plastic fdd11: Recent Episodes
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From the use of new molds to the failure to scrap..?? Generally speaking. You should choose to fail and scrap in advance and re-manufacture the mold. Until the burr of the punched part exceeds the standard, the size and shape accuracy of the part are out of tolerance, and the mold can no longer be repaired or has no repair value at all, the mold can only be scrapped.??Under normal circumstances, the main failure mode of the die is excessive wear. And the small punch breaks, the punch upset becomes shorter, the concave template cracks, and the blanking edge cracks. but. This is because, in addition to the difficulty and high cost of mold manufacturing. When the mold repair technology is too complicated and the mold repair cost is too large, the difficulty will inevitably make the repair cycle too long, which will seriously affect the normal production of stamping. Generally, it will be repaired and sharpened Plastic Injection Molded Automotive Parts many times.?? After the mold is damaged, there is a choice of repair and scrapping. Therefore, timely maintenance of molds to prevent mold damage can greatly reduce mold costs for stamping production. When the key parts of the mold are seriously damaged, sometimes the convex and concave molds are damaged at the same time.?In the previous article, I wrote about the common problems of stamping die: die failure. Usually mold costs account for 1/5 to 1/4 of the total cost of the parts.??
I hope my summary is useful to everyone. Most of them can be completely restored to normal state through maintenance methods, and then put into stamping production again. Unnatural wear failure of the stamping die, such as the destruction of non-critical parts. So here I will introduce you to maintenance.??
The cost of stamping production die is high. From the new mold manufacturing and delivery. After the production is put into production, the cost of mold repair and sharpening maintenance is also high, and the original cost of the mold only accounts for about 40% of the entire mold cost. The maintenance is of little significance, and scrap molds should be considered at this time: except for large molds and continuous molds with complex structures. The one-time repair cost exceeds 70% of the original cost of the die, or the die life is near
Also, because there is no heating in the system, a higher injection pressure is required, which often causes deformation or bending of the cavity plate. The material must flow continuously between the insulating wall and the heating shuttle. The latest technological development has reduced the size of the header and made installation easier. The design of the header has a variety of thermal insulation structures that are isolated from other parts of the mold. Hot runner plate: Manifold plate: connected with the nozzle and injection molding machine, the plastic melt in the molten state is evenly divided to each nozzle through the pressure of the heated manifold. The advantage of this system is better temperature control, but the cost is also higher and the equipment is complicated.??
Heating type: Heating runner system also has two designs: inner heating runner and outer heating runner: ??1, inner heating runner: the characteristic of the inner heating runner is the annular small household appliances OEM runner with internal heating. This, combined with the annual flow effect, will cause the pressure in the system to drop, so the importance of balance is very important. Heating is provided by probes and heating shuttles (also called distributor tubes) in the flow channel. The external heating system can also be balanced by diameter instead of length. Considering this problem, the internal heating system is most suitable for processing a wide range of materials and equidistant balance runners to each gate. Internal heating provides improved heat distribution relative to thermal insulation systems, but the cost of the system is higher and the design is more complex. Despite the annular heater in the distributor tube, there will still be material condensation between the heating shuttle and the runner wall. This system is not suitable for the use of heat-sensitive plastics. The disadvantage is that condensation sometimes forms at the gate; in order to maintain the molten state, a fast working cycle is required; in order to reach a stable melting temperature, a long preparation time is required. Another major problem is that it is difficult to achieve the consistency of injection molding, or it cannot be guaranteed. The heat insulation effect provided by the plastic condensed on the runner wall under working conditions is used in combination with the heat of each injection to maintain the melt in the runner Unblocked.??2, External heating system: Another design of the hot runner is an external heating system.??
Second, the hot runner system is generally divided into two categories according to the heating method of the heat flow guide: ?? (1) Heat insulation: The heat insulation runner mold has an oversized runner composed of a template.. This design consists of an annular heating header with internal flow channels. The runner is not heated, but the size of the runner should be large enough. This type of system requires careful balancing and sophisticated thermal control. This kind of system is earlier and simpler among the two types, and the advantage is that the design is not so complicated and the manufacturing cost is low. This system uses the thermal insulation effect of molten plastic to reduce heat transfer and loss elsewhere in the mold.?Although there are many hot runner manufacturers and multiple hot runner product series in the world, a typical hot runner system consists of the following major parts: (1) hot runner plate (2) nozzle (3) temperature controller (5) ) Auxiliary parts 1
Today, the Shenzhen injection mold manufacturer To share with you the necessity of temperature control for injection mold molding.. In high speed injection molding process general molding conditions, keeping the mold core temperature low can increase the number of shots. ??
This is a material problem of the molded product. These problems affect the quality of the mold, and sometimes increase our production costs. The cooling time is short, even if one part is hardened and the other part is still soft, the stress caused by uneven shrinkage can still be avoided.??
The above is what we have introduced is the necessity of injection mold molding temperature control.??2. However, the molding cycle related to the shape of the molded product and the type of finished material also depends on the temperature at which the mold core is filled. I hope that after understanding these, you can pay more attention to the stable temperature when processing the injection mold, so as to ensure the yield of the injection mold., are significantly affected by the mold core temperature.??1. The purpose and effect of temperature control on formability ??The appearance of molded products, physical properties of materials, molding cycles, etc. Adjusting the degree of crystallization of molding materials for temperature control. That is, proper temperature control can improve the properties of cooling stress. This requires a cooling rate. Temperature control to prevent stress.??3.?In the process of injection mold molding, many problems will be encountered, such as filling, burrs, sink marks, temperature, etc. ??Polythionine (nylon), polyacetate, polypropylene and other crystalline materials can adjust the degree of crystallization and improve the mechanical properties, generally requiring higher mold core temperature
??Lower the material temperature, adjust the temperature of the barrel section by section, and increase the mold temperature appropriately. These silver streaks are also called sparkles or cracks. Increase the injection pressure and reduce the injection speed.??4. This is because the stress is generated in the vertical direction of the tensile stress, and the use-right polymer molecules undergo a heavy flow orientation, which shows the difference in the folding rate of the unoriented part. Eliminate the interference of gas and other impurities, and fully dry the plastic.??
Follow the editor of the high speed injection molding process mold manufacturer to see what solutions are available: ???Melt spots, silver streaks, cracked polystyrene, plexiglass transparent parts, sometimes you can see some shimmering silver streaks through light.. Clean up the possible blockage of the nozzle, runner and gate.??2. Increase or decrease the pre-plastic back pressure and decrease the screw speed. Improve the flow channel and cavity exhaust. Shorten the molding cycle.??7. After demolding, annealing can be used to eliminate silver streaks: hold for 15 minutes at 78°C for polystyrene, or 1 hour at 50°C, and for polycarbonate, heat to over 160°C for several minutes.
Complex shape The working parts of precision molds are generally two-dimensional or three-dimensional complex surfaces (especially cavity molds), rather than simple geometrical surfaces of general machining. The production management, design and process of the mold should meet this requirement, and the design, manufacturing and standardization of the mold should be improved to shorten the manufacturing cycle. Compared with general machinery manufacturing, mold manufacturing is usually more difficult, especially precision molds. Plastic molds are actually a kind of machining tool with high hardness requirements.?The price of plastic mold making and design is familiar to everyone.??2.??Plastic mold design and production steps: ??
Due to the acceleration of product upgrading and increasingly fierce market competition, the production cycle of molds is required to be shorter and shorter. As a special process equipment, mold production and process mainly have the following characteristics.. They are generally made of quenched alloy tool steel or cemented carbide. We all know that plastic mold design and making have common features of general mechanical products, but also have their particularities. If they are made by traditional machining high speed injection molding process methods, they are often more Difficult, so the mold processing method is different from general mechanical processing. The production cycle of plastic molds is short. High hardness of materials. 3c
Assemble the molded parts of the plastic mold to ensure that the parting surface is tightly closed. Generally, the parting surface of the cavity and core insert is higher than the upper surface of the fixed and movable template by 0.02?0.04mm, so that the clamping force can be relatively concentrated. On the parting surface, to avoid flashing and burrs on the plastic parts, add venting grooves where necessary after the first mold trial.??Second, plastic mold ejection mechanism assembly.??
It is necessary to ensure that the action of the push rod or the push rod and the push plate must be synchronized when pushing out. The holes are basically concentric, and the push rod and the reciprocating movement in the holes are flexible. In general, when assembling, ensure that the top surface of the push rod small household appliances OEM is higher than the surface of the core by 0 mm?0.1 mm, the top surface of the reset rod should be lower than the parting surface 0 mm?0.05 mm, and the top surface of the inclined push rod should be lower than the surface of the core. 0.1??0.2? (to ensure that the inclined push rod does not damage the inner surface of the plastic part during the pushing process). Based on the thickness of the bottom shoulder of the push rod, it is matched with the depth of the counterbore of the push rod fixing plate to ensure an axial clearance of 0 mm to 0.05 mm after assembly, and avoid excessive axial movement of the push rod. 3. Plastic mold mold base assembly.
When the processing volume of the template is relatively large, it will more or less cause some changes in the template. The upper and lower surfaces of the template need to be ground and smoothed. At the same time, to ensure the flexible operation of the guide column and the guide sleeve, it is necessary to correct The guide post and guide sleeve are to be ground.
In recent years, the adjustment of product structure in the mold industry has accelerated. The development speed of high-tech molds represented by large, Plastic quality household mould/mold precise, complex, and long-life molds is higher than the overall development speed of the industry, accounting for about 35% of the total molds. my country's mold industry should take a new path of industrialization with Chinese characteristics, pay attention to new keywords in the development of the industry, and implement specific measures to promote the better development of China injection molding suppliers the domestic mold industry.??
First, we must expand the international market. In terms of market development, my country's mold industry must seize the opportunity of industrial transfer in developed countries, seize the opportunity, and actively and effectively explore the international market.??Secondly, we need efficiency from management. The domestic mold industry must actively guide enterprises to focus on management and improve management efficiency.?? Third, we must implement the requirements of the revitalization plan. The domestic mold association should continue to strengthen cooperation with the Ministry of Industry and Information Technology, the Ministry of Finance, etc. In order to promote the healthy, orderly and stable development of the domestic mold industry, mold experts proposed that during.
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