Investment Casting

Investment Casting

One of the most varied casting techniques utilised in manufacturing is investment casting. Engineers like it because it provides excellent dimensional precision, a clean surface finish, complicated design, quick production, and other advantages.

We delve into the nuances of investment casting in this piece.

One of the first known methods of metal shaping, lost-wax casting, is the foundation of the industrial process known as investment casting. We can also use “lost-wax casting” to describe contemporary investment casting procedures.

In different forms, investment casting has been utilised for the past 5,000 years. Beeswax was first used to create the patterns required for the casting process. The ability of investment casting to produce components in a range of metals and outstanding performance alloys with accuracy, reproducibility, adaptability, and integrity makes it highly regarded.

The delicate wax designs must survive the pressures used to create the mold. A large portion of the wax used in investment casting is recyclable. A recent variation on investment casting that omits some processes is called “lost-foam casting.”

Iron Casting

Investment casting comes from the method’s use of refractory material to surround the pattern and create a mold, which is then used to cast a molten substance. Glass, carbon steel, brass, aluminium, and stainless steel alloys are among the materials that can be cast. The hollow inside the refractory mold is a nearly perfect replica of the intended part, albeit somewhat enlarged. The outstanding surface characteristics produced by investment casting can lessen the requirement for further machine processes because of the refractory materials’ hardness.

The two most popular investment casting techniques are silica sol and water glass. The primary distinctions are the casting cost and surface roughness. The ceramic mold is formed of water glass quartz sand, and the water glass process dewaxes into the hot water. The ceramic mold is made of silica sol zircon sand, and the flash fire is dewaxed using this approach. The silica sol process is more expensive than the water glass approach but yields a superior surface.


Both tiny castings weighing a few ounces and massive castings weighing several hundred pounds can be made using this procedure. While initially more expensive than sand casting or die casting, the unit cost decreases with increased production. Complex shapes that might be challenging or impossible to create with other casting techniques can be produced with investment casting. Additionally, it can make goods with low tolerances and remarkable surface characteristics with little need for surface finishing or machining.

Investment casting: a brief history

Various techniques of investment casting were used by ancient Egyptians between 4000 and 3000 B.C. However, the increased need for components for airplane engines and the airframe industry during World War II boosted its economic relevance and appeal.

Lost wax casting has evolved over time from its first iteration, which involved stuffing clay into a beeswax mold, to the use of ceramic molds and the development of specialized dewaxing furnaces, etc.

Historically, investment casting has only been possible in large production volumes due to the expensive expense of master die manufacturing. However, the cost of die production has been minimised, and shorter die-run times have been made possible by the recent development of 3D printing of wax patterns.

Investment Casting

Investment Casting: The Pros and Cons

Pros of Investment casting

  • Investment casting allows for the one-piece production of components with extremely intricate designs and geometries.
  • Short length or shallow depth features allow for casting of thin sections as small as 0.40 mm (0.015 in) without cold shut problems.
  • Tolerances of 0.075 mm (0.003 in) or better can be easily achieved using low wax casting.
  • Investment casting, when compared to similar production methods, can give an exceptionally polished surface without the need for further finishing steps. RMS Rah typically ranges from 1.30 to 0.40 microns in size.
  • Although there is essentially no limitation on the types of materials that can be invested in, aluminum alloy, cast iron, and non-ferrous alloys are the most common choices. High-melting-point alloys are a prime candidate for this method.
  • A breeze on the face will help when using a master die to make wax patterns; nevertheless, wall drafts are not required.
  • Since there are no final lines, the cast would not receive any publicity. However, the wax patterns may show separation lines from the master die.

Frequently, an allowance as small as 0.4 to 1 mm (0.015 to 0.040 in.) is acceptable, and additional machining can be avoided or reduced to a minimum.

  • Extremely smooth as-cast surfaces can be achieved alongside high dimensional accuracy. These benefits shine brightest when working with metals that are difficult to machine and have high melting points, precluding the use of plaster or metal molds in the production process.
  • In many cases, wax can be salvaged for further use.

Cons of Investment casting

  • Lost wax casting is more expensive than other metal casting techniques like die casting and sand casting because it requires a lot of intricate procedures. Some of the processes can be automated, and while the upfront investment may be higher than with sand casting or die casting, the price per unit declines with increased production. Large-scale production of investment casting has permanently been restricted by the expensive cost of dies needed to create patterns.
  • The high cost also results from the need for specialised equipment, the high cost of labour, and the expense of refractory material.
  • If a part needs cores or has holes deeper than 1.5 times the diameter or smaller than 1.6 mm, casting the part becomes challenging.
Investment Casting Process

Investment Casting vs. Other Manufacturing Processes

It’s essential to consider several criteria when choosing a manufacturing process for your components, including design complexity, accuracy, surface polish, material adaptability, cost-effectiveness, production volume, tool complexity, weight range, and detail intricacy. The benefits of investment casting are illustrated in this table by contrasting it with other widely used manufacturing processes, including forging, sand casting, die casting, CNC machining, and CNC machining.

Value-Added Services

The Importance of Investment Casting in Today’s Industries

The capacity to make high-quality, complicated, and precise components invests casting crucial in today’s industries. The following are some main arguments in favour of investment casting:

Flexibility in size and weight: Investment casting offers considerable flexibility in the size and weight of components that can be manufactured, with pieces ranging from a few grams to several hundred kilos.

High precision and accuracy: Investment casting can create components with extremely tight tolerances and great dimensional consistency and accuracy. This saves time and resources by eliminating or reducing the need for extra machining or finishing.

Excellent surface finish: The surface finish of components made via investment casting is often of superior grade. This lessens the need for extra surface treatment or finishing procedures while enhancing the component’s visual appeal.

Cost-effectiveness for small batch production: Investment casting might initially have a high setup cost, but it becomes more affordable for small to medium production volumes, particularly when making complex components.

Complex designs and complicated geometries: With investment casting, pieces with elaborate detailing and intricate shapes that would be challenging or impossible to create using conventional casting techniques can be produced. This is especially helpful for sectors like aerospace and medicine, where intricate geometries are frequently needed for components.

The versatility of materials: Many metals and alloys, such as steel, stainless steel, brass, aluminium, bronze, and other superalloys, can be used with investment casting. Because each industry has different material requirements, it is suited for various industries.

Why Investment Casting in China?

Investment casting has become more prevalent in China as a highly accurate and efficient manufacturing technique. With a wide range of capabilities and competence, China has emerged as one of the world’s top producers of investment castings. Here are some significant benefits in China when comparing investment casting services across many domains:

Reduced Production Expenses: China can produce investment castings more affordably than the USA since labour expenses there are often cheaper. This can be especially helpful for projects that

Talented Labor Force: China boasts a sizable labour force with proficiency in investment casting methods. Many Chinese foundries have been in business for many years and have the know-how to create castings of the highest calibre.

Huge Manufacturing Capacity: China has several investment casting foundries and a sizable manufacturing capacity. This implies that choosing an appropriate manufacturer to fulfil particular production requirements has more options and flexibility.

Options for Materials: China provides many metals and alloys suitable for investment casting. Because of their adaptability, materials that satisfy particular needs—like strength, resistance to corrosion, and temperature resistance—can be chosen.

Modern Technology and Equipment: Chinese investment casting factories frequently use contemporary technologies and equipment, such as computer-aided design and manufacturing (CAD/CAM) capabilities, quality control systems, and advanced moulding equipment. High accuracy and effective production processes are made possible by this.

Supply Chain Integration: China has established a highly integrated supply chain ecosystem to facilitate investment casting. These consist of easily accessible raw materials, equipment, and machining skills, all of which can help create more efficient manufacturing procedures and shorter lead times.

While investment casting in China has these benefits, it’s vital to remember that different producers may offer different levels of quality. Selecting a trustworthy manufacturer for investment castings is crucial before placing an order.

Investment Casting Process

For thousands of years, investment casting has been a successful method for producing near-net shape goods in various forms. 

Investment Casting Process

For thousands of years, investment casting has been a successful method for producing near-net shape goods in various forms. 

Investment Casting Process

For thousands of years, investment casting has been a successful method for producing near-net shape goods in various forms. 

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