be treated with titanium plating.

2. The depth of the welding rib is deep, and sometimes there will be air inclusions and poor lighting. It is made into an insert and adopts an embedded structure, which is not only conducive to exhaust but also conducive to the processing of the flat ejector hole. More importantly The most important thing is to facilitate the welding trimming of the orifice flash.

3. The two-color molds of lamps and lanterns are all rotated by moving molds, and the precision of the turntables of injection machines in Taiwan is not too high. The moving mold will drop with the product when the mold is opened, and the product is easy to pull off the given mold. Therefore, the fine positioning of the mold is very important, and a large area of fine positioning should be used in the design (the fine positioning area is small and easy to pull).

4. Lamps are generally made of PMMA and PC materials. Since the fluidity of these materials is relatively poor, if we use side gates in our design, we need to design larger and deeper side gates. Otherwise, it is difficult to get enough and there are many defects at the gate, such as flow marks and shrinkage.

5. Requirements for boarding:

A． The size of the center distance between the two ends of the injection molding machine and the size of the positioning ring. The positioning ring is 15MM higher than the upper plate, and there must be a unilateral 15-degree guide chamfer at the 5MM of the mouth, and the size of the positioning ring is 0.1-0.2MM smaller than the nominal size;

B． Dimensions of die screws and center distance of the upper plate;

C． The positioning ring should be on the rotation center axis, and after the half-pair die is assembled and the datum plane is aligned, according to the center pin hole of the die fixing plate, the positioning ring of the upper plate is processed on No. 31 five-axis CNC milling;

6. The fixed plate of the convex and concave molds should be designed:

A． There must be a center pin hole in the center of the formwork;

B． Template guide post holes need to be symmetrical to the center pin as the template rotates

7. Need to know about the bottom plate:

A． There are three positioning rings on the bottom plate of the injection molding machine. Confirm the size of the injection molding machine. The center positioning ring should not exceed 10MM above the bottom plate, because sometimes there is a water pipe in the center that is easy to interfere. The positioning rings on both sides are 15MM higher than the bottom plate, and there must be a unilateral 15-degree guide chamfer at the 5MM of the mouth, and the size of the positioning ring is 0.1-0.2MM smaller than the nominal size;

B． Bottom plate molding screw specifications and center distance specifications;

C． The bottom plate needs to confirm the specification and size of the ejection hole;

D． The positioning ring should be on the axis of the rotation center. After the half pair of punches are assembled and the datum plane is aligned, according to the center pin hole of the punch fixing plate, the positioning ring of the bottom plate is milled by No. 31 five-axis CNC milling.

Note: Points 5, 6, and 7 are very important, otherwise the mold trial cannot be done normally. Be sure to confirm it, otherwise it will be very troublesome to debug the mold during the mold trial (two-color machine is recommended to open two sets of molds, and there will be no special restrictions at the beginning of the mold trial.

8. The ejection distance should be reduced as much as possible, as long as the product is ejected, the effective length of the flat ejector rod can be shortened, and the strength of the flat ejector rod will be increased, so that the flat ejector rod will not be flattened or broken.

9. Forming of white chips:

A． The cavity of the white chip is 0.1MM deeper than the theoretical size, which is beneficial to the secondary injection molding of the white chip without filling it, which is not only beneficial to protect the strength of the thin-walled die from cracking, but also has a white chip in the final molding. Preloading amount, the white sheet is not easy to move and be broken during the injection molding process;

B． The side slope of the white sheet cavity should be 10 degrees on one side as much as possible to avoid the product leaving a concave mold, but at the same time, it is necessary to consider strengthening the thin-wall strength of the parting surface;

C． The outer surface of the white sheet is 0.5mm away from the surface of the punch to strengthen the strength of the thin-walled parting surface; at this time, it is necessary to carefully check the position of the reflective photoelectric casting, and the height should not interfere with it, because the electroforming is higher than the surface of the punch, which is very easy Neglected, otherwise the consequences will be very serious. Generally, the price of electroforming parts is 80,000-100,000.

D． Put 0.1M between the white side and the punch facing the insertion surface, and the M gap is not easy to be too large, and the graphics are well done;

Otherwise, the thin wall will break due to pressure injection. If the mold is too small, the outer parting surface of the white sheet will easily rub the molding surface of the red sheet after the mold heats up, which will increase the product's tightness and cause the product to crack;

E． The side and periphery of the white sheet prevent the corners of the retaining surface from being cleared. Increase the R angle by 1 0.5 as much as possible to improve the strength of the thin wall.