Injection molding is one of the most popular processes for producing plastics. It manufactures identical parts in mass and large production series cost-effectively.
Plastic injection molding is a fast and intense way to inject molten material into a mold. The process uses high pressure and heat to penetrate cavities in the molds to mirror the end features of a product.
That said, several factors determine the cost of plastic injection molding. The processes that a product goes through to reach its final stages determine the final price tag. This article reviews the cost of plastic injection molding, cost drivers, and how to reduce production costs.
The cost of a plastic injection mold is one of the main questions for those seeking to source injection molders. That is because the mold is the most influential cost-driver in upfront production.
Simply put, molds requiring complex molds in high volume can cost as much as $100,000. Typical low-volume molds printed using the 3-dimensional technique can be priced as little as $100. While plastic injection molding may seem more expensive than CNC machining, the nature of thermoplastics, the workforce, and short cycle times reduce cost variables. Automated manufacturing processes and economies of scale also reduce total costs. Essentially, low-cost variables and low-cost per part are distributed across thousands of other parts to reduce overall production costs while maintaining efficiency.
This ability to manufacture and scale thousands of parts enables companies to mass-produce injection-molded parts more cost-effectively compared to 3D printing and CNC machining. Defining the injection molding cost is a combination of many factors, which you’re going to see shortly. When you factor in molding costs, more complex geometries increase manufacturing costs. Simple parts without advanced finishing touches and undercuts are pocket-friendly.
Understanding the various costs in plastic injection molding requires an in-depth evaluation of different factors. These include:
The plastic injection molding process uses special-purpose equipment, ranging from small desktop devices to large in-house machines. The latter are mainly controlled by mega factories, contract manufacturers, and service providers. Large machines can be expensive, costing anywhere from $50,000 to more than $200,000. The equipment also has advanced operational features requiring skilled labor, close monitoring, and maintenance.
Complex plastic molds require more intense processes and technical expertise.
As such, small-scale enterprises are better placed to outsource design and fabrication aspects to plastic injection molding companies. Businesses that have the right equipment can still produce plastic molds in-house as long as mold costs are affordable. Simple 3D molds are cheaper in low volumes, while mid-volume 1,000-5,000 aluminium molds require more expenses-$2,000 at the bare minimum.
However, outsourcing intensive projects will factor out the expenses for developing plastic molds from scratch. More complex plastic molds for larger productions can cost up to $100,000.
Injection molding utilises multiple plastics depending on the final products, i.e., TPU, PC, PS, PP, ABS, and PE. The price of materials varies, with thermoplastic pellets costing between $1 and $5 per kg. A product’s model design and the specific amount of molding material also affect the overall material cost.
Plastic injection molding relies on technical labor to get the job done. Most CNC, 3D, and EDM machines are automated and self-regulating to produce molds with different specifications. Moreover, the molding equipment automatically injects molten materials into the mold. Other labor automation expenses include:
- Configuration costs: The plastic injection molding process takes time to configure machines for producing molds and final products.
- Monitoring costs: Personnel have to monitor plastic injection molding processes despite systems being automated. Their wages are added to the total process.
- Repair and maintenance costs: Replacement of faulty machine parts adds to total manufacturing expenses. That also includes the tools required for repairing the defects.
All these costs factor into labor costs when producing in-house injection-molded plastics. They are mainly affected by the factors discussed below.
Plastic injection molding is convenient for manufacturing different plastics. However, the overall production costs are affected by:
If your part’s design or prototype is more complex, making the actual mold would also be difficult. Achieving the final product will require more expensive technical tooling to meet your expectations. For instance, secondary EDM processes might be necessary to create special undercut features that take more time. If the part design is large, you’ll most likely spend more.
Resin is simply the material used in plastic injection molding. The availability of a suitable material along with its subsequent additives and compounding parts greatly affects the total cost. Grade, color, quantity of parts, and plastic molding temperature are also crucial when choosing resin.
Steel is the material used in the creation of molds. It is mostly used to create plastic molds, but the specifics of the process vary with the types of materials. Additionally, different molds have different durability properties. Those that last longer require more complex processes, thus increasing the manufacturing costs. When selecting the material, also consider factors that affect a mold’s lifespan. These include cycle time, production volume, and final surface finishes.
A part that requires more cavities to form the final product requires longer press time. Rapid production is not ideal for creating such products, thus increasing costs.
When your plastic injection molding company adheres to specific designs in production principles, you can significantly reduce the overall costs. Here’s what you can do:
- Remove potential bottlenecks and undercuts that require complex geometry. That means the CAD model in your company has to be feasible enough to undertake manageable projects.
- Eliminate unnecessary features in the model’s design to save on material.
- Integrate the core cavity method into sink wall cavities, thereby eliminating the need to work at steep angles.
- Embracing universal molds for creating self-mating parts.
Before venturing into a plastic injection molding project, consider the above factors to calculate all costs. They will assist you in improving the quality of your parts without breaking the bank.