In Investment castings, the mold is your first major expense, and prices tend to be high. Have you ever been puzzled by the high costs when purchasing castings? Have you racked your brain trying to figure out how to reduce these costs? This article will provide buyers with a thorough understanding of the hidden costs in investment casting tooling and how to minimize them.

Factors Influences Costs

Many factors influence tooling costs, and understanding them will give you a clearer picture of why casting molds are so expensive.

The Size of Components

The size of a component directly affects the cost of the tooling. The larger it is and the more complex its shape, the more tooling is required, and the more wax material is needed to produce it, which naturally increases the cost.

The Design of Cavity

The cavity is the most critical component in tooling manufacturing, which has important functions. When hot wax is injected into the cavity, it fills the space; after cooling and solidifying, the resulting wax pattern is a replica of the cavity. The number of cavities and the complexity of the design significantly influence the tooling cost.

Cavities are classified into “Single-cavity Tooling” and “Multi-cavity Tooling”.

A single-cavity tooling produces only one wax model in a single injection cycle. Parts produced by this type of tooling are cheap, but the efficiency of production is low.

Instead of a multi-cavity tooling can produce multiple wax models simultaneously in a single injection cycle. Parts produced by multi-cavity tooling are more expensive, but the efficiency of production is very high.

As such, single-cavity tooling is suitable for small-batch production, while multi-cavity tooling is suitable for high-volume production. If the wrong type of tooling is selected, the cost of the tooling will increase significantly.

The Material of Tooling

The materials used for tooling manufacturing are typically categorized into aluminum (6061/7075) and steel (P20, H13, and D2). Aluminum tooling is relatively cheap, softer in material, easier to machine, and lighter in weight, resulting in lower initial costs. Steel tooling is more expensive, harder in material, and requires complex heat treatment during the manufacturing process.

However, the initial purchase price is only one part of the total cost of ownership. Due to their low compressive strength, aluminum tooling is likely to develop flash after several thousand wax injections, leading to increased tooling maintenance costs down the line. While steel tooling involves higher initial costs, its exceptional wear resistance ensures they remain in good condition for 100,000 or even 500,000 production cycles, thereby preventing any increase in tooling maintenance costs later on.

The materials mentioned above have a direct impact on tooling costs, while casting alloys have an indirect effect. If you need to produce alloy products with highly corrosive materials, you will require more durable tooling materials to prevent excessive wear that could hinder subsequent operations. 

The Complexity of Structure

The complexity of the structure will significantly affect the tooling cost. The more complex the design, the more complex the cavities inside the tooling, which leads to higher tooling costs. For example, if a part has a simple design, the cavities can be created with just two split molds. However, if the part has a horizontal hole on the side, the cavities will require sliders to be completed. Since sliders are moving components, adding them will directly increase the cost of tooling.

If a part has many complex designs, such as internal channels, undercuts, thin walls, or other complex contours, the tooling must be constructed using two or more components that fit together. In some cases, these structures may even require precision electrical discharge machining (EDM), which will significantly increase working hours and, consequently, costs.

Dimensional Tolerances

Dimensional tolerance refers to the permissible range of dimensional deviation. If you require a very narrow tolerance, it becomes difficult to anticipate the casting shrinkage that occurs when molten metal solidifies. If dimensions deviate, the tooling may have to be scrapped or machined directly. In other words, the smaller the tolerance, the higher the cost of trial.

Regional Cost Differences

Have you ever found that even for the same product drawings, quotes from factories in different regions can vary? This is because different regions have different labor, material, and operating costs, which also vary. In some cases, there are even differences in factory infrastructure.

For example, in regions such as North America and Western Europe, labor costs are extremely high, leading to correspondingly high production costs. In contrast, China boasts a vast manufacturing capacity and relatively lower labor costs. In terms of infrastructure, companies equipped with automated machinery can produce tooling much more efficiently than those with traditional methods.

How to reduce investment casting tooling costs?

Understanding the aspects where costs can be reduced will go a long way toward helping you cut tooling costs at the source.

Follow the principle of Design for Manufacturing(DFM)

The principle of DFM refers to considering how to reduce costs through design optimization while ensuring product quality during the period of product design. Specific optimization approaches can be explored from the following perspectives.

Draft Angle

In investment casting, when removing the wax pattern from the tooling, if the side walls of the tooling are vertical, the wax pattern will encounter significant friction during extraction. This will cause the pattern to tear or deform, resulting in the need to remake it. Therefore, in accordance with DFM principles, a draft angle of 0.5° to 2° can be added to the vertical surfaces of the tooling. This allows the wax pattern to be easily removed, protecting its surface while also improving production efficiency.

Wall Thickness

When metal is injected into a mold, the casting will shrink. If the thickness of the tooling wall is uneven at this point, it is highly likely that shrinkage cavities will form inside the casting. Therefore, wall thickness should be kept as uniform as possible; if variations in thickness are necessary, you should let them be implemented with smooth transitions.

Requirements of Dimensional Tolerances

Many designers tend to specify extremely high tolerances for parts during the design process, such as +0.05 mm. But achieving this level of precision in investment casting is extremely difficult, because tolerances are often one grade higher than those specified on the drawings, which will lead to multiple reworks or even reform. Therefore, relaxing the tolerance requirements in non-critical areas can significantly reduce scrap rates and lower costs.

The Design of the Logo

Maybe you prefer to have your company name or logo engraved on castings, but there are specific considerations regarding how to do so in a way that minimizes costs. Engraving can be divided into two types: Raised and Sunken. We generally consider raised letters to be preferred because the raised letters are recessed into the tooling, making them the easiest to machine and the cheapest. If you want to design a sunken letter, it requires additional CNC machining or the insertion of new metal inserts, which significantly increases production costs.

Part Consolidation

When designing a complex component, if you only want to make a single mold, the complexity of its internal structure would be unimaginable. However, by dividing the part into individual sections and designing the molds for each section separately, it is possible to simplify the mold design and reduce costs.

Optimizing prototype design

 Before creating metal tooling, you can directly identify any potential casting issues by creating a wax model through 3D prototyping. Once everything has been verified, you can proceed to design the metal tooling, thereby significantly reducing the trial costs.

Comparative Analysis of Casting Tooling

Knowing the costs of different types of casting tooling will help you evaluate your options from multiple perspectives and reduce unnecessary costs.

In conclusion, if you don’t have too strict requirements for part dimensions, we recommend sand casting, as it has the lowest tooling costs.

If you have extremely high precision and tolerance requirements for the parts, the part design is not overly complex, and you need to produce a very large quantity, then we recommend die casting. Although it has a high tooling cost, when spread across multiple parts, the unit cost will not be too high.

However, if you do not need to produce such a large quantity of parts and the part design is somewhat complex, then considering material quality, precision, and cost, investment casting is the best choice for you.

Strategic Checklist for Buyers

Tooling production costs can be divided into initial investment and post-maintenance. While the initial investment is crucial, post costs must also be taken seriously. Understanding the key points you must confirm with the manufacturer will help you clarify future costs in advance, preventing an inexplicable extra cost.

Ownership

Before the manufacturer begins producing the tooling, you must confirm ownership of the tooling. Once you have paid for it, ownership is transferred to you, and your tooling cannot be reused or sold to other competitors.

Tooling Modification Cost

If your design changes midway through the process, you need to understand the rationale behind any additional tooling modification costs. Tooling modifications are categorized into material removal and material addition.“Material Removal” means enlarging the part. This is straightforward, the manufacturer just needs to remove excess metal from inside the cavity to increase the internal space. This can be accomplished through machining, so that the tooling modification cost is relatively low. However, “Material Addition” requires “growing” metal inside the cavity. This necessitates welding or cutting out and replacing a section of metal. Such modifications not only incur high costs but also reduce the tooling’s service life.

Maintenance Cost

While initial investment is certainly important, it is also crucial to consider long-term maintenance costs. To avoid incurring additional tooling repair expenses due to improper maintenance by the manufacturer, you must confirm the details regarding mold maintenance and repair before signing the contract. After production, tooling must be coated with a rust inhibitor and stored in a warehouse with constant temperature and humidity. After repeated use, the tooling may experience some damage, at which point the manufacturer will need to perform repairs. So when you sign the contract, what you should do is to confirm whether the current payment already includes future repair costs.

Final Thoughts

The above provides a comprehensive overview of the causes of high tooling costs and how to reduce them. We believe you already understand how to optimize tooling costs. Looking for a reliable investment casting supplier in China? Renowned for its high-quality control, CNC machine tools, and 3D prototyping services, Pingheng Machinery enables you to directly achieve cost savings in your strategic sourcing with a variety of tooling materials and one-stop customization services.

FAQ

Q1. What is the average cost of an investment casting tooling?

The average cost of a mold is generally determined by the number of precision machining hours required for its production. The vary of the price significantly depending on the materials used and the complexity of the part design. Tooling for smaller production runs typically ranges from $1,500 to $8,000, including those for pump castings or certain industrial machinery castings. While tooling made from high-grade H13 tool steel, featuring multiple cavities and complex designs, often costs over $40,000.

Q2. What is the average lead time for investment casting tooling?

Generally speaking, tooling typically needs to take 3–4 weeks to complete, while those with complex designs require 6–8 weeks. This time includes design, CNC machining, assembly, and the first trial run.

Q3. How many shots are typically guaranteed for an investment casting tooling?

The warranty on the tooling does not equate to its lifespan, which means that the manufacturer is responsible for maintaining its precision during that period. The warranty period depends on the material. Aluminum tooling typically has a warranty covering 5,000 to 10,000 wax injections, while steel tooling usually has a warranty covering around 100,000 wax injections.

Q4. Does a design revision necessarily mean the tooling must be scrapped?

Of course not. It depends on what design changes you’re making. If you just want to make the components smaller, you’ll only need to pay a small tooling modification cost. But if you want to make more complex design changes, you may need to have the tooling remade.

Q5. What is the difference between 3D and traditional tooling production?

3D prototyping eliminates the time required for tooling manufacturing, requires no initial investment, and offers extremely fast lead times; however, the unit cost is very high, making it suitable only for runs of 1 to 50 pieces. Instead of, although require a higher initial investment, traditional mold production results in a very low unit cost when producing larger quantities, making it suitable for runs of more than 100 pieces.

Q6. Is it possible to transfer old tooling from one factory to a new one for production?

In theory, this is feasible. However, since the interfaces of injection molding machines and standards are different among different manufacturers, it may be necessary to retrofit the old tooling.

Q7. Why does a tooling quotation include options for both single-cavity and multi-cavity?

Since this depends on your annual demand, if your annual demand is high, such as exceeding 5,000 units, then I will advise you to choose a multi-cavity mold, which will result in lower overall costs. Although the initial cost of this type of mold is higher, it can pay for itself in just one year.

Q8. What is “tooling shrinkage compensation”, and why does it impact the price?

When producing an investment casting tooling, it will experience casting shrinkage. And you need to know that different alloys have different shrinkage rates. If your component is made of a special material, we will need to create a more complex, precision-compensated tooling to account for the shrinkage. This requires a greater investment in design costs.

Q9. Is tooling cost all the expenses we need to pay?

No, it is only part of the total cost. If you want to know the total cost of ownership, please see “The Ultimate Guide to Investment Casting Costs: What Determines Your Quote?“