IAQ Concerns During the Investment Casting Process

Investment Casting Defined

Investment casting is a modern version of the ancient technique of lost-wax casting. As a manufacturing process, investment casting was developed during WWII when demand for aircraft, artillery, and military parts increased, and the need for fast, cheap, and large-scale die-casting was critical. Today, investment casting is used in virtually all industries and can present health risks to workers if indoor air pollution prevention measures are not in place.

The original method of using wax to create a mold to duplicate an object into a different material form dates back 6500 years. The present industrial version of investment casting (also known as precision casting), involves constructing a mold out of wax or plastic and then pouring liquefied metal or metal alloy inside the template. After the metal solidifies, the outer cast is removed, leaving the final product, a metal replica. The term “investment” refers to the pattern being “invested” or bounded, with a heat-resistant material.

Industrial Use

Industries that rely on investment casting include aerospace, automotive, chemical, military defense, dentistry and medical, tooling, and countless others. Aerospace, for example, relies on this process to manufacture intricate and lightweight components that require strength, durability, and a wide range of metal and alloy options. The parts and objects needed vary from turbine blades to landing gear, metal clamps to valves, and pipes to gears. 

Advantages of Investment Casting

Investment casting is prized for its ability to create vast numbers of complex molds with speed, precision, and efficiency.

It is a versatile method, allowing for endless possibilities in sizing, intricacy of design, and finishes. It can produce highly durable objects with a tolerance to extreme temperatures and pressures. For high-volume products, investment casting has lower production costs, minimizes waste, and has a reduced environmental impact as compared to other casting methods.

IAQ Concerns

For all its benefits, investment casting is a manufacturing process and, like many other industrial practices, can create indoor air quality problems. 

Let’s use the example of aerospace turbine blades. Mass-produced by investment casting, the process requires a hollow cast in the shape of the blade, which is then filled with molten nickel-based superalloys. The alloys contain other metals, such as cobalt, that, when heated or melted, can emit toxic gases into the environment. In an indoor setting, these emissions can be inhaled and cause illness.

Negative Health Effects

We’ll use cobalt as an example of one of the many potentially hazardous metal toxins that can cause indoor air pollution during investment casting. Of course, the level of harm will depend on the amount of exposure and duration. According to the CDC, occupational exposure to cobalt dust and fumes has been linked to respiratory illness, skin allergies, ear, nose, and throat irritation, asthma, lung dysfunction, and, in some cases, cancer.

Symptoms include:

Cough, dyspnea (breathing difficulty), wheezing, decreased pulmonary function; weight loss; dermatitis; diffuse nodular fibrosis; respiratory hypersensitivity, asthma

In most cases, working with metals does not pose a health risk as long as proper precautions are taken to protect workers and maintain a healthy indoor environment.

How Source Capture Can Help

To avoid problems related to the inhalation of dust and fumes emitted during the investment casting process (and during post-casting operations), the following measures should be in place:

Engineering Controls such as proper ventilation

Equipment Maintenance, performed regularly

Occupational Training to educate workers about the potential risks involved in working with VOC metal dusts and fumes

The use of Personal Protective Equipment (PPE) such as facemasks, googles, etc. where needed

Air Cleaning Equipment, such as dust collectors and fume extractors, can be used to remove emissions at the source, before they enter a worker’s breathing space

For our customers requiring IAQ solutions for their investment casting applications, we supply a variety of products. Our powerful source-capture model, the Extract-All SP-800, is particularly effective in removing smoke, dust, and fumes before they can be released into the air.

At AIRS, Inc., we provide our customers with stellar products and a depth of knowledge. Contact us today to set up a free air quality assessment from one of our experienced indoor environmental specialists.