DIE & MOULD INDIA, Mumbai, India

Detailed explanation of injection mold design steps
1 The composition of the injection mold.
It is mainly composed of molding parts (parts related to the moving and fixed mold parts), the pouring system (the channel through which the molten plastic enters the mold cavity from the injection machine nozzle), and the guide parts (to make the mold close accurately. Alignment), push-out mechanism (the device that pushes plastic out of the cavity after the mold is parted), temperature adjustment system (to meet the requirements of the injection process for mold temperature), and exhaust system (to reduce the air in the cavity during molding) The volatilized gas of the plastic is discharged out of the mold, and the parting surface is often opened with an exhaust groove) and supporting parts (used to install and support the molded parts and parts of other mechanisms), and sometimes there are lateral parting With core pulling mechanism.
2. Design steps of injection mold
1. Preparation before design
(1) Design task book
(2) Familiar with plastic parts, including its geometry, requirements for use of plastic parts, and raw materials of plastic parts
(3) Check the molding processability of plastic parts
(4) Clarify the model and specifications of the injection machine
2. Develop a molding process card
(1) Overview of the product   such as diagram, weight, wall thickness, projected area, external dimensions, undercut and inserts
(2) Overview of the plastic used in the product, such as product name, model, manufacturer, color, and dry condition
(3) The main technical parameters of the selected injection machine, such as the relative size, screw type, and power between the injection machine and the installed mold (4) The pressure and stroke of the injection machine
(5) Injection molding conditions   such as temperature, pressure, speed, clamping force, etc.
3. Design steps of injection mold structure
(1) Determine the number of cavities. Conditions: Maximum injection volume, clamping force, product accuracy requirements, economy
(2) Select the parting surface. Should be based on the principle of simple mold structure, easy parting without affecting the appearance and use of plastic parts
(3) Determine the layout plan of the cavity. Use a balanced arrangement as much as possible
(4) Determine the pouring system. Including main runners, runners, gates, cold slugs, etc.
(5) Determine the demolding method. Different demoulding methods are designed according to the different parts of the plastic part left in the mold.
(6) Determine the structure of the temperature control system. The temperature control system is mainly determined by the type of plastic.
(7) When it is determined that the cavity mold or core adopts the insert structure, the propositional division of the inserts and the simultaneous inserts, the workability and the installation and fixing methods.
(8) Determine the type of exhaust. Generally, the exhaust can use the mold parting surface and the gap between the ejection mechanism and the mold. For large-scale and high-speed injection molds, corresponding exhaust forms must be designed.
(9) Determine the main size of the injection mold. Calculate the working size of the molded part according to the corresponding formula and determine the side wall thickness of the mold cavity, the thickness of the cavity bottom plate, the core backing plate, the thickness of the movable template, the thickness of the cavity plate of the block cavity and the closing height of the injection mold .
(10) Use standard mold bases. According to the design and calculation of the main size of the injection mold, choose the standard mold base of the injection mold, and try to choose the standard mold parts.
(11) Draw the structural sketch of the mold. Drawing a complete structure sketch of the injection mold and drawing a mold structure drawing is a very important job of mold design.
(12) Check the relevant dimensions of the mold and the injection machine. Check the parameters of the injection machine used: including the maximum injection volume, injection pressure, clamping force, and the size of the mold installation part, mold opening stroke and ejection mechanism verification.
(13) Review of the structural design of the injection mold.  Conduct a preliminary review and obtain the user's consent. At the same time, it is necessary to confirm and modify the user's requirements.
(14) Draw the assembly drawing of the mold. Clearly indicate the assembly relationship, necessary dimensions, serial number, schedule, title bar and technical requirements of the various parts of the injection mold (the technical requirements are as follows: a. Performance requirements for the mold structure, such as the introduction of the mechanism, Assembly requirements for the core-pulling mechanism; b. Requirements for mold assembly process, such as the fitting gap of the parting surface, the parallelism between the upper and lower molds; c. The use requirements of the mold; d. Anti-oxidation treatment, mold numbering, lettering, Oil seal and storage requirements; e. Requirements related to mold trial and inspection. (15) Drawing mold parts drawings.  The sequence of drawing parts from the mold assembly drawing or the part drawing is: first inside and then outside, first complex and then simple. Form parts first and then structural parts.
(16) Review the design drawings. The final review of the injection mold design is the final check of the injection mold design, and more attention should be paid to the processing performance of the parts. 
3. Review of injection molds 1. Basic structure
(1) Whether the mechanism and parameters of the injection mold match the injection machine.
(2) Whether the injection mold has a mold clamping guide mechanism and whether the mechanism design is reasonable.
(3) Whether the selection of the parting surface is reasonable, whether there is the possibility of flashing, whether the plastic part stays on the side of the movable mold (or the fixed mold) of the ejection and ejection mechanism.
(4) Whether the layout of the cavity and the design of the gating system are reasonable. Whether the gate is compatible with the plastic raw materials, whether the gate position is equivalent, whether the gate and runner geometry and size are appropriate, and whether the flow ratio is reasonable.
(5) Whether the design of molded parts is reasonable.
(6) Ejection and demoulding mechanism and lateral male type. Or whether the core pulling mechanism is reasonable, safe and reliable. Whether there is interference and bite.
(7) Whether there is an exhaust mechanism and whether its form is reasonable.
(8) Do you need a temperature regulation system.
 Whether the heat source and cooling method are reasonable.
(9) Whether the structure of supporting parts is reasonable.
(10) Whether the external dimensions can ensure the installation, whether the selection of the fixing method is reasonable and reliable, and whether the bolt holes for installation are consistent with the screw holes on the injection mechanism and the fixed mold fixing plate.
 2. Design drawings
(1) Assembly drawing 
Whether the assembly relationship of the parts is clear, whether the matching codes are marked appropriately and reasonably, whether the parts are fully marked, whether they correspond to the serial numbers in the detailed list, whether the relevant instructions have clear marks, and how standard the entire injection mold is.
(2) Parts drawing  Are the part numbers, names, and processing quantities marked exactly, whether the dimensional tolerances and various tolerance markings are reasonable and complete, whether the parts that are prone to wear on the molded parts are reserved for grinding, which parts have ultra-high precision requirements, and whether this requirement is reasonable , Whether the material cushion of each part is appropriate, whether the heat treatment requirements and surface roughness requirements are reasonable.
(3) Drawing method
 Whether the drawing method is correct, whether it conforms to national standards, and whether the geometric figures and technical requirements expressed on the drawing are easy to understand.
3. Design quality of injection mold
(1) When designing the injection mold, whether the process characteristics and molding performance of the plastic raw materials are correctly considered, the type of injection machine may have an impact on the molding quality, and whether the corresponding injection mold design is adopted for the possible production during the molding process. Precaution.
(2) Whether the requirements of the plastic parts for the guiding accuracy of the injection mold are considered, and whether the guiding structure is designed reasonably.
(3) Whether the calculation of the working size of the formed parts is correct, whether the accuracy of the product can be guaranteed, and whether it has sufficient strength and rigidity.
(4) Whether the supporting parts can ensure that the mold has sufficient overall strength and rigidity.
(5) Have you considered the requirements of mold trial and repair?
4. In terms of assembly and disassembly and handling conditions Is there any slots, holes, etc. that are convenient for assembly and disassembly, and whether they are marked.