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3D printing sand casting production process

Sand casting is a commonly used casting process in the production of castings. Casting is one of the methods of metal processing. It is a metal processing method in which liquid metal is poured into a casting cavity suitable for the shape of the part. After it cools and solidifies, a metal part blank with a certain shape, size, and performance is obtained. However, the more complex the structural shape of the casting, the more troublesome the casting mold will be. Rapid prototyping technology makes the difficulty of the forming process independent of the complexity of the physical entity shape to be formed. Therefore, many modeling tasks of sand molds today must be completed with 3D printers. This valuable technical feature enables it to best adapt to the competitive environment of the contemporary manufacturing market and develop rapidly.

The currently very popular additive manufacturing technology (often referred to as 3D printing technology) is a breakthrough in manufacturing principles. It does not require any special auxiliary tools and is not limited by batch size. It can quickly produce products directly from CAD three-dimensional models. It can be directly transformed into a three-dimensional solid model, and the product cost has almost nothing to do with the complexity of the parts. It is especially suitable for manufacturing complex parts with fine internal structures, and the manufacturing flexibility is extremely high, one machine can be used to manufacture various types of parts. parts of the same shape.

Rapid prototyping technology only requires 30% to 50% of the labor hours and 20% to 35% of the cost of traditional processing methods to directly manufacture product samples or molds. 3D printing prototypes have been widely used in the fields of machinery, electronics, automobiles, aviation, and aerospace. With the improvement of this technology, it has brought a revolution to the manufacturing industry.

Rapid prototyping casting molds can be used for sand casting, investment casting, ceramic precision casting, and plaster precision casting. Direct 3D printing of sand molds eliminates the need for traditional craft models. The molding process of the molding material is accurately controlled based on the geometric information of the casting CAD model (including process information such as the pouring system) and the casting mold is directly manufactured, which is a major change in the traditional casting process.

So how to combine casting and 3D printing?

The mold for industrial parts is made up of a complete set of combinations.

This entire set of molds can be completed through 3D printing technology. In the CAD file of the 3D printer, a complete set of molds is “lying flat” on the printing table like this.

Since the sand 3D printer has ample space in the molding cylinder, for the sake of cost savings, engineers can import many model files into it before printing. So before each printing, the model data looks dense.

Unlike common desktop 3D printers, a sand 3D printer is quite large, so it can only be seen in factories. The molding size is up to 2 meters × 1 meter × 1 meter

The process of 3D printing is to first lay a layer of sand, solidify it with an adhesive, and then stack it layer by layer. The material of the sand mold is quartz sand. Since resin is used to bind the sand materials together, this sand is also called resin sand. Layer thicknesses of resin sand materials can be as low as just 300 microns (the thickness of three human hairs).

Let’s take the production of a turbine industrial part as an example to see how this part is manufactured.

In the third step, we see “the combination of 3D printing molds and traditional molds.” Because a set of molds is often composed of a sand core and an outer mold. The structure of the sand core is relatively complex and the outer mold is relatively simple. Therefore, due to cost considerations, many manufacturers only use 3D printing to make sand cores, and the outer molds are still made using traditional processes. Of course, it can be directly printed and manufactured in one piece.

The traditional sand mold manufacturing process is generally: CAD design → process simulation → module production → tooling and fixture manufacturing → sand mold manufacturing → casting. After using 3D printing, the process is CAD design → process simulation → 3D printing sand mold → casting. It used to take a month, but now it can be completed in just a few days, which greatly shortens the production cycle and saves a lot of manual work.

Here are some application cases:

Advantages of 3D printing sand casting

●Saving time: short delivery cycle

●Cost saving: tool-free construction

●High flexibility for quantity, shape design, and variations

●Almost any complex geometric shape

●Complex cores can be built in one piece and accurately recreated

●Dimensions: from small parts to 2000 x 1000 x 1000 mm

●No storage and maintenance costs compared to traditional mold-making

●Any hybrid manufacturing method and combination with traditional crafts

●Components/reverse engineering