Raw material: PP+EPDM
Part dimension: 650*1150*235mm
Part thickness: 2mm
Mold cavity: 1+1, left+right
Cavity steel: Thyssen Krup DIN1.2738
Core steel: Thyssen Krup DIN 1.2312
Slides: Thyssen Krup DIN1.2738 + Nitrided
Mold base: 1.1730
Injection system: Synventive Nozzles
Ejection system: Hydraulic cylinders
Surface Finishing: Moldtech texture
Design principles of plastic automobile mudguard mold
1. Design basis
* Correctness of dimensional accuracy and its associated dimensions
According to specific requirements and functions of the entire product of Molded products, which kind of external quality and specific size are determined: Molded products with higher appearance quality requirements and lower dimensional accuracy such as toys and functional Molded products with strict size requirements, cameras with strict appearance and size.
* Whether draft angle is reasonable.
Draft angle is directly related to release and quality of Molded products, that is whether injection can be carried out smoothly during Moulding process: draft angle has sufficient slope to match plastic product informed parting or parting surface; whether it will affect the accuracy of appearance and wall thickness dimensions;
* Whether it will affect the strength of a certain part of Molded products.
2. Design process
* Analysis and digestion of molded products drawings and entities (real samples):
The geometry of the article
Dimensions, tolerances, and design basis
* The number of cavities and cavity arrangement:
Weight of product and injection volume of injection machine
The projected area of product and clamping force of the injection machine
Outer dimensions of mold and effective area of mold for injection machine, (or spacing inside injection rod)
Product accuracy, color
Whether the product has a side core and a treatment method thereof
Production batch of products
Economic benefit (production value per mold)
After the number of cavities is determined, arrangement of cavities, that is the arrangement of cavities, arrangement of cavities involves the size of the mold, design of gating system, the balance of gating system, design of core pulling (slider) mechanism, design of core and inserts, design of heat exchange system, these problems are related to the selection of parting surface and gate position. Therefore, in a specific design process, necessary adjustments should be made to achieve a more perfect design.
3. Determination of parting surface
* Does not affect the appearance
* Conducive to ensure product accuracy, Moulding process, especially the processing of cavity
* Conducive to the design of gating system, exhaust system, cooling system
* Conducive to mold opening (parting, demolding) to ensure that product is left on the side of movable mold when mold is opened
* Facilitate arrangement of metal inserts
4. Design of pouring system in the application of injection molding
Design of gating system includes a selection of main flow path, shape, and size of cross-section, choice of position of the gate, the form of gate, and size of the cross-section of the gate. When using the gate, the branch is also removed. Attention should be paid to the design of the degasser device, de-sinking device, and gate mechanism.
When designing a gating system, first select the location of the gate.
Choice of gate location is directly related to the quality of product and smooth progress of injection process. Choice of gate location should follow the following principles:
* Gate position should be selected on the parting surface as much as possible to facilitate the cleaning of the gate during processing and use of Short-run injection molding
* Distance between gate location and each part of the cavity should be as uniform as possible, and the process should be the shortest
* The position of the gate should ensure that plastic flows into the cavity, and a wide, thick-walled part of the cavity is used to facilitate the smooth flow of plastic
* Gate position shall be opened at the thickest section of plastic part
* Avoid plastics directly flowing into a cavity wall, core, or insert when flowing down cavity, so that plastic can flow into all parts of the cavity as soon as possible, and avoid deformation of core or insert
* Try to avoid causing weld lines in the product, or make weld marks appear in unimportant parts of the product
* Position of gate and direction of its plastic inflow should be such that plastic can flow uniformly in the direction parallel to cavity when flowing into the cavity, and facilitate discharge of gas in the cavity
* Gate should be placed on the most easily removed part of the product without affecting the appearance of the product as much as possible
5. Design of exhaust system in the application of injection molding
The exhaust system plays a vital role in ensuring the quality of the product.
With venting groove, venting groove is generally located at the end of the cavity where the cavity is filled. Depth of venting groove varies from plastic to plastic and is basically determined by the maximum allowable gap in which plastic does not generate burrs, such as ABS0. .04 is 0.02 or less with an ash of 0.02 mm or less.
Use matching clearance of core insert push rod or special exhaust plug to exhaust; sometimes in order to prevent the product from causing vacuum deformation when it is ejected, air pin must be provided; sometimes in order to prevent vacuum adsorption of product and Short-run injection molding, an anti-vacuum adsorption element is designed.
6. Design of cooling system in the application of injection molding
Design of the cooling system is a relatively cumbersome task, considering the cooling effect and uniformity of cooling, and the influence of the cooling system on the overall structure of the mold.
* Arrangement of the cooling system and specific form of the cooling system
* Determination of specific location and size of the cooling system
* Cooling of key parts such as moving molds or inserts
* Cooling of side slider and side core
* Design of cooling element and selection of cooling standard Plastic injection mold components
* Sealed structure design