In the past, mold creation was a more manual machining process. It was less efficient, slower, and time-consuming. Molds used in the casting process were more dependent on machinery. However, things have changed as those molds are now being made with 3D printing. But the question is: How to make 3D printing molds for casting?
As you know, casting involves using a mold, where molten material is poured into it. Once molten material solidifies, it adopts the shape of the mold. Therefore, the proper shape, dimension, and quality of mold are paramount for this process. Interestingly, the 3D printing process enables us to create a perfectly shaped mold. In this article, I’ll explain the whole mold creation through 3D printing. So, let’s get started!
Overview of 3D Printing for Mold Creation
Before delving into the details, let’s first understand what 3D printing is.
3D printing is a type of additive manufacturing process. It makes final products layer by layer. A 3D printer is used in this type of manufacturing, which uses digital instructions. The printer then interprets instructions and pours the molten in layers to make the product. It can be used to create molds for the casting process.
Molds are tools that consist of cavities. The molten material is generally filled in these cavities. When the molten material cools and solidifies, it adopts the shape of the mold. We eject this solidified material and get the desired product (mold). Remember, this process of pouring molten material into a mold and making products is called casting.
In the past, different machining methods were used to create the molds. Those methods were not accurate and were used to make molds with minor defects. If the mold is defective, it won’t give us a product with precision. For casting, the mold must be precisely similar to the desired shape of our product. Therefore, the machining process is becoming less popular now.
3D printing, on the other hand, is gaining popularity. The reason is that 3D printers use digital models as instructions to make the mold. As a result, we get the mold with precision. It will be identical in shape to the given digital models. We can create complex shapes of molds with the help of 3D printing methods.
3D printers can utilize various materials, including plastics and resins. The printer creates the mold in layers, interpreting the coded instructions provided by the operator. What makes this process stand out is its cost-effectiveness. Creating molds for casting was very costly when done with conventional machining processes.
Step-by-Step Guide: Making 3D Printing Molds for Casting
There is no doubt that the 3D printing method is straightforward. All you need is material. The printer will use that material and make the product layer by layer. However, when it comes to creating mold, the process can be a bit tedious. Understanding all the ins and outs of mold creation is key.
There are multiple steps involved which help us get molds for casting. In the section below, I will outline each step to help you understand the entire mold creation process.
1- Design the Mold in CAD Software
The first step in creating a mold is to design a digital model of it. It is the most crucial step, and even small mistakes can ruin the entire process. As I said earlier, 3D printers require models or instructions in the coded form. So, we first create that model using CAD software. Remember, various CAD software options are available for use, such as TinkerCAD or Fusion 360.
If you don’t have any design skills, I wouldn’t recommend creating designs. The chances are high that you’ll make a mistake resulting in the wrong shape or dimension of the mold. You can hire an expert CAD designer for this step. Remember, the mold consists of pouring channels, air vents, and other parts. You should design all those parts for the best result.
2- Creation of G-Coded Instructions
The 3D printers are not compatible with the digital model or design that you can use in CAD software. Therefore, it is key to convert those digital models into G-coded instructions. The 3D printer can interrupt these coded instructions and create the product. For converting digital models into G-codes, slicer programs are used.
Different types of such programs are available that you can install on your computer. Some of those include Ultimaker Cura, PrusaSlicer, and Simplify3D. You can feed a digital file (CAD file) to this software. These programs will provide you with G-coded instructions that your 3D printer will accept. You can save this coded file on your USB.
After that, you can feed this G-coded file to the 3D printers. The printer will decode the instructions. Those coded instructions help printers know many parameters. Those include:
- Where to move
- How much material to use
- What temperature to heat the nozzle
- What should be the height & density of the layer
- How thick or thin a layer should be during printing
Once you feed the G-coded instruction to the printer, you’re ready to print the 3D mold for the casting process.
3- Material Selection for 3D Mold
Choosing the right material when creating a 3D mold for casting is crucial. Select a material that suits your needs and preferences. There are various types of materials available for use in molds. Each of these materials offers unique properties. Some popular materials used for making mold are as follows:
- Resin (SLA/DLP)
- PLA (Polylactic Acid)
- TPU (Flexible Filament)
- ABS (Acrylonitrile Butadiene Styrene)
- PETG (Polyethylene Terephthalate Glycol)
Remember, the mold made with PLA will be less heat resistant. But its creation would be easier. On the flip side, the mold made with TPU (Flexible Filament) will be crack-resistant. Similarly, using ABS (Acrylonitrile Butadiene Styrene) material will give a heat-resistant mold. You should further analyze the properties of the materials and your needs to select the most suitable material.
4- 3D Print the Mold Using 3D Printer
This is a step where you’ll physically see the mold creation. With various types of 3D printers available, you can choose one that suits your needs. Moreover, it is crucial to check all parameters, such as the nozzle temperature and the printer’s position. Ensure the bed of the printer is perfectly level and balanced.
You’ll have to feed the G-coded instruction to the printer. As a result, the printer will interpret the instructions. It will understand how to move, which speed to print, etc. Now, the printer heading will start to move. The material will exit the printer nozzle and form layers on the bed. The head will continue to move according to the G-coded instructions.
As a result of this movement, the printer head will create layers. In this way, you’ll have a high-quality mold for the casting process. This mold will be 100% similar to the shape you designed in the CAD software. As the printer follows the G-coded instructions, the chances of errors are very low. After this process, allow the mold to cool and solidify perfectly.
Quick Highlight: It is crucial to closely monitor the creation of the first few layers. There can be issues such as warping, layer shifting, or even poor adhesion in the early stage. If you encounter such problems, stop printing and address these issues. If you don’t fix it, you’ll end up having a defective mold.
5- Post-Processing the Mold
Once the mold is created, it undergoes post-processing. As you know, during the manufacturing process, some roughness remains on the surface of the mold. The post-processing helps remove that roughness. First, you can use pliers, flush cutters, or even simple cutters to cut any desired extruded materials.
It will help smoothen the surface of the mold. Moreover, you should inspect the mold for any small holes. You can fill these holes, gaps, or rough edges using epoxy putty. You should let the epoxy putty dry to close those small gaps permanently. In the final step, use your soft brush to remove all debris from the inside of the mold gently.
Quick Highlight: As you are aware, molds typically consist of two halves. You should check the alignment pins and clamps to ensure the mold parts are correctly aligned. There should be no leakage when you close both parts of the mold. If either part of the mold does not fit or align properly, you should address this issue immediately.
6- Mold Release Coating
The casting process involves pouring molten material into a mold. Right? When the material solidifies, it adopts the shape of the mold. However, as the material solidifies inside the mold, its ejection can be a bit tricky. A careless approach can result in breaking the solidified product inside the mold. Therefore, I recommend applying a coating on the interior side of the mold.
The casting process involves pouring molten material into a mold. Right? When the material solidifies, it adopts the shape of the mold. However, as the material solidifies inside the mold, its ejection can be a bit tricky. A careless approach can result in breaking the solidified product inside the mold. Therefore, I recommend applying a coating on the interior side of the mold.
Frequently Asked Questions
Can you 3D print a casting mold?
Yes, you can 3D print a cast mold with the help of a 3D printer. For this, you have a digital model and then convert it into G-coded instructions. The printer will interpret this code and create the mold of your desired shape.
What is the best material for 3D printing molds?
There are various materials available for 3D printing molds used in casting. However, I consider raisins the best material as they provide excellent detail and smoothness on the surface. You can also use PLA, TPU, and ABS (Acrylonitrile Butadiene Styrene) as needed.
Can I make mold through CNC machining?
Yes, the molds can be made by both CNC machining and 3D printing. Remember, both of these processes are different in their working and operations. The molds made by 3D printing are cost-effective and more precise.
Conclusion
The mold is an essential tool for casting and injection molding processes. Its right shape, size, and dimension are crucial for its efficient performance. Its shape must be similar to your desired product. Minor errors in shape or even size will result in products of the wrong dimension. Therefore, we recommend using 3D printing technology to create molds.
First, mold creation with 3D printing is less costly. Moreover, 3D printers use G-coded instructions to create products. By providing the correct G-coded instructions, we can obtain high-quality molds with precision. This process enables us to create a 3D mold of any complex shape and design with ease. This article will help you understand the process of mold creation.