Design steps of injection mold

An injection mold primarily consists of molding components (parts related to the moving and stationary mold sections that form the mold cavity), a gating system (the channel through which molten plastic is injected from the nozzle of the injection machine into the mold cavity), a guiding component (ensures accurate mold clamping), an ejection mechanism (a device that ejects the plastic from the mold cavity after mold parting), a temperature control system (to meet the requirements of the injection process for mold temperature), a venting system (to vent air and gases volatilized by the plastic itself from the mold cavity during molding, often with vent slots on the parting surface), and supporting components (used to install, fix, or support molding components and other mechanism components). Sometimes, there are also lateral parting and core-pulling mechanisms.
Design steps of injection mold
1. Preparations before design
(1) Design specification.
(2) Familiarize yourself with plastic parts, including their geometric shapes, usage requirements, and raw materials.
(3) Check the moldability of the plastic parts.
(4) Specify the model and specifications of the injection machine.
2. Develop a molding process card
(1) Product overview. Such as sketch, weight, wall thickness, projected area, overall dimensions, presence or absence of undercuts and inserts.
(2) Overview of the plastic used in the product. Such as product name, model, manufacturer, color, and drying condition.
(3) The main technical parameters of the selected injection machine, such as the relevant dimensions between the injection machine and the installed mold, screw type, and power.
(4) Injection machine pressure and stroke.
(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, and economy.
(2) Select the parting surface. The principle should be based on a simple mold structure, easy parting, and not affecting the appearance and use of the plastic parts.
(3) Determine the layout plan of the mold cavity. Adopt a balanced arrangement as much as possible.
(4) Determine the gating system, including the main runner, branch runners, sprues, cold spots, etc.
(5) Determine the demolding method. Design different demolding methods based on the different parts of the plastic part left in the mold.
(6) Determine the structure of the temperature regulation system. The temperature regulation system is primarily determined by the type of plastic.
(7) When determining whether to use an insert structure for the die or core, it is necessary to divide the insert and consider its machinability and installation and fixing methods.
(8) Determine the venting method. Generally, venting can be achieved through the mold parting surface and the gap between the ejection mechanism and the mold. However, for injection molds with large and high-speed molding, corresponding venting methods must be designed.
(9) Determine the main dimensions of the injection mold. Calculate the working dimensions of the molded parts according to the corresponding formulas, 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 moving platen, the thickness of the cavity plate for the split-type cavity, and the closing height of the injection mold.
(10) Select standard mold base. Based on the main dimensions of the injection mold designed and calculated, select the standard mold base for the injection mold, and try to choose standard mold components.
(11) Draw a structural sketch of the mold. Drawing a complete structural sketch of the injection mold is a crucial task in mold design.