Injection molds are used to manufacture plastic parts according to customer’s design. In general, common plastic materials are relatively cheap, and therefore the unit price of the plastic part is low. However, the cost of the injection mold is very high.
Why are Injection Molds so Expensive? Injection molds are expensive because it requires a high precision CNC machining and polishing for the mold cavities. The molds are made from steel which is harder to machine compared to Aluminum. The number of cavities, size, and the grade of steel are the main parameters that determine the cost.
There are other smaller costs that factories always include in the pricing of injection mold such as the testing of the molds in the plastic injection machines. In this post, we will review all the processes in the production of an injection mold, and estimate the cost of each process.
Below are the production steps of injection mold:
Before we proceed with the step of mold design using 3D CAD software, let us know what a mold design is. Mold design is a process used in manufacturing to shape material using a frame to create a pattern and produce a part/ product.
A 3D CAD (Computer-Aided Design) is a process used to create complex 3D models and drawings using computer software. Complex geometry is laid out using computer software to enhance its features, size, and dimensions.
We use 3D CAD software for mold design to reduce errors and be able to modify the design and ensure the accuracy of size, dimensions, and shapes. The concepts of the products were generated from ideas. Once the concept has been finalized, then we use the 3D CAD software to lay out the plans and make the design consistent by using uniform patterns and designs.
In this phase, adjustments, revisions and other quality control are done during the designing process. It is faster to make modifications because we are using software via computer to enhance the designs. After the concept has been finalized, then we build a full representation of the mold.
A mold design using 3D CAD software is the initial process used for injection molds. The engineers will make the modifications and create the plans before the items are molded. Injection mold is a complex tool that is used for the manufacturing of many kinds of products.
The overall process of mold design usually takes 2-3 days to finish. The manufacturer usually supplies the 3D model to the customer for approval before starting the production of mold. The cost of this process takes approximately 10% of the total cost of an injection mold.
An injection mold is a manufacturing tool used to create many products such as automotive parts, kitchen aids, musical instruments, children’s toys and many more. This is widely used by many factories in creating their products. An average lifespan of an injection mold ranges from one hundred thousand to a million cycles in its lifetime.
There is a wide range of alloys that can be used in making an injection mold. Depending on the product used for an injection mold, the price range will also increase. Generally, injection molds are made up of mild steel.
Because of practical reasons, we want to go for materials that are more expensive because of the following reasons. (1) The quality of the injection mold is better compared with cheaper materials, (2) those injection molds with more expensive materials tend to last longer than the cheaper ones. The more costly raw material is used for an injection mold, the more expensive it may be, yet its lifespan will also be longer.
For the reasons mentioned above, the cost of raw materials used to create an injection molding machines takes approximately 30% of the overall product cost. Typically, the purchase of raw material for the injection mold takes around five to ten days to accomplish.
There is a long list of products manufactured using the CNC machine process. There are thousands of CNC machined parts around us. This may be parts used for automotive, airlines, space and many other high precision metal parts. It used by many manufacturing factories because of its ability to produce products at high precision and speed.
As the age of technology and computer continues to improve in the twentieth century, more and more machines are used to enhance the manufacturing experience and process of factories. One of the innovations of manufacturing is the CNC machining process.
CNC (Computer Numerical Control) machining process is a process that involves computer devices that manipulates tools for productions. The manufacturing process uses a program that is run by a computer to operate. Engineers or machinists use the program to generate a product using the software to enhance the productions and speed up the process from a computer design.
A CNC machining process works in contrary to 3D printers which use the additive process. A CNC machining process is a subtractive method wherein a material is removed from a stock to make its form. It uses many kinds of raw materials such as plastics or metals.
In the case of an Injection mold, we subtract the material from a steel block by CNC machining to create cavities; then in the injection process, a liquid plastic will be injected into these cavities to form of the required parts.
The CNC machining industry has improved over time and is making manufacturing seamless as it can create products with complex geometry. About 45% of the total cost of injection molds are coming from the CNC machining process and may take 5-10 days to complete.
There are three processes used in a CNC machining:
1. Drilling – this is a process used wherein a drill (cutting tool) is stationary while spinning at a rate of hundreds to thousand spins per minute. It is used to cut or make a hole to the material to produce the required design.
2. Lathes – lathes work in reverse to drilling whereas the drill bed is stationary and the stock spins in contact against the drill bed. It has limited functions compared with other techniques.
3. Milling machine – the most common technique in the CNC machine process. It involves a rotary cutting tool similar to drills but it’s cutting capability is more complicated.
Next on the process would be polishing. Polishing is a manual process in injection molding to enhance the finished product. It is a requirement used to improve the surface of the finished product depending on the material used. There are different types of polishing used in injection molding.
The polishing process takes 5-10% of the total cost of an injection mold and may take 2-3 days to finish.
Different types of polishing process:
Injection molds are very useful in the manufacturing industry. If you look around you, you will see thousands of things that are created using an injection mold. With this, the innovations for injection mold continues to improve to enhance the production of many things.
Plastics are easily reproduced to another finished product because of molding machines. Injection molds are used highly in the manufacturing and production industry. It makes recreating materials and parts easily and improves the speed of production.
The entire process would take hours because of the injection molds. It is programmed in computer software to design the plastic and be formed into something new. The initial process is to create a draft of a design. At the end of the process, it is essential to test the finished product to check the quality. But let us go back and understand how mold affects the production.
Each injection mold has a mold that is used to form the finished product. It is essential that the mold is designed correctly with the right angles so that air can come in and make it easier to release the product from the mold using ejector pins. At the end of the process for creating injection molds, checking the angle, and spaces in between the molds are critical to secure a successful mold.
The testing of mold usually takes 5-10% of the total cost of an injection mold. It takes 2-3 days to ensure that molds are made accurately as this will provide smooth mass productions of the plastic parts.
Injection molds come at a high price. This is an investment for manufacturing companies because it improves the overall production in factories. It is an intricate and complex process used in manufacturing to recreate new products from scratch. The method of making an injection tool also takes time to complete. The time spent in making injection molds affect how the price of one is evaluated. Also, a significant contributor to the cost would be the materials used on an injection mold.
In a manufacturing business, speed is critical as well as quality. By using injection molds, it ensures quality and accurate product yields while keeping production errors to a minimum, thus reducing cost.
