Calculating Injection Molding Costs: Tips and Facts You Need to Know

The injection molding cost is a common focus of plastic product manufacturers who use the process. It is an agglomeration of different factors and elements, and understanding such factors and elements plays a critical role in optimizing the cost of any project. As a result, this article breakdown everything you need to know about how much injection molding cost and how you can optimize it for your project.  

Is Injection Molding Expensive?

The answer is not straightforward, but the injection molding process is cost-effective if you look at the mass production of plastic parts. However, the initial setup cost can be high due to the high machine prices. In that instance, plastic injection molding cost is highly expensive. Nevertheless, the overall manufacturing cost reduces as you produce parts in mass. As a result, many consider plastic injection molding one of the most cost-effective for the mass production of plastic parts.

In short, the higher the number of parts produces, the lower the price per part.

Key Factors that Affect Injection Molding Cost 

Many factors directly affect how much injection molding costs. Below are key elements you need to take note of.

· Part Costs

Part costs depend on the size, design, and volume of parts. As a result, knowing how these factors can affect plastic injection molding costs can greatly optimize your project’s cost.

– Part Size

Making a large part will mean two things. One is that it will require more injection molding material, increasing the cost of injection molded parts. Aside from that, a large part will require using the right injection molding machine and manufacturing the right mold size to hold such parts. The larger the injection molding machine and the more sophisticated the mold manufacturing process, the higher the injection molding cost.

– Part Complexity

Complex parts will require a mold of equal complexity made using a capable manufacturing process such as CNC machining, EDM machining, or 3D printing. Aside from that, complex parts often require more material to fill the mold, which can further drive up the material costs of injection molding. The production time can also increase for complex parts, as they may require longer cycle times or additional steps in the production process. This can lead to longer production times and ultimately higher costs.

– Part Design for Manufacturability

Businesses that provide manufacturing services with design for manufacturability (DFM) analysis ensure the CAD design is optimized for manufacturing and assembly. Design for manufacturability is critical in product development as it helps reduce errors and part costs and improves productivity and efficiency. Products whose designs are unsuitable are more likely to incur additional costs due to elongated production processes or material wastage.  

· Tooling Costs

The tooling cost incurred during injection molding depends on the machining process used in making the mold, the material used, mold complexity, and mold cavity size.

– Choice of the Mold Manufacturing Process

Injection mold manufacturing uses various methods, including CNC, electric discharge, and 3D printing. Each method is unique with the following properties:

3D printing

3D printing is suitable for making molds with complex designs or less durable injection molds at a low cost. Furthermore, 3D printing allows mold designers to test and change the design at any point in time before mass production begins.

Stereolithography (SLA) is the most common 3D printing process for making such molds. The cost depends on the material. With plastic materials, the mold can cost about $100. With aluminum and low details, the mold can cost about $2000 to $5000. For a mold with higher details, the price can be as high as $100,000.   

CNC Machining

CNC machining is a highly accurate molding manufacturing process suitable for steel and aluminum materials. The machining process is subtractive and suitable for making injection molds with intricate and complex designs. Due to requirements such as large space and high machine costs, businesses often outsource making a mold using CNC machining to third-party service providers.

EDM Machining

EDM machining is the most suitable for creating a mold from hard and conductive materials. Like CNC machining, businesses often make such molds by outsourcing to third-party service providers.

Of the three methods, CNC machining is the costliest (costing about five to ten times the cost of 3D printing).

– Choice of Mold Material

Injection molds are made using steel and aluminum, each with unique properties. For example, aluminum molds are lightweight, rust-resistant, heat-resistant, and highly formable, while steel is more suitable for high-volume production due to its immense durability. As a result of its properties, steel molds are more expensive, causing an increase in the cost of injection molding.

– Mold Complexity

Mold design for complex parts will require a compatible manufacturing process and higher technical expertise. Therefore, such molds have a higher cost than simpler parts. Although most will require aluminum materials due to the material’s formability, technical expertise comes into play. Moreover, if the manufacturer prefers a steel mold which is already expensive, damage to the mold can increase the cost of production as steel molds are difficult to repair.

– Mold Cavity Size

An increase in the mold cavity will increase the press time, reducing the production speed and increasing the cost of injection molding. Aside from the cavity size, the number of the cavity also plays a huge role in the plastic injection mold cost.

Single cavity molds have one cavity, making it easier to produce. However, the cycle time increases, reducing the production rate and increasing part cost. On the other hand, multi-cavity molds (have many cavities of the same design) and family cavity molds (have many cavities of different designs) increase the cost of mold manufacturing but increase the production rate and reduce the cost per part.

· Materials Costs

Injection molding raw materials come in different properties, applications, availability, and price. Generally, thermoplastics used in the process can cost between $1 to $5 per kilogram. However, other factors also play more role in the cost. For example, the more versatile the material, the lower the price visible in the case of polypropylene and polyethylene. Their price pales compared to thermoplastics such as PEEK, known for its durability, chemical, heat, and wear resistance.

Note: the material cost incurred during the plastic injection molding process also depends on the amount of material you use to manufacture the product.

· Production Volume

The production volume also plays a huge role in the injection molding cost. It affects the amount of raw injection molding material required, the sophistication of the injection molding machine, and the injection mold’s strength/durability/other mechanical properties. The volume of production is divided into three major categories:  

– Low-Volume Production

This will require a simple mold made from less costly aluminum or a 3D-printed mold. Furthermore, it will require low raw materials and less sophisticated machines. Overall, the injection molding cost is low. However, there is a higher cost per unit part.  

– Medium and High-Volume Production

This will require a strong injection mold made from steel due to its long life expectancy, many materials, and, if possible, a sophisticated machine. This should increase the injection molding cost. However, the high cost will be distributed among the parts, reducing the cost per part manufactured.

It is important to note that there is a higher cost distribution per part in high-volume production than in medium-volume production. As a result, they have a lower cost per part manufactured.

Additional Elements Increasing Injection Molding Cost

Aside from the part, tooling, material, and production cost, other elements can affect the injection molding cost. Below is an explanation of how they can affect the cost.  

· Equipment Costs

The equipment used in the molding process is unique. The cost of a machine depends on the size and its level of sophistication (often measured in terms of automation), and it ranges from $10000 (small) or less suitable for low-volume injection molding to $200,000 (large) suitable for high-volume injection molding. Medium molding machines ($50,000 or more) can also be tailored for medium-level molding. Also, you need to consider the following types of injection molding machines and how they affect the cost:

– Hydraulic Injection Molding Machines

Hydraulic molding machines use a hydraulic pump to control the machine during molding. They have high durability, consistent ejection and injection, and affordable initial purchase cost. However, they consume excessive energy and are imprecise.

– Electric Injection Molding Machines

Electric injection molding machines use an electro-servo motor to control the machine during molding. They consume less energy, are accurate, incur low operating and maintenance costs, and are easy to use. However, they require a high initial investment cost and need routine maintenance.

– Hybrid Injection Molding Machines

Hybrid injection molding machines are a combination of both machines. They are characterized by energy efficiency, high precision, and repeatability. However, they require heavy maintenance procedures due to the use of hydraulic pumps and electric motors and have a very high initial investment cost.

Instead of buying a machine, businesses outsource their project to injection molding service providers. So they no longer incur the heavy cost of purchasing the machine but are subject to the service provider’s service cost.  

· Labor Costs

Labor costs comprise several costs associated with human operators:

• Setup costs include the cost of configuring and setting up the injection molding machine. It takes much time because of the accuracy and technical expertise required for such a process.  
• Repairs cost comprise replacing faulty parts, tools, and several components during the molding process.  
• Operator cost is essential even though injection molding machines are most time automatized.  

· Additional Services

Additional services rendered by the injection molding services providers, such as finishing or post-processing services, product inspection, and packaging, can increase the cost of injection molding.

– Surface Finishing

Surface finishing includes processes such as annealing, sandblasting, powder coating, etc., in which the part is subjected to increase its aesthetic appeal or functionality. They are separate from the injection molding process itself. However, many service providers will give a discount to clients using them for both injection molding and surface finishing. Also, there are secondary services which can be manufacturing processes(e.g., machining and drilling), assembly services (e.g., sonic welding) and decorating (e.g., pad printing), which can increase the injection molding cost.

Note: not all parts will require surface finishing or other secondary services. As a result, you should ensure you need such services to increase overall production efficiency and less material wastage.

– Part Packaging

Part packaging costs depend on whether the packaging is consumer-facing (i.e., recognizable and short-span) or more costly shipping packaging. Consumer-facing packaging is suitable for products that are ready to use. However, larger manufacturers can use automatic packaging, which reduces damage and incur fewer errors.  

– Part Inspection Requirements

Part inspection costs can be specialized or standard. On the one hand, standard inspection is an internal process that requires trained personnel to check for part defects (cosmetic or critical) and a quality verification team to identify the probable cause. On the other hand, specialized inspection involves inviting specialized engineers to inspect the product. Thus, specialized certification costs more, and sometimes injection service providers offer the certification at a cost.

Best Practices to Reduce Costs in Injection Molding

Injection molding is highly reliable and cost-effective compared to alternatives. Nevertheless, you can still reduce the injection molding cost using the pointers below:

· Simplify Tooling Design

Having a simple product will limit the requirements for complex molds. As a result, the mold manufacturing process can be simpler, reducing the injection molding cost.

· Reduce Unnecessary Part Features

Stemming from the product, you can maximize the product design by focusing only on basic features that will actualize the part’s optimum performance. Avoid elements or components that do not provide market value.

· Optimize Material Selection

Every material is unique. However, many have the same properties, which can allow them to be substituted for each other. For example, POM and PEEK are durable and resistant to heat, wear, and chemicals. However, POM is less costly at $1500-3200 per 1000kg than PEEK, which sells at $450/kg.

Aside from selecting the right material, you can reduce injection molding costs by reusing plastic. These include hardened plastic in the sprue and runner and post-processing. However, the plastic’s mechanical properties might dwindle, especially due to additives.

· Eliminate Cosmetic Appearance

If aesthetic appeal is unimportant, having glossy finishes is unimportant. Since they are not vital to your project’s market values, you can eliminate them and reduce the overall costs of injection molding.

· Reusing Molds

Reusing the molds can also help reduce the cost of production, especially when working with 3D-printed molds. Make full use of the molds by reusing them for various applications. You can use the same mold for not only the same part but also similar parts as well. This can be done by adjusting the wherever possible.

· Choose Insert Molding

Insert molding involves placing a product in an injection mold and molding it in plastic. Therefore, the injection process becomes a more versatile technique and reduces the costs of injection molding.

Injection Molding Cost Estimator – Get Competitive Quotes

Quality injection molded parts and a cost-effective process are achievable by trusting the right injection molding services. At RapidDirect, we offer custom plastic injection molding services to help you make different plastic prototypes or real parts based on your requirements.

Please navigate to our online quotation platform and uploads an injection molding CAD file to get a quick quotation. Our quotation process is comprehensive from start to finish and involves configuring different materials, finishes, quantities, etc. Furthermore, we will confirm the DFM analysis of the mold so that you get the most accurate part possible.

We have several plastic materials chosen using a stringent and streamlined selection process and an engineering team that can provide professional design suggestions and material selection. Our highly sophisticated manufacturing capabilities and network allow us to ensure high-quality molds and plastic parts. Upload your design today and get instant quotes and free DfM analysis at a competitive price.  

Example of Injection Molding Cost Analysis

We know that pricing can vary and that knowing the injection molding cost estimates is crucial in any project. As a result, we put together an example that can act as an injection molding cost estimator or plastic injection molding cost calculator.

Conclusion

Knowing about the injection molding cost can help in optimizing using the manufacturing process. This is achievable by understanding different factors and elements, and this article discussed everything you need to know about costs in injection molding and how to use it. Looking for a quality-focused injection molding service provider? At RapidDirect, we offer the best at a competitive price.