Stack Mold

What is stack mold

A stack mold, also known as a stack mold system or stack molding or multi-layer molding, is a specialized type of injection molding system that allows for the production of multiple plastic parts in a single molding cycle. It achieves this by using multiple mold cavities arranged in a vertical or stacked configuration within a single mold assembly. Stack molds are particularly useful for high-volume production and can significantly increase the output of a single molding machine, making them cost-effective for applications where efficiency and productivity are critical.

SINCERE TECH ( is a plastic mold company that provides plastic injection mold solutions to industries of all types and sizes. Our state-of-the-art mold building facilities include high-speed CNC Machines and EDM Machining to create many types of high precision plastic injection molds, including complex speciality injection molds, such as two-shot molds, unscrewing molds, stack molds, insert mold, gas assist molds and many other types.

Stack Mold

Stack Mold

The Pros of Stack Molding

Here are some key features and advantages of stack moulds:

  1. Multiple Cavities: A stack mould consists of two or more sets of mold cavities stacked on top of each other. Each set of cavities functions as a separate mold. This design allows for multiple parts to be molded simultaneously in a single shot.
  2. Improved Productivity: Stack molds can produce twice as many parts as a traditional single-cavity mold in a single molding cycle, significantly increasing production output and reducing cycle times. The number of cavities in a stack mold can vary depending on the design and application.
  3. Space Efficiency: Stack molds save space compared to using multiple single-cavity molds, as they utilize a single molding machine and take up less floor space.
  4. Reduced Energy Consumption: While they produce more parts per cycle, stack molds generally use less energy per part, making them more energy-efficient in high-volume production scenarios.
  5. Cost Savings: Despite the initial investment in a stack mold system, it can lead to cost savings over time due to increased production efficiency, reduced labor costs, and lower energy consumption per part.
  6. Part Consistency: Stack molds offer excellent part-to-part consistency because all parts in a single cycle are produced under identical molding conditions.
  7. Complex Geometries: Stack molds can produce parts with complex and intricate geometries by utilizing multiple mold cavities for each part, allowing for the creation of undercuts, inserts, or multi-material components.
  8. Multiple Materials: Stack molds can be designed to accommodate multiple plastic materials, enabling the production of multi-material or multi-color parts in one molding cycle.
  9. Core and Cavity Variations: Stack molds can be designed with variations in core and cavity configurations, allowing for different part designs or sizes within the same mold assembly.
  10. Cooling System: Efficient cooling systems are essential in stack molds to maintain consistent part quality and ensure that all parts solidify properly.

Stack molds are commonly used in industries that require high-volume production of parts, such as the automotive, packaging, consumer goods, and medical device industries. The design and construction of a stack mold require careful engineering and consideration of factors like cooling, ejection, and maintenance to ensure their reliable and efficient operation.

The Cons of Stack Molding

While stack molds offer numerous advantages for high-volume plastic injection molding, they also come with some disadvantages and challenges. Here are some of the drawbacks and considerations associated with stack molds:

  1. High Initial Cost: Stack moulds are more complex and costly to design, manufacture, and maintain than single-cavity molds. The upfront investment can be a significant barrier for some manufacturers.
  2. Complex Design and Engineering: The design and engineering of stack injection molds are more intricate and demanding than those of single-cavity molds. They require careful consideration of factors such as cooling, ejection, and alignment to ensure proper functioning.
  3. Increased Maintenance: Stack molds have more components, including moving parts and cooling systems, which can require more maintenance and upkeep than traditional molds. Proper maintenance is crucial to prevent downtime and ensure consistent production.
  4. Longer Setup Times: Setting up and fine-tuning a stack injection mold can take more time than setting up a single-cavity mold, particularly when adjusting and aligning the various mold components.
  5. Limited Molded Part Size: Stack molds are most effective for small to medium-sized plastic parts. Larger parts may not fit within the confines of a stack mold, limiting their applicability.
  6. Increased Complexity: Stack moulds introduce a higher degree of complexity to the injection molding process, which can result in more opportunities for errors and defects if not managed properly.
  7. Cooling Challenges: Cooling is crucial in stack molds, and it can be challenging to maintain consistent cooling across all cavities. Poor cooling can lead to uneven part quality and potential warping.
  8. Injection Pressure and Timing: Stack molds require precise control of injection pressure and timing to ensure that all cavities are filled uniformly. Inconsistent pressure or timing can lead to part defects.
  9. Tooling Wear: The increased use and demands on a stack mould can lead to faster tooling wear and may require more frequent maintenance and repair.
  10. Limited Applications: Stack moulds are not suitable for all molding applications. They are best suited for high-volume production of smaller and simpler parts. Complex or large parts may not be efficiently produced with a stack mould.
  11. Ejection Challenges: Ejecting parts from a stack mold can be more challenging due to the vertical arrangement of cavities. Special ejection systems and strategies may be required.

Despite these disadvantages, stack molds remain a valuable tool for certain production scenarios where high efficiency and output are paramount. Manufacturers must carefully evaluate their specific needs and weigh the pros and cons of stack molds to determine whether they are a suitable solution for their injection molding operations.mold manufacturer china

Why We Need Stack Moulding

Stack molding is an essential process in the plastic manufacturing industry, as it allows for the creation of multi-colored or multi-material parts in one process. This method offers a cost-effective, time-saving, and efficient solution for creating plastic products that have unique design features, such as soft-touch grips or different textures on different surfaces.

Stack molding is also increasingly important in the production of consumer products, as it allows manufacturers to create products that are not only functional but also visually appealing, and this is a crucial aspect of attracting and retaining customers.

In conclusion, Stack molding is a valuable process in the plastic manufacturing industry, as it allows for the creation of multi-colored or multi-material parts in one process, resulting in cost-effective, time-saving and efficient solution for creating plastic products that have unique design features. It is increasingly important in the production of consumer products, as it allows manufacturers to create visually appealing products, which is crucial in attracting and retaining customers.

At Sincere Tech, we are dedicated to maintaining our position as a leading plastic mold company by embracing industry advancements and anticipating future trends. We actively explore innovative materials and composites that offer improved performance and sustainability. Through ongoing investments in research and development, we deliver cutting-edge solutions that address the evolving needs of our customers. As one of the best injection mold suppliers in China, we pride ourselves on our commitment to excellence.

In line with our commitment to sustainability, we prioritize environmentally friendly practices. We proactively seek sustainable alternatives, such as biodegradable polymers, and implement recycling initiatives to minimize the environmental impact of our manufacturing processes. By choosing our custom injection molding services, you can align your brand with sustainable manufacturing practices and contribute to a greener future.

Quality is of the utmost importance to us, and we maintain stringent quality control measures throughout the entire manufacturing process. Our state-of-the-art facilities and skilled technicians ensure that each product undergoes rigorous inspection and testing, guaranteeing exceptional performance, reliability, and customer satisfaction.

When you partner with Sincere Tech as your preferred China mold maker, you can expect the highest level of professionalism, expertise, and innovation. We are dedicated to helping you bring your ideas to life, delivering superior products that excel in performance, durability, and cost-effectiveness.

Our expanded capabilities include:

  1. Rapid Prototyping: We offer rapid prototyping services to quickly transform your concepts into tangible prototypes, allowing for iterative design improvements and accelerated product development.
  2. Precision Tooling: Our advanced tooling capabilities enable us to create high-quality molds with tight tolerances, ensuring consistency and precision in your injection-molded products.
  3. Overmolding: We specialize in overmolding, which allows for the combination of multiple materials or components, resulting in enhanced functionality, aesthetics, and durability.
  4. Insert Molding: Our expertise in insert molding enables us to securely encapsulate inserts within the molded parts, facilitating efficient assembly and enhancing product performance.
  5. Two-Shot Molding: With two-shot molding, we can produce complex, multi-material components in a single operation, reducing assembly requirements and enhancing design possibilities.
  6. Value-Added Services: In addition to injection molding, we offer a range of value-added services, including product assembly, packaging, and logistics support, streamlining your supply chain and reducing costs.

Partner with Sincere Tech Mould suppliers for your custom injection molding needs, and benefit from our comprehensive capabilities, unwavering commitment to quality and sustainability, and our drive to exceed your expectations at every step of the process. Together, let’s bring your innovative ideas to life.

Injection moulding service
Plastic Mold Cost

How Much Does Injection Molding Cost?

Injection molding is a widely used manufacturing process that involves injecting molten material into a mold cavity to create complex and precise parts. if you need injection molding parts, it’s crucial to understand the injection molding cost. By gaining insights into the factors that influence injection molding cost and implementing effective cost reduction strategies, businesses can optimize their production and maximize profitability.

Plastic Injection Molding Cost

Plastic Injection Molding Cost

If you are looking for the plastic molding parts for your new project, I believe the most important thing you want to know what will be the cost for the plastic mold and injection molding parts. Because all of this cost will affect your project going smoothly and success or failure. To carefully check this before you are running a new project if the project fails you will lose lots of money and time.

Let me give you some idea to help you understand plastic mold and plastic injection molding cost, this will save your time for your new development products.

The other easy way to understand those costs for your new project will be sending us your 3D part design or sample pictures, and tell us your requirements, like material for each part? Estimate the number of parts per time? Any special surface requirement to the visible side?

We will send you the best competitive price, we could offer the lowest mold cost $550, molding part cost $0.1, you could have this as a reference for your product and market research, welcome to contact us by [email protected]

Plastic Injection Molding Cost Guiding Tips

There are meanly four parts of cost: Plastic Material Cost, Molding Production Cost, Plastic Mold Cost, Part Color Cost, let us explain those four mean costs one by one.

Plastic Material Cost

First, the plastic raw material cost will effect the plastic injection molding cost, it is determined by the weight of material that is required and the unit price of that material. The weight of the material is a result of the part volume and material density; however, the part’s maximum wall thickness can also play a role. The weight of material that is required includes the material that fills the channels of the mold.

The size of those channels, and hence the amount of raw material, is largely determined by the thickness of the part, the selection of the material affects the unit part price as well, a different type of plastic material has a different price, for example, PP material is a totally different price than ABS material, so the material cost for plastic part includes two parts, one is the weight of the material, one is the type of material for the plastic part.

Second, the injection molding machine process cost will effect the plastic injection molding cost, it is primarily calculated from the hourly rate and the cycle time. The hourly rate is proportional to the size of the injection moulding machine being used, so it is important to understand how the part design affects machine selection. Injection molding machines are typically referred to by the tonnage of the clamping force they provide.

The required clamping force is determined by the projected area of the part and the pressure with which the material is injected. Therefore, a larger part will require a larger clamping force, and hence a more expensive machine. Also, certain materials that require high injection pressures may require higher tonnage machines. The size of the part must also comply with other machine specifications, such as clamp stroke, platen size, and shot capacity.

Injection Molding Processing cost

The cycle time will effect plastic injection molding cost, cycle time can be broken down into the injection time, cooling time, and resetting time. By reducing any of these times, the production cost will be lowered. The injection time can be decreased by reducing the maximum wall thickness of the part and the part volume. The cooling time is also decreased for lower wall thicknesses, as they require less time to cool all the way through.

Several thermodynamic properties of the material also affect the cooling time. Lastly, the resetting time depends on the machine size and the part size. A larger plastic part will require larger motions from the machine to open, close, and eject the part, and a larger machine requires more time to perform these operations.

Plastic Mold Cost

Third, the plastic mold cost has two main components – the mold base and the machining of the cavities. The cost of the mold base is primarily controlled by the size of the part’s envelope and design feature. A larger plastic part requires a larger mold, more expensive mold base. the complex part design requires complex molds, that will effect the mold cost.

The cost of machining the cavities is affected by nearly every aspect of the part’s geometry, complex mold cavity requirement lots of CNC machining cost and time, that will increase the plastic injection mold cost, on the other hand will increase the plastic injection molding cost as well.

The primary cost driver is the size of the cavity that must be machined, measured by the projected area of the cavity (equal to the projected area of the part and projected holes) and its depth. Any other elements that will require additional machining time will add to the cost, including the feature count, parting surface, side-cores, lifters, unscrewing devices, tolerance, and surface roughness.

The quantity of parts also impacts the plastic injection mold cost. A larger production quantity will require a higher class mold that will not wear as quickly. The stronger mold material results in a higher mold base cost and more machining time.

One final consideration is the number of side-action directions, which can indirectly affect the plastic injection molding cost. The additional cost for side-cores is determined by how many are used. However, the number of directions can restrict the number of cavities that can be included in the mold. For example, the mold for a part that requires three side-action directions can only contain two cavities. There is no direct cost added, but it is possible that the use of more cavities could provide further savings.

Injection molding Color Cost

Forth, the plastic molding color is also cost effect to the plastic injection molding cost, normally does not have too much effect, but this is still depending on which parts color do you require if you need white color for your plastic parts, then the cost will be 10% more than another color, if you require clear color (transparent molding parts) molding parts, then the cost will be 25-40% high than normal color molded parts.

When you need white color injection molding parts, then the molding shop needs to clean the barrel very well, and not allow any other color max in this injection unit and material, this will take time and waste some material, and the other thing is the waste rate will be increased, that is the reason the white color plastic parts is little high than other colors.

When you are looking for transparent injection molding parts like PC injection molding, PMMA molding, or PS molding parts, the molding shop needs use special injection unit to produce this type of molding parts, they need to clear the unit barrel very well and use some good quality injection molding machine to produce the clear plastic molding parts, because any tiny molding defects on the transparent molding parts will be easy to identify.

So you need to make the best quality molding parts, the waste rate is higher, and need to use the high tech injection molding machine, and all of those are more costly than normal molding production.

Plastic Injection molding Cost Estimating mothed- plastic injection mold and molding parts cost

1. Feature-based estimate

This feature-based cost estimator is for the plastic molding of production quantities (over 10,000 units), where more durable and costly tooling can be used due to its small impact on the per-part cost. The material cost is estimated from the part geometry and uses current material prices.

For the production cost, a compatible injection molding machine is selected from a database of over 50 machines and the cycle time is estimated from the part geometry, material properties, and machine specifications.

For the tooling cost, a suitable mold base is selected using standard mold dimensions and mold classes, and the required mold machining is estimated from the part geometry and other user specifications. These three costs (material, production, and tooling) are calculated for 4 different cavity arrangements (1, 2, 4, and 8 cavities) and the most cost-effective option is provided.

2. Low volume injection molding cost estimate

This feature-based cost estimator is for the injection molding of low volumes (under 10,000 units), where rapid tooling methods (high-speed machining of Class 104 molds) are used to create the mold due to the large impact on the per-part cost. The material cost is estimated from the part geometry and uses current material prices.

For the production cost, a compatible injection molding machine is selected from a database of over 50 machines and the cycle time is estimated from the part geometry, material properties, and machine specifications.

For the plastic tooling cost, a suitable mold base is selected using standard mold dimensions, and the required mold machining is estimated from the part geometry and other user specifications. These three costs (material, production, and tooling) are calculated for 4 different cavity arrangements (1, 2, 4, and 8 cavities) and the most cost-effective option is provided.

3. Standard estimate

This standard plastic injection molding cost estimator does not require any part geometry but requires more process parameter inputs to calculate a more accurate estimate. The material cost is estimated from the part and runner volumes, an up-to-date material database with pricing, and customizable process parameters.

For the production cost, the cycle time must be specified, as well as the machine rate and labor rates. After adding the mold cost, a detailed cost breakdown is provided for the material, production, and tooling costs.

4. Plastic mold cost estimate

This feature-based cost estimator calculates the mold cost for plastic molding. Based on the part geometry and mold requirements, such as the number of cavities, a suitable mold base is selected using standard mold dimensions. The required mold machining is estimated for the selected SPI mold class and rapid plastic tooling methods may be chosen for a Class 104 mold or so low volume products.

Hope all of that information could help you to get an idea about the cost idea for your project, are you ready to have your project start working on plastic injection molding, welcome to send us your requirement for quotation, we will quote you completely mold and molding price, you will have a complete plan for your project.

Injection molding Cost Reduction Strategies

Cost reduction is a critical aspect of injection molding that can significantly impact a company’s profitability. Implementing effective cost reduction strategies can help businesses optimize their manufacturing processes and reduce expenses without compromising quality. Here are some cost reduction strategies to consider:

  1. Material Selection: Choosing cost-effective materials is an effective way to reduce injection molding costs. Alternative materials such as recycled or bio-based materials can be cost-effective and environmentally friendly. However, it’s essential to balance cost savings with material quality and performance requirements.
  2. Part Design Optimization: Designing parts for manufacturability and cost efficiency is critical. Simplifying part geometries, minimizing undercuts, and reducing material waste can help lower production costs without compromising functionality. By collaborating with designers and engineers, businesses can optimize part design for cost reduction.
  3. Tooling Optimization: Efficient tooling design and construction are essential for cost reduction. Regular maintenance, proper cooling, and repair of molds can extend their lifespan, reducing the need for frequent replacements and associated expenses. By investing in high-quality tooling and implementing efficient maintenance practices, businesses can reduce tooling costs.
  4. Production Volume Optimization: Striking the right balance between cost and demand is key to optimizing production volume. Analyzing market trends, forecasting demand, and implementing flexible manufacturing strategies can help businesses scale production up or down as needed, minimizing costs. By optimizing production volume, businesses can reduce setup and tooling expenses while maintaining quality and delivery times.
  5. Automation: Automating injection molding processes can help reduce labor costs and increase production efficiency. By implementing automation technologies such as robotics and sensors, businesses can optimize production and reduce expenses associated with manual labor.
  6. Lean Manufacturing: Implementing lean manufacturing principles can help eliminate waste and reduce costs. By analyzing and optimizing production processes, businesses can identify areas of waste and inefficiency and implement strategies to reduce them. Lean manufacturing can help reduce expenses associated with material waste, setup times, and labor costs.


Reducing injection molding cost is critical for businesses aiming to optimize their manufacturing processes and maximize profitability. By implementing effective cost reduction strategies such as material selection, part design optimization, tooling optimization, production volume optimization, automation, and lean manufacturing, businesses can reduce expenses without compromising quality. By continuously analyzing and refining these strategies, companies can stay competitive in the ever-evolving manufacturing landscape.

Contact us to get your injection molding cost quotation now.