Die casting production process will appear the quality problem of the different factors, in addition to the die casting equipment, equipment performance and quality to cause system instability factors, there are some accessories and equipment (such as pressure cylinders, punch, cooling pipe, etc.) process parameter accuracy, and the quality of the material can produce certain influence on die casting production (such as release agent, lubricating bead, the cooling water), The purity of liquid aluminum will also bring the corresponding unstable factors to die casting (such as waste, gate, overflow block, the proportion of cleaning material), and smelting process control. Although the above reasons cause great adverse factors to the production and quality of die casting, these problems are more intuitive and easy to solve, and in the process of die casting production, common and difficult to solve the quality problems, often troubled each of our enterprises (such as bubbles. Porosity, slag hole, pinhole, cracking, collapse, strain, deformation, dislocation, cold material, cold grain, cold separation, undercasting, loose, shrinkage hole, mold flying material, etc.), and even hinder the development of die casting enterprises, and cause difficult and frequent quality problems, it is the leading cause of die casting mold.
From the understanding of the above analysis, we can understand, improve efficiency, product quality assurance, good economic returns and mold development, design, closely related to the maintenance, the technical personnel to the whole process of die-casting production quality, efficiency, income control, divided into, mould (65%), machine performance is occupied 10%, attachments and accessories (6%), melting (4%), Debugging process parameters (10%), artificial operation (5%), as a basic for die casting production process management standards, but with the die casting is widely used in the field of all walks of life, especially in recent years is widely used in the high-end equipment and equipment (e.g., automotive, communications, aerospace, etc.), the more strict with the quality of die casting, industries also made the corresponding technical standards, Therefore, the management and control division of the past die casting production process, I think it is also necessary to keep pace with The Times, the new integration division, I personally believe that the improvement of product quality, first of all, is to have higher requirements for the performance and stability of equipment, and to have a deeper understanding of the quality and use of auxiliary materials (release agent, lubrication bead). Die casting mould, of course, are also constantly improve the design ability and service life (such as increased a little bit cold, die out, inclined top before, on the surface of electrode, etc.), so the die casting production process control, quality, efficiency, income, etc.) should click on the classification, mould accounted for 50%, die-casting equipment (20%), auxiliary materials 5%, attachment is occupied 5%, melting accounted for 5%, parameter debugging accounted for 10%. At present, the die casting equipment is basically automatic or semi-automatic in production, so the human operation accounts for 3%, and the cooling water quality accounts for 2%.
From the past to the present, we divided the die casting production process control, mold is the dominant position, so it can be understood that the core of die casting production lies in the manufacturing quality of mold, mold success or failure is the watershed of the development of die casting enterprises, we must have a clear understanding, enough awareness, The mold design, manufacturing, maintenance as a top priority project special management, enterprise can better progress and development.
The following points should be paid attention to in the design and manufacture of die casting molds and the common quality problems in the production process.(For reference only)
A good die casting mold is from the beginning of casting research and design
Casting performance and the process and requirement of the standard is a customer demand, customers will not be easily consider mould manufacture and die-casting production technology can meet the needed for the casting technical standard, but the structure of castings often cannot meet the die-casting molds and die-casting production technology and technological conditions, so that to the early stage of the structure of castings, the technical requirements for a full range of audit, One is the design of die casting mould, manufacturing can meet the requirements of casting technology review (not to negotiate with customer), 2 it is to evaluate the casting production equipment capacity and its own technical force, 3 it is expected to production efficiency and the qualified rate, four is manufacture cycle, cost, and life, five orders, returns, six is customer trust.
After the above confirmation, it is necessary to start from the first step of mold design
- The positioning of the mold is to consider the market demand, the monthly and annual output, and the purpose of the positioning is to consider the cost of mold manufacturing (the main reference is who bears the cost, is the full payment or product sharing, the quantity of good products required by the customer, and the cost of replication mold).
- To determine the mold size, first consider the mold size, mold meat in addition to considering the surrounding parting surface reserved, straight runner, cross runner, inside gate, exhaust position, overflow groove, Core pulling mode and size and quantity, cooling system, whether the need for temperature control system, vacuum exhaust or large exhaust, mold meat size affects the future life of the mold, whether you can control the flying material, whether the structure needs a front top device, to determine the size of the mold meat, while considering the size of the mold frame.
- Thimble position, confirm that the customer have any requirements, the second is the size of the thimble, quantity, and the third is to consider whether affect product ejection and balance in production, four location thimble is considered whether to affect the water system, the position of plunger, would increase the cost and the die life also can produce certain effect, but can have good exhaust effect, It has a good auxiliary effect on ejection and exhaust of complex parts.
- Cooling system, it is recommended to adopt straight cooling as far as possible, when the straight through can not be solved, take point cooling, pay attention to mold temperature control, point cooling effect is not the best, high cost, loading and unloading is not conducive to production, but can take straight through and point cooling method.
- The size selection of the gate sleeve, large diameter injection projection area, small side on the contrary, it will produce many problems than pressure, such as large diameter waste, set than small pressure, flow rate impact on the mold is small, the equipment and mold life has the corresponding benefits, suitable for the structure is not very complex product castings. Small gate sleeve, material to reduce burning loss, impact speed, filling performance is better, complex structure castings are more used.
- Mould structure vulnerability, cracking, aging protruding parts and ejector pin to insert mode design as much as possible, by adopting the working style of the original body manufacturing for future production will bring inconvenience, such as not easy to repair, alteration, also go against to the structure of the exhaust, but the original way can reduce costs in manufacturing, manufacturing cycle is short, to die life is also good, The USE of inserts in the production can shorten the replacement, maintenance time, easy to use, fast, and the biggest advantage can play a better role in exhaust.
- The design of the runner and gate, regardless of the sprue, runner and gate design, and product molding, plays an important role, if the mould is the core of die casting production, so they are the design of the mould core, it will be liquid aluminum parts imported from pressure cylinder cavity, the flow speed, the fill time it import, Flow to the location, within the cavity temperature and need to keep steady, in the process of filling aluminium liquid temperature control, easy to hit parts of protection, the sequence of flow liquid aluminum mold, etc., must be short of one cannot, long kind of SPR is to import the first important position of the liquid aluminum, too wide, impact velocity is too long will be pressure, too thick is the above two defects exist side by side, They will increase the mold temperature of the runner and make it difficult to control, easy to break the material handle, produce more waste, and increase the filling time, but they all have a common advantage, stable flow rate, so should be carefully considered in the design, (reference data, generally less than 400 tons of machines, The spout length is 20nn-40mm, the width is generally 15mm-25mm, the thickness is 10mm-15mm,630 tons to 1000 tons of machine, the length is 35mm-65mm, the width is 30mm-50mm, the thickness is 15mm-25mm,1250 tons to 2000 tons of machine, the length is 45mm-80mm, Nn 35-65 - mm wide, it is 30 mm thick - 45 mm,)
In short, we pay attention to the long and width structure of the product in the design of direct casting, to ensure that the flow into the cross runner is smooth, flow speed and flow, to prevent the production of mold temperature is too high, waste waste caused by burning.
When a runner is designed generally adopt two into the water ways, one is the gate, the second is shunt type, ladder (split type) that is mainly based on product structure and setting, runner design, it is very important to choose tap position, shunt is to import the first step into the gate filling, smooth flow, flow velocity, it contains, Pressure is the most critical component to ensure the whole process of die casting, not only that, but also the shunt must ensure that the liquid aluminum entering the cavity can not easily impact each other, or premature collision, so as to avoid vortex formation of gas, reduce the flow rate and injection force, in the design of the length and thickness of the runner and deceleration parts, Should first consider whether the length and thickness can meet the flow and stability required by the diversion, too short or too thin will cause the space of direct casting aluminum water is not enough, so that the aluminum liquid can not smoothly and orderly into the diversion filling, and even cause pressure relief phenomenon. If the design is too wide or too thick, it will affect the flow rate of aluminum water, so that the aluminum water into the cavity to weaken the impact force, resulting in insufficient pressure transmission, and cause more burning loss. The deceleration part can not be too complex. When ensuring normal water entry on both sides, reduce the deceleration part as far as possible, so as not to cause excessive rolling of aluminum water, affect the flow rate and weaken the pressure. General casting and shunt connection, usually 45 degrees beinclined Angle, Angle affects the flow rate, weaken the strength, the flow rate can not be stable, small Angle flow rate too fast on the die surface impact, aluminum water is excessive insufficient, pressure dispersion is not concentrated, and even can weaken the injection force transmission.
The main design of the inner gate is set according to the location of the split. It is worth noting that the Angle of the gate into the water directly affects the direction and speed of the water, and will also cause cross impact, forming eddy current to weaken the pressure and prolong the filling time. But the rational use of water entry Angle, with the aid of aluminium in the cavity in the collision force of reflection, can change the flow velocity and direction, achieve the goal that we need filling quality, this is according to the hydraulics knowledge combined with working experience in die casting, also is the highest state of the die casting technology, is the goal of our die-casting technical workers unremitting pursuit.
- The overflow tank is an important part of the layout of the die casting mold. Usually, we are used to the overflow as the excretion of cold material, gas discharge, auxiliary ejection, the role of the equilibrium mold temperature, but the reasonable use of overflow, it can change the flow direction and velocity of liquid aluminum, to achieve the filling effect we do not expect.
- Know mould manufacturing value and market value, in a wide range of die casting enterprise often in the development of the mould, always put the mould manufacturing costs as the primary position to consider, but ignore the mould quality plays a crucial efficiency in production process, only consider cheap mould, starting looking for manufacturers, with production in the future in frequent prolonged labor laid the adverse factors, Mold failure, frequent maintenance, production is not smooth, low efficiency, high rejection rate, aging fast, cracking early, resulting in the whole casting processing process is not smooth, the plan can not be produced according to the expected, increase the manufacturing cost, which reflects the manufacturing value of the mold. Delivery delay, quality can not meet customer requirements, lost customer trust, mold to the company caused irreparable market value. So in the early development of mold, consider the cost, but must not be stingy, must ensure the quality of mold, fully reflect the core value of mold in die casting production.
- There are several points that should be paid attention to in the manufacture of molds. One is to absolutely avoid sharp corners. Second, try to eliminate the location of excessive stress concentration. Three is the die surface can not be left machine, electrode processing traces, so as not to easily produce stress. Four cavity die surface can not be over-polished, if the die surface is too light, too bright, it will lose heat dissipation function, resulting in premature aging, cracking. Five where there are concave and convex parts, including the step position, increase the arc position as far as possible, to avoid stress concentration, improve the fluidity of aluminum water.
- Do a good job in mold maintenance and maintenance, a good mold not only by manufacturing, daily maintenance, maintenance can also play a role in extending the life of the mold, improve production efficiency, reduce manufacturing costs. We all know how to do basic maintenance and maintenance, but it is difficult to do a good job in the production process. First of all, we should understand and understand the mold, understand the characteristics of the mold, understand the importance of the mold. Through the combination of training and education for employees and managers, make everyone understand this principle
- Common, analysis of the causes of the quality of die casting for the quality problem of the common performance, shrinkage, shrinkage, loose, porosity, air bubble, slag inclusion, pinhole, cold, cold, cold insulation, deformation, displacement, strain, crack, collapse and owe casting and so on, causes the quality of these factors are various, but the main reason from the mold, to solve these reasons, The first is to clear the reason and identify type, many people will confuse the porosity, slag inclusion, pinhole the cold wen as a cold, the cold material and as a cold, so the understanding and the understanding of it is difficult to make the right judgment, judgment is wrong, the solution is different, the result is not ideal, of course, wrong not only delay time will cause great waste. We take air holes, slag holes. Pinhole as an example to do a show, stomatal internal smooth, hole more rules, the cause of porosity, mainly, the gas discharge breakdown, vortex cavity, complex structure without the exhaust port, both into the water too fast, the overflow, airway open not ideal, the fill time and gate flow direction is not correct, material temperature is high, the left cavity in too much water, aluminum water contains gas, too fast, and so on. The slag hole is characterized by the hole shape and internal inhomogeneity. Most of the factors causing the slag hole are low mold temperature, low material temperature, unstable pressure, and impurities in liquid aluminum. The main reason for the pinhole is that the liquid aluminum contains oxides, (the residue of the large furnace when cleaning the furnace wall) and the low material temperature and mold temperature also have certain factors. After such careful screening and clear judgment, we can timely and correctly come up with effective solutions, so that the production is orderly and smooth, quality assurance, customer satisfaction of the die casting supplier.
We usually process and process of maintenance is one of the traditional approach, here I introduce a simple and more effective way of maintenance, in the mold of spare time, will die meat cleaning and polishing, into the electric box began to heat up, after the temperature rise to 500 degrees (not above the final annealing temperature) stop heating, the temperature dropped to 350 degrees or so, will die out empty cold meat, The mold meat surface to form an oxide film, oxide film can increase the flow of aluminum water can prevent aluminum water directly impact the mold surface, but also play a role in tempering stress, not only save costs, but also easy to maintain conducive to production. This way can be carried out at any time, the more times the effect is good, the equipment can be done, can also be purchased, the operation of the equipment is convenient, the mold can improve the life of 40%. You might as well try.
