Originally Published EMDM
May 2003
Equipment News
Recent developments in moulding equipment |
Moulding control technology automates and optimizes processing
Modular process automation and control technology affords machine operators an easy way to set up, optimize, and control injection moulding processes, and thus ensure desirable quality in moulded products. The simple-to-learn Moldflow Plastics Xpert (MPX) software package is available from Moldflow Europe Ltd. (Orpington, Kent, UK).
The first of three modules, Setup Xpert, enables users to perform a variety of injection-velocity- and pressure-phase-related setup routines to fix any defects such as short shots, flash, burn marks, or sink marks. A part is moulded, and feedback to the MPX system relating to both part quality and machine function is analyzed to determine process changes that would improve the result.
The next step is to obtain a robust processing window to compensate for normal process variations and ensure that the processing parameters that were found to produce a good part will not stray beyond that window. Optimize Xpert is the module that produces this window using an automated, easy-to-run design of experiments algorithm.
The third MPX module is Production Xpert, a comprehensive process control system that maintains the optimized processing conditions defined by Optimize Xpert. It can be called upon to correct the established process automatically should it drift or go out of control.
Injection moulding machines apply artificial intelligence to shorten cycle time
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All-electric, servo-driven, robotic injection moulding machines available in four sizes with clamp forces of 55–330 tn can provide high-volume lights-out moulding of medical devices, gears, and packaging products. Roboshot Si-B–series machines from Milacron Inc. (Batavia, OH, USA) minimize cycle time because of their overlapping functions and artificial intelligence (AI) control for mould and ejector protection and injection metering. Fanuc Alpha–series servomotors and drives minimize inertia and offer a 0.1-millisecond response; this rapid updating, aided by noise-immune fibre-optic communications, makes possible injection acceleration from 0 to 300 mm/sec in 27 milliseconds.
The machines are well suited for moulding thin-wall and precision parts. A rigid, reduced-inertia injection unit makes injection-pressure-transfer variations insignificant, and an improved temperature control board holds heat variation to within 0.2°C. Heat-up times are short and problems caused by overheating are minimized by a new barrel-and-nozzle-heating design. Comprehensive Windows CE–based control by means of a touch screen is intuitive for operators, who can customize menus and jump to any screen via multiple pathways.
The sophisticated AI protection capabilities have been developed to minimize costs related to tool damage. AI control also ensures performance consistency; the tunable metering function modulates screw speed to achieve repeatability of at least ±0.2 seconds on every cycle. In conjunction with pressure profile control, this can essentially eliminate variation in part weight, even with regrind blends.
Si-B–series machines are designed to be interfaced with Fanuc SR Mate robots for part removal, insert moulding, gate-cutting, and palletizing applications.
Benchtop cleanroom machine moulds small precision components
A range of benchtop injection moulding machines includes a unit capable of producing precision 0.02- to 12-g components such as catheters and cannulae from a variety of engineering thermoplastics. The Minimolder 12/90HSP, available from MCP Equipment (Stone, Staffs, UK), is a pneumatically controlled 9-tn machine that can deliver sprue- or runnerless mouldings by injecting directly at the cavity via an integral hot tip, thus minimizing material waste and component-handling problems.
The cleanroom-capable machine can mould glass-filled nylon, ABS, Noryl, polycarbonate, acetal, PBT, PEEK, PPS, and biodegradable materials. High shot accuracy is ensured by means of screw plasticizing with a choice of screw ratios and through plunger injection control via linear transducers.
The easily installed Minimolder 12/90HSP requires only compressed air, single-phase power, and a supply of chilled water. Tool change takes 5 minutes and material changes as little as 10 minutes. A touch screen control panel driven by programmable logic control facilitates the setting of all mould parameters.
Moulding/coating system is fully programmable
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A closed-loop automated moulding and coating system is intended to create or treat medical products such as catheters, stents, gloves, and sleeves by means of dipping. Supplied by ACC Moulding Systems Ltd. (Shepperton, Middx, UK), the system includes a four-axis robotic manipulator that carries out completely programmable dipping profiles and pallet-transfer motions.
The dip moulding and coating system is designed for 24-hour continuous duty. It can be configured to incorporate a variety of components, including temperature-controlled tanks, pallet-transfer conveyors, drying chambers, automated product-removal equipment, and associated computer controls and machine validation functions.
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