Share the design points and design principles of molds

Sat May 27 14:20:17 CST 2023

One. Review matters before design

1、Mold material

2、Molding products

3.Selection of molding machine

4.Basic structure of mold base

Two. Important items of mold design

1、Multi-color injection combination method

2. Sprue system

(1) Low injection pressure.

(2) Fast filling completion, can improve the output.

(3) Uniform injection, better product quality.

(4) Reduce scrap and shorten injection time.

3. Molding equipment:

(1) The injection volume of each injection cylinder determines which cylinder is used for that color.moulds manufacturer

(2) The position of the striking bar and the striking stroke.

(3) The configuration of water, oil, and electric circuits on the rotating disk.

(4) The load weight of the rotating disk.

4. Mold base design: mold kernel configuration design

First of all, considering that the male side of the mold must be rotated 180 degrees, the die insert must be crossed and symmetrically arranged, otherwise it is impossible to close the mold.

(1) Guide pillar: it has the function of guiding the male mold and the female mold. Concentricity must be maintained in the multi-color mold.

(2) Return pin: Since the mold has to rotate, it is necessary to fix the ejector plate and add spring to the return pin to keep the ejector plate stable.

(3) Positioning block: to ensure that the two die holders fixed in the big solid plate does not cause deflection due to the clearance of the screws.

(4) Adjustment block (wear block): mainly used for mold height z coordinate value error when closing the mold can be adjusted.

(5) ejector mechanism: the design of the ejector method is the same as the general mold.

(6) Cooling circuit design: the cooling circuit design of mold one and mold two is the same as possible.

Because different molding molds have been applied to many fields, plus the manufacturing technology of professional molds has also changed and developed over the years, so in this part, the general design rules of vacuum blister molding molds are summarized.

The design of vacuum suction molding mold includes the batch size, molding equipment, precision conditions, geometry design, dimensional stability and surface quality, etc. 1, the size of the batch for experimental use, mold production hours, can use wood or resin for manufacturing. However, if the experimental mold is used to obtain data about shrinkage, dimensional stability and cycle time of the product, etc., a single-cavity mold should be used for experiments, and it can be guaranteed that it can be used under production conditions. Molds are generally made of plaster, copper, aluminum or aluminum-steel alloy, rarely used aluminum - resin. 2, geometry design, design, often take into account the dimensional stability and surface quality. For example, the product design and dimensional stability requires the use of a negative mold (concave mold), but the surface requirements of high gloss products require the use of a positive mold (convex mold), so that the plastic parts orderer will take into account both points, so that the products can be produced under the best conditions. Experience has shown that designs that do not meet the actual processing conditions are often failures.3 , dimensional stability, during the molding process, the surface of the plastic part in contact with the mold is better than the part leaving the mold in terms of dimensional stability. If the material thickness is required to be changed later due to the need of material stiffness, it may lead to the conversion of the positive mold to the negative mold. The dimensional tolerance of the molded part should not be less than 10% of the shrinkage.4 , The surface of the molded part , as far as the molding material can be wrapped, the surface structure of the molded part that can be met should be molded at the contact with the mold. If possible, the glossy surface of the plastic part should not be in contact with the surface of the mold. Just like the case of using the negative mold to manufacture bath and laundry tubs.5. Trimming, if the clamping edge of the plastic part is sawed off using a mechanical horizontal saw, a margin of at least 6 to 8 mm should be left in the height direction. Other trimming work, such as grinding, laser cutting or jet, must also leave a margin. The gap between the cutter die cutting line is minimum, and the distribution width when punching die trimming is also small, these are to be noted.6 , shrinkage and deformation , plastic is easy to shrink (such as PE), some plastic parts are easy to deform, no matter how to prevent, plastic parts will be deformed in the cooling stage. Under such conditions, the shape of the molding mold should be changed to accommodate the geometric deviation of the plastic part. For example, although the wall of the plastic part is kept straight, its reference center has deviated by 10mm; the base of the mold can be raised to adjust the shrinkage of this deformation.7. Shrinkage, the following shrinkage factors must be taken into account when manufacturing the blister molding mold. ① shrinkage of molded products. If the shrinkage of the plastic cannot be clearly known, it must be obtained by taking samples or using similarly shaped molds through tests. Note: By this method, only the shrinkage rate can be obtained, not the deformation size. ② Shrinkage caused by the adverse effect of intermediate medium, such as ceramic, silicone rubber, etc. ③ Shrinkage of the material used in the mold, such as shrinkage when casting aluminum.