Injection molding is one of the leading processes for manufacturing plastics. It is widely used for mass-producing identical parts with tight tolerances. It is a cost-effective and extremely repeatable technology that yields high-quality parts for large series production.
It is a fast, intensive process where high heat and pressure are involved to inject molten material inside a mold. The molten material depends on the scope of the manufacturing project. The most popular materials are various thermoplastics, such as ABS, PS, PE, PC, PP, or TPU, but metals and ceramics can be injection molded as well. The mold consists of a cavity that accommodates the injected molten material and is designed to closely mirror the final features of a part.
Normally, the main cost driver in injection molding is the cost of the mold, also known as the tooling cost. The cost of designing and building a mold depends on the required production volume, the complexity of the part design, mold material, and the process used to create the mold.
Simple low-volume 3D printed molds can cost as little as $100, while the cost of designing and manufacturing complex molds for high-volume production may hit the $100,000 mark. Despite the considerable fixed start-up costs, the injection molding process has low variable costs due to the inexpensive thermoplastics materials, short cycle times, and the labor needs decrease progressively due to automation and economies of scale. This means that the variable costs of production are low and the process becomes more efficient and the cost per part decreases at higher volumes as the costs get distributed among hundreds or thousands of parts.
Types of Costs in Injection Molding
Understanding the different types of costs associated with injection molding requires an in-depth analysis of the process.
Equipment Costs
Special-purpose machines are used for injection molding that can range from smaller desktop injection molding machines that businesses can use in-house to large industrial injection molding machines that are mostly operated by service providers, contract manufacturers, and large manufacturers.
Producing low volumes of parts with injection molding is the most cost-effective with smaller desktop injection molding machines and 3D printed molds. If you are new to injection molding and are looking into testing it with limited investment, using a benchtop manual injection molding machine such as the Holipress or the Galomb Model-B100 could be a good option. Automated small-scale injection molding equipment such as the desktop machine Micromolder or the hydraulic machine Babyplast 10/12 are good alternatives for medium-series production of small parts.
Large industrial injection molding machines can cost anywhere from $50,000 to $200,000+. These machines also come with more stringent facility requirements and require skilled labor for operation, maintenance, and monitoring. As a result, unless injection molding is a core competence, most enterprises outsource mass production to service providers and contract manufacturers, in which case the equipment costs are included in the service costs.
Mold Costs (Tooling Costs)
As we mentioned in the introduction, mold costs or tooling costs are usually the main cost driver in injection molding.
Molds for injection molding are generally made using three methods:
CNC machining: CNC machines are the most commonly used tools for manufacturing aluminum and stainless steel molds with high precision levels. CNC machining removes material by a spinning tool and fixed part. Machining can produce molds where the cavity design is highly complex, but they might require multiple tool changes that can slow down the process, which means that costs increase in line with complexity. CNC machines are industrial tools that require a skilled workforce and a dedicated space, which means that many companies outsource mold production to service providers.
Electrical discharge machining (EDM): The EDM method is generally used to create highly complex mold designs that cannot be easily reproduced using standard machining methods. EDM involves the use of a workpiece and a tool electrode to create the desired mold shape. The tool electrode and workpiece electrode are separated by a dielectric fluid and subjected to voltages that cause recurring current discharges. The discharges are responsible for shaping the workpiece electrode into the final mold. EDM is highly accurate and does not generally require any additional post-processing. Similar to CNC machining, EDM is also an industrial process that many companies outsource to machine shops.
3D printing: 3D printing is a powerful solution to fabricate injection molds rapidly and at a low cost. It requires very limited equipment, saving CNC time and skilled operators for other high-value tasks in the meantime. Manufacturers can benefit from the speed and flexibility of in-house 3D printing to create molds that can be used on both desktop and industrial molding machines. Furthermore, product development benefits from the ability to iterate on the design and test the end-use material before investing in hard tooling for mass production. Stereolithography (SLA) 3D printing technology is a great choice for injection molding. It is characterized by a smooth surface finish and high precision that the mold will transfer to the final part and that also facilitates demolding. 3D prints produced by stereolithography are chemically bonded such that they are fully dense and isotropic. Desktop SLA printers, start below $5,000 and can seamlessly be integrated into any injection molding workflow as they are easy to implement, operate, and maintain.
Developing more complex molds requires technical expertise. As a result, enterprises often outsource specific aspects of the injection molding process such as the design and fabrication of the mold.
For enterprises with the equipment and tools for injection molding, choosing to create molds in-house could be the least expensive option if the technical know-how is also available. If the tools needed for injection molding are not readily available, then outsourcing reduces the cost associated with developing a mold.
Simple low-volume 3D printed molds can be produced on an SLA 3D printer for as little as $100. An aluminum mold for a mid-volume production run of approximately 1,000-5,000 units falls within the range of $2,000 to $5,000. For molds with more complex geometries and primed for larger production runs of approximately 10,000+ units, the cost of mold can range from $5,000 to $100,000.
There are four basic items to be analyzed for determining molding costs: material, labor, machine rates, and toolings’ costs.
When calculating material costs, the volume, or cost per cubic inch is the factor to look for, not just the cost per pound of raw material.
If possible, it is wise to utilize regrind plastic, as the price is usually half the cost of virgin material.
The amount of regrind that can safely be utilized is usually 15% of the total by weight. However, tests have shown that 100% regrind can be just as good as 100% virgin concerning final physical properties.
Unless hot runner systems are being utilized, the amount of material that makes up the runner and sprue should never be more than 15% of the total shot size, by weight. Following this rule of thumb will ensure that there is no more than 15% regrind material available for use.
Clamp tonnage determines the size of machine needed for molding. This is calculated by determining the projected area of the cavities and multiplying that number by a factor from 2 to 8, which is the number of tons required to keep the mold closed against injection pressure.
The machine hour rate, or MHR, fluctuates because of geographical location, with the Northeast and far West being the most expensive areas in the U.S.
The total molding cycle is primarily dependent upon the cooling portion of that cycle.
Tooling costs are not normally amortized over the life of a product, but rather are paid for up front in a lump sum.
1. When considering the cost of a raw material, attention should be paid to the density of the material. For materials with the same unit price, the lower the density, the lighter the product is and the lower the cost;
2. Mold costs vary greatly. The cost of a high-quality mold and that of an average mold may differ by 5 – 10 times. The service life of a high-quality mold can reach up to 500,000 cycles, while that of an average mold is only 100,000 – 300,000 cycles.
3. Molding cycle determines the processing cost. The shorter the cycle, the lower the energy consumption and the cost are. For example, the addition of a nucleating agent can reduce the molding cycle.
4. The demographic dividend in China is gradually fading away. Due to the aging of the population, the demographic dividend in China will disappear after 2013, so the proportion of labor cost in the cost of a product will be getting higher and higher.
The cost of a plastic injection molded component is determined by several factors, including:
Part size and complexity: Larger and more complex parts generally require more expensive molds and longer processing times, which can increase the overall cost.
Material selection: The cost of the plastic resin used to make the part can vary widely depending on the type of material and its quality.
Tooling costs: The cost of creating the mold or tooling required for injection molding can be a significant factor in the overall cost of the component.
Production volume: The cost per part can be reduced as production volumes increase due to economies of scale.
Part tolerances: Tighter tolerances require more precision in the manufacturing process, which can increase costs.
Production location: The cost of production can vary depending on the location and the availability of labor, raw materials, and equipment.
To calculate the cost of a plastic injection molded component, it’s important to consider all of these factors and work with a reputable manufacturer who can provide an accurate quote based on your specific requirements.
The cost of a plastic injection molded component is determined by several factors that impact the production process. These factors include the cost of materials, tooling, production volume, manufacturing process, design complexity, tolerance requirements, and quality requirements.
The material cost is a crucial factor in determining the overall cost of the component. The type of plastic used, its quality, and the quantity purchased all play a role in determining the material cost. For example, high-quality plastics may cost more than lower-quality materials.
The cost of tooling is another significant factor in determining the overall cost of the component. This includes the cost of the mold itself, as well as any necessary machining or finishing processes. The complexity of the mold and its manufacturing process can also impact the cost of tooling.
The production volume is also an important factor to consider when calculating the cost of the component. The cost per part can be reduced as the production volume increases, as the fixed costs associated with tooling and set-up are spread over a larger number of parts.
The manufacturing process used to produce the component can also impact its cost. For example, components that require additional post-molding operations, such as trimming or assembly, will typically have a higher cost.
The design complexity of the component is another factor that can impact the cost. More complex designs may require additional tooling or production steps, which can increase the cost of the component.
The required tolerance and quality level for the component can also impact the cost. Tighter tolerances may require more precise tooling or production methods, while higher quality standards may require additional production steps or testing.
In conclusion, the cost of a plastic injection molded component is determined by a variety of factors that impact the production process. By carefully considering these factors, manufacturers can optimize the cost of production while ensuring that the component meets the required specifications and quality standards.
The cost of injection molding is influenced by a multitude of factors, but is mainly comprised of the following:
Raw material cost – This cost is quite easy to be calculated. Ask the raw plastic material supplier how much 1kg costs, multiply the product weight by 3% of loss rate, and then multiply the raw material price to get the cost of the raw material;
Machine cost – Regarding this cost, ask a plastic injection molding factory what the hourly processing rates of different plastic injection molding machines are? Assume that the processing cost per hour for a 100-ton plastic injection molding machine is 60 RMB/hour, then the cost per minute is 1 RMB; at this point, it is necessary to calculate the injection molding cycle of the plastic part, as well as the number of cavities of the mold. Assume the injection cycle of the plastic part that you are evaluating is 30 seconds, then there are 60/30 = 2 shots in 1 minute, which means that two rounds of molding can be achieved in 1 minute. And, assume it is a two-cavity mold, then the machine cost of the plastic part is 1 yuan divided by the number of shots in 1 minute, and then divided by the number of cavities in the mold. So, the final machine cost is 1 RMB/ 2 shots / 2 cavities = 0.25 RMB / piece.
The secondary processing cost includes painting/screen printing/electroplating, etc. You may ask their respective processing plants for the figures.
Packaging costs – According to the size and volume of the plastic part, the cost of the carton/bag can be obtained;
Transportation cost – According to the delivery location and the cost of the container truck, the transportation cost per piece can be obtained by dividing the total loading amount;
Other expenses: Because the above costs do not include the costs of indirect personnel or other related personnel, it is necessary to add some fees according to the different conditions of each factory;
The profit equals the total sum of the six items mentioned above multiplied by the profit rate of 10-30%. Then you can get the final cost of a plastic part. The profit should be determined on the basis of the situations in each factory and the order amount.