Introduction to the method of aluminum alloy die casting to solve casting porosity

The precision requirements of precision CNC machining parts mainly refer to the precision requirements of size, shape, position and surface, and the surface precision mainly refers to the surface roug(2021年)

cncmachiningptj — 2021-07-02T12:31:22+0900

1. Parts with high precision requirements

The precision requirements of precision CNC machining parts mainly refer to the precision requirements of size, shape, position and surface, and the surface precision mainly refers to the surface roughness. Because the CNC lathe has good rigidity, high precision in manufacturing and tool setting, and can easily and accurately perform manual compensation and automatic compensation, it can process shaft parts with high dimensional accuracy. In some cases, it can achieve the effect of turning instead of grinding. In addition, because the motion of the CNC lathe is realized by high-precision interpolation and servo drive, it can process parts with high shape accuracy requirements such as straightness, roundness, and cylindricity.

Because the CNC lathe can complete a lot of processing content in one clamping, it can effectively improve the position accuracy of the parts, and the processing quality is stable. The CNC lathe has the function of cutting at constant linear speed, so it can not only cnc machine parts with small and uniform surface roughness, but also suitable for turning parts with different surface roughness requirements. Generally, the machining accuracy of CNC lathes can reach 0.001mm, and the surface roughness Ra can reach 0.16μm (precision CNC lathes can reach 0.02μm).

2. Parts with small surface roughness values

The precision CNC machining numerical control lathe has a constant linear speed cutting function, which can machine parts with small and uniform surface roughness values. The problem is that the surface roughness depends on the feed rate and cutting speed when the material, the finishing allowance and the tool have been determined. The cutting speed changes, resulting in inconsistent surface roughness after turning. Using the constant line cutting function of the CNC lathe, you can choose the best line speed to cut cones, spheres and end faces, so that the surface roughness values after turning are small and consistent. .

3. Parts with complex surface contour shapes

Because the precision titanium machining CNC lathe has linear and circular interpolation functions (some CNC lathes also have some non-arc curve interpolation functions), it can turn complex shapes composed of arbitrary straight lines and various flat curves. Body parts, including list curves that cannot be described by equations that are processed by fitting calculations. As shown in Figure 4-1, the molding surface of the closed cavity of the shell part cannot be machined on an ordinary lathe, but it can be easily machined on a CNC lathe.

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Compared with conventional CNC titanium machining processes, the outstanding advantages of turning-milling combined machining are mainly manifested in the following aspects:(2021年)

cncmachiningptj — 2021-07-02T12:30:50+0900

Compared with conventional CNC titanium machining processes, the outstanding advantages of turning-milling combined machining are mainly manifested in the following aspects:

(1) CNC turning and milling compound processing manufacturers introduced to shorten the product manufacturing process chain and improve production efficiency. A variety of special tools can be installed, new tool arrangement, reduce tool change time, improve processing efficiency, turning-milling composite processing can complete all or most of the machining procedures in one clamping, thus greatly shortening the product manufacturing process chain. In this way, on the one hand, the production assistance time caused by the change of the installation card is reduced, and the manufacturing cycle and waiting time of the tooling fixture are also reduced, which can significantly improve the production efficiency.

(2) Reduce the number of clamping and improve cnc brass machining accuracy. The reduction in the number of card loading avoids the accumulation of errors due to the conversion of positioning benchmarks. CNC turning-milling composite processing manufacturers analyze, at the same time, most of the current turning-milling composite processing equipment has the function of online detection, which can realize the in-position detection and precision control of key data in the manufacturing process, thereby improving the processing accuracy of the product; high-strength integration The design of the machine bed improves the gravity processing ability for difficult-to-cut materials; the machine is equipped with an automatic feeding device, which can realize automatic feeding and continuous, basically realizing the assembly line operation of a single machine tool.

(3) Reduce floor space and reduce production costs.

CNC delrin machining composite processing manufacturers analyze that the compact and beautiful appearance design improves the use of space, and makes maintenance and repair more convenient, so that customers can get the greatest satisfaction; although the single unit price of the turning-milling composite processing equipment is relatively high, but due to the manufacturing process chain The shortening and the reduction of the equipment required for the product, as well as the reduction of the number of fixtures, workshop area and equipment maintenance costs, can effectively reduce the overall fixed asset investment, production operation and management costs.

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1. Sufficient hardness and strength: After many tests, engineers can find out and master the hardening conditions and working conditions of beryllium copper machining alloy precipitation and the mass (2021年)

cncmachiningptj — 2021-07-02T12:29:44+0900

Nowadays, more and more beryllium copper mold materials have been used in the manufacture of plastic molds, and there is a rising trend. What is the reason for this phenomenon? Let me learn about the use of beryllium copper in plastic molds with the editor, and why.

1. Sufficient hardness and strength: After many tests, engineers can find out and master the hardening conditions and working conditions of beryllium copper machining alloy precipitation and the mass characteristics of beryllium copper (this is the point that the beryllium copper alloy is based on A prelude to the application of formal products in the market); beryllium copper materials need to go through multiple cycles of tests before they are used in plastic molds to finally determine the physical properties and chemical components that meet the manufacturing and processing; the proof of theory and practice-beryllium When the hardness of copper is hrc36-42, it can reach the hardness, strength, high thermal conductivity required for tungsten die manufacturing, simple and convenient machining, long mold life, and save development and production cycle.

2. Good thermal conductivity: The thermal conductivity of beryllium copper material is beneficial to control the temperature of the plastic machining mold, and it is also easier to control the molding cycle, while ensuring the uniformity of the mold wall temperature; if compared with the steel mold, the molding of beryllium copper The cycle is much smaller, and the average temperature of the mold can be reduced by about 20%. When the difference between the average ejection temperature and the average wall temperature of the mold is small (for example, when the mold parts are not easy to be cooled), use the beryllium copper mold material to cool The time can be reduced by 40%. The mold wall temperature is only reduced by 15%; the characteristics of the above beryllium copper mold materials will bring several benefits to the mold manufacturers using this material to shorten the molding cycle and increase the productivity; the uniformity of the mold wall temperature improves the quality of the drawn products; The mold structure is simplified because the cooling pipes are reduced; the temperature of the material can be increased, thereby reducing the wall thickness of the product and reducing the cost of the product.

3. Long service life of the mold: Budgeting the cost of the mold and the continuity of production, the expected service life of the mold is very important for the manufacturer. When the strength and hardness of the beryllium copper meet the requirements, the temperature of the beryllium copper Stress insensitivity can greatly improve the service life of the mold. Before determining the use of beryllium copper mold materials, the yield strength, elastic modulus, thermal conductivity and temperature expansion coefficient of beryllium copper should also be considered. The resistance of beryllium copper to thermal stress is much stronger than that of die steel. From this point of view, the service life of beryllium copper is remarkable!

4. High thermal penetration rate: In addition to the thermal conductivity of the pull, the thermal penetration rate of the powder metallurgy mold material is also very important to the plastic products. On the mold using beryllium bronze, the traces of overheating can be eliminated. If the thermal penetration rate is low, The contact temperature of the distal region of the mold wall will be higher, which will increase the temperature difference of the mold, and in extreme cases will cause the temperature of the region to change from the sink mark at one end of the plastic product to the trace of overheated product at the other end .

5. Excellent surface quality: beryllium copper is very suitable for surface finishing and can be directly electroplated, and the adhesion performance is very good, and the polishing treatment of beryllium copper is also very easy.
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For zinc alloy die castings to be electroplated surface treatment, this link is very important. If the electroplating is not done well, all the work in the early stage will be wasted.(2021年)

cncmachiningptj — 2021-07-02T12:28:32+0900

For zinc alloy die castings to be electroplated surface treatment, this link is very important. If the electroplating is not done well, all the work in the early stage will be wasted. Therefore, we must pay attention to the electroplating process of the product. Then the quality of electroplating is affected by those factors. Carbide die casting summarizes the following for you:

1. For the selection of raw materials for zinc alloy die-casting parts, regular national standard materials must be selected for product die-casting.

2. The design of zinc alloy die-casting parts should be reasonable. The shape of die-casting parts should consider the concealing ability of electroplating, and try to reduce the impervious holes, so that it is not easy to carry the solution in the washing. Cut sharp corners and other parts to make the power lines evenly distributed during electroplating.

3. The die casting and die-casting mold manufacturing design are reasonable, so that the die-casting parts will not suffer from the shortcomings of shrinkage, pinholes and looseness. The above-mentioned shortcomings will directly affect the adhesion of the coating.

4. In the production process of zinc alloy die castings, try to reduce the segregation phenomenon. If aluminum segregates in certain parts, aluminum will firstly dissolve during degreasing, which will cause pores and pinholes on the surface of the die-casting parts and cannot be cleaned, resulting in poor bonding strength, resulting in peeling and blistering of the coating.

5. Pay attention to the scale during the grinding and polishing process. The fine layer of 0.05-0.1mm formed during the cooling process of the Magnesium die casting is very important for electroplating. The loss of the fine layer should be reduced as much as possible during the grinding and polishing. If this layer is ground and thrown away, What will be revealed will be a porous structure, and no good electroplating layer will be obtained on this layer.

6. The copper-nickel-chromium electroplating layer composed of multiple plating types is a negative plating layer relative to the substrate. As long as the soft magnetic mold core materia maintenance is effective, the zinc alloy parts will corrode in the humid air, so it is necessary to ensure that the plating layer is free hole. Otherwise, the corrosion products of the zinc alloy will cause blistering of the coating. Compared with steel parts, the coating should be thicker to be suitable for zinc alloy die castings.

7. Residues of die-casting parts in the process of die-casting and die machining should be cleaned as much as possible after processing. Because the residue is a vivid metal, in any process of electroplating, it will react with the solution and damage the plating solution, which will affect the quality of electroplating.

Zinc alloy die casting

The main factors affecting the electroplating quality of zinc alloy die castings are summarized in the above seven points. We focus on the customization of the die casting industry and have our own surface treatment department. The quality is controllable and the cost is controllable. Welcome to consult if you need it!
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The existence of forging defects may affect the processing quality or processing quality of the subsequent processes, and some seriously affect the performance and use of the forgings,(2021年)

cncmachiningptj — 2021-07-02T12:25:59+0900

The existence of forging defects may affect the processing quality or processing quality of the subsequent processes, and some seriously affect the performance and use of the forgings, and even greatly reduce the service life of the finished parts and endanger safety. Therefore, in order to ensure or improve the quality of cold forgings, in addition to strengthening quality control in the process and taking corresponding measures to prevent the occurrence of forging defects, necessary quality inspections should also be carried out to prevent subsequent processes (such as heat treatment, surface treatment, cold processing, etc.). ) And forgings with defects that have adverse effects on performance will flow into the subsequent process. After quality inspection, remedial measures can be taken on the forgings made according to the nature of the defect and the degree of influence to use, so that it meets the technical standards or requirements for use. Therefore, in a sense, the quality inspection of forgings, on the one hand, is to check the quality of the forgings that have been made, and on the other hand, to point out the improvement direction for the forging process, so as to ensure that the quality of forgings meets the requirements of forging technical standards and meets the design Requirements on processing and use.

Forging
The quality inspection of hot forgings includes the inspection of appearance quality and internal quality. Appearance quality inspection mainly refers to the inspection of the geometric size, shape, surface condition and other items of the forging; the internal quality inspection mainly refers to the inspection of various items such as the chemical composition, macrostructure, microstructure and mechanical properties of the forging. Specifically, the appearance quality inspection of forgings is to check whether the shape and geometric dimensions of the forgings meet the specifications of the drawings, whether the forgings have defects on the surface, what kind of defects are they, and what are their morphological characteristics. The inspection content of the surface condition is generally to check whether the forging surface has surface cracks, folds, wrinkles, pits, orange peel, blisters, scars, corrosion pits, bruises, foreign objects, underfill, pits, lack of meat, Defects such as scratches. The internal quality inspection is to check the internal quality of the forging itself. It is a quality condition that cannot be found by the appearance quality inspection. It includes the inspection of the internal defects of the forgings and the inspection of the mechanical properties of the forgings. Parts or large metal forgings should also be subjected to chemical composition analysis.

Forging
For internal defects, we will use low-power inspection, fracture inspection, and high-power inspection to inspect the forgings for the presence of internal cracks, shrinkage holes, porosity, coarse crystals, white spots, dendrites, and streamlines that do not conform to the shape, Defects such as streamline turbulence, penetrating flow, coarse crystal ring, oxide film, delamination, overheating, overburning organization, etc. For the mechanical properties, it is mainly to check the normal temperature tensile strength, plasticity, toughness, hardness, fatigue strength, high temperature instantaneous rupture strength, high temperature permanent strength, permanent plasticity and high temperature creep strength.
After the forgings are produced into rigging, their stress conditions, importance, and working conditions are different during use, and the materials and metallurgical forging used are also different. Therefore, different departments will classify forgings according to the above conditions and the requirements of the department. , Different departments and different standards have different classifications of forgings.
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