Analysis of several steps in the design and manufacture of injection molds

Author: MULAN -Plastic Molding Manufacturer

The design and development of injection molds needs to follow certain steps in order to more accurately design injection mold tools that are consistent with the size and structure of plastic products. The specific steps are as follows: 1. Analysis of plastic parts Figure, consider the feasibility and economy of the injection molding process from various aspects such as the plastic variety of the product, the shape of the plastic part, the dimensional accuracy, and the surface roughness. If necessary, discuss with the product designer the type of material and structural modification of the plastic part. possibility. ②Clarify the production batch of plastic parts In small batch production, the mold should be as simple as possible in order to reduce costs; in mass production, under the premise of ensuring the quality of plastic parts, try to use one mold with multiple cavities or high-speed automatic production to shorten production cycle and improve productivity, so strict requirements are placed on the ejection mechanism of the mold, the automatic demoulding mechanism of plastic parts and runner aggregates. ③Calculating the volume and mass of plastic parts The purpose of calculating the volume and mass of plastic parts is to select injection molding machines, improve equipment utilization, and determine the number of mold cavities.

2. The selection of injection molding machine roughly determines the structure of the mold according to the volume or weight of the plastic part, initially determines the model of the injection molding machine, and understands the technical parameters related to the injection molding machine used and the design mold, such as: the diameter of the positioning ring of the injection molding machine, the front end of the nozzle Aperture and spherical radius, injection volume of injection molding machine, clamping force, injection pressure, area size of fixed template and movable template and location of mounting screw holes, spacing of tie rods of injection molding machine, closing thickness, mold opening stroke, ejection stroke, etc. 3. Calculation of mold injection design ①Calculation of working dimensions of concave and convex mold parts; ②Determination of cavity wall thickness and bottom plate thickness; ③Determination of mold heating and cooling system. 4. Mold structure design ①Selection of molding position and parting surface of plastic parts; ②Determination of the number of mold cavities, arrangement of cavities, layout of runners and setting of gate positions; ③Structural design of working parts of the mold; ④Side parting The design of the core-pulling mechanism; ⑤ the design of the ejector mechanism; ⑥ the selection of the form of the pulling rod; ⑦ the design of the exhaust method.

5. Determination of the overall size of the mold, the purchase of the mold base The mold base has gradually been standardized. According to the mold base atlas provided by the injection mold manufacturer, the mold base is selected, and the complete structure of the mold is initially drawn on the basis of the above mold parts design picture. 6. Checking of injection molding machine parameters ① Checking of injection volume; ② Checking of injection pressure; ③ Checking of clamping force; Relevant size checks in several aspects such as the installation size of the mold base. 7. Drawing of mold structure general assembly drawing and parts working drawing The drawing of mold general drawing must conform to the national standard of mechanical drawing. For the setting of the gate position, on the top view of the mold general drawing, the fixed mold can be removed, and only the top view of the movable mold part can be drawn.

Mold general assembly drawing should include necessary dimensions, such as mold closing dimension, external dimension, characteristic dimension (dimension of positioning ring matched with injection molding machine), assembly dimension, limit dimension (moving starting and ending points of moving parts) and technical conditions, and preparation of parts list, etc. . Generally, the processing cycle of the main working parts is long and the processing accuracy is high, so it should be carefully drawn first, and the rest of the parts should be standard parts as much as possible. 8. Comprehensive review and production Mold designers should generally participate in the whole process of processing, assembly, mold testing and production.