Sand casting is not very backward?! Can it be replaced with die casting?

Sand casting does not lag behind.

The die casting method also has the following disadvantages:

1) Die-casting alloys are restricted.

At present, there are only six kinds of die-casting alloys, such as zinc, tin, lead, copper, magnesium, aluminum, etc., among which copper alloy has the highest melting point and aluminum alloy die-casting is widely used. Recently, there have been reports of cast iron die casting, but for economic reasons, it is still necessary to study the relevant materials, mold materials and working methods.

2) The equipment is expensive.

The equipment required for die casting production such as die casting machines, melting furnaces, holding furnaces and die casting molds is quite expensive.

3) The air tightness of the casting is poor.

Because when the molten liquid is filled into the die-casting mold at high speed, there will be turbulence, and local porosity or shrinkage holes will be formed, which will affect the air tightness of the casting. There is currently a dipping treatment that can be used to improve air tightness.

No, sand casting looks a little backward, but in fact, sand casting is quite real, a pile of sand can do a variety of things.

However, in the case of die-casting, it is very troublesome to have different molds, but the effect of the two is also completely different, and it can only be said that each has its own strengths.

After all, sand casting in China has gone through the baptism of history.

The two are not the same level of casting, and sand casting also has its advantages.

Die casting, due to the different melting points of alloys, is prone to produce many problems, so when choosing molds and casting materials, it should be considered.

How many tons of stuff do you go die casting?

Sand casting is a traditional casting process that uses sand as the main molding material to make casting molds. Sand molds are generally mined.

Gravity casting, low-pressure casting, centrifugal casting and other processes can also be used when there are special requirements. Suitable for sand casting.

It has a wide range of adaptability, small parts, large parts, simple parts, complex parts, single pieces, and large quantities. For sand casting.

In the past, most of the molds were made of wood, commonly known as wooden molds. The disadvantage of wood mold is that it is easy to deform and be damaged; Except for a single piece of life.

In addition to the sand castings, aluminum alloy molds or trees with high dimensional accuracy and long service life can be used.

Grease molds. Although ** has improved, it is still much cheaper than molds for metal mold casting in small batches and more.

In the production of large parts, the best advantages are particularly prominent. In addition, sand molds are more refractory than metal types, so they are like copper molds.

Materials with high melting points, such as gold and ferrous metals, are also commonly used in this process. However, there are some nots to sand casting.

Sufficient: Because each sandy mould can only be poured once, the mould is damaged after the casting is obtained and must be rebuilt.

mold, so the production efficiency of sand casting is low; And because the overall nature of sand is soft and porous, sand mold casting.

The dimensional accuracy of the castings is low, and the surface is rougher.

Summary. Pressure casting.

Pressure casting is a pouring process of molten metal, and it is achieved through the action of external force and casting molds, which is one of the casting methods often adopted.

Sand casting. Different from pressure casting, the main molding material of this process is sand, which can effectively overcome the various drawbacks brought by other materials, but sand casting also has some shortcomings, because each sand casting can only be poured once, so the production efficiency will not be very high, and the dimensional accuracy needs to be improved.

Can pressure casting replace sand casting?

Pressure casting. Racket pressure casting is a pouring process of molten metal, and it is achieved through the action of external force and casting molds, which is one of the methods that are often used to cast the head of the mold. Sand casting.

Different from pressure casting, the main molder of this process is sand, which can effectively overcome the various drawbacks brought by other materials, but sand casting also has some shortcomings, because each sandy casting mold can only be poured once, so the production efficiency will not be very high, and the dimensional accuracy needs to be improved.

Pressure casting can replace sand casting.

Can it be replaced.

OK. Can you give an example?

I've already sent you the difference between the two of them, and it's already obvious to you.

Pressure casting. Racket pressure casting is a pouring process of molten metal, and it is achieved through the action of external force and casting molds, which is one of the methods that are often used to cast the head of the mold. Sand casting.

Different from pressure casting, the main molder of this process is sand, which can effectively overcome the various drawbacks brought by other materials, but sand casting also has some shortcomings, because each sandy casting mold can only be poured once, so the production efficiency will not be very high, and the dimensional accuracy needs to be improved.

The casting method of making molds and producing castings with molding sand is called sand casting; When the casting is finished and the casting is taken out, the sand mold is destroyed, so the sand casting mold can only be used once;

Sand casting tool: sample this carry infiltration and type forest spine core box;

Methods of metal mold casting:

1. The method of pouring liquid metal into a casting mold made of metal to obtain or obtain a casting is called metal mold casting;

2. The metal mold can be poured many times, which saves a lot of man-hours of molding and improves the labor efficiency.

3. The size of the casting is accurate, the surface is smooth and clean, and the mechanical properties are good;

4. However, the metal type is difficult to manufacture, the cost is high, and the poured iron parts are easy to produce white mouths;

5. Metal mold casting is mostly used for batches.

What you want to ask is what die casting is? Die casting is the metal mold pressure casting carried out on the die casting machine, which is the casting process with the highest production efficiency at present.

Die-casting machines are divided into two categories: hot chamber die-casting machines and cold-chamber die-casting machines. The hot chamber die-casting machine has a high degree of automation, less material loss, and higher production efficiency than the cold-chamber die-casting machine, but due to the restriction of the heat resistance of the parts, it can only be used for the production of castings with low melting point materials such as zinc alloy and magnesium alloy.

Aluminum alloy die castings, which are widely used today, can only be produced on cold chamber die casting machines due to their high melting points. The main feature of die casting is that the molten metal fills the cavity under high pressure and high speed, and is formed and solidified under high pressure.

The disadvantage of die casting is that because the molten metal is inevitably wrapped in the cavity inside the cavity in the process of filling the cavity under high pressure and high speed, forming subcutaneous pores, aluminum alloy die castings should not be heat treated, and zinc alloy die castings should not be sprayed on the surface (but can be painted).

When the internal pores of the casting are heated by the above treatment, they will expand when heated, resulting in deformation or bubbling of the casting. In addition, the machining allowance of die castings should also be obtained. It can not only reduce the weight and cost of castings, but also avoid penetrating the dense layer on the surface, exposing subcutaneous pores, and causing the workpiece to be scrapped.

Sand casting is the most traditional casting method, using sand to make cavities for pouring to obtain castings, but the pressure of molten metal in sand casting is often insufficient, resulting in the formation of defects such as incomplete filling and cold separation;

As a result, a new casting method was born: pressure casting, that is, die casting.

Artificial pressure is provided to strengthen the fluidity and filling ability of molten metal, and better quality castings are obtained is a casting method in which molten gold is poured into the pressure chamber, the cavity of the steel mold is filled at high speed, and the molten alloy is solidified under pressure to form castings.

The main feature that distinguishes die casting from other casting methods is high pressure and high speed.

Sand casting – a casting method for producing castings in a sand mold. Steel, iron, and most non-ferrous alloy castings can be obtained using the sand casting method. Because the molding materials used in sand casting are cheap and easy to obtain, the casting manufacturing is simple, and it can adapt to the single production, batch production and mass production of castings, and has been the basic process in casting production for a long time.

The basic raw materials for the manufacture of sand molds are foundry sand and molding sand binders. The most commonly used foundry sand is siliceous sand. When the high-temperature performance of silica sand cannot meet the requirements of use, special sands such as zircon sand, chromite sand, and corundum sand are used.

In order to make the sand mold and core have a certain strength, and not be deformed or damaged when handling, fitting and pouring liquid metal, it is generally necessary to add molding sand binder in casting to bond the loose sand particles into molding sand. The most widely used molding sand binder is clay, and various dry or semi-dry oils, water-soluble silicates or phosphates and various synthetic resins can also be used as molding sand binders. The outer sand mold used in sand casting can be divided into three types: clay green sand mold, clay dry sand type and chemically hardened sand type according to the binder used in the molding sand and the way it builds strength.

Example (1) Requirements for mold sprue on cold chamber horizontal die-casting machine:

The size of the inner diameter of the pressure chamber should be selected according to the required specific pressure and the filling degree of the pressure chamber, and at the same time, the inner diameter deviation of the gate sleeve should be appropriately enlarged by a few wires compared with the deviation of the diameter of the pressure chamber, so as to avoid the problem of punch jamming or serious wear caused by the different shafts of the diameter of the gate sleeve and the pressure chamber, and the wall thickness of the gate sleeve should not be too thin. The length of the sprue sleeve should generally be smaller than the ejection lead of the injection punch so that the paint can be removed from the chamber.

The inner hole of the pressure chamber and the gate sleeve should be finely ground after heat treatment, and then ground along the axis direction, and its surface is rough.

The sink and the cavity that forms the paint have a recess depth equal to the depth of the cross sprue, and its diameter is matched with the inner diameter of the gate sleeve, and it has a 5° slope along the demoulding direction. When a coated sprue is used, the volume of the effective length of the chamber is shortened, and the filling degree of the chamber can be improved. The entrance of the horizontal sprue of the cold horizontal mold should generally be located in the upper inner diameter of the pressure chamber 2 3 or more, so as to avoid the molten metal in the press chamber from entering the sprue prematurely under the action of gravity and starting to solidify in advance.

The cross-sectional area of the sprue should be gradually reduced from the sprue to the inner gate, and in order to expand the cross-section, negative pressure will occur when the molten metal flows through, which is easy to inhale the gas on the parting surface and increase the eddy current wrapping gas in the flow of molten metal. Generally, the cross-section of the outlet is 10-30% smaller than that of the inlet.

The sprue should have a certain length and depth. The purpose of maintaining a certain length is to play the role of stabilizing the flow and guiding. If the depth is not enough, the molten metal will cool down quickly, and if the depth is too deep, the condensation will be too slow, which will not only affect the productivity but also increase the amount of return material.

The cross-sectional area of the cross-sprue should be larger than the cross-sectional area of the inner gate to ensure the speed of metal liquidation. The cross-sectional area of the main cross-sprue should be greater than the cross-sectional area of each branch cross-sprue.

The bottom two sides of the sprue should be rounded to avoid early cracks, and the two sides can be made with an inclination of about 5°. The surface roughness of the sprue part. The parting surface should not be closed immediately after the metal liquid enters the mold, and the overflow groove and exhaust groove should not hit the core head-on.

The flow direction of the liquid metal into the mold is as much as possible along the ribs and heat sinks that are cast, and the thick wall is filled from the thick wall to the thin wall.

When selecting the location of the inner gate, the molten metal flow is as short as possible. When using multi-strand inner gate, it is necessary to prevent several strands of molten metal from converging and impacting each other after entering the mold, resulting in defects such as eddy current gas encapsulation and oxidation inclusion.

The thickness of the inner gate of the thin-walled part should be appropriately small to ensure the necessary filling speed, and the setting of the inner gate should be convenient for removal, and the casting body should not be defected (eat meat). The overflow groove should be easy to remove from the casting and try not to damage the casting body.

When an exhaust groove is set up on the overflow groove, it is necessary to pay attention to the position of the overflow port to avoid prematurely blocking the exhaust groove and making the exhaust groove ineffective.

Several overflow ports or a very wide and thick overflow port should not be opened on the same overflow groove, so as to avoid the cold liquid, slag, gas, paint, etc. in the molten metal from returning to the cavity from the overflow groove, resulting in casting defects.