Rapid mold manufacturing promotes the transformation and upgradi

Table of Contents

Digital additive manufacturing technology

 

Digital additive manufacturing technology is an emerging three-dimensional solid rapid free-form manufacturing technology, commonly known as 3D printing, which combines the advantages of many advanced technologies such as computer graphics processing, digital information and control, laser technology, electromechanical technology, and material science. At present, there are many different descriptions of this technology in academia. Some experts call it digital additive manufacturing, others call it incremental manufacturing or additive manufacturing, and some experts use three-dimensional (3D) printing technology. This technology has been developed in rapid prototyping since the 1980s, and rapid mold manufacturing is also an indispensable part of rapid prototyping technology.

 

Fig1. Many rapid mold manufacturing methods are derived from printing technology

In the 1980s, market demand changed from a seller’s market to a buyer’s market and gradually globalized. Unprecedentedly fierce market competition forced manufacturers to design and manufacture high-performance and reasonably priced products more quickly, and product development speed gradually became the core contradiction of market competition. Under such circumstances, manufacturers relied on their independent and rapid product development capabilities to establish a strong foundation in global competition. At the same time, to meet the ever-changing needs of users, the manufacturing industry urgently needs to improve flexibility and control costs through small-batch or even single-piece production.

Therefore, the speed of product development and the flexibility of manufacturing technology have become the key to competition. The use of technology that can directly convert design data into three-dimensional entities can not only quickly and intuitively verify the correctness of product design, but also show the physical model of future products, helping companies to quickly occupy the market. From the perspective of technological development, the advancement and popularization of computer technology, material science, CNC technology, and laser technology have laid the foundation for the emergence of new manufacturing technology.

Advantages and selection of rapid prototyping technology

 

Rapid prototyping technology combines modern means such as computer technology, laser technology, CNC technology, and precision transmission technology, integrating computer-aided design and computer-aided manufacturing. By building a three-dimensional model of the product on the computer, technicians can directly manufacture product samples in a short time without using traditional tools, fixtures, and molds. This not only shortens the product development cycle but also speeds up the product replacement speed while reducing the risk of enterprises investing in new products.

In rapid tooling, there are currently six main rapid prototyping technologies to choose from. Each technology has its characteristics, and companies must weigh their pros and cons when choosing a rapid tooling method. The advantage of these technologies is that they can quickly transform prototypes into products. When manufacturing die-cast products, producing molds is usually the most time-consuming link. Traditional mold design and manufacturing methods usually take 5 to 20 weeks, while new rapid mold manufacturing methods shorten the time to 1 to 5 weeks. In addition, the cost of rapid mold manufacturing technology is often lower than that of traditional mold manufacturing processes.

Table 1. Comparison between rapid mold manufacturing technology and traditional mold manufacturing process

Complex design advantages of rapid mold manufacturing

 

Another significant advantage of rapid mold manufacturing is its ability to achieve more complex designs. Because the technology is essentially based on printing methods, rapid mold-making makes it possible to reshape models that are often not possible with other manufacturing methods. For example, designers can place cooling channels at precisely designated locations in the mold. For sheet-shaped molds, engineers can directly create cooling channels that meet the requirements, significantly improving thermal management and producing better molds.

Traditionally, it was thought that these advantages were compromised by rapid mold manufacturing methods resulting in a shorter mold life. However, some rapid prototyping methods today have enabled tool life of up to 100,000 pieces, greatly increasing their value.

Even for molds with a short service life, rapid mold manufacturing still shows significant advantages in production. This is because advances in geometry and the use of computer-aided design can speed up the process of converting initial molds into production molds, thereby shortening manufacturing times.

As manufacturers become increasingly eager to quickly obtain market feedback, test new products, and respond to changes caused by competition, their interest in rapid tooling has increased significantly. For example, the mold manufacturer mentioned that they need to manufacture 500 high-brightness headlight housings to test their application in tractors and construction site equipment. Manufacturers point out that more and more farmers and construction workers are working at night, so the need for brighter lamps is becoming more urgent. However, the plastic shell of previous headlights cannot withstand the heat generated by high-intensity lights and easily melts, thus failing to meet usage requirements.

Nowadays, by manufacturing headlight housings through die casting, manufacturers can test products according to on-site working conditions and accumulate useful data, thereby improving the applicability of new headlights, meeting user needs, and promoting market promotion. In this case, rapid mold manufacturing not only helps OEMs open up new markets but also creates more business opportunities for mold manufacturers who use die castings instead of plastic parts.

Factors to consider when choosing a rapid mold manufacturing method

 

1. Delivery time

 

Rapid mold manufacturing methods significantly reduce delivery times compared to traditional methods, sometimes reducing lead times to as little as five weeks. In addition, some manufacturing methods have greater advantages when manufacturing multi-cavity molds. For example, a rapid curing method may take ten days to produce the first cavity, but each additional cavity can be completed in half a day.

2. Quality

 

Rapid tooling provides flexibility for the production of small batches of mold products and is even suitable for the production of die castings. Although some methods can achieve mold durability of 100,000 pieces, many methods cannot provide high-grade H13 steel hardness under sufficient heat treatment conditions, nor can they fully ensure its durability, so rapid mold manufacturing may not be suitable for large-scale production.

3. Size

 

While some methods, such as direct metal deposition, can produce molds as large as 41 by 78 by 24 inches, most rapid mold-making methods limit mold size to within 10 inches.

 

Fig2.Direct metal deposition can be used for larger molds

4. Complexity

 

Layering materials in rapid mold manufacturing makes it more difficult to add certain complex features, such as cooling fins or other independent metal units. However, printing technology allows these methods to replicate small surface details easily.

5. Cost

 

Rapid mold manufacturing is often more cost effective than traditional tooling, but the size of the tooling and the materials used can affect costs. We can reduce costs by using substrates and high-performance materials, such as expensive high-thermal conductivity materials in critical areas of the mold cavity, thereby reducing the cost of mold inserts.

The main methods used in rapid mold manufacturing

 

1. Direct Metal Deposition (DMD)

 

Direct Metal Deposition (DMD) is an advanced manufacturing technology that uses a computer-controlled CO₂laser to inject metal powder into the laser beam, precisely welding and melting the powdered metal to produce inserts. This method has a typical lead time of nearly a week and can use almost all types of metal materials to meet diverse production needs. Although we usually estimate the mold life to be 1,000-10,000 pieces, the latest research shows that the mold life may be longer.

DMD technology can manufacture larger inserts (up to 41 x 78 x 24 inches) with a tolerance of 0.003 inches per 39 inches. Depending on the production method, inserts using base plates can cost as little as $2,500, while inserts made entirely with DMD can cost as much as $60,000. The technology’s rapid delivery and wide applicability make it an important part of mold making.

 

Fig3.Direct metal deposition forming process diagram

2. Selective Laser Sintering (SLS)

 

Selective Laser Sintering (SLS) is an extremely advantageous method for rapid mold manufacturing, with a delivery time as low as 2 to 3 days, making it the fastest option in some cases. SLS is similar to Direct Metal Deposition (DMD) in that both use CO2 lasers to fuse metal powders, but they operate differently. SLS achieves continuous production without laser marks by dispersing metal powder layer by layer, rather than injecting a single particle into the laser beam. This layer-by-layer process accurately manufactures the mold, and the diameter of the metal particles is typically 0.05 mm.

The SLS method can use almost all types of metal powders, and the durability of the manufactured mold is about 1,000 pieces, with a maximum mold size limit of 8×10×5 inches. In addition, SLS technology can achieve tolerances up to 0.002 inches, making it excellent in high-precision mold manufacturing. The cost of manufacturing a standard mold insert is generally between $6,000 and $8,000, providing manufacturers with an efficient and economical solution.

3. Direct Metal Laser Sintering (DMLS)

 

Direct Metal Laser Sintering (DMLS) is an efficient mold manufacturing method that can typically reduce lead times to 1 to 3 weeks. The technology relies on 3D CAD-driven automated machines to first create mold inserts by cyclically spreading metal powder layers. Subsequently, the laser sinters the desired cross-section, and these two steps are repeated until the entire insert is completed.

DMLS can manufacture workpieces in steel and bronze materials, and its durability is expected to be 1,000-10,000 pieces, which can meet the needs of various applications. Its maximum manufacturable size is 9.75×9.75×7.75 inches, and the tolerance range is maintained between 0.001 and 0.002 inches per inch, ensuring high-precision mold production.

Depending on the size of the insert and its complexity, DMLS prices range from$2,000-25,000, providing manufacturers with flexible and economical mold mold-making to meet the needs of different projects.

4. Rapid Solidification Process（RSP）

 

Rapid Solidification Processing (RSP) is an efficient and flexible method of rapid mold manufacturing that starts with a rapid prototype or machined prototype. From this prototype, the manufacturing team creates a “female mold” of ceramic material in the shape of the desired mold. Molten H13 or similar tool steel is then sprayed over the ceramic “female mold” to form the final mold. The entire manufacturing process takes approximately 2 weeks.

Once completed, the mold durability is estimated at 1,000 to 10,000 pieces, and some cases may exceed this range. Currently, the largest mold size RSP can manufacture is 7×7×4 inches, with a tolerance of 0.003 inches.

In terms of cost, the RSP method is typically about $1,500 cheaper than a typical production insert, making it a cost-effective mold-making solution that is particularly well-suited for projects that require rapid production.

5. Laser Engineered NetShaping(LENS)

 

Laser Engineered NetShaping(LENS) is an innovative mold manufacturing method. This method uses a laser to create a molten pool on a metal substrate and adds metal powder to the molten pool to build the mold insert layer by layer. The workpiece moves in the XY plane according to the programmed path, while the laser head and metal powder feeder move in the Z direction, forming multiple cross-sectional layers to complete mold manufacturing.

To improve efficiency and reduce costs, LENS allows the use of prefabricated substrates as “blanks” for molds, which are particularly suitable for molding complex functional parts. Depending on the material and complexity, the typical durability of LENS molds is 10,000-100,000 pieces, with a maximum size limit of 36×36×60 inches and a tolerance of ±0.005 inches.

In terms of cost, Laser Engineered NetShaping costs about $250 per cubic inch, and manufacturers typically deliver within 2 to 4 weeks. This makes LENS an efficient and economical mold production solution suitable for manufacturers who need to respond quickly to the market.

Fig4. Schematic diagram of Laser Engineered NetShaping process

6. Electron beam melting (EBM)

 

Electron beam melting (EBM) is an advanced mold manufacturing technology that is similar to selective laser sintering (SLS) and direct metal laser sintering (DMLS), but it differs in the way it melts metal powder. EBM uses an electron beam to melt the powder and build the insert layer by layer.

EBM specializes in using iron powder, and the typical life of the mold is expected to be 10,000-100,000 pieces. The maximum mold size that can be manufactured by this technology is 8×8×7 inches, and the maximum practical tolerance is 0.013 inches. The delivery time is usually 3 to 4 weeks, which makes it advantageous to respond quickly to market needs.

 

Fig5.Electron beam melting process diagram

In terms of cost, EBM is relatively economical, with manufacturers typically pricing inserts at $2,500-4,500. This makes EBM an efficient and cost-effective metal mold manufacturing solution for a wide range of industrial applications.

Table 2 Comparison of several rapid mold manufacturing technology methods

 

Conclusion

 

Rapid mold manufacturing technology has become an important tool in the modern manufacturing industry with its advantages of shortening delivery time, reducing costs, and improving production flexibility. Although traditional processes perform better in mold durability, rapid mold manufacturing has unique advantages in complex designs and small batch production, and can respond quickly to market demand. With the continuous advancement of technology, rapid mold manufacturing will be more and more widely used in the manufacturing industry, promoting the development of the industry.