Manifold design
Published:
2023-01-07 08:44
Source:
(Summary description)A wide variety of mold steels can be used to make injection molds. The following table lists the properties of commonly used mold steels and the typical mold parts that can be manufactured with them. Soft metals such as aluminum and beryllium copper can be used to make prototype workpiece molds or short-term production molds with fewer than 10,000 workpieces.
• An externally heated manifold system is best.
• Internally heated manifolds are not suitable for TPE. These systems often have hot spots and stagnant areas, the latter causing partially hardened materials to stick to the cooler manifold walls.
• In order to achieve maximum flexibility, its structure should achieve natural equilibrium or geometric equilibrium. Rheological equilibrium is possible, but only for a specific species or rheological curve.
• All channels should be highly polished, with circular cross-sections and gentle bends to minimize the possibility of stagnant areas.
• In order to maintain high shear force, minimize residence time and promote flow, the diameter of the channel should be 0.250 inches-0.375 inches.
• It is recommended to adopt zone control for the hot runner, so that the operator can slightly adjust the equilibrium state, so as to make the finished workpiece more consistent.
Back to top
Hot runner gate design
Valve gate
For those parts whose surface quality is critical, such as medical products and cosmetics, valve gates provide the best solution for their mass production. Because the valve gate leaves only a small ring mark on the workpiece, the gate residue is reduced to a minimum.
For decorative products, if the valve is set below the surface of the workpiece or the gate is hidden in some parts of the workpiece, further improvements can be obtained. The figure below shows an example of a hot runner system with valve gates:
Depending on the size and thickness of the workpiece, the diameter of the valve gate should be about 0.030 inches-0.125 inches.
Valve gates do not require the workpiece material to harden before the valve gate is closed and the holding pressure is released. Therefore, the screw retraction of the next cycle can be started earlier, and the total cycle time can also be shortened.
The components of the valve gate should be insulated from the template to maintain proper temperature control. Due to the low viscosity of some types of Gelex, it is necessary to properly maintain the tightness of the valve gate to prevent leakage or slight flashing.
Hot tip gate
Hot tip gates are suitable for SBC composites, but they will leave some gate residues (the height can reach 50%-75% of the gate diameter). If the gate is slightly lower than the surface of the workpiece, the residual marks can be reduced to a minimum. The length of the hot tip should be less than the gate diameter.
The components of the hot tip gate should be completely insulated from the template and cavity. To achieve this, the gate length may need to be increased, and part of the gate length should be part of the cavity.
All channels in the hot tip should be highly polished and streamlined to minimize stagnation and degradation zones. The efficiency of the design can be verified by recording the time required for the color of the workpiece to completely change during production. This can indicate whether there are any remaining dead ends that continue to enter the melt stream.
For hot-tip gate systems, there should be a long enough delay time so that the workpiece is completely hardened before the start of the next cycle of plasticizing. If there is no delay time, the workpiece may be overfilled. This is particularly important for materials with low hardness and high flow index. In order to reduce the phenomenon of overfilling of workpieces with large gates and thick walls, the lowest back pressure should be used during plasticizing.
Since the TPE composite material is slightly compressible in the molten state, a runner with a larger capacity may cause dripping of the hot tip gate after the mold is opened. In order to prevent drooling, the runner system should be as small as possible, and the melt should be decompressed before the mold is opened.
Related news
On October 13, the 2020-2021 annual plastic recycling "Golden Apple Award" award ceremony was grandly announced at the opening ceremony of ChinaReplas2021 China International Plastics Recycling Exhibition.
The "Opinions of the Central Committee of the Communist Party of China and the State Council on the Complete, Accurate and Comprehensive Implementation of the New Development Concept to Do a Good Job in Carbon Peak and Carbon Neutrality" was released on the 24th. What are the important deployments of the opinions to promote carbon neutrality? A reporter from Xinhua News Agency interviewed the head of the National Development and Reform Commission.
Generally, people call waste plastics generated after circulation, consumption, and use as post-consumer plastics (ie, Post Consumer Recycling, referred to as PCR).
Carbon Footprint Popularization: Carbon Footprint Calculation and Case Studies
In nature, there are all kinds of footprints There is another kind of footprint that is invisible and intangible
TÜV Rheinland will debut at the 4th CIIE
Carbon footprint calculation and certification, corporate carbon integrated system management, product carbon emission intelligent simulation calculation, carbon strategy talent training and certification, biodegradable testing services, zero solid waste landfill, Green Mark certification. Double cycle consumption upgrade service
(Summary description)A wide variety of mold steels can be used to make injection molds. The following table lists the properties of commonly used mold steels and the typical mold parts that can be manufactured with them. Soft metals such as aluminum and beryllium copper can be used to make prototype workpiece molds or short-term production molds with fewer than 10,000 workpieces.
Follow Us
COPYRIGHT 2022 Dongguan Renergy Plastic Technology Co.,Ltd. All copyrights