Advantages and disadvantages of plastic injection moulding

The plastic injection molding industry is very popular among manufacturers, but like any type of manufacturing method, it also has its own advantages and disadvantages. The advantages of plastic injection molding focus on high precision and high repeatability. At the same time, it combines high speed, low single piece cost and a wide variety of plastics to choose from. Disadvantages include higher initial costs and delivery times than some other processes.

 

Plastic molding advantages

1. Precision plastic injection molding part

Plastic injection molding is very suitable for very complex parts. Compared with other technologies, molding allows you to integrate more functions with very small tolerances. Look at the picture on the right. You can hold this mold in the palm of your hand. It has bosses, ribs, metal inserts, side cores and holes. The tool has sliding closing function. This is a small part of a large number of functions! It is impractical to use plastic manufacturing, and it is impossible to use vacuum forming process.

2. High repeatability

Once your mold is finished, you can make the same product again and again. Then again. A properly made mold tool has a long service life as long as it is handled by the molding machine installer!

3. Low single piece cost

Although the initial investment of plastic injection molding tools is very high, the subsequent single piece cost is very low. Other plastic processing technologies may require multiple operations, such as polishing, while injection molding can be completed at one time. If you choose to CNC the above parts, the cost of each part will be as high as hundreds of pounds. If you want to put into full production, injection molding is your best choice.

4. Fast

The cycle time can be as low as 10 seconds. Combined with multi impression injection molding tools, you can get a large number of products very quickly. The upper part takes longer because it is a professional material and has many functions that need to be molded correctly, but you can still get 70 parts per cavity per hour in about 50 seconds. CNC processing takes half a day at a time - 3D printing takes longer!

5. Material selection

If injection molding is really good at one thing, it is the ability to customize materials and finishes according to almost any type of requirements. You can choose from plastics, thermoplastic rubber, chemical resistant plastics, biodegradable plastics and many other materials, so be sure to find out what you need from the parts, and you will have many choices.

You can also choose almost any conceivable color, or choose from a variety of finishes, whether for aesthetic or functional purposes.

6. Special surface treatment, engraving and printing

In addition to a range of colors, injection molding tools can also be made into special finishes, which will be displayed on the mold. Almost any finish you like, such as leather appearance, soft touch, spark, high gloss, everything. You can also engrave a logo or other text in the tool. Finally, you can print your mold because a range of inks can print well on plastic.

7.Eco-Friendly

A well-designed mould can produce parts without runners by using hot runner systems. Commonly most moulds produce runners for every part moulded. A majority of the moulders recycle these runners by grinding for reuse.

 

Now that we know why injection molding is so effective, let's take a look at some of its shortcomings to provide you with a more comprehensive understanding.

 

Disadvantages of plastic molding

1. High initial cost

As we mentioned earlier, injection molding can be very cost-effective, especially for larger production runs, because the cost of a part is relatively low.

However, before you actually manufacture, you need to design and create your own mold, which may take a lot of time and manpower to perform correctly.

Nevertheless, even if the process may be complex, once completed, you can quickly produce thousands of parts using molds.

2. Initial delivery time

From the product concept to the final part, it may take months of design, review, testing and tool manufacturing. Once the mold is completed, as mentioned in the advantage, it takes only a little time to produce the required parts, especially when you have a multi cavity / embossing mold.

But even if the mold development project may take time, once completed, the process will become very fast and reliable. If you know what you're looking for and have past experience, you can significantly reduce time.

3. Size limit of large parts

Huge machines are needed to make plastic injection molding. Very large parts require huge mold tools and are very expensive to manufacture. In this case, processes such as plastic manufacturing may be a better choice, depending on the type of product required.

4. Design restrictions

Plastic molds need to be designed very carefully to avoid tool problems such as undercut (which will significantly increase mold cost), locking features and insufficient drawing modulus (what is the drawing angle of plastic molds?). The wall design needs to consider the material and temperature, otherwise the mold may not be fully filled. The placement of ejector and cooling pipeline needs to be considered to ensure the beauty of the product.Unless an experienced design team works with mold manufacturers and raw material suppliers to handle the required parts, plastic injection molded parts may be almost unlimited.

 

WIT MOLD is a very professional mold design and mold manufacturer located in southern China, and has passed the ISO2009:2015 international quality standard certification. We started to build complete molds in 2011, specializing in the production of different types of injection molds, which are mainly exported to North America and Europe.Our longstanding experience allows us to help you choose the best manufacturing process for your new project. We also share our knowledge on our plastic moulding advice pages. Or just:Get a Quote now !