xiehe model

Creating items from molds is a common practice. Most kitchens have a range of cookie cutters, cake tins, or jelly molds. Mould-made items fill our homes, cars and hospitals. They are also essential for aerospace and defense engineering. So whether it is household goods or parts of spacecraft, molds are very common.

Manufacturers use injection molding to create parts for many consumer and industrial applications. The method involves melting raw material and injecting it into a mold under high pressure. In high volume, injection molding offers low cost and relatively competitive speed. For parts that require higher precision, such as medical devices or those commonly used in defense and aerospace applications, other manufacturing methods may provide better results.

In these cases, consider computer numerical control or CNC machining. A CNC machine shop makes plastic parts using software-controlled milling, turning and drilling equipment that removes material layer by layer from solid blocks. This approach has clear advantages in terms of time, cost, accuracy and performance of the product you design.

The pros and cons of CNC machining versus injection molding are detailed below to help you make the best choice for the production of your next prototype or part.

Advantages and disadvantages of injection molding

Comparing and contrasting injection molding and CNC machining, we must first understand the advantages and disadvantages of injection molding.

Advantages of injection molding

When making large numbers of nearly identical parts, most manufacturers choose injection molding. This process supports everything from toys to car engine parts—anything that needs to be mass-produced from moldable plastic.

Injection molding offers a wide variety of materials, and more are being created regularly to meet the demand for high-performance plastic parts. While CNC machining cannot accommodate softer parts that require TPE or rubber materials, injection molding can.

Disadvantages of injection molding

When the batch is larger, the price of a single piece of injection molding is lower. Costs associated with manufacturing the actual molds for injection molding drive up startup costs. Certain materials, such as fiberglass-reinforced plastics, require molds made of hardened tool steel to handle the increased pressure.

Another disadvantage of injection molding involves the costs associated with part replacement, which often requires the production of new tooling or molds. Additionally, the mold consists of two halves, which must be put together for injection, leading to potential surface defects. Injection systems can introduce air bubbles into the material, causing further defects.

There are many good reasons to use injection molding, especially when it comes to mass production of parts. Depending on your product usage, material specifications, and desired quantities, CNC machining may provide a better solution for sourcing high-quality plastic parts.

Advantages of CNC machining and injection molding of precision parts

Here are four things to consider when evaluating injection molding and CNC machining:

Quantity: Generally, CNC machining provides faster delivery and lower cost to reduce the number of parts. The exact quantitative threshold for cost reduction from injection molding depends on part size, part complexity and material selection.

Speed ​​and expense: CNC machining offers higher speeds for small batches. Or rapid prototyping or limited parts production runs without breaking your development budget, machining provides faster turnaround times at a lower cost. For production volumes in the tens or hundreds of thousands, injection molding usually makes more sense.

Accuracy: Machined parts give you more control and fewer variables when dealing with tight tolerances. Machining focuses on the precise specifications of the part itself, rather than injection molding, which considers the tolerances of the mold rather than the part. When absolute precision is required in the final product, especially for aerospace, medical and defense applications, CNC machining often provides more accurate results.

Performance: For high-performance hard plastics that cannot be molded, manufacturers choose CNC machining. Certain applications require hard plastics that must be machined. The melting and rehardening of plastics in injection molding can bring unwanted changes to the material properties of the final part.

Both injection molding and cnc machining offer high-quality methods designed to produce the best possible product, and each method has its own advantages and disadvantages. Many end products include combinations of components made by each method. To make the best choice for your production needs, seek help from the manufacturing experts who know these methods best.

Machine shops see a wide variety of part needs and understand the capabilities of different manufacturing processes. They have first-hand experience working with a variety of materials and make informed choices for your product. With this knowledge and experience, experts will advise you on the best approach for your components.

In many cases, product development teams start with CNC machining to build prototypes and then transition to injection molding for a full production run, and the material requirements of the part may dictate which production method will best support your overall project.

Shenzhen Xiehe Company is mainly engaged in the production and manufacture of non-standard precision hardware parts. It has been deeply involved in the industry for many years and has rich experience. If you have requirements for CNC machining, CNC lathe machining, and five-axis machining services including aluminum, copper, stainless steel, iron, titanium alloys, plastics and other products, you can contact Xiehe, and we will provide you with an integrated solution.