A03-1-TOOLING APPLICATIONS WITH EOSINT M

Figure 6:
(a) left: machined aluminium tool and DMLS inserts.
(b) right: tool with DMLS sliders and guides in different materials.
Courtesy of General Pattern, Linear.

DMLS is often combined with other production methods for one tool, an approach which is often called hybrid tooling and which can be applied in many variations. For example if only one half of the tool has intricate geometry, like a mobile phone housing with a simple free-form outer (visible) surface but a complex rear (hidden) surface with ribs and clips, then it is often economical to machine the cavity (for the outer surface) whilst building the more complex core using DMLS. In other cases, only relatively small regions of a tool are so complex that they cannot be milled.

In such cases it can be sensible to build small inserts using DMLS and machining pockets in the main tool for these to fit into, either as fixed or loose inserts. An example with a machined aluminium tool is shown in Figure 6 (left picture), and a similar approach can also be used with cast epoxy tooling, in which case DMLS inserts are also used for any features such as thin walls where the epoxy would not be strong enough to resist the moulding forces [3]. DMLS can also be effectively used to build various other tooling elements. The example shown in Figure 6 (right picture) used DMLS for moulding cavities, sliding inserts and also the guides for the sliders. To prevent galling, different DMLS materials were used for elements which repeatedly slide over each other.
Intelligent tooling concepts also help a lot to apply optimized cooling in a cost-effective way. Figure 7 shows three examples. Figure 7 (a) shows a blow moulding tool for PE bottles. The cycle time and therefore production rate of such tools is typically limited by the cooling time for the necks of the bottles, which have the thickest cross-sections.
In the case shown, small DirectTool inserts with conformal cooling were built to extract the heat from these regions more quickly, and were integrated into a standard machined production tool. In this way the cycle time was reduced from 15 seconds to just 8-9 seconds, giving a productivity improvement of approximately 75 percent, with no loss of quality. 7(b) shows a cooling core designed to be inserted into the rear of the ejector side of a mould to remove heat from the injection area. This reduced the cycle time in production by two-thirds. 7(c) shows a core with integrated conformal cooling. The dome includes a spiral-shaped cooling channel, but the core has been designed so that the lower half can be easily machined.
In this way, the core was cost-effectively produced by machining the lower part, mounting it in an EOSINT M270 system and adding the top part by DMLS [2]. 0.3mm machining allowance was added for finish-machining of the outer surface.

Figure 7: Cooled inserts for tooling.
(a) left: for the necks of bottles in a blow mould.
(b) middle: core for cooling the injection point of a mould.
(c) right: hybrid core with conformal cooling built on top of machined base. Courtesy of SIG Blowtec, Es-Tec, DemoCenter, LBC.

DMLS is also sometimes used to implement design changes to existing tools or to repair worn or damaged tools.