Bonding Integrity of Hybrid 18Ni300-17-4 PH Steel Using The Laser Powder Bed Fusion Process For The Fabrication of Plastic Injection Mould Inserts

Laser powder bed fusion (LPBF) is a metal additive manufacturing (AM) process for fabricating high-performance functional parts and tools in various metallic alloys, such as titanium, aluminium and tool steels. The process can produce geometrically complex features such as conformal cooling channels (CCC) in plastic injection mould inserts to improve cooling efficiency. A recent attempt using a hybrid-build LPBF AM technique to fabricate aluminium mould inserts with CCC attained a substantial reduction in processing time, making it an attractive alternative method to the mould-making industry. Also, the successful bonding of aluminium powder with wrought aluminium alloys proved the practicability of this concept. This study further investigates whether a similarly successful outcome could apply to tool steel since tool steel is the preferred material for constructing high-grade high-volume plastic injection moulds. In this investigation, hybrid 18Ni300 powder-wrought 17-4 PH steel parts were additively fabricated using the hybrid-build LPBF technique, followed by various post-build heat treatments. The mechanical and metallurgical properties of the samples’ bonded interface were examined. Microstructure analysis revealed homogenous powder-substrate fusion across the interface region. Results from tensile tests confirmed strong powder-substrate bonding as none of the tensile fractures occurred at the interface. A direct post-build one-hour age-hardening treatment achieved the best combination of hardness, tensile strength, and ductility. The overall result demonstrates that hybrid-built 18Ni300-17-4 PH steel can be a material choice for manufacturing durable and high-performance injection mould inserts for high-volume production.

Selective laser melting for improving quality characteristics of a prism shaped topology injection mould tool insert for the automotive industry

Manufacturing process constraints and design complexities are the main challenges that face the aftermarket automotive industry. For that reason, recently, selective laser melting (SLM) is being recognised as a viable approach in the fabrication of injection moulding tool inserts. Due to its versatility, SLM technology is capable of producing freeform designs. For the first reported time, in this study SLM is recognized for its novel application in overcoming fabrication complexities for prism shaped topology of a vehicle headlamp’s reflector injection moulding tool insert. Henceforth, performance measures of the SLM-fabricated injection mould tool insert is assessed in comparison to a CNC-milled counterpart to improve quality characteristics. Tests executed and detailed in this paper are divided into two stages; the first stage assesses both fabricated tool inserts in terms of manufacturability; the second stage assesses the functionality of the end-products by measuring the surface roughness, dimensional accuracy and light reflectivity from the vehicle reflectors. The results obtained show that employing SLM technology can offer an effective and efficient alternative to subtractive manufacturing, successfully producing tool inserts with complex surface topology. Significant benefits in terms of surface roughness, dimensional accuracy and product functionality were achieved through the use of SLM technology. it was concluded that the SLM-fabricated inserts products proved to have relatively lower values of surface roughness in comparison to their CNC counterparts.

Design and construction of a sensor analytic system for the monitoring of the parameters of a plastic injection mould

PurposeValues of parameters such as temperature, humidity, number of plastic products and the location of plastic injection moulds are required to determine the efficiency of plastic injection moulds with a view to improving the quality of the outputs. This article determined the appropriate sensors for the measurement of these essential parameters in the most suitable form of representation of the data to aid a proficient analysis of the data.Design/methodology/approachThe outputs of these sensors were obtained by connecting the sensors to the general-purpose input/output (GPIO) pins of a Raspberry Pi and writing a Python programme for the connected GPIO pins. The values of the outputs of these sensors were represented in a graphical form. The connection of the Raspberry Pi and the sensors were done with a full-sized breadboard and jumper wires. A computer-aided design (CAD) of the connections was produced using Fritzing software.FindingsThe appropriate sensors determined are MLX90614 infrared thermometer sensor, DHT11 humidity sensor, pixy2 vision sensor and Neo-6m GPS sensor. This study proposed that the sensors analytic system be applied on an industrial plastic injection mould to measure and display the various parameters of the injection moulds for the purpose of understanding and improving the performance of the injection mouldOriginality/valueAn electronic system that provides the continuous values of essential parameters of a plastic injection mould in operation.

Investigation of an inverse thermal injection mould design methodology in dependence of the part geometry

The production of injection moulded components with low shrinkage and warpage is a constant challenge for manufacturers. The thermal design of the injection mould plays an important role for the achievable quality, especially the placement of the cooling channels. This design is usually based on empirical knowledge of the mould designers. The construction is supported iteratively by injection moulding simulations. In the case of thick-walled plastic optics with big wall thickness jumps, the shrinkage is compensated by injection compression moulding. In this process, the thin-walled areas freeze earlier and the necessary compression pressure introduces stresses into these areas which reduces the optical performance. An adapted cooling channel design can reduce these problems. At the IKV, Institute for Plastics Processing in Industry and Crafts at the RWTH Aachen University, a methodology was developed which inversely calculates the cooling requirement of the moulded part A demand-oriented cooling channel system is derived based on the computed results. The aim of the research projects is to minimise displacement and internal stresses by temperature control of the moulded parts according to the demand. In this paper, the methodology is applied to three different geometries, representing three classical parts for the injection moulding process. Three different quality areas in the mould for the inverse optimisation are defined and investigated. For each geometry the cooling channel designs are then validated in injection moulding simulations based on the results from the thermal optimisation. It can be shown that for different component geometries and thicknesses, different quality areas are advantageous and decrease the maximum warpage of the parts. For thin-walled ribbed components, a 2D approach leads to a 15% smaller displacement, for components with wall thickness jumps, all investigated quality ranges show no differences in displacement, but a surface in the middle of the part is preferred due to a 3 °C lower standard deviation of the temperature distribution.