What are the necessary characteristics of precision mold accessories?

 

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What are the necessary characteristics of precision mold accessories?

Die accessories refers to the general term for metal accessories used in stamping molds, plastic molds or FA automation equipment that are proprietary to the die industry. Mold accessories include: punching needle, block punch and dies, guide post, guide sleeve, thimble, cylinder, steel ball sleeve, no oil guide sleeve, no oil slide, guide post assembly, etc.

1. Wear resistance
When the billet is plastic denaturated in the mold cavity, it flows and slides along the surface of the mold cavity, causing severe friction between the surface of the mold cavity and the billet, resulting in the failure of the mold due to wear. Therefore, the wear resistance of the material is one of the most basic and important properties of the mold.
Hardness is the main factor affecting wear resistance. Under normal circumstances, the higher the hardness of the mold parts, the smaller the wear amount, and the better the wear resistance. In addition, the wear resistance is also related to the type, quantity, shape, size and distribution of carbides in the material.
2. Strength and toughness
Most of the working conditions of the mold are very bad, and some often bear a large impact load, resulting in brittle fracture. In order to prevent the sudden brittle break of the mold parts during work, the mold should have high strength and toughness. The toughness of the mold mainly depends on the carbon content, grain size and microstructure of the material.
3. fatigue fracture performance
In the process of mold operation, the long-term action of cyclic stress often leads to fatigue fracture. Its forms include low energy multiple impact fatigue fracture, tensile fatigue fracture, contact fatigue fracture and bending fatigue fracture. The fatigue fracture performance of the die mainly depends on its strength, toughness, hardness, and the content of inclusions in the material.
4.high temperature performance
When the working temperature of the mold is high, the hardness and strength will decrease, resulting in early wear or plastic deformation of the mold and failure. Therefore, the mold material should have a high tempering stability to ensure that the mold has a high hardness and strength at the working temperature.
5.cold and heat fatigue resistance
Some molds are in the state of repeated heating and cooling during the working process, so that the surface of the cavity is strained and the pressure changes the stress, causing the surface cracking and spalling, increasing the friction force, hindering the plastic deformation, reducing the dimensional accuracy, resulting in the failure of the mold. Hot and cold fatigue is one of the main failure forms of hot working die, and this kind of die should have high resistance to cold and heat fatigue.
6. Corrosion resistance
Some molds, such as plastic molds, when working, due to the presence of chlorine, fluorine and other elements in the plastic, after heat decomposition and precipitation of HCI, HF and other strong corrosive gases, erosion of the surface of the mold cavity, increase its surface roughness, exacerbate wear failure.

The importance of precision mold parts maintenance

 

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The annual maintenance procedure required for each injection molding location depends on the mold cycle. The following are some mold parts repair tips that each mold user can use to ensure the effective operation of hot runner, heater, guide post and thimble, molding inserts and other mold components in case of unexpected situations.

1. Check whether there is early-warning rust or moisture at the loose pores. If you find rust or moisture near the hot runner vent, it means internal condensation, or the pipe may break. Moisture can cause a fatal short circuit to the heater. If the machine is not running year-round and needs to be shut down at night or on weekends, the chance of this condensation will increase.

 

2, interactive check the resistance value of the heater. You should have measured the resistance of the heater when you first started using it, and it is time to measure it again and compare it at the end of the year. If the resistance value fluctuates ±10%, it is time to consider replacing the heater to ensure that it does not fail at critical points in the production process. If the initial resistance value has never been measured, then measure it now and use the resulting value as reference data for future inspections of the heater.

The importance of precision mold parts maintenance

4. Check whether the guide post and guide sleeve have signs of wear. Look for scratches or scratches and other marks, this mold accessories wear is caused by lack of lubrication. If the mark is just appearing, you can also extend the life of the guide post and sleeve by adding lubricant. If the wear is too severe, it is time to replace new parts. Otherwise, the cavity and core parts may not fit well, resulting in different parts of the cavity wall thickness.

5. Check the water flow. Connect a hose at the outlet of the waterway and let the water flow through the pipe to the bucket. If the flowing water is not clear or colored, rust may occur, and the flow of water is not smooth, which means that there is a blockage. If you find these problems, drill all the pipes again (or clean them by whatever method you use most often) to keep them clear. Improving the plant’s water treatment system can prevent future problems caused by rust and congestion.

6. Clean the thimble. Over the course of a year, the thimble will become very dirty due to gas accumulation and film-like impurities. A good cleaning with mold cleaner is recommended every 6 to 12 months. After cleaning, apply a layer of lubricant to the thimble to prevent chafing or breakage.

Surface treatment technology of precision mold accessories

 

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The surface treatment technology of precision mold accessories is a system engineering that changes the morphology, chemical composition, organizational structure and stress state of the surface of precision mold accessories through surface coating, surface modification or composite treatment technology to obtain the required surface properties. Nitriding process has gas nitriding, ion nitriding, liquid nitriding and other ways, each of which has several kinds of nitriding technology, which can adapt to the requirements of different steel types and different workpieces. From the way of surface treatment, it can be divided into: chemical method, physical method, physical chemical method and mechanical method. Although new treatment technologies aimed at improving the surface properties of precision mold parts continue to emerge, the main applications in the manufacturing of precision mold parts are nitriding, carburizing and hardened film deposition. Because the nitriding technology can form a surface with excellent performance, and the nitriding process has good coordination with the quenching process of precision mold parts steel, at the same time, the nitriding temperature is low, there is no need for intense cooling after nitriding, and the deformation of precision mold parts is very small, so the surface strengthening of precision mold parts is the earliest and most widely used nitriding technology.

In addition to requiring high enough strength and toughness in the work of precision mold accessories, its surface performance is crucial to the working performance and service life of precision mold accessories. The improvement of these properties, relying solely on the improvement and improvement of the base material is very limited and uneconomical, and through surface treatment technology, you can often receive twice the result with half the effort, which is also the reason for the rapid development of surface treatment technology. These surface properties refer to: wear resistance, corrosion resistance, friction coefficient, fatigue performance, etc.

The purpose of carburizing precision mold parts is mainly to improve the overall strength and toughness of precision mold parts, that is, the working surface of precision mold parts has high strength and wear resistance, and the technical idea introduced is to replace the higher level material with a lower level material, that is, by carburizing and quenching, so as to reduce manufacturing costs. Hardened film deposition technology was first applied to tools (cutting tools, cutting tools, measuring tools, etc.), with excellent results, and a variety of tools have been coated with hardened film as a standard process. At present, CVD and PVD are more mature technology of sclerotic film deposition. In order to increase the bonding strength of the surface of the film layer, a variety of enhanced CVD and PVD technologies have been developed. Precision mold accessories have been coated with hardened film technology since the 1980s. Under the current technical conditions, the cost of hardened film deposition technology (mainly equipment) is higher, still only in some precision, long-life precision mold accessories applied, if the use of heat treatment center, the cost of coating hardened film will be greatly reduced, more precision mold accessories if the use of this technology, can improve the overall level of China’s precision mold accessories manufacturing.

What role do precision mold accessories play in the use and maintenance of molds

 

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Precision mold accessories play a crucial role in the use and maintenance of molds, and the specific role is reflected in the following aspects:

1. Ensure mold accuracy and stability

Precision machining: Precision mold parts are precision machined, and their dimensional accuracy and shape accuracy are very high, which can ensure that the mold maintains a high degree of accuracy and stability during use. This is essential for the production of high quality, high precision products.

Positioning and orientation: such as guide posts, guide sleeves and other accessories, they can ensure that the upper and lower dies of the mold can be accurately aligned when the mold is closed, avoid deviation or dislocation, so as to ensure the dimensional accuracy and appearance quality of the product.

2. Improve mold durability

Wear resistance: Precision mold accessories are usually made of materials with good wear resistance, such as cemented carbide, high-speed steel, etc., which can maintain good wear resistance during long-term use, reduce wear, and extend the service life of the mold.

Corrosion resistance: Some special purpose mold accessories also have corrosion resistance, can maintain stable performance in harsh working environments, and prevent failure or damage caused by corrosion.

3. Easy to maintain and replace the mold

Modular design: Many precision mold accessories adopt modular design, easy to disassemble and replace. When a part in the mold is damaged or seriously worn, it can be quickly replaced with a new part, without the need to overhaul the entire mold, thereby shortening the maintenance time and reducing maintenance costs.

Standardization and versatility: Some precision mold parts follow unified standards and specifications, and have high versatility. This means that when it comes to repair or replacement, it can be easier to find the right parts and improve maintenance efficiency.

4. Implement special functions

Lateral parting: such as sliders, inclined guide posts and other accessories, they can achieve the lateral parting of the mold, so that the mold can produce products with complex structures such as side holes and side pits.

Hot runner system: Hot runner plate, hot runner nozzle and other accessories composed of hot runner system, can provide a uniform heat source for the mold, so that the plastic melt in the mold to maintain a stable temperature and fluidity, thereby improving product quality and production efficiency.

5. Optimize the production process

Automated production: The precise coordination and efficient operation of precision mold parts make it possible to achieve automated production, reduce manual intervention, and improve production efficiency and product quality.

Reduce scrap rate: Due to the high precision and stability of precision mold parts, the mold can more accurately control the size and shape of the product during the production process, thereby reducing the scrap rate and improving the material utilization rate.

In summary, precision mold accessories have multiple roles in the use and maintenance of molds to ensure mold accuracy and stability, improve mold durability, facilitate mold maintenance and replacement, achieve special functions and optimize production processes. They are of great significance for improving the overall performance of molds, reducing production costs and improving product quality.