CNC Machining VS Injection Molding

Nowadays, CNC machining and injection molding are widely used. Many people may be confused when choosing which one to use. They do not know which one is better to satisfy their requirements since they have no idea of the advantages and disadvantages about CNC machining and injection molding. This article will tell you the advantages and disadvantage about CNC machining and injection molding, what’s more, we will inform you of the comparisons between CNC machining and injection molding.

List: 1. Advantages and Disadvantages of CNC Machining

         2. Advantages and Disadvantages of Injection Molding

         3. Comparisons Between CNC Machining and Injection Molding

Advantages and Disadvantages of CNC Machining

Pros:

• A person can supervise many CNC machines, because once they are programmed, they can usually work by themselves. Only cutting tools need to be replaced occasionally.

• The programming design of NC machine tools can be manufactured hundreds or even thousands of times and every manufactured product is identical.

• A large number of tooling reductions are made, and complex tooling parts are not required for complex tooling. If you want to change the shape and size of the part, you only need to modify the part processing program, which is suitable for new product development and modification.

• High production efficiency in multi-variety and small-volume production, reducing production preparation time, machine tool adjustment and process inspection time, and reducing cutting time due to the use of the best cutting amount.

• It can process complex profiles that are difficult to machine with conventional methods, and even process unobservable parts.

• CNC machine tools can be used 24 *7 continuously throughout the year, and can be maintained once closed.

Cons:

• Compared with manual machines, fewer workers are needed to operate CNC machines. Investment in CNC machine tools may lead to unemployment.

• Machine tool equipment is expensive and requires a high level of maintenance personnel.CNC machine operators only need basic training and skills to supervise multiple machines. Over the past few years, engineers have required years of training to operate central lathes, milling machines and other hand-operated machines. This means that many old skills are being lost.

Advantages and Disadvantages of Injection Molding

Pros:

• Since the melt plasticization and flow molding of the molding material are carried out in the cylinder and the cavity, respectively, the mold can always be in a state in which the melt is quickly condensed or crosslinked and solidified, thereby facilitating the shortening of the molding cycle.

• An operator can often manage two or more injection molding machines, especially when the molded parts can be automatically unloaded, and therefore the labor required is relatively low.

• The production efficiency is high. Two sets of molds can contain dozens or even hundreds of cavities, so dozens or even hundreds of plastic parts can be formed in one molding.

• Due to the high pressure during molding, it is possible to form a plastic part with a complicated shape, a surface pattern and a clear marking and high dimensional accuracy.

• When molding, the mold must be locked before the melt is injected, and the melt-to-die with good fluidity is added.The cavity wear is small, so a set of molds can produce large quantities of injection molded products.

• The molded plastic parts can be used only with a small amount of trimming, and the waste generated during the molding process can be reused, so that waste of raw materials during injection molding is small.

Cons:

• The quality of molded products is limited by many factors, so the technical requirements are high and the difficulty is mastered.

• The key tool for injection molding is the mold, but the cycle of design, manufacture and trial of the mold is very long and the production is slow.

• Since the cost of the injection molding machine and the injection mold are relatively high, the startup investment is large, so it is not suitable for the production of small-volume plastic parts.

• Due to the limitation of the cooling conditions, it is difficult to form a plastic part having a thick wall and a large change.

Comparisons Between CNC Machining and Injection Molding

• CNC is the mechanical finishing of metal, wood and hard plastic blanks while Injection molding is to use an injection molding machine to heat the plastic particles and then inject them into the mold for cooling and setting, which belongs to thermoplastic processing.

• CNC processing provides more materials for manufacturing parts. For injection moulded parts, material selection may be more limited.

• CNC processing produces more waste than injection molding. It may take longer to set up the initial injection mold. Once it is finished, it is almost zero scrap, because it is liquid in the first use, while CNC cuts off a lot, and then it is often melted back to form another block (higher production time and energy cost) or completely scrapped, which is expensive and cost-effective.

Having seen the advantages and disadvantages of CNC machining and injection molding listed and the comparisons of these two methods, we believe that you will choose a better method for you to use.