Surface quality of parts is vital to the appearance and often the performance of components, which is why it is important to avoid pitting in castings. Pitting is a commonly occurring problem that can be avoided through careful process management. Contamination in a mold can result in indentations or pits on the surface of the casting. It can also happen when a sprue is poorly designed and allows trapped air bubbles to pit the part’s surface. Such bubbles can also result from overheated alloys, which may create gas in the mold. An under-heated mold can have remanent wax bits from the pattern when it is melted away. An expert foundry staff can avoid these and other pitting issues.

While part consistency is essential for the vast majority of manufacturers, all too often they receive more out-of-spec parts than is acceptable. Investment casting can be the cure for inconsistent castings. Investment casting is a near-net-shape process, which means the castings come out of the molds extremely close to the desired geometry and specifications. They require little or no machining and finishing work, which greatly reduces the occurrence of flaws and inconsistencies.

When investment castings become brittle and are discolored and rough, it is likely the foundry is experiencing issues that require attention. There could be several possible causes for such problems. The quality of the alloy being used could be substandard or defective. An alloy that is too high in sulfides and oxides could cause the problem, especially when using recycled metal. The issues could also occur if the molten alloy is overheated or if the dewaxing temperature is too high. Experienced foundry staff, including an expert metallurgist, have the expertise, equipment, and resources necessary to address and prevent these problems.

Investment casting can produce an extremely broad range of top quality parts, but it requires expertise and care to avoid casting defects. This is because investment casting is far more complex than it appears on the surface. In addition to mastering the science and metallurgy of investment casting, the foundry team must have process expertise and extensive experience to avoid such common defects as poor surface finish, porosity, incomplete casting, distortion, casting voids, and many more. Do your background research and choose your foundry carefully.

The investment casting process can be effectively used for both stainless steel and aluminum casting. When choosing the best material for your parts, consider these facts:

• Strength vs. Weight – Aluminum is not as strong, but approximately one third the weight, giving it an excellent strength-weight ratio.
• Heat Resistance – Stainless steel has a much higher heat tolerance, which can make it more suitable for certain applications. Aluminum softens at 400 degrees Fahrenheit.
• Workability – Aluminum is more malleable than stainless steel, which can make it easier to work with and more cost-effective in some cases.
• Welding – Aluminum is more difficult to weld than stainless steel.
• Electric Conductivity – Aluminum is an excellent conductor of electricity. Stainless steel is poor.
• Cost – Stainless steel usually costs more than aluminum but is well worth it for some applications.    

When manufacturers are deciding whether to use investment casting or metal injection molding, they often go with investment casting because of the advantages it offers. Investment casting can use a wider variety of alloys and typically achieves better results related to the hardness, density, tensile strength, elongation, and other properties of the finished parts. The near-net-shape process ensures consistent quality and repeatability over very long runs. This significantly reduces the number of out-of-spec and faulty parts, saving time, money, and production hassles.

If you are giving consideration to both investment casting and green sand casting for your parts, you should know that investment casting offers some important advantages. Green sand casting can be less costly in some cases on a per-part expense basis. Investment casting has the advantage with its ability to handle very complex geometries, deliver better surface finishes, create thinner part walls, and it requires less machining and finishing work. Plus, investment casting can be more economical for long and repeat part runs.

When trying to decide whether to use investment casting or sand casting to produce parts, consider the following:

Investment Casting

• Can produce complex parts, even with very thin walls.
• Offers the accuracy to achieve precise specifications.
• Delivers high-quality surface finishes with little or no machining and finishing.
• Can utilize duplex alloys and both ferrous and non-ferrous metals.
• Is an economical option over long and repeat runs.

Sand Casting

• Can be lower cost in some situations, like shorter runs.
• Can produce very large castings.
• Also accommodates ferrous and non-ferrous alloys.
• May be a good option when top quality and precision are not required.

Investment casting is an ideal process for making a wide range of medical & pharmaceutical parts. Many applications in the medical, dental, and pharmaceutical field require very high quality, exceptional precision, and unwavering consistency. Investment casting’s near-net-shape process can meet even the most demanding requirements and exacting specifications. It can also accommodate numerous specialized alloys, as well as common metals that are utilized in medical, pharmaceutical, and other areas. With virtually no margin for error in these professions, investment casting can be a life saver.

Valves play a vital role in a near-endless range of components and industries, which is why many manufacturers rely on investment casting to produce their valves’ cast parts. Many valve specifications require complex, extremely precise parts to function properly. Investment casting is able to meet those requirements when other processes cannot. In some cases, they also call for specialized alloys, which investment casting can utilize. It is versatile enough to meet the needs of virtually any application and industry, delivering top quality, dependability, and cost effectiveness.

Investment casting is an excellent option for producing air and gas compressor cast parts. These applications typically have precise specifications and tolerances that other processes find difficult or impossible to achieve. Investment casting’s near-net-shape process utilizes molds that are extremely accurate, which produces very consistent parts, even over very long runs. It also delivers excellent finishes that are required for many compressors and similar components. In addition, it is a highly cost-effective process for many types of parts. Investment casting is a perfect fit for the compressor industry.

Many manufacturers and other businesses rely on investment casting to produce highly precise instrumentation and controls parts. It can deliver the dependability and accuracy that is needed for even the most complex designs and geometries. It can also produce parts runs with exceptional consistency and reliability. Investment casting makes parts that are very close to their finished specifications, so little or no machining and finishing work is necessary, which saves time, money, and waste.

What is investment casting robotic dipping, and what are its benefits?

Robotic dipping is the partial automation of mold production for investment casting. After wax patterns of desired parts are made, a cutting-edge robot will repeatedly dip sprue assemblies (a number of connected patterns) into a coating of stucco and ceramic. This is done several times to achieve the desired thickness and strength. The resulting shell will receive molten alloy and hold it until it cools into a cast part. Robotic dipping can add efficiency, consistency, and economy to the investment casting process. View a video of PPCP’s robotic dipping: https://youtu.be/m5MTCxd-knk

Can investment casting accommodate a variety of alloys?

One of the most substantial benefits of investment casting is the large variety of traditional and specialized alloys it can utilize. It can cast common alloys such as iron, copper, and carbon steel, but it is also ideal for stainless steel, aluminum, duplex alloys, and many others. The special properties of numerous alloys used in investment casting enable manufacturers to produce better performing and longer lasting parts and components. Make sure to select a foundry with experienced metallurgists who can produce custom alloys needed for your castings.

What are the characteristics of investment casting parts?

There are many highly desirable parts characteristics, including abrasion resistance, parts consistency, corrosion resistance, heat resistance, ability to achieve tight tolerances, wear resistance, little or no material waste, and more. In addition, investment casting delivers top quality parts that perform reliably and to the highest standards. For many applications, other processes cannot compete.

Why is investment casting’s near-net-shape process superior to other processes?

There are many advantages offered by near-net-shape casting. Among the biggest benefits are it produces less waste, little or no machining and finishing work is required, it can accommodate very complex geometries and designs, it meets exacting specifications and performance requirements, and much more. It all adds up to better quality, exceptional performance, and lower cost.