Plastic injection molding is a popular manufacturing process that is best used to create high volumes of identical objects. Although injection molding has a higher upfront cost than other production methods, this process often has the lowest price per unit for high production runs.
Injection molding prices can vary greatly based on the size and scope of the project. Initial tooling costs usually range between $1,000 and $15,000; however, once the mold is created, parts can be made for at little as $0.75 per unit. A single mold can be reused for thousands of units, resulting in an extremely low overall cost of production.
Because every project is different, a new injection molding quote will need to be generated for every unique project. Read on to learn about the factors that will influence the final injection molding price.
Cost #1: The injection mold
A unique injection mold needs to be created for every new project. Once the mold is made, it can be re-used for new machine cycles until it wears out.
Injection molds can cost anywhere from $1,000 for a small, single-cavity mold to $100,000 for a complicated and durable family mold. There are several factors that determine how much the mold will actually cost.
- Size: Smaller injection molds take fewer materials and are usually cheaper to produce. This is especially true if the molds are made with CNC machining since removing large amounts of metal will increase production times and costs.
- Material: Most injection molds are made from metal and tooled with CNC machining. Durable metals like tool steel or carbon steel are more expensive, but they can withstand more machine cycles and will produce more units in the long run. Soft metals like aluminum can be used to make cheaper molds, but they will break down quickly and are best suited to low-run production.
- Cavities: The number of unique cavities in a mold will determine how many objects can be made in a machine cycle. Adding more cavities will make the mold more expensive but will usually reduce the overall production cost per unit.
- Complexity: Injection molding services can be used to create surprisingly complex items, but additional details always increase production costs. Factors that add complexity include enclosed spaces, undercuts, and small details like ridges or engraving.
Many of the factors that increase the initial cost of an injection mold, like material or complexity, may actually decrease the overall price per unit. Engineers should consider the scope of the project and whether the mold will be needed to produce more units in the future.
Cost #2: The materials
There are a wide variety of thermoplastics that can be used for injection molding. Options range from cheap and flexible plastics like ABS to expensive and durable plastics like PEEK. Thermoplastic materials can cost anywhere from $7 to $140 per kilo.
Thermoplastics should be chosen based on both the price and their intended purpose. Disposable consumer products are usually made from ABS or polycarbonate; these plastics are cheap and easy to work with, minimizing production costs. Materials like nylon or POM are better suited for mechanical applications, but they come with unique engineering considerations such as potential warping or moisture resistance.
Cost #3: The production cycle
Final cost consideration is the actual labor required to make the objects. Injection molding is an automated process, but manual labor is still required to ensure smooth production. Factors that might increase the amount of labor include:
- Complicated molds that require rotation or a manual adjustment between cycles
- Post-processing to remove unnecessary parts or achieve a specific surface finish
- In-house assembly of multiple molded parts
To avoid these costs, design simple molds that can make the desired part with as little additional interaction as possible.
Planning your next project with online injection molding services
The easiest way to check the price of an injection molding project is to upload your design to an online manufacturing shop near you. The online manufacturing platform will automatically check your design for viability and generate an instant quote based on the complexity of the design, the chosen materials, and the number of units requested.