What Is Molding?
Molding is one of the five core processes involved in rubber and plastic manufacturing, alongside casting, forming, machining, and additive manufacturing. Though they share some similarities, the processes are quite different.
A molding process uses pressure and heat to fill the cavity of a mold, a rigid frame also known as a matrix. The raw material, typically a pliable one like plastic, glass, or ceramic, is kept under pressure until it solidifies or vulcanizes (i.e., begins to harden). Advantages of molding include greater accuracy, versatility, and efficiency.
Molding is different from casting, which is when a liquid or melted polymer is poured into a mold and solidifies to form the part. No pressure other than gravity is used to fill the mold and form the part. The advantages of casting include durability and a greater complexity of design – however, it may not be possible to cast large parts.
Types of Molding Processes: Applications and Advantages
Molding serves a wide range of industries and offers exceptional quality, sustainability, and adaptability of parts. Understanding the types of molding processes can be pivotal in ensuring the success of your next project. Below we would like introduce two kinds of molding for you, compression molding and injection molding
1) Compression Molding
The compression molding process is used to make rubber and plastic parts. In the rubber compression molding process, a preformed section of rubber is placed in a heated mold, then the mold is closed and held under pressure until the rubber takes the shape of the cavity and vulcanizes. Vacuum-assisted compression molding is similar but placed under vacuum to remove any gases and ensure the best possible mold filling and shape adherence.
Compression molding offers several benefits over other molding processes, including low tooling costs and fast lead times. However, the process requires manual handling of the mold and products, resulting in slower cycle times.
2) Injection Molding
The injection molding process can be used with both thermoplastic materials and thermosets. Injection molding machines inject molten polymer materials under high pressures and speeds into closed molds. Though creating these molds can be more expensive, the process can ultimately provide finished parts at a high production rate.