Investment casting is also called lost wax casting. It is a casting method that uses fusible (soluble) primary mold and primary mold (core) to form castings. The casting produced in this method is smooth on the surface and accurate in size, so it is also called investment precision casting. Compared with other casting methods and part forming methods, investment casting has the following basic characteristics:

The castings are accurate in size and smooth in surface investment castings are the main characteristics of high dimensional accuracy and geometric accuracy, and the surface roughness is fine. At present, the dimensional accuracy of fine castings can exceed -0.005cm/cm, and the finest surface roughness can reach Rα0.63~1.25μm (equivalent to ▽7~▽8), which can greatly reduce the cutting and processing allowance of castings and achieve margin-free casting.

Castings with complex shapes can be casted with very complex shapes. They can also cast casts with wall thickness of 0.5mm and weight as small as 1g. Combined and integrated castings can also be cast to replace welding or assembly of several parts and reduce the weight of the parts. Therefore, investment casting can maximize the similarity between blanks and parts, which brings great convenience to the structural design of parts.

Unlimited by alloy materials, investment casting can cast carbon steel, alloy steel, ductile iron, copper alloy and aluminum alloy castings, and can also cast castings of high-temperature alloys, magnesium alloys, titanium alloys, and precious metals. For alloy materials that are difficult to forge, welding and cutting, it is particularly suitable for casting by fine casting.

The utilization rate of metal materials can be improved. Investment casting can significantly reduce the processing volume of the forming surface and matching surface of the product, and save the consumption of material during processing tables and cutting tools. Scrap metal materials can be recycled, and almost all the pouring risers of the fine casting workshop and the waste castings can be reused, thus greatly improving the utilization rate of metal materials. Taking the CA6140 ordinary lathe as an example, the first type, when 74 parts are invested in casting, the material utilization rate can reach 81.72%, and some parts can reach 100%. When the same parts are produced by forging, the material consumption is 2.8 times that of the fine casting.

High production flexibility and strong adaptability Investment casting is suitable for both large-scale production, small-scale production or even single-piece production. The production process does not require complex mechanical equipment. Tooling molds can be manufactured using a variety of materials and processes to facilitate the development of new products. Some urgent single pieces, even mold cutting and processing and hand-made investment molds, can greatly shorten the trial production cycle and save development costs, so investment casting production has high flexibility and wide adaptability.

Compared with other casting methods, investment casting does not have certain limitations in application. These are:

The casting size should not be too large. The process is complicated. The casting is slow to cool. Investment casting is the most complex among all blank forming methods, and the casting cost is also very high. However, if the product is selected properly, the parts are designed reasonably, and the high casting cost is compensated by reducing cutting, assembly and saving metal materials, investment casting has good economicality.

Especially for products with complex shapes, precision, high melting point alloys that are difficult to process, the technical and economic advantages of investment casting are undoubtedly unparalleled by other processes.

Investment casting is an ancient and young casting technology. It is said that it is ancient because this method has existed long ago 3,000 years ago; it is said that it is young because this method has entered the industrial field, which is only in the past 40 years. Lost wax casting technology was born in my country at the earliest, middle and middle of the Spring and Autumn Period, that is, 2,500 years ago, and has witnessed unearthed cultural relics. In recent years, on the basis of inheriting traditional craftsmanship, my country casting workers have used modern materials and craftsmanship to cast and copy many exquisite cultural relics, such as large Sakyamuni bronze Buddha statues, fish wash basins and chimes, making this ancient craft shine again. From exquisite bronze art products to modern and complex machine parts, investment casting has always been known for its unique advantages and excellent quality in its forming method. This is the decisive factor in the long-lasting and sustainable development of this technology.

In addition, the competition between military industry and high-tech industries always puts higher and higher requirements on the variety and quality of castings; the development of materials science provides a theoretical basis for the research of fine casting technology; and the advancement of industrial technologies such as metallurgy, machinery, chemical, energy and electronics provides a material and energy basis for the development of fine casting, all of which are the driving forces on which investment casting develops.
Chapter completed!