Precision mold manufacturing serves as a foundational pillar for modern industrial production, covering industries from consumer electronics and household appliances to aerospace and medical devices.
Machining centers constitute the core processing equipment for mold fabrication.
Traditional three-axis machining centers have long dominated the field, undertaking mold blank roughing, mold base processing, semi-finishing of regular features and auxiliary structure machining.
Nevertheless, constrained by axis configuration, spindle performance and intelligent capabilities, they face obvious bottlenecks when dealing with complex free-form surfaces, hardened high-strength steel and ultra-precision forming requirements.
The emergence of new-generation machining centers, integrated with five-axis simultaneous motion, high-speed cutting, artificial intelligence, digital twins and hybrid additive-subtractive manufacturing technologies, has broken through these technical limits.
This paper systematically elaborates the practical applications of traditional machining centers in precision mold production, analyzes their inherent drawbacks, and further introduces the technical strengths of new-generation machining centers.
By comparing their performance in complex-structure processing, hard-material cutting and ultra-precision manufacturing, the article clarifies their respective positioning and complementary relations within the mold manufacturing industry, and explores the future technological development directions of precision mold processing equipment.
Applications of Traditional Machining Centers in Precision Mold Manufacturing
Roughing and Semi-Finishing of Mold Blanks
Materials such as Cr12, S136, and 718H are commonly used for precision mold blanks, which are typically forgings or castings. To ensure smooth subsequent finishing operations, 50% to 80% of the machining allowance must first be removed.
Practical experience shows that using high-rigidity equipment for the roughing and semi-finishing of mold blanks can significantly reduce tool wear and improve machining efficiency.
Workpieces include cavity and core blanks, as well as platen-type blanks.
Machining operations cover face milling, step milling, and rough contour milling.
When machining on traditional machining centers, face mills with a diameter (ø) of 50–100 mm are commonly used, operating at spindle speeds of 1,000–3,000 r/min and feed rates of 500–1,000 mm/min.
This cutting method relies on spindle rigidity to achieve efficient material removal while preventing workpiece deformation caused by high-speed vibrations.
At this stage, precision requirements are relatively low, with dimensional tolerances typically maintained between 0.1 and 0.5 mm;
the focus is on effectively controlling cutting forces and suppressing the release of residual stresses within the workpiece.
A layered cutting strategy is employed to prevent localized overheating, which is highly effective in mitigating thermal deformation.
Precision Machining of Mold Base Components
As the “skeleton” of the mold assembly structure, mold bases (such as guide pillar hole bases, locating plates, and cavity retaining plates) play a decisive role in the overall closing accuracy of the mold.
The geometric accuracy of their hole patterns, planar configurations, and step positions—such as hole positional accuracy and planar parallelism—is directly related to the final assembly quality.
The machining targets include locating holes and guide pillar/sleeve mounting holes with diameters ranging from 10 to 50 mm, cavity-fixing steps with depths ranging from 0.5 to 5 mm, and flat surfaces with a surface roughness (Ra) of 3.2 to 1.6 μm.
In terms of machining logic, the linear interpolation function of the CNC system is used to ensure the positional accuracy of the hole patterns, with typical positional accuracy values ranging from 0.02 to 0.05 mm.
For example, the “G81 drilling + G85 boring” process effectively constrains the coordinate deviations of multiple holes relative to a unified reference.
At the same time, a rigid spindle paired with an end mill is used to meet the parallelism and perpendicularity requirements of the template surface (0.01 mm and 100 mm, respectively), laying the foundation for subsequent interference fits between the guide columns and the template.
Semi-Finishing of Regularly Shaped Parts
For components in precision molds with relatively simple geometries and less complex surfaces—such as rectangular cavities, circular cores, or stepped grooves in small injection molds—conventional machining centers can directly perform semi-finishing, and in some cases, even handle certain finishing tasks.
For stamping dies with simple structures, such as injection molds for small household appliances, connector molding dies, and gasket blanking dies, conventional machining centers can achieve semi-finishing of the dies.
Machining operations cover flat surfaces, cylindrical surfaces (achieved through arc interpolation), and inclined cavity surfaces.
Cores containing stepped and boss structures are machined with precision controlled within 0.01 mm, achieved through layered milling.
Cavity edges are rounded; when milled with a ball-nose or round-nose cutter, the surface roughness (Ra) can reach 1.6 to 3.2 μm.
Machining of Auxiliary Structures
Auxiliary structures in precision molds—such as threaded holes, vent grooves, and locating grooves—though subject to lower precision requirements than the mold cavities, have a direct impact on mold assembly stability and molding results.
Traditional machining centers can efficiently complete the machining of auxiliary structures in precision molds.
For the machining of threaded holes ranging from M4 to M20, traditional machining centers follow the sequence of “center drilling for positioning—drilling with a drill bit—tapping with a tap.”
The perpendicularity of the thread axis relative to the template plane must be maintained, with a maximum allowable deviation of 0.02 mm over any 100 mm measurement length.
For the machining of vent grooves, narrow grooves with a width of 0.1 to 0.5 mm and a depth of 0.05 to 0.2 mm must be milled along the edges of the cavities.
Traditional machining centers achieve this using small-diameter end mills (ø = 0.5 to 2 mm) with micro-feed rates.
For positioning slot machining, traditional machining centers control the width of T-slots and rectangular positioning slots on the template by using CNC programming to control the milling cutter’s path, thereby limiting errors to ±0.02 mm.
Limitations of Traditional Machining Centers in Precision Mold Manufacturing and Solutions
Traditional machining centers are not “universal” solutions in precision mold manufacturing; they have the following limitations.
First, they cannot machine complex surfaces.
Parts with three-dimensional free-form surfaces—such as automotive body panel molds and impeller molds—require multiple setups on a three-axis machining center, leading to cumulative positioning errors that prevent achieving surface accuracy requirements at the 0.01 mm level.
Second, there are limitations in machining hard materials.
Due to low spindle speeds (generally ≤ 8,000 r/min), machining quenched mold steel often results in excessive cutting forces that cause tool wear (such as chipping of end mills), and it is difficult to control surface roughness, frequently resulting in Ra values greater than 3.2 μm.
To address these limitations, a closed-loop process combining “conventional machining centers + finishing equipment” is established with the assistance of other processes.
When coordinated with heat treatment, mold components requiring hardening—such as cavities and cores—are semi-finished on conventional machining centers prior to hardening, leaving a 0.1–0.3 mm allowance.
Applications of New-Generation Machining Centers in Precision Mold Manufacturing
Five-Axis Simultaneous Machining: The “Ultimate Solution” for Complex Structures
New-generation machining centers, equipped with five-axis simultaneous machining capabilities and high-precision dynamic response characteristics, are widely used in fields such as aerospace and medical technology.
Taking the Evermi GMU-400 five-axis simultaneous machining center as an example, this machine employs gear-driven cradle technology paired with a Heidenhain TNC640 CNC system.
When used for the machining of insert sliders at Taizhou Binyu Mold Co., Ltd., it reduced machining time from 8 hours to 5.5 hours and boosted the first-pass yield rate from 68% to 98%.
This demonstrates that five-axis machining centers offer significant advantages in the machining of complex structures.
High-Speed Cutting: An “Efficiency Revolution” in Hard Material Machining
The new machining center enables high-speed cutting. Equipped with an ultra-high-speed spindle (rotating at up to 54,000 r/min) and utilizing linear motor drives (with feed rates of 120 m/min), it overcomes the limitations of traditional machining centers in the machining of hard materials.
Direct Machining of Hardened Steel:
Using cubic boron nitride (CBN) tools to machine die steel with a Rockwell hardness (HRC) of 60 or higher (such as NAK80), cutting speeds can reach 150 m/min with a surface roughness of Ra ≤ 0.4 μm.
Practical examples demonstrate that this method can replace the traditional post-hardening EDM process, reducing the machining cycle by more than 40%.
One-step mirror-finish mold machining: The DMG DMC75V linear 5-axis high-speed machine uses polycrystalline diamond (PCD) cutting tools and helical milling paths to directly machine the mirror-finish cavities (Ra ≤ 0.02 μm) of cosmetic case molds, thereby eliminating the manual polishing step and tripling efficiency.
AI-Powered Machining: AI-Driven “Adaptive Manufacturing”
New-generation machining centers, empowered by AI algorithms and IoT technology, have transitioned from passive execution to active optimization.
In terms of real-time error compensation, if a machining center used for automotive grille molds is equipped with a Renishaw probe, it can automatically adjust toolpaths based on the inspection data, achieving precise Z-axis compensation down to 0.001 mm.
This keeps dimensional variations in batch production within 0.005 mm.
In terms of intelligent optimization of cutting parameters, taking Beijing Jingdiao’s Surf-Mill 10.0 software platform as an example, this new machining center uses machine learning algorithms to analyze historical machining data, automatically deriving the optimal combination of cutting parameters for specific mold materials.
As a result, the machining efficiency for cell phone case molds has increased by 25%.
Digital Twin Systems and Cloud-Based Collaborative Machining: Full-Process “Virtual Mapping”
New-generation machining centers utilize digital twin systems and cloud-based collaborative machining to achieve closed-loop optimization across the entire process, from design to production. For example:
Sany Heavy Industry uses a digital twin system to simulate automotive mold machining in a virtual environment, enabling the early identification of tool collisions and path interference issues and reducing on-site debugging time by 60%;
Gree Electric Appliances relies on a cloud-based collaboration platform to integrate data from machining centers distributed across its nationwide production bases, enabling real-time dynamic resource allocation.
This has improved the efficiency of cross-plant collaboration on air conditioner compressor molds by 35% and yielded significant results in multi-machine collaborative manufacturing.
Furthermore, new machining centers that incorporate digital twin systems and cloud-based collaboration ensure that data—such as machining parameters and tool life—cannot be tampered with.
Hybrid Manufacturing: “Seamless Synergy” Between Additive and Subtractive Processes
A new type of machining center that integrates 3D printing and high-speed milling technologies is opening up new manufacturing pathways for precision molds.
This new machining center enables rapid prototyping of lightweight molds using 3D printing and high-speed milling technologies.
For example, in the manufacturing of aircraft engine blade molds, the center first uses selective laser melting to fabricate a titanium alloy substrate, then employs five-axis milling to finish the flow channel surfaces, reducing the machining cycle by 50% and cutting the mold’s weight by one-third.
In the integrated application of functionally graded materials, the new machining center employs laser cladding technology to manufacture molds for medical implants.
It first deposits a biocompatible coating onto the surface of a steel substrate and then shapes the mold through milling, thereby precisely matching the mold’s mechanical properties with its bioactivity.
Taking the German Ogiso Mold Center as an example, this machining center integrates electrical discharge machining (EDM) with high-speed milling, thereby enabling integrated “milling-discharge” processing of graphite electrodes.
This has doubled the production efficiency of mobile phone molds, with electrode precision reaching 0.003 mm.
A Comparison of the Applications of New-Generation Machining Centers and Traditional Machining Centers in Precision Mold Manufacturing
Capabilities for Machining Complex Structures
(1) Traditional Machining Centers.
Traditional machining centers are limited to three-axis motion, restricting machining to flat surfaces, inclined surfaces, and simple arcs—a significant limitation.
For example, automotive body panel molds contain free-form surfaces and must be completed through a series of separate machining operations.
Cumulative errors in the manufacturing of such molds using traditional machining centers often exceed 0.05 mm.
In the production of cell phone case molds, frequent tool changes during the machining process on traditional machining centers can easily lead to tool interference, resulting in a final mold surface roughness (Ra) greater than 1.6 μm.
(2) New-generation machining centers.
These centers employ five-axis simultaneous machining technology, allowing real-time adjustment of tool orientation.
For example, when directly milling deep cavities and narrow slots in medical catheter molds with a depth-to-diameter ratio greater than 10, the Ra surface roughness can be as low as 0.2 μm, eliminating the need for additional electrical discharge machining (EDM).
When manufacturing molds for aircraft engine blades, the Evermi GMU-400 machining center enables the spindle to swing ±120° while the worktable rotates synchronously through 360°.
This reduces machining time from 8 hours to 5.5 hours and increases the first-pass yield rate from 68% to 98%.
Cutting Efficiency of Hard Materials
(1) Conventional machining centers.
Conventional machining centers have low spindle speeds and lack dynamic compensation mechanisms.
When machining mold steel with a hardness of HRC 50 or higher, tool chipping occurs frequently, often resulting in a surface roughness (Ra) greater than 3.2 μm.
This necessitates supplementary electrical discharge machining (EDM) after quenching, extending the cycle time by 30% to 50%. Consequently, their cutting efficiency for hard materials is significantly limited.
(2) New-generation machining centers.
When equipped with cubic boron nitride (CBN) cutting tools and an ultra-high-speed spindle (54,000 r/min), new-generation machining centers can directly machine workpieces made of steel with a hardness of HRC 60 or higher, achieving cutting speeds of up to 150 m/min. with a surface roughness of Ra ≤ 0.4 μm.
This eliminates the need for the “hardening + EDM” process, reducing the cycle time by approximately 40%.
For example, the DMG DMC75V linear, using polycrystalline diamond (PCD) tools to machine NAK80 mirror-finish molds, can achieve a surface roughness of Ra as low as 0.02 μm.
Ultra-Precision Machining Capabilities
(1) Conventional Machining Centers.
Conventional machining centers have relatively low positioning accuracy and thermal stability.
When machining micro-shaft components (ø=0.5 mm) for semiconductor packaging molds, dimensional control is prone to fluctuations of up to 0.02 mm, making it difficult to meet the precision standards required for chip packaging.
(2) New-Generation Machining Centers.
New-generation machining centers utilize a constant-temperature oil-cooling system (with temperature control accuracy of 0.05 °C) and nanometer-level error compensation technology.
When machining aspheric surfaces for optical lens molds, the contour error is less than or equal to 0.001 mm, with Ra ≤ 0.01 μm, achieving optical-grade precision.
For example, the YASDA five-axis machining center from Japan is equipped with Kern hydrostatic guideways and a compact spindle with internal cooling, enabling stable, nanometer-level machining.
Technological Trends
(1) Traditional machining centers.
Traditional machining centers are undergoing cost-effective intelligent upgrades, such as the installation of simple monitoring modules and basic collision-avoidance functions;
However, due to limitations in their mechanical structure, improvements in precision remain limited.
(2) New-Generation Machining Centers.
New-generation machining centers continue to advance toward ultra-high precision, with spindle speeds approaching 300,000 r/min and positioning accuracy reaching the nanometer level (e.g., 0.0001 mm), meeting the machining requirements for optical lens molds.
The deep integration of artificial intelligence has also become a trend; the application of AI facilitates “design-as-manufacturing,” with machining path optimization boosting efficiency by 80%.
In addition, new-generation machining centers utilize closed-loop coolant recycling systems for green manufacturing, reducing waste fluid discharge by 70%. Through real-time monitoring, energy consumption in new-generation machining centers has been reduced by 20%.
Conclusion
In precision mold manufacturing, new-generation machining centers leverage five-axis simultaneous machining, high-speed cutting, AI control, and digital twins to achieve a leap from “functional” to “excellence.”
In scenarios such as the machining of complex structures, the processing of hard materials, and intelligent production, the role of new-generation machining centers is irreplaceable.
Traditional machining centers remain widely used by small and medium-sized mold manufacturers for machining regular-shaped components, thanks to their lower costs, experienced operators, and good process adaptability.
New-generation and traditional machining centers do not exist in a relationship of complete substitution but rather form a complementary ecosystem: basic machining tasks are primarily handled by traditional machining centers, while high-value-added, skilled tasks are performed by new-generation machining centers.
The mold manufacturing industry is moving toward high precision, short lead times, and low energy consumption.