Dimensional and shape analysis of an additively manufactured DIEVAR tool steel mold component with a conventional design for die casting

Pressure casting is a key technology used in the manufacturing of geometrically complex castings with high dimensional accuracy, especially from aluminum alloys. The process itself involves injecting molten metal into a metal mold under high pressure at temperatures often exceeding 700°C (Nunes et al. 2017). During operation, molds are exposed to extreme thermal and mechanical stresses, leading to various degradation effects such as thermal fatigue, erosion, aluminum adhesion and wear (Nunes et al. 2017; Matisková et al., 2013; Tušek et al., 2010; Koutiri et al., 2013). Cyclic thermal loading is the main cause of crack formation and significantly limits the service life of molds (Matisková et al., 2013; Tušek et al., 2010). The durability and quality of molds depend primarily on the correct choice of tool steel, with H13 steel being commonly used in practice (Nunes et al., 2017; Guanghua et al., 2010), but optimized heat treatment and design play an important role too (Guanghua et al., 2010; Sinha et al., 2021; Naimi and Hosseini, 2014).

The extension of mold life is also enabled by protective coatings based on titanium nitrides or their alloys (e.g. TiN, TiAlN, ZrN), which increase resistance to wear, adhesion and corrosion (Nunes et al., 2017; Koutiri et al., 2013; Pereira et al., 2011; Norwood et al., 2007; Jhavar et al., 2013). Surface treatment and proper cooling design are therefore essential factors for achieving long mold life and stable casting quality (Matisková et al., 2013; Sinha et al., 2021). Additive manufacturing, specifically the selective laser melting (SLM) method, is innovating aspects of the foundry industry in the manufacturing of molds for high-pressure die casting. SLM enables the creation of molds components with highly complex geometries that would be difficult or even impossible to produce using conventional methods (Laakso et al., 2016; Liu et al., 2018; Holzweissig et al., 2015). In particular, laser powder bed fusion technologies allow the fabrication of complex internal geometries, such as conformal cooling channels, which significantly enhance thermal control of molds components during operation (De Lima et al., 2025). A significant advantage of SLM is the speed of producing prototype components, which considerably shortens the development time (Shi et al., 2021; Brøtan et al., 2016). Thanks to the layer-by-layer deposition of additive material, moldsparts can be produced without the need for special tooling, which reduces costs and allows for easy design modifications (Liu et al., 2018; Shi et al., 2021). The disadvantages of SLM include, in particular, lower dimensional accuracy and higher surface roughness compared to conventional manufacturing methods, which can affect the mechanical properties of the resulting molds (Laakso et al., 2016). For this reason, optimization of the additive printing process and any subsequent machining is essential to achieve the desired properties and service life of molds and their parts (Liu et al., 2018; Shi et al., 2021). Recent studies focusing on additively manufactured mold inserts report that optimized cooling channel design combined with appropriate surface engineering can lead to higher thermal efficiency, significantly extended service life and reduced maintenance frequency compared to conventionally manufactured H13 inserts (De Lima et al., 2025).

The relationship between thermal behavior during operation and wear mechanisms of mold components has also been investigated. It has been shown that the rate of heat transfer from the molten metal to the mold during solidification directly determines the cooling rate of castings and significantly influences thermal loading and degradation of mold surfaces. Furthermore, the use of additively manufactured inserts with suitably designed cooling channels enables effective control of heat transfer across the entire mold, contributing to more uniform thermal loading and potentially reduced wear during cyclic operation (Capela et al., 2023).

DIEVAR tool steel is a modern martensitic steel alloyed with chromium, molybdenum and vanadium, designed for demanding, hot applications. In practice, it is most often used in die casting and forging. It excels in high toughness, resistance to thermal stress and wear, even at higher temperatures (Uddeholm, 2025). Compared to conventional H13-type materials, it offers higher resistance to thermal cracking and longer tool life (Uddeholm, 2025; Sjöström and Bergström, 2004). Thanks to its high Cr and Mo content, Dievar is also highly resistant to high-temperature oxidation (Balaško et al., 2018). It is available both in the form of forged semi-finished products and in a variant for additive manufacturing, where it retains its excellent mechanical properties (DIEVAR datasheet, 2025). In the foundry industry, 3D measurement is essential for checking the quality and accuracy of castings and molds. 3D scanning enables fast and noncontact digitization of complex surfaces, product documentation and reverse engineering; however, it has lower accuracy and other limitations when used for deep cavities (Edl et al., 2018; Stojkic et al., 2020; Hawryluk et al., 2020). In contrast, 3D CNC CMM coordinate measurement provides very accurate results for even complex shapes, but is slower and requires physical contact with the part (Stojkic et al., 2020). The choice of method depends on the required accuracy and complexity of the surfaces to be measured (Stojkic et al., 2020; Hawryluk et al., 2020).

Pressure casting is a key technology used in the manufacturing of geometrically complex castings with high dimensional accuracy, especially from aluminum alloys. The research focused on studying the service life of a conventional design solution for an additively manufactured component made from DIEVAR tool steel, as well as on the methods used to evaluate its durability. Additive 3D printing was carried out using SLM technology. The evaluation covered all the manufacturing stages, including additive 3D printing, heat treatment, machining and the application of a protective coating, resulting in the final manufacturing parameters prescribed in the drawing documentation. After the manufacturing was completed, operational testing was carried out in real foundry conditions. Dimensional and shape analyses were performed using a combination of noncontact 3D scanning and contact measurement on a 3D CNC CMM. This method of 3D measurement enabled the monitoring of changes in shape and dimensions while providing a complete geometric picture of the component from the manufacturing cycle to operational testing up to 66,400 operating cycles, with an expected service life of 120,000 operating cycles. The research was carried out in cooperation with MOTOR JIKOV Fostron a.s., MOTOR JIKOV Slévárna a.s. and partner universities, University of West Bohemia in Pilsen, Technical University in Liberec and Institute of Technology and Business in České Budějovice. The design and manufacturing of the component using SLM additive technology was carried out in cooperation with MOTOR JIKOV FOSTRON, Technical University of Liberec and University of West Bohemia. The shape and dimensional analysis was provided by the Institute of Technology and Business, while operational testing took place directly at the MOTOR JIKOV foundry.

The die casting mold contains a total of eight molded parts, all produced additively from DIEVAR tool steel. Six of these components feature a full conventional structural design, while the remaining two are additively manufactured with a lightweighted design. For the research, a conventionally designed additive component was selected, characterized by a complete hexagonal extended molded part, referred to as the crown. The design was implemented with a focus on ensuring maximum rigidity and dimensional stability during operation. The aim of this research was to evaluate its dimensional and shape stability throughout the whole manufacturing cycle and operational testing. Figure 1(a) shows the CAD model of the selected design solution and Figure 1(b) shows its actual appearance after additive 3D printing.

During production, the component underwent machining, which modified its shape and resulted in the desired production dimensions, especially in the area of the hexagonal crown. The model for machining is shown in Figure 2(a), while the actual appearance after this operation is shown in Figure 2(b).

Manufacturing of shape mold part: Manufacturing was similar to that of conventional die casting tools, with the difference being the use of additive printing instead of conventional manufacturing. The process involved four main steps:

Additive printing: The base geometry of the component was produced using SLM on an SLM280HL system from DIEVAR tool steel. The additive manufacturing process was carried out with an emphasis on build stability and geometric accuracy of the final part. The applied process parameter settings, including laser characteristics, are summarized in Table 1.

Heat treatment: After completion of the additive manufacturing process, the components were subjected to heat treatment using a VTC 324R furnace to homogenize the microstructure and achieve the required mechanical properties. The thermal cycle included homogenization annealing at 1,080°C, hardening at 1,030°C, followed by controlled cooling at a rate of 28°C/min. Final mechanical properties were obtained through triple tempering, resulting in a hardness of 46 ± 2 HRC and an ultimate tensile strength of approximately 1,360 ± 200 MPa.

Machining: Geometric accuracy and functional surfaces of the component were achieved through mechanical machining performed in several successive steps. The process included grinding of rotational surfaces and overall lengths, CNC milling of geometrically complex regions and finishing milling in the heel area of the component. Each machining stage was completed with an interoperational inspection of dimensional and geometrical tolerances.

Coating application: After reaching the final shape, the component was surface-treated using ALWIN SHM PVD technology. The applied coating was selected to enhance wear resistance and to ensure stable performance of the component under operational loading conditions.

After the manufacturing was completed, the component was placed in the working mold, the exact position of which is shown in Figure 3 and was then monitored during operational testing until 66,400 operating cycles were achieved.

The dimensions and shape of the component were determined using two different methods: laser 3D scanning and point measurement on a 3D CNC CMM device.

3D laser scanning: a ROMER Absolute Arm 7525SI 3D laser scanner was used for the analysis. This method enabled detailed monitoring of the actual surface shape and subsequent comparison with a 3D CAD model with an accuracy of ±0.05 mm, allowing changes in shape to be monitored across the entire component.

3D coordinate measurement: measurements were performed on a Thome Präzision GmbH 3D CNC CMM coordinate measuring machine, which operates with an accuracy of ±0.005 mm. Key points were checked point by point using the contact method, especially in the area of the crown, where the greatest load occurs during the casting cycle. The measured values were then entered into a table, from which a graph was created for an easier overview of dimensional development during the life cycle. The measurements were evaluated using MS PolyWorks software, which was used to process and visualize the acquired data. The component was analyzed continuously throughout all the manufacturing and operational steps, from 3D printing through heat treatment, machining and protective coating application to operational testing until 66,400 operational cycles were reached.

Alignment method: three basic geometric elements based on the CAD model were used for precise spatial alignment. These were a reference plane, vector and center point of a circle. These elements served as fixed points for aligning the actual measured model with the nominal geometry, both for noncontact 3D scanning and for contact measurement on the coordinate measuring machine. This approach ensured repeatable and reliable data alignment throughout the life cycle.

3D scanning: a polygonal model was created by scanning the surface of the component, which was then used for comparison with the nominal 3D CAD model. The selected reference elements enabled precise alignment of the scanned data, which is essential for evaluating shape changes.

3D CNC CMM: during contact measurement the correct position of the component was first ensured using the same three reference elements as above. After this alignment, it was possible to perform repeatable and accurate measurements at defined locations in the hexagon area throughout the entire cycle.

Evaluation method: the following section describes how the geometric accuracy of the component was determined using two independent 3D measurement methods.

3D scanning: data obtained by the 3D laser scanner was evaluated using a color deviation map tool. This visualization shows where the actual geometry deviates from the nominal CAD model according to a color scale describing the permissible values, with the permissible tolerance set to ±0.200 mm according to the drawing documentation. The results were always presented in two views, from the front and rear, as shown in Figure 4(a) and (b).

3D CNC CMM: the evaluation of measurements using 3D CNC CMM focused on the upper hexagonal part of the component, known as the crown, which is crucial in terms of operational load. The hexagon was divided into six color-coded locations 1–to 6, with two points measured at each location, as shown in Figure 5(a) and (b).

The experimental section summarizes the results of dimensional and shape analysis of the component obtained from 3D scanning and 3D measurement on a coordinate measuring machine. Attention was paid to changes in geometry in the individual manufacturing steps and during operational testing. The results provide an overview of the stability and behavior of a conventionally designed solution throughout the entire life cycle.

Dimensional tolerances always refer to the final state after completion of manufacturing, i.e. after the application of the protective coating. From this point on, the measurement results should not exceed the permissible tolerance, ±0.200 mm.

Figures 6 and 7 show the results from scanning the component during its manufacturing cycle, which includes additive printing, heat treatment, machining and the application of a protective coating.

Additive printing: after the completion of manufacturing by SLM with an allowance on all shaped surfaces, the dimensional status was predominantly within the negative deviation of the permissible tolerance. Deviations in the heel area ranged from −0.10 to −0.15 mm. The body of the component was characterized by relatively uniform deviations around −0.08 mm. Minor deviations ranging from +0.05 to −0.10 mm were observed in the crown area.

Heat treatment: led to a slight change in dimensional deviations, especially in the crown area, where green zones indicating deviations of up to +0.08 mm are visible. The component’s base showed persistent negative deviations of up to −0.15 mm, while the body remained relatively stable, with values mostly around −0.05 mm.

Machining: contributed significantly to improving geometric accuracy and achieving manufacturing dimensions according to the drawing documentation. The body is mainly within the tolerance range of ±0.05 mm, with deviations evenly distributed. The crown achieved better values, ranging locally to positive values of up to +0.10 mm. More significant negative deviations remained at the heel, especially in the rear view, where they reached values of up to −0.17 mm.

Coating application: caused a slight change in dimensional values toward positive deviations, corresponding to the layer of the material applied. The crown ranges from +0.15 to −0.08 mm. The body is very stable in terms of dimensions, with values of ±0.07 mm, with the front and rear sides showing almost identical distribution. The heel remains the most problematic area, with local deviations ranging from +0.10 to −0.15 mm.

The following section focuses on the results of measurements taken during the operational testing of the component up to 66,400 operating cycles. Data collection was carried out according to the foundry’s time constraints, and the shape deviations obtained were again visualized using 3D scanning. An overview of these results is shown in Figures 8–10.

Operation after 15,840 cycles: initial operational testing measurements revealed deviations in the crown area ranging mainly between ±0.10 mm. At the heel, especially on the front side, the deviation values locally reach +0.20 mm. Measurement of the heel also revealed a gray spot, which indicates a dimension outside the permissible tolerance, but when compared to the other results, this was found to be only a reflection that occurred during scanning. The front of the body remains relatively stable with a predominantly blue color, indicating deviations of around -0.08 mm. On the back of the body, the dimensions vary within a deviation of ±0.15 mm.

Operation after 28,600 cycles: green-yellow areas corresponding to a deviation range of ±0.12 mm are visible on both the front and rear sides of the component, especially at the base and transition to the crown.

Operation after 36,300 cycles: led to stabilization of the shape profile of the entire component. At the base and crown, the deviation decreased to values ranging from +0.08 to −0.10 mm. The body shows uniform coloring of deviations corresponding to values of −0.08 mm on the color scale, but without signs of greater wear that could be caused by operational influences.

Operation after 42,400 cycles: measurements maintain similar dimensional characteristics as in the previous phase. The crown and upper part of the body remain slightly below the nominal values with a deviation of ±0.08 mm, and the color map is still dominated by a blue tone. The heel shows minor local deviations to negative values corresponding to a range of ±0.08 mm.

Operation after 48,825 cycles: a slight increase in deviation appears on the front side in the heel and crown area, mainly up to ±0.10 mm. The body is again dimensionally stable with an increase in deviation to values corresponding to −0.10 mm. Overall, it can be said that there are no significant changes compared with the previous measurement.

Operation after 66,400 cycles: the last measurement shows an increase in green and yellow zones across the entire component, indicating a dimensional shift toward the upper positive tolerance. Overall, the dimensional deviation ranged from +0.18 to −0.05 mm. More significant changes may indicate mechanical wear or thermal deformation.

The results of the point measurement of the component crown obtained using a 3D CNC CMM are shown below. The values measured in the individual phases of manufacturing and operation are listed in Table 2 and graphically represented in Figure 11. The placement of the measuring points corresponds to the diagram shown in Figure 5. These data describe the dimensional changes throughout the entire life cycle.

Additive printing: after printing, all points of the hexagon were within a tolerance of ±0.200 mm. The largest negative deviations were recorded at points 1d (−0.159 mm) and 6d (−0.158 mm), indicating more significant deviations at the lower edges of crowns 1 and 6, as shown in the diagram in the upper right corner of Figure 10. Conversely, surface no. 4 (points 4u and 4d) shows positive deviation values of around +0.160 mm, indicating a local increase in material.

Heat treatment: caused the greatest variation in deviations within the manufacturing cycle. Points 1u and 6u achieve deviations of +0.211 to +0.215 mm, which is beyond the upper tolerance limit, but these are not the final manufacturing dimensions of the component. In contrast, points 3u, 3d, 4u and 4d fell into the negative tolerance range to values of up to −0.165 mm, indicating possible release of residual stresses and deformation in the side surface area.

Machining: achieved almost final manufacturing dimensions and significantly stabilized component values. All points came closer to the nominal (ideal) values. Deviations range from ±0.030 mm. However, the measurement was taken after rough machining; as part of the manufacturing cycle, fine machining was then performed, followed by the application of a protective coating.

Coating application: caused changes in the order of thousandths of a millimeter. All values remain within the tolerance range. The dispersion of values between ±0.010 mm confirm the uniform application of the coating.

Operation after 15,840 cycles: the first operational testing measurement revealed an increase in values on the surface of hexagon No. 1 at points 1u and 1d, which dropped to the lower tolerance limit of −0.200 mm and −0.160 mm. Since these are points on the same surface (No. 1), this deviation could have been caused by contamination on the component at the measurement point. The other points of the crown remain around the nominal dimensions, most of them within ±0.05 mm. This phase of operation demonstrates the stability of the dimensions, except for one surface, which will be emphasized in the next measurement.

Operation after 28,600 cycles: deviations at most measured points, including previously critical ones, showed a slight increase and range from −0.080 to +0.111 mm. Critical area No. 1 was treated with technical alcohol in order to remove all unwanted impurities.

Operation after 36,300 cycles: stable condition persists, most points vary by ±0.080 mm. The largest deviations (−0.085 and −0.076 mm) are at the upper points of surfaces No. 1 and No. 6. This trend indicates long-term uniform wear.

Operation after 42,400 cycles: Compared with the previous measurement, there are increases in dimensional deviations in several areas. More significant positive deviations are evident at points 3u, 3d, 4u and 4d, where the values reach the upper tolerance of +0.200 mm. Increased deviations were also recorded at points 1u and 6u, which moved closer to the lower tolerance limit of −0.200 mm. Nevertheless, all points remain within the permissible tolerance range of ±0.200 mm, and the component thus retains its functional dimensions and can be put back into operation, with critical measurement points continuing to be monitored.

Operation after 48,825 cycles: the condition remains similar. The differences between the upper and lower points are minimal, with areas No. 3 and No. 4 continuing to slightly exceed the other areas with deviations of up to +0.180 mm.

Operation after 66,400 cycles: the last measurement showed a reduction in the dispersion of all the measured points, especially 4u (+0.028 mm) and 6d (−0.036 mm). This reduction in dimensional deviations may be a result of surface wear of the contact surfaces by coming into contact with molten metal causing repeated mechanical and thermal stress. All of the measured values remain within the tolerance range of ±0.200 mm and the component is ready for further testing.

The research monitored the service life and geometric stability of a conventional, additively manufactured die casting shape mold part made of DIEVAR steel. Additive 3D printing, specifically the SLM method, was used in the manufacturing process. The main objective was to verify dimensional and shape stability throughout the entire manufacturing and operating cycle.

• As part of the research, geometric changes in the component were monitored using a combination of 3D scanning and 3D measurement on a coordinate measuring machine. 3D scanning provided an overview of the shape stability of the component across the entire cross-section, while 3D measurement using a 3D CNC CMM enabled detailed inspection of key areas of the crown, which had high requirements for dimensional accuracy.

• The results showed that the component demonstrated dimensional and shape reliability throughout the operational testing period. No deviations exceeding the permissible tolerance of ±0.200 mm were recorded during the operational cycles. Local fluctuations in the measured values remained within the functional requirements, and the component retained its operability.

• The findings confirm that the additively manufactured conventional design solution is suitable for use in foundry conditions requiring long service life, functionality and reliability. The tested component remained functional after reaching 66,400 operating cycles, and operational testing can continue until the expected service life of 120,000 cycles or until it ceases to meet the functional requirements for the manufacturing of castings.