Molds were introduced in the Bronze Age and changed the way our ancestors manufactured goods. Since then, mold-making techniques have improved and become more widespread. Today, many manufacturers use injection molding, thermoforming, or casting to create plastic, silicone, rubber, composite, and metal parts. Molds play an important role in these advanced manufacturing processes.
Professional manufacturers and hobbyists who want to utilize these processes must understand how the mold-making process works, how it is used, and how to optimize usage to meet required throughput.
If you are looking for a guide that will give you all the information you need about getting started with mold making, then look no further! This comprehensive guide will provide you with detailed information about different molding processes, choosing the best molding technique, and the role of 3D printing in mold making.
Insight into optimizing the mold making process with different equipment will also be discussed, and every step of the way to ensure successful molding projects.
Uses of Molds
Molds are designed to shape raw materials into a desired form. Manufacturing processes usually involve using a mold, which can have either a concave or convex shape. The shape of the mold depends on the final design that the manufacturer wants to create.
Molds play an important role in many manufacturing processes by creating duplicates of a given design. Materials used to make molds include metals, plastics, ceramics, wood, foam, and more. To create a mold, mold-making tools are used to design and develop the mold.
Once created, the mold is fitted into molding equipment and raw materials such as thermoplastics are poured into it or formed around it. Once solidified, the mold imprints its patterns onto the material to form the finished product.
Molding techniques are used to create a variety of objects, from prototypes to complex end-use parts. Some examples of items that are manufactured using molding techniques include automotive parts, consumer products, packaging, jewelry, medical devices, and more.
In other words, it would be difficult to find a functional product that doesn’t have at least one component that was made using molding techniques.
Types of Molds
There are many types of molds that can be used in various manufacturing processes. For example, in aluminum casting, there are approximately seven types of mold, including sand casting molds, ceramic molds, and shell molds.
To simplify the classification of the different mold types, the following categorization applies:
One-Part
One-part molds are the simplest type of mold to produce and are frequently used to create objects with uniform surfaces or those with just one flat surface. These molds can be created from CAD models, but they are often developed from a physical master model.
Two-Part
Two-part molds are defined as molds with two separate parts that are joined together at a parting line. This type of mold is usually used to produce more complex designs. Each individual part mirrors the different features of both parts of the model design or the master model. Making a two-part mold usually involves developing both parts of the mold from a master model.
Multi-Part
Multi-part molds are beneficial for mold designs that entail more intricate geometries. This process is different from developing one or two-part molds. With a multi-part mold, each individual part accounts for a different aspect or feature of the model. Therefore, the completed mold will be composed of multiple parts, each one replicating a different feature of the model.
Types of Molding Process
Injection Molding
The injection molding process is a popular manufacturing process for thermoplastic, silicone, or rubber parts. It is a cost-effective and repeatable technology that yields high-quality parts for large series production. With this process, the developed mold is inserted into the injection molding machine.
Then, heated thermoplastics or liquefied raw material are poured into the mold. Once the material solidifies, the final part is ejected from the machine and the process is repeated.
Compression Molding
Compression molding is a manufacturing process that uses preheated molding material to create the desired form by compression between two heated molds. Compression molding is often used as an alternative to injection molding for simple designs and low to medium series production.
Blow Molding
Blow-molding is a technique that is similar to glass-blowing. In blow-molding, a machine blows air into a heated tube-like piece that is clamped into a mold. The air that is blown into the tube helps to push the plastic out so that it matches the shape of the mold. This method is commonly used for manufacturing hollowed products, such as bottles.
Different Ways to Create Molds
Silicon Molds
Casting with silicone molds is a popular method for creating parts from plastics and other materials. This process is used by product developers, engineers, DIY enthusiasts, and chefs to make single items or small batches.
Silicone molds offer several advantages over other types of mold-making methods. For example, custom designs can be easily created with silicone molds, and the molds themselves are also quite durable so they can be reused multiple times without fear of breakage.
Depending on your design, you might need a one-piece or two-piece mold. The process for making a two-part mold is slightly different and will take a bit longer.
Injection Molds
Molds for injection molding are typically made out of metal. These can be expensive to produce, and as a result, the production of a metal mold can take a significant amount of time.
The production of a mold also usually requires specialized equipment and software, as well as skilled labor. All of these factors can contribute to the high cost of producing a metal mold, depending on the shape and complexity of the part.
In-house 3D printing can be used to create prototypes and small production runs of parts quickly and at a lower cost than metal molds traditionally used for injection molding. This process still produces high-quality, consistent results.
Compression Molding
There are several options for creating molds, including die casting, CNC machining, or 3D printing. The key is that your molds need to be able to withstand the compression molding process. This means that if you are using heat, you will need to create molds that can handle dramatic temperature changes. Molds also need to be able to withstand the amount of pressure applied during compression.
Key Takeaway
Molds are often used in manufacturing processes to create duplicates of a design. In order to optimize throughput and to use molds effectively, it is important to understand how the mold-making process works and how molds are used.