Solutions for Plastic Injection Molding

In addition to the technical function of a plastic molded part, aesthetic aspects in particular play a decisive role in the purchase decision nowadays. In the case of housing components – such as this demonstrator – non-optimized thermal management of the mold insert can lead not only to dimensional deviations, but also to visible weld lines and flow lines in the area of functional elements and cutouts. This often results in higher reject rates as well as longer cycle times due to process-related corrective measures.

» Avoidance of visible surface defects through conformal, variothermal process control

AM-POWDER (premium materials from BOHLER and UDDEHOLM)
Our long history of developing materials for the injection molding industry means that the powders we use are of the highest quality and provide superior tool life. Our AM powders are developed and manufactured by the same experts responsible for our premium tool steels.

We ensure the highest possible part quality, reliability and consistency by managing every step of the value chain from powder production to the delivery. Whether for a single part order or series production, our internal quality systems ensure we meet your requirements every time. We use state-of-the-art tools to continually improve and refine our internal printing processes. Design of Experiments, Statistical Process Control, and Process Monitoring form the basis of our methodology. Continued innovation from our AM and materials groups ensures we deliver superior material properties in the most demanding applications. As a result, our customers can put parts into service with the highest degree of confidence.

We understand the interactions between laser and material. This deep understanding of AM and PIM allows customers to add value to their business and realize competitive advantage.

left: De-powdered mold insert

We understand the interactions between the additive manufacturing process and the material, and this in-depth understanding enables a process-safe solution as well as pore-free surfaces for the highest part surface quality.

left: Optimization goal „build zone“ detected by process monitoring using EOSTATE Exposure OT (top) and EOSTATEMeltPool (below)
middle: Design of Experiments for paramter optimization using contour map of response surface design for porosity (top) and the related metallographic sample after optimization (below)
right: Microstructure of AM processed H13-type analyzed by SEM (top) and EBSD (below)

The mechanical processing of the additive manufactured insert was carried out by our cooperation partner FBB Formenbau Buchen GmbH. This forms the basis for all downstream machining steps.

FBB is an experienced expert in the manufacture of plastic and silicone products, developing customized tools and molds that take into account customer requirements and quality standards. Whether for injection molding or silicone injection molding, FBB is your reliable partner for high-quality and functional products in professional and private use.

left: Mold insert after EDM

Eschmann Textures offers a wide range of technologies worldwide for the surface treatment of plastic processing molds according to individual customer requirements. Depending on the specific requirements for mold geometry and design, we always provide the appropriate technology for subsequent mold processing. For this purpose, we utilize a diverse production portfolio, which includes high-precision 5-axis laser processing as well as classic etching technology. In this way, we open up new perspectives for plastic molds by realizing appealing visual and haptic surface textures, ranging from automotive applications to lifestyle products.

The mold insert is finished with a background texture into which a digital watermark has been integrated. Thanks to the femto-laser technology used, even the finest structures can be introduced.

Digital watermarks can be used to integrate invisible information into the surface of plastic products. We have integrated the digital watermark into the laser structuring of the housing surface. Possible uses of this technology include efficient tracking of content, increasing consumer interaction and maintaining brand reputation. Furthermore, the technology can gain importance in the future for the integration of recycling information directly into the component surface.

Using the demonstrator as an example, you could follow the watermark directly to this website. For the integration of digital watermarks into tools for plastics processing, Eschmann Textures is your partner.

Link to Digimarc-App

The flame-retardant PC/ABS molding compound used for the housing makes wear protection of the fine hologram texture necessary in order to maintain the effect over the tool life. The required wear resistance of the surfaces while maintaining the high gloss surface is achieved with the TiN-ultrafine or CHROME-X coating from voestalpine eifeler Coating. In addition to wear protection, the coating also has a positive effect on demolding. The TiN-ultrafine is a wear-resistant Arc-coating that is produced using SPCS technology and therefore has fewer droplets than the conventional Arc-TiN-coating. In contrast, CHROME-X uses sputtering technology, which enables droplet-free application. TiN-ultrafine or CHROME-X can therefore be used to achieve the ideal compromise between wear resistance and gloss preservation.

With its advanced services, technologies and products, voestalpine eifeler Coating has been offering targeted adjustments to surface properties for over 40 years, thereby enabling the optimization of manufacturing processes and mold properties. The right product solution for the respective customer application reduces wear and increases the service life of molds and components.

Our femto-laser technology allows extremely precise fine structures to be engraved into cavity inserts, such as hologram effects that back the logo „voestalpine – ONE STEP AHEAD.“. These structures use the phenomenon of diffraction, in which light waves hitting the structure spread out instead of being reflected in only one direction. Depending on the position of the observer and the light source, the light is refracted in various spectral colors. This effect can be controlled by laser parameters.

The hologram-effect can be molded onto the surface of the part using the injection molding process and not only serves an optical purpose but can also be used for security applications.

The mold insert was sampled by the cooperation partner FBB Formenbau Buchen GmbH. Both the conventionally drilled insert with continuous water tempering (90 °C) and the additively manufactured insert with conformal, variothermal tempering (70/140 °C) were sampled. The increased flow front temperature in the variothermal process completely eliminated flow lines. The conformal cooling channel layout allowed rapid heating of the mold insert to the target temperature of 120 °C. This made it possible to achieve heating during secondary times. The lower mold temperature in the holding pressure phase and residual cooling time enabled the cycle time to be reduced by 18 %.

Our patented technology for integrating thermocouples into additively manufactured mold inserts enables extremely precise placement of the measuring points directly below the mold wall. In doing so, we use the greater design freedom of additive manufacturing for the integration of the sensors without affecting the layout of the tempering channels. The application possibilities of this technology are numerous. They range from monitoring the mold temperature to analyzing the functioning of cooling channels over a certain period of time. In addition, potential faults in the temperature control can be detected. In this demonstrator, variothermal process control is quantitatively recorded. Process monitoring systems such as the ComoNeo from our cooperation partner, the Kistler Group, can be used to perform these tasks.

Two thermocouples are integrated in the demonstrator shown. One sensor measures the mold wall temperature in the area of the flow line, the other in the area of the hologram structure. With the help of these sensors, the heating and cooling phases in the areas of the flow line formation and the hologram structure could be quantitatively captured. This provided insights into the process that can be used to both improve part quality and optimize cycle time. Due to the precise positioning of the thermocouples, the heating and cooling phases could be measured without any time delay compared to the measurement of the backflow temperature. This enabled the variothermal injection molding process to be optimized efficiently in terms of cycle time.

FULL ELIMINATION OF SURFACE DEFECTS

18 % CYCLE TIME REDUCTION BY LEVERAGING CONFORMAL COOLING