What is Permanent Mold Chill Casting?

Permanent mold casting is the process of using a metal mold to create uniform products. The material used to fill these molds is molten and will solidify in the mold. The mold is created using hyper-durable materials — tool steel or exotic copper alloys. These materials can withstand many thermal cycles.

While sand casting uses a sand mold that is disposed of after one use, permanent mold casting is different. With permanent mold casting, you can use the same mold over and over, which allows you to save resources and provides extra confidence that the part will deliver the specific results you need over and over. 

In order to make the mold last, permanent molds are often made of sturdy metals like copper and steel alloy. Permanent molds come in different forms and are built for different purposes; depending on your needs, you might want a gravity mold casting or a low-pressure mold casting.

WHY Should You Use Permanent Mold Chill Casting?

Permanent mold chill casting offers many benefits that you won’t experience with standard mold casting. Depending on your project, these differences can save you a significant amount of time and effort. Expect all the following benefits:

• Smaller Cast Holes. You can maintain tight tolerances with smaller cast holes, and permanent mold chill casting allows you to create smaller cast holes than other methods.
  
• Less Variation. Because permanent mold casting eliminates the need to create new molds for each cycle, you’ll be able to eliminate even the smallest variations between cycles—as low as +/-0.010.
  
• Thinner Walls. If your project could benefit from thinner walls than the average casting process can create, use permanent mold casting. The process allows for thinner walls than other casting methods.
  
• Save the Planet. Process is silica and lead free. Partly thanks to its reusable nature, permanent mold tooling uses less energy and fewer materials than other casting methods, which is better for the environment and potentially your wallet as well.
  
• High-Volume Production. Once you have the permanent mold cast itself, you’ll save a significant amount of money on high-volume production projects. Permanent mold casting has been proven to be the most cost-effective high-volume casting method.

WHEN Should You Use Permanent Mold Chill Casting?

If your project doesn’t specifically need smaller cast holes or thinner walls, you might not be sure whether permanent mold casting is your best option. If you’re not sure which mold casting method to use, the following are good times to consider permanent mold casting:

• You’re Producing More. If your company is growing and you’ve recently started producing more than 500 pieces a year, permanent mold casting will almost certainly be a good investment. You’ll save more energy and resources by reusing your mold cast, and you’ll be able to expect less variability between your pieces.
  
• You Want a Better Surface Finish. Compared to other methods, like sand casting, permanent mold casting offers a significantly smoother finish with fine coatings that look and feel better than their alternatives.
  
• You’re Trying to Cut Down on Defects. When you use a new mold for every piece, there will inevitably be some variation, even if those variations are small. You can reduce this risk dramatically by reusing the same permanent casting mold.

Permanent Casting Mold Types

Permanent mold casting describes the process by which molten metal is poured into a steel or cast iron mold to make new metal. The metal produced is reusable and has better dimensional tolerance, a superior surface finish, and higher mechanical properties. Permanent mold casting is often used to create parts for automotive pieces such as gears and engine pistons. 

There are 2 main types of permanent casting molds: BVS permanent mold process and pressure die casting. The type you choose will depend on the kind of cast component being produced, so you should be aware of how each type of mold is made and what they entail.

Pressure Die Casting

Pressure casting, sometimes referred to as low-pressure casting, is a type of permanent mold casting in which air pressure is used to force metal through the casting’s cavity. Pressure is applied to a chamber holding molten material, which is then forced up a refractory tube and throughout the mold. Is pressure casting the right method for you? There are some factors to consider before going this route.

• Due to the high setup cost associated with pressure casting, you’ll get the most bang for your buck if you use it for bulk manufacturing instead of smaller operations.
• It yields castings with good mechanical properties and surface finishes, and higher dimensional accuracy.
• The constant pressure used in this process ensures low turbulence, thus minimizing gas porosity.
• Pressure casting results in better quality casting, as it allows you greater control over mechanical properties and casting details.
• Because the mold needs to be able to open and close, internal geometry is limited.

Pressure casting is a great permanent casting method for producing large quantities. A primary disadvantage to this method, though, is that you are limited in terms of what you can do with the cast’s internal geometry.

Permanent Mold Casting

Permanent mold casting (often referred to as “chill casting”) is a metalworking process that utilizes permanent, reusable molds to create durable parts. The mold (or die) is created using hyper-durable materials — tool steel or exotic copper alloys. These materials can withstand many thermal cycles.

Molten materials are then poured into the mold via gravity as opposed to the injection. This makes permanent mold casting ideal for projects that require high-volume or ultra-high durability. Permanent mold casting produces parts with tighter tolerance and superior finishes when compared to other traditional casting processes — such as sand casting.

Overall, both options have its cons and pros but permanent mold chill casting is the superior between the two.

Permanent Mold Casting Process

Permanent mold casting is also sometimes referred to as gravity die casting. Despite their different names, these are actually identical terms for the same process. Gravity is used to pour a molten medium into a mold, thus giving this method its name. The process involved has many steps, each of which contributes to the finished product. 

How it’s done

• First, the mold must be created. The mold is made from heat-tolerant, steel alloy or copper based alloy, and can be composed of two or more parts. This step requires incredibly specific attention to detail to be sure that a perfect mold is made to create perfect castings. At Burnstein von Seelen, careful steps are taken to ensure that each and every mold is held to rigorous quality control standards. 
  
• Then, the mold is coated with a heat-resistant coating and die release agent. This will allow the mold to withstand heating and cooling cycles and ensure that casting to be properly removed. This coating contributes to the finish of the final product. The mold is also heated at this step. 
  
• Next, the metal is poured into the mold. The mold’s component pieces are assembled and typically held together with a clamp. Using a ladle, molten metal is poured into the mold’s channels until the entire mold is filled. Commonly used metals include pure copper, as well as alloys of aluminum, magnesium, copper, tin, zinc, or lead. 
  
• Once poured, the metal is chilled immediately enhancing physical properties. This process is relatively self-explanatory: Now filled with hot metal, the mold is placed aside somewhere where it will be allowed to cool quickly. Depending on the size of the casting and the type of metal used, the time required for this stage will vary. 
  
• After cooling, the mold is opened and the cast is carefully removed. In permanent mold casting, especially if the mold is being used to create a high-volume of product, the mold is reset to begin the process again while the casting is taken to be treated for finishing touches. 
  
• Finally, the casting is trimmed. The excess material is removed and returned to be used for re-melt. The casting can also be sanded or treated with another layer of coating to change or improve the finish. As with the first step, close quality control is crucial at this stage to produce a perfect finished product.

Advantages and Disadvantages

Permanent mold casting is the process of creating casts, or die, from a permanent mold made of hardy material. Like any process, there are advantages and disadvantages to using this method. Depending on what specifically you need to cast, some of these factors need to be considered. 

Advantages

There are many benefits to utilizing permanent mold casting for your project. This method produces high-quality, uniform pieces with a lot to offer.

• Extremely regular castings, with very low dimensional tolerances. This means that every casting in the batch will be nearly indiscernible from one another. They have a dimensional tolerance of typically around 1 mm, making for perfect pieces, every time. 
• Rapid production due to the repetitive nature of the process means that your products will be made more quickly than with other methods
• Low shrinkage and gas porosity mean that your castings are less likely to shrink as they cool, as well as less likely to have defects than with other casting methods.
• Optimal surface structure and grain uniformity. Their finish is uniform and ideal for many applications.
• Minimal scrap process leads to better savings from the metal remaining after trimming. Scraps are simply thrown back into the melt, meaning there is almost no waste.
• Ideal for mechanical applications. Due to their uniformity both from cast to cast, and along the surface, die cast by this method work extremely well in precision machinery. 

Disadvantages

As with all processes, there are some drawbacks to permanent mold casting. Some of these are minor, but others may mean it isn’t a great fit for your project. 

• High initial cost can be a big drawback for very small operations or those on a tight budget. Creating the molds for permanent casting is an expensive process, so it may not be worth it in the long run if you only need a small number of castings.
  
• Melting point limitations mean that whatever you’re casting must have a lower melting point than the metallic mold.
  
• Highly detailed and difficult shapes can possible be cast via this method. Likewise, textured surfaces with a high level of delicate detail are also not possible.
  
• If your project calls for very large castings, permanent mold casting is not the best option. It’s designed for medium to small objects, and not practical for bigger casts.
  

Whether you’ve used permanent mold casting frequently in the past or are just now learning about its benefits, permanent mold casting is easy to access and available to you now. If it’s been a while since you’ve used permanent mold casting, it can be beneficial to refresh your understanding of exactly what permanent mold casting is. The process involves pouring molten metal into a steel alloy or copper alloy mold to create customized, precise new metal pieces. This metal mold is called a permanent mold because it can be reused to duplicate pieces exactly, which makes for dependable pieces and no surprises or hidden mistakes. Permanent mold casting can go a long way for any of your projects, thanks to the following benefits.

What To Look For In A Permanent Mold Casting Company

Competitively Priced/Low Cost

Permanent mold casting is affordable. Because you can reuse the same mold multiple times, you won’t need to pay for multiple parts or worry about any extra costs for precise replication. While other part-building processes will charge for details on each created piece, the mass-production style of permanent mold casting eliminates that need and allows you to pay for your tools at a generally lower price. At Burnstein von Seelan, we work hard to make sure your permanent mold casting needs can be met affordably, because we want the benefits of permanent mold casting to be readily available to everyone who could benefit from them.

Easy Make/High Production Run

Effciency is a casting company key. Naturally, your permanent mold casting process will provide some of the easiest manufacturing possible. Once you’ve got a mold that works, you can replicate your results again and again with no flaws or variation in your production. This also allows for a very high production run; as soon as your permanent casting mold has been emptied you can fill it again, making for a nonstop cycle of production that will benefit you immediately.

It’s common for other assembly methods to create one part of the piece, wait until the entire production line has finished that aspect, and then resume production again, which can lead to a significant amount of dead time. If you need your tools quickly, or are simply tired of unnecessary waiting periods during tool assembly, permanent mold casting can combat both of these problems simultaneously. 

Provides Utmost Accurate Dimensions

When your mold is made correctly, everything that comes out of that mold will be completely accurate and identical to all the other pieces made from that mold. This means your final project will be that much more dependable and uniform. The materials that come out of your mold will have the exact same dimensions as your mold itself, so you can rely on total accuracy. Additionally, at Burnstein von Seelen we promise dimensional accuracy thanks to our ultramodern quality control lab. We are ISO 9001:2015 certified and Military Standard 105 D. You’ll be able to rep all the benefits of our commitment to cutting-edge technology and improved permanent mold casting ability.

Creates Long-Lasting Tools

Wear and tear on tools can be a major expense for any venture, which is why it’s such good value for money to use tools and materials that are designed to last. The metals you use in your permanent casting mold can create tools that will last for years into the future. The mold itself will also play a significant role; when you know that you’ve got a dependable mold, you can create more pieces with a higher expectation of their durability and a higher level of trust. When you’ve got a good permanent mold casting process, from the metals to the mold itself, your tools can last more than 10,000 cycles. We want our customers to have the longest-lasting materials possible, which is why we provide a reliable way to create them.

The Takeaway

Permanent mold casting can be a fantastic way to make a large number of parts quickly, accurately, and inexpensively. Because this method makes identical pieces every time, if you’ve managed to make one good piece, you now have access to an infinite number of those same dependable tools. Your final projects will be dependable and predictable thanks to the ability to make your pieces identically.

Burnstein Von Seelen does high-quality permanent mold casting, using virgin metals to provide you with the best parts for applications which require strength, conductivity, and precision. If you are considering the benefits of permanent mold casting and have any questions about the process or whether it’s right for you, contact us today. We will give you a quote, provide professional advice, and help you make the most of your project, whatever it might be.