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Plastic Injection Molding

Plastic injection molding is a widely used manufacturing process for producing plastic parts of various sizes and shapes and is commonly encountered in our daily lives. It plays a crucial role in various areas, from automotive parts to home appliances, toys to medical devices. If you have a product idea, you may wonder if it can be made using injection molding, what the cost would be, and how to design it. Read on for more information.

Production Process of Plastic Injection Parts

People create injection molding parts by melting plastic granules and injecting the molten material under high pressure into a mold cavity. When the plastic cools and solidifies, the mold opens and the part is removed. Injection molding is a versatile manufacturing process capable of producing complex, finely detailed parts with high precision and consistency. Common products made through injection molding include automotive parts, medical devices, home appliances, and consumer products.

What is the Cost of Plastic Injection Parts?

The cost of plastic injection parts can vary widely based on several factors, including the size and complexity of the part, the type of plastic used, and the quantity of parts produced. Typically, larger and more complex parts may require more expensive molds and longer cycle times, which can increase the cost of the finished product. The type of plastic used can also affect the cost of injection molding parts, as some materials may be more expensive than others. Additionally, the quantity of parts produced can impact the cost per part, with larger production runs typically reducing the unit cost. The mold represents a significant initial cost, usually ranging from several thousand to tens of thousands of dollars. However, once made, parts can usually range from a few cents to a few dollars each, although this can vary depending on the size and complexity of the part.

Plastic injection molding
Plastic injection molding

How Do I Design Plastic Injection Molding Parts?

Designing plastic injection molding parts involves considering several factors to ensure the final product meets the desired specifications. It is also important to design effectively and cost-efficiently for production. When designing plastic injection molding parts, you should consider the following important rules:

Design for Manufacturability

: To create injection molding parts that can be effectively and consistently produced, it is important to design with the manufacturing process in mind. Consider factors such as the size and shape of the part, the number of cavities in the mold, and the type of plastic to be used.

Use of Appropriate Wall Thickness

The wall thickness of a plastic injection molding part is critical for its structural integrity and manufacturability. It is important to balance the desired durability and rigidity of the part with the ability to fill the mold cavity and effectively cool the plastics. Generally, thicker walls can be stronger but may also lead to longer cycle times and higher costs.

Optimizing Gate Location

The gate location is the point where molten plastic enters the mold cavity, and its position can affect the durability, aesthetics, and manufacturability of the part. Choosing a gate location that minimizes the visibility of weld lines, maximizes the durability of the part, and makes mold filling efficient is important.

Considering Angles

Angles are slopes added to the design of plastic injection molding parts to facilitate their removal from the mold. To prevent sticking to the mold and damage during removal, it is generally recommended to include at least a one-degree angle on both sides.

Testing and Iteration

Designing, testing, analyzing, and continuously improving plastic injection molding parts is an iterative process that requires ongoing efforts to achieve the desired outcome. Working closely with your injection molding partner to test and improve the design throughout the development process is crucial. These considerations might seem daunting if your project is still in its early stages. However, the engineers at MARM ENGINEERING think about these details every day while designing parts for their clients. You can leave the nuances of ensuring a plastic part runs smoothly in an injection molding machine to us!