How to Choose CNC Machining and Injection Molding?

When designing custom CNC machining parts, what kind of machining method should I choose? When designing to manufacturing parts, you can optimize the processing according to the design plan. There are usually three methods: CNC machining, 3D printing, and injection molding. This article mainly tells: How to choose CNC machining and injection molding?

When choosing a CNC machining process, the design feasibility of the part, the use of materials, the size of the part, the processing speed and the cost are generally considered.

In terms of design:

If the parts do not need to spend money to make molds, then you can choose CNC machining because it provides great flexibility. The mold is expensive in the early stage and difficult to manufacture, and in many cases it is impossible to modify it according to the change of the design.

Material selection:

There are more machinable materials processed by CNC than by injection molding, but it is easier to select harder plastic materials for CNC processing. However, injection molding processing parts have more limitations in material selection. As more and more high-performance materials are considered for injection molding, some materials that cannot be processed, such as soft materials such as rubber, can be molded.

Tolerance/surface finish:

One advantage of injection molding is the repeatability between batches. The mold can withstand millions of parts with minimal wear. Allow the parts to be almost the same from one batch to the next. Through CNC machining, each part is placed on the manufacturing machine and will see more variability. The advantage of CNC machining is that it can maintain strict tolerances and better surface finish for most materials.

Machining speed:

If you need to process a small number of parts in a short time, then CNC machining is the best choice. For example, if you need to make 15 parts in two weeks, CNC machining is the best choice. When you need 40,000 parts in a few months, injection molding takes time to make the mold and ensure that the parts are within tolerance, which may take several weeks to several months. On the other hand, our CNC machining factory machine workshop has hundreds of equipment processing, which can shorten the delivery time.

Machining cost:

It is cheaper to choose CNC machining parts. If you want to get some quantitative benefits from the price, you usually have to see between a few to a hundred pieces.

The actual cost per piece of injection molded parts is much cheaper than machined parts. Unfortunately, for injection molding, creating a mold upfront is a big cost.
 

Summarize        

It is not easy to make a decision between CNC machining and injection molding from the above. You need to consider the tolerance, price, design features, etc., and choose the corresponding processing method based on the comprehensive cost price.