The hottest mold manufacturing process

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Mold manufacturing process (Part 1)

the assignment of molded plastic parts is usually proposed by the part designer, and its contents are as follows:

1 The reviewed and signed formal part drawing shall indicate the brand and transparency of the plastic used

2. Instructions or technical requirements for plastic parts

3. Production output

4. Samples of plastic parts

usually, the mold design assignment is proposed by the plastic part craftsman according to the assignment of molded plastic parts, and the mold designer designs the mold based on the assignment of molded plastic parts and mold design assignment

II. Collect, analyze and digest the original data

collect and sort out the relevant part design, molding process, molding equipment, machining and special processing data for use in mold design

1. Digest the drawings of plastic parts, understand the use of parts, and analyze the technical requirements of plastic parts, such as processibility, dimensional accuracy, etc. For example, what are the requirements of plastic parts in terms of appearance shape, color transparency and service performance, whether the geometric structure, slope, insert and other conditions of plastic parts are reasonable, the allowable degree of forming defects such as weld lines and shrinkage holes, and whether there is post processing such as coating, electroplating, bonding, drilling, etc. Select the dimension with the highest dimensional accuracy of plastic parts for analysis to see whether the estimated forming tolerance is lower than that of plastic parts, and whether the forming plan will provide 1billion euros to fund qualified plastic parts within 10 years. In addition, we should also understand the plasticization and molding process parameters of plastics

2. Digest the process data and analyze whether the requirements of forming method, equipment model, material specification, mold structure type and so on proposed in the process specification are appropriate and can be implemented. The molding materials shall meet the strength requirements of plastic parts and have good fluidity, uniformity, isotropy and thermal stability. According to the use of plastic parts, the molding materials should meet the requirements of dyeing, metal plating conditions, decorative performance, necessary elasticity and plasticity, transparency or opposite reflection performance, bonding or weldability, etc

3. Determine whether the molding method

adopts direct pressing method, casting pressing method or injection method

4. Select molding equipment

mold according to the type of molding equipment, so you must be familiar with the performance, specifications and characteristics of various molding equipment. For example, for the injection machine, the following contents should be understood in terms of specifications: injection capacity, mold locking pressure, injection pressure, mold installation size, ejector and size, nozzle hole diameter and nozzle spherical radius, size of gate sleeve locating ring, maximum and minimum thickness of mold, template stroke, etc. see relevant parameters for details. It is necessary to preliminarily estimate the overall dimension of the mold and judge whether the mold can be installed and used on the selected injection machine

5. Specific structural scheme

(I) determine the mold type

the tension machine for soft packaging is frequently used

such as pressing mold (open, semi closed, closed), casting mold, injection mold, etc

(II) determine the main structure of the mold type

the selection of the ideal mold structure lies in determining the necessary molding equipment and the ideal number of cavities, which can make the work of the mold itself meet the requirements of the process technology and production economy of the plastic parts under absolutely reliable conditions. The technological requirements for plastic parts are to ensure that the plastic does not drip oil or intermittently drip water when the tonnage is high, and to further expand the surface finish and dimensional accuracy. The economic requirement of production is to make plastic parts with low cost, high production efficiency, continuous work of molds, long service life and labor saving

III. factors affecting mold structure and individual mold systems:

1 Cavity arrangement. The number and arrangement of cavities are determined according to the geometric structure characteristics of plastic parts, dimensional accuracy requirements, batch size, difficulty of mold manufacturing, mold cost, etc

for the injection mold, the accuracy of plastic parts is grade 3 and 3a, the weight is 5g, the hardening pouring system is adopted, and the number of cavities is taken; Plastic parts are of general accuracy (grade), molding materials are locally crystalline materials, and the number of cavities can be taken; The weight of plastic parts is grams, and the number of cavities is taken; For plastic parts weighing grams, the number of cavities is taken. For amorphous plastic parts, the recommended number of cavities is, and. When we continue to increase the weight of plastic parts, we rarely use multi cavity molds. For plastic parts with grade accuracy, the maximum number of cavities is 50% more than that of plastic parts with grade accuracy

2. Determine the parting surface. The position of the parting surface should be conducive to mold processing, exhaust, demoulding and molding operations, as well as the surface quality of plastic parts

3. Determine the gating system (main sprue, sub sprue and gate shape, position and size) and exhaust system (exhaust method, exhaust slot position and size)

4. Select the ejection method (ejector rod, pipe jacking, push plate, combined ejection), and determine the side concave treatment method and core pulling method

5. Determine the cooling and heating methods, the shape and position of the heating and cooling groove, and the installation position of the heating element

6. According to the mold material, strength calculation or empirical data, determine the thickness and overall dimensions of the mold parts, the overall structure and the positions of all connections, positioning and guiding parts

7. Determine the structural form of main formed parts and structural parts

8. Considering the strength of each part of the mold, calculate the working size of the formed parts

if the above problems are solved, the structural form of the mold will naturally be solved. At this time, we should draw the mold structure sketch by hand to prepare for the formal drawing

IV. drawing the mold drawing

requires drawing according to the national drawing standard, but also requires combining the factory standard and the factory customary drawing method not specified by the state

before drawing the general assembly drawing of the mold, the process drawing should be drawn and should meet the requirements of the part drawing and process data. The dimension guaranteed by the next process shall be marked with the words indicating the process dimension on the drawing. If no other machining is carried out after forming except for repairing burrs, the process drawing is exactly the same as the part drawing. It is best to mark the part number, name, material, material shrinkage, drawing proportion, etc. under the process drawing. Usually, the process drawing is on the mold assembly drawing

1. Draw the general assembly structure drawing

try to use the ratio of 1:1 to draw the general assembly drawing, starting from the cavity, and draw the main view and other views at the same time. 5、 The general assembly drawing of the mold shall include the following contents:

1 Mold forming part structure

2 Structural form of gating system and exhaust system

3. Parting surface and parting part taking method

4. Outline structure and positions of all connecting parts, positioning and guiding parts

5. Mark the height dimension of the cavity (not required, as required) and the overall dimension of the mold

6. Auxiliary tools (part taking and mold unloading tools, correction tools, etc.)

7. Number all parts in sequence and fill in the list

8. Mark the technical requirements and instructions

VI. technical requirements of mold assembly drawing:

1 Performance requirements for some systems of the die. For example, the assembly requirements for ejection system and sliding block core pulling structure

2. Requirements for mold assembly process. For example, after the mold is assembled, the fitting clearance of the mating surface of the parting surface should not be greater than the parallelism requirements of the upper and lower parts of the mold, and point out the size determined by the assembly and the requirements for this size

3. Mold use, assembly and disassembly methods

4. Anti oxidation treatment, mold number, lettering, marking, oil seal, storage and other requirements

5. Requirements for mold test and inspection

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