What are the common metal 3D printing processes in mold manufacturing?

一, Powder bed melting technology: this means high precision and a complicated structure.
Powder bed melting technology uses high-energy beams to selectively melt metal powder layers. It is now the most common type of procedure utilized in mold making. Some examples of these technologies include selective laser melting (SLM) and electron beam melting (EBM).
1. SLM technology: a game-changer for mold cooling systems
SLM uses high-power laser beams to melt metal powder one layer at a time. This can make metal parts with a density of over 99.9%. The design of conformal cooling channels is where its fundamental value shows up in mold making. Drilling procedures confine traditional mold cooling channels to linear or simple zigzag patterns, which makes them less effective at cooling. SLM technology can make water channels that aren't straight, such spirals and dendrites. This makes cooling more than 40% more effective. For instance, when Huawei phones switched to topology-optimized canal design for the frame mold, the time it took to make a single piece went from 120 seconds to 75 seconds, and the yield rate went from 89% to 98%.
2. EBM technology: the best way to make molds for high-temperature alloys
EBM technology employs an electron beam to melt metal powder in a vacuum. Its special benefits are:
Material adaptability: It works well with active metals like titanium alloys and nickel-based high-temperature alloys. These metals are commonly used in high-end molds like those used in aerospace and automobile engines.
Controlling residual stress: The electron beam scanning speed is quite high, which can greatly lower heat stress and the chance of mold deformation.
How well things are made: The energy density of an electron beam is 3 to 5 times that of a laser, and the printing speed is 30% to 50% faster than SLM.
Platinum's titanium alloy molds for aircraft engines are made utilizing EBM technology, which adds complicated aerodynamic channels. This makes the molds last longer (from 8000 to 25000 cycles) and makes them 42% lighter.
2, Directed Energy Deposition Technology: A Great Way to Fix Big Molds and Make Things Additively
Directed energy deposition technology is good for making and fixing big molds because it can move metal powder or wire and melt deposition at the same time. Laser near net shape (LENS) and arc additive manufacturing (WAAM) are two of its main methods.
1. LENS technology: a new way to make gradient material molds
LENS technology makes it possible for different materials to change smoothly from one to the other by melting metal particles and moving them at the same time through a concentrated laser beam. This technology is used to make die-casting molds with functionally graded structures in the mold-making process:
Surface layer: very strong and very resistant to wear To make the mold more resistant to wear, cobalt chromium alloy is employed.
Core layer: Using an aluminum alloy that is strong and low-density to make the mold lighter and better at getting rid of heat.
Compared to standard homogeneous materials, this gradient structure makes the mold last 2–3 times longer and uses 15–20% less energy.
2. WAAM Technology: A Cost-Effective Way to Make Big Molds
WAAM has the following features: it employs an electric arc as a heat source to melt metal wire.
Low cost of materials: Metal wire costs only one-third to one-half as much as powder materials.
High sedimentation efficiency: 3–5 kg of metal may be deposited every hour, which is enough to make massive molds that are a meter wide.
Strong repair ability: can fix cracks and wear by directly depositing materials on existing molds.
A certain car company used WAAM technology to fix a mold for a 2-ton engine cylinder. This cut the cost of the repair by 68% compared to getting a new mold and cut the time it took to fix it from 45 days to 7 days.
3, Adhesive spraying technology: a way to make small-scale molds more efficient
The adhesive spraying technology sprays adhesive only where it is needed to attach metal powder particles. After degreasing and sintering, it makes dense metal pieces. This technology gets around the size limits of powder bed melting technology, making it the best solution for making small molds.
1. Benefits in terms of technology
Quick production: There's no need to melt each layer separately, and the printing pace is 5–10 times faster than SLM.
High material use: Unbound powder may be recycled 100% of the time, which cuts material costs by 30% to 40%.
A lot of geometric freedom: may make molds with complicated internal cavity geometries, including plastic injection molds with conformal cooling.
2. Examples of Use
A specific medical device company uses adhesive spraying technology to make custom molds for orthopedic implants. The cost of making one mold has gone down from 12,000 yuan to 4,800 yuan, and the time it takes to make a mold has gone down from six months to 50 days. This technology is also commonly utilized in areas like jewelry molds and precision electronic molds. It is helping mold manufacturing move toward more flexibility and customisation.
4, The future of mold making is multi-process integration.
As technology has advanced, a single process is no longer sufficient to satisfy the varied requirements of mold manufacture; hence, the amalgamation of several processes has emerged as a novel trajectory within the industry.
SLM+CNC composite processing: First, use SLM to print the mold blank. Then, use CNC for precision machining, which balances the speed of molding with the accuracy of the surface.
Combining LENS and heat treatment: During the LENS deposition process, laser quenching is done at the same time to raise the mold's surface hardness to over 55HRC.
Adhesive spraying plus HIP densification: Hot isostatic pressing (HIP) gets rid of the interior pores in the parts that were coated with adhesive. This makes the mold density over 99.5%.