Competition and progress of investment casting

Move forward in competition with other processes

It develops rapidly in the competition of powder metallurgy, precision forging and other similar finishing processes, as well as metal parts manufacturing processes such as machining and investment casting.The following three aspects are worth noting:

(1) investment casting can produce not only small parts, but also large parts with a maximum profile size of 1.8m, with a minimum wall thickness of less than 2mm and a maximum component weight of nearly 1,000kg.Castings are becoming more accurate: tolerances range from 25.4 mm to 254 mm±O 254 mm within 254 mm}.For every 25.4mm increase, the tolerance increases by 0.076mm;For every 254 mm increase of 25.4 mm, tolerance increases by ±0.127 mm.The surface roughness Ra is about 0.63 microns (7 to 8).The mechanical properties of investment casting are getting better and better.The words "precision", "big" and "thin wall" can be used to reflect the trend of investment casting to produce more refined, larger and stronger high-value products.

(2) advances in mechanization and automation have shattered the notion that investment casting processes cannot be mechanized.In Japan, Britain and the former Soviet union, the investment casting process has been successfully used to produce low-cost cars and other civilian components..

(3) in recent years, the combination of investment casting fork and rapid prototyping technology has greatly shortened the casting production cycle.

All of these aspects allow the investment casting surface to be expanded and competitive.Therefore, it is well positioned to compete with other processes.Investment casting should be one of the most promising casting processes.

Over the past 50 years, investment casting has made great progress in forming, shell making, casting and post-treatment.There are many new materials, new technology and new equipment have a great impact on the development of investment casting: such as water-soluble core, ceramic core, metal material improvement, large investment casting technology, titanium gold casting technology, directional solidification and single crystal technology, filtration technology, thermal isostatic pressure technology, rapid prototyping technology;The application of computer in investment casting, mechanization and automation.Here are just a few.

2.1 heat-resisting alloy

With the development of aircraft engine, the requirements of heat resistance and high temperature creep resistance of blades and other components are getting higher and higher.For example, turbine blades, from IN 100 and B1900 IN the 1960s to MM247 IN the 1970s, MM200 and PWA1480 IN the 1980s.In order to meet the different requirements of different parts, a complete series of superalloy materials, such as cobalt base, nickel base, iron nickel base, have been formed.Examples include 1N700,1N738LC/C, x-40, x-45, u-710, MA6000, m-ar-m 002, m-ar-m 247, MG A2400, MM O07, ulti-mel, Nim ocast90, Nimom ic75, Rene80, rr102.h 46, H $25.Ecy-768, fsx-414, G TD222, B1 900, DSCM247LC, DSGTDll and other grades of heat-resistant alloy materials.

In recent years, with the development of industrial gas engines, especially those for large power stations, heat-resistant alloys of aero-engines have been introduced into industrial gas turbines and are still being improved.