Micro UHMW‐PE column array molded by the utilization of PCB as mold insert

Abstract

Purpose -The purpose of this paper is to present a method for ultrasonically molding polymer powder in a micro plastic part mold. In the method, a printed circuit board (PCB) in which micro-hole arrays are drilled is used as a micro cavity insert. With the utilization of ultrasonic vibration, the polymer powder, which is prefilled and compacted in a micro cavity, mutually generates great sliding friction heat so as to be rapidly plasticized and molded. Design/methodology/approach -Micro carbide drill bits of which the diameters are 100.0 mm, 150.0 mm and 200.0 mm, respectively, are used for drilling the PCB to form a micro-hole array insert. Next, two kinds of various ultra-high molecule weight polyethylene (UHMW-PE) powder with various grain diameters are directly filled into a charging barrel and a mold cavity with the micro-hole array insert. Proper process parameters are set on ultrasonic plasticizing and molding equipment so that a molding test can be performed. The melt of UHMW-PE can be rapidly filled into the cavity. Finally, micro-column array plastic parts are successfully prepared. Findings -The micro-hole array PCB is a mold insert which is quite applicable for the ultrasonic molding of the powder in the mold. When a molding material is the coarse UHMW-PE powder with the grain diameter of about 350 mm, the diameter replication rates of the micro-column array plastic parts become good in order with the increased micro-hole diameter of the PCB. When the fine UHMW-PE powder with the grain diameter of about 80 mm is adopted, the diameter replication rates of the micro-column array plastic parts become good in order with the decreased micro-hole diameter of the PCB. Originality/value -In this paper, the micro-column array plastic parts with good replicability are successfully prepared by a technique for ultrasonically plasticizing and molding in the cavity. The technique can be applied to the fields of medical treatment, communication, optics, chemistry and so on, such as biological micro needle arrays, micro biological chips, optical memories, and micro chemical reaction chips.

Ultrasonic Molding Technology: Recent Advances and Potential Applications in the Medical Industry

“…Moreover, UCM is capable of processing polymeric and eutectic alloy powders [24] in a relatively short time cycle (usually less than 10 s). It comprises the following steps [25]. Once a mold assembly is installed and the sonotrode is well aligned with the charging barrel hole, polymeric powders are poured, filling the mold cavity and part of the charging barrel hole (Figure 3a).…”

“…In 2013 Liang et al [25] introduced the use of UCM to manufacture micro-parts. They fabricated ultra-high-molecular-weight polyethylene (UHWPE) column micro-arrays, achieving good replication results reaching up to 91.9% replication rates of a micro-column of 117.3 µm of diameter.…”

“…Regarding their manufacturing, it has been reported that the use of micro-staged laminated object manufacturing (DLOM), wire electrical discharged machining (WEDM) [13] and micro-drilling [25] have been used for the manufacturing of cavity inserts. However, traditional manufacturing processes, such as micro-milling, micro-EDM and micro-laser ablation could be employed for this purpose [30].…”

“…Table 1 presents a clear trend of increasing the compacting pressure as the product dimensions are reduced. Moreover, compacting pressure also influences on the flash thickness of polymeric parts scaled down when higher pressures are applied [25]. On the other hand, the effect of the amplitude of vibration in the UCM has not been fully explored.…”

“…Liang et al [24] obtained single melt-recrystallized micro-columns of ultra-high molecule weight polyethylene when the mold was preheated from 25 °C to 85 °C (Table 1 reveals the processing conditions). Previous studies reported only micro-parts with a nascent and melt-recrystallized of ultra-high molecule weight polyethylene [13,25]. Considering that increasing the mold temperature could lead to prolonged cooling times, preheating must be performed at temperatures as close as possible to the environmental temperature without compromising the molding quality.…”