Metal casting is a critical component of the United States economy. Over 90%of all manufactured parts in the US have one or more parts that were created via metal casting. And, the metal casting industry is expected to generate over $33.7 billion in 2019. There are so many metal casting operations in the United States that most people are currently within 10 feet of a metal casting product.
There are many different methods of metal casting utilized to create all of the parts needed to stock the global industrial casting supply chain. One of these methods is permanent mold chill casting — which produces high-quality products with low costs at-scale.
What is Permanent Mold Chill 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 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.
How Does Permanent Mold Chill Casting Work?
The permanent mold chill casting process can be broken down into four key components. Each of these components may differ depending upon the metal casting business you are working with. Some metal casters leverage the latest technology to produce superior results, while others still rely on traditional methods due to equipment availability or training.
Step 1. Mold Creation
The first step is to create the mold. This process requires careful attention to detail and incredible ingenuity. At Burnstein Von Seelen, we ensure that the mold meets the quality and specifications of each project precisely.
The mold itself is comprised of two or more sections and cores, which are inserted to form many complexities. It’s important to note that no sand is used during this process and that the entire mold is a permanent, solid part.
The surface of the mold is coated in a heat resistant material to allow it to withstand heating and cooling cycles. The coating also influences the heat conduction and lubrication of the die, so a unique coating may be utilized depending upon the needs and complexity of the project.
Step 2. Pouring the Molten Metal
Once the mold has been assembled, high-quality molten metal is gently poured into the mold via a ladle on the top of the mold. The molten metal will then flow down a runner into the mold for solidification.
Step 3. Cooling the Metal
This process is simple. The metal is allowed to cool within the cast for a set period of time. This timing varies by the material used.
These are some of the common materials used with permanent mold casting.
- Pure copper
- Aluminum alloys
- Magnesium alloys
- Copper alloys
- Tin alloys
- Zinc alloys
- Lead alloys
Step 4. Opening the Cast
Once the metal has been cooled, the cast is opened and the part is removed. At this point, depending upon the cycle stage, the mold will be set back up and use at a later operation.
Any excess material that was attached to the part is also trimmed away and used for re-melt.
To learn more about the complexities involved in permanent mold casting, including the mathematical properties, see here.
The Benefits of Permanent Mold Chill Casting
There are multiple benefits to permanent mold chill casting.
- Good for high-volume productions: The primary cost associated with permanent mold casting is the cast itself. When applied to high-production cycles, chill casting provides better cost-per-part than other casting methods. The cost savings of permanent mold casting has been the subject of research for years. And, permanent mold casting has proven to be the most cost-effective high-volume casting method in a plethora of case studies.
- Tighter grain boundary: At Burnstein Von Seelen, we guarantee a conductivity of 98% IACS.
- Uniform properties: The homogeneous properties of permanent mold chill casting ensure that all parts of incredibly uniform.
- Incredible surface finish: Permanent mold casting produces a superior surface finish compared to other casting methods (e.g., sand casting, shell molding, etc.)
- Smaller cast holes: Permanent mold chill casting can cast smaller cast holes than other methods, which helps maintain tight tolerances.
- Minimized part variation: Since you aren’t creating new casts for each cycle, permanent mold castings offer variations that are as low as +/-0.010.
- Thinner walls: Permanent mold chill casting allows thinner walls than other casting methods.
- Superior mechanical properties: The mechanical properties (e.g., strength, yield, ductility, etc.) are higher with permanent mold casting due to the nature of the process.
- Environmentalism: Permanent mold chill casting consumes much less energy and produces less waste than other casting methods — like sand casting.
Permanent Mold Chill Casting vs. Sand Casting
While permanent mold casting shares many similarities with sand casting and investment casting, it has a few key differences. First, it doesn’t use an expendable mold. Both sand casting and investment casting utilize throw-away molds that are only good for one cycle. Permanent molds maintain accuracy and durability for many cycles — which makes them cost-effective for projects with a large scope and run-time.
Another key difference is how the molten metal is handled. Permanent mold casting uses gravity instead of injection to insert molten metals into the mold. And, these differences ensure that permanent mold casting produces a superior surface finish and dimensional accuracy when compared to sand casting.
The primary differences between the two are the quality of the end product and the cost-per-unit.
Another important point is that permanent mold casting doesn’t emit as much waste product as sand casting — which creates excessive sand byproduct.
- Permanent mold chill casting is better for high-production runs.
- Sand casting is lower cost in small batches.
- Permanent mold chill casting produces a higher quality part.
- Sand casting uses throw-away molds, which can increase waste.
- Permanent mold chill casting has higher initial tooling costs.
- Permanent mold castings are cast to near net shape with minimal allowance needed for machining.
Permanent Mold Chill Casting vs. Investment Casting
Like sand casting, investment casting utilizes a disposable mold for production cycles. However, it uses wax to create the mold instead of sand, leading to slightly higher costs-per-unit than sand casting. The wax mold gives it relatively good dimensional accuracy — though not as good as permanent mold casting.
The primary differences between these two outside of the mold casting process are the cost-per-unit, quality, and speed at which the parts are delivered. Investment casting often has lower costs when production is kept to small-to-medium sized runs. But, like sand casting, investment casting costs remain steady throughout each cycle. Permanent mold casting has higher initial tooling costs due to the permanent nature of the mold, but the labor and production costs are much lower than investment casting.
This makes permanent mold casting superior for high-production runs or situations where incredible part quality and low variance are a necessity.
- Permanent mold chill casting is more cost-effective for high-production runs.
- Investment casting is more expensive than permanent mold casting.
- Permanent mold chill casting produces a more competitive price point than investment casting.
- Investment casting uses throw-away molds.
- Permanent mold chill casting has lower production and labor costs but higher initial tooling costs than other casting methods.
Why Burnstein Von Seelen
Burnstein Von Seelen is the only ISO Certified copper-based permanent mold facility in North America. We only purchase the highest-quality raw virgin metals from incredible suppliers. And, each of our projects starts is handled by managers certified in quality control who leverage the latest technology and graphs to help cut costs and improve throughput on each project utilizing our state-of-the-art CNC machinery.
We are currently ISO 9001:2008 Certified and in the final steps of achieving Military Standard 105 D. We also assure dimensional accuracy and alloy integrity using our ultramodern quality control lab with advanced testing and inspection technology. We don’t just create incredible parts using permanent mold chill casting; we create happy customers.
Click here to see some of our past case studies.
Are you looking for a permanent mold casting solution that reduces costs, improves throughput, and is based in the United States?
Contact us. We’re a one-stop-shop, and we provide a wide range of metal casting services, including alloys, tooling, plating, and machining.