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Fast & flexible controls for extrusion, injection, blow molding.

New enhancements to the MACO series of controllers based on the "Alpha" hardware platform will be a major focus of Barber-Colman Industrial Instruments, Loves Park, Ill., at NPE '94 this June. The Alpha platform is a chassis-based, rack-and-card design that supports multi-processing capability and high-speed communications through dedicated buses across a common backplane. It was first introduced in 1991 with the MACO 4000 injection molding control, and later expanded to include the MACO 5000 series of extrusion controls, Now, that same architecture has been extended into the brand-new MACO 6000 series of blow molding controls.

The first product in the MACO 6000 series will be featured at NPE '94. It's the MACO 6500, a key feature of which is high-speed, multi-stepped parison control that is said to be suited to consistently molding parts with demanding profiles. The MACO 6500 can be used for closed-loop control of up to eight parison heads. Each parison-head control loop is run every 0.1 millisec--reportedly about 20 times faster than the industry average. Each head may have its own 100-step user-programmed profile. For more details on the MACO 6500, see PT, Jan. '94, p. 28.

In addition to the MACO 6500, Barber-Colman will be introducing its new MACO 4500 control for injection molding and MACO 5500 control for extrusion. These new controllers offer all of the same features of the existing MACO 4000 and MACO 5050 controls. However, the new generation expands the controls with a 16-card chassis, increasing the number of temperature zones, analog and discrete I/Os, logic sequences, timers, counters, and communications options. In addition, up to four chassis units can be used in multiple-chassis installations to further increase the control capability of the system. Multiple injection units, each with closed-loop process control, can be run from the same MACO 4500 chassis. Similarly, the MACO 5500 has enough I/O and computing power to provide complete, closed-loop melt-pressure control for multiple extruders.

Other enhancements include a flat-panel EL or LCD display, internal memory storage of up to 16 job set-ups (with additional external storage on Insta-Set memory cartridges), and universal power supply. The high-voltage power supply and digital I/O functions are isolated from analog I/O and control electronics to provide a high level of noise immunity. More key features of these controllers are covered in detail below.


A number of significant new enhancements will be added to the MACO 4000, 5000, and 6000 series.

* Expanded chassis: The original 12-slot chassis frame has been expanded to 16 slots, a feature that will be incorporated into the new MACO 6500 for blow molding, as well as the MACO 4500 and MACO 5500. One advantage of the expanded chassis is the ability to handle more options, such as temperature loops, valves, or position sensors.

* Multi-chassis capability: The multi-chassis system takes this concept one step further, allowing a master (16-slot) chassis to communicate with up to three slave (12- or 16-slot) chassis, all of which are tied into a single user interface. Each chassis has intelligent modules to handle specific control functions; communication between each chassis is handled by the master. Multi-chassis systems essentially quadruple the number of I/Os available, which can have utility in extrusion, blow molding, and high-tonnage injection molding machines running with a large complement of auxiliary equipment.

* Programmable math option: Four-function math capability allows molders to perform operations on combinations of setpoints and values for advanced control functions and reporting.

* SPI protocol: Implementation of the SPI Phase I protocol facilitates communication between primary processing machinery and auxiliary equipment. It eliminates the need to write software drivers for every piece of machinery, and allows recipes and set-ups for all equipment to be stored on a single cartridge, shortening changeover times.

* High-density d-c I/O: The number of d-c inputs per card has been increased from 24 to 48, and the number of d-c outputs has grown from 16 to 24. High-density a-c I/O will also be shown at NPE '94.

* DOS co-processor: A 486 CPU can be added to the card rack to allow a machinery OEM to create its own operator interface and tie it to the MACO control with the use of optional operator-interface software.

* OptiGrafix editor: The MACO 6000 series includes enhancements to the OptiGrafix editor, a graphical "Windows"-like display that allows users to modify screens. Additions include a 100-segment profile display for parison programming.

* "Slimline" LCD display: A version of the standard LCD display will be introduced for injection machines under 150-200 tons and for small extruders. List price will be about 40% less than the larger panel. The new Slimline LCD, about 4 in. narrower than the standard display, will be offered without the machine-function keys or Insta-Set port for memory cards, although these features will be available as options. Initially, the Slimline display will show only text characters, although limited graphics capability (such as bar graphs) is planned for the future.

The new Alpha platform does not replace the MACO 8000 control, which Barber-Colman will continue to offer and refine, according to Frank H. Dyke, manager of marketing and sales. Improvements to the MACO 8000 center on communications and SPC capability. An RS-485 communications link can connect processing machines to each other and to a host computer at distances up to 10,000 ft. (At NPE '94, the RS-485 link will be introduced as a feature on MACO 4000, 5000, and 6000 products--both for host communications between the processing equipment and supervisory computer, and for SPI Phase I protocol.) In addition, the MACO 8000 will be able to buffer up to 10 loops of sample parameters. This will allow it to trend more parameters and provide more data samples within a given amount of time.


Other new developments to be shown at NPE include a compact and modular 6881 web thickness-gauging system that installs easily in limited space. The model 6881 is a single-frame system with standalone modules. Electrical-interface components are mounted on a 30 x 27 in. subpanel, or may be installed in an existing enclosure. It's available with any of Barber-Colman's sensing devices: Betamike, Calimike, IR, or microwave.


A new line of single-zone temperature controllers will also be introduced. The first member of the series is the 10Q, a 1/4-DIN unit designed for the replacement market on injection and blow molding machines, extruders, and auxiliary equipment. Key features of the 10Q include auto-tuning, color-coded display, and eight keys with direct access to the control function (i.e., no need for scrolling). The self-tuning algorithm reportedly has been refined to handle all plastics applications, including slow, medium, and fast processes. Auto-tuning is performed with no operator involvement and includes adaptive tuning to compensate for changes in the process. It's also equipped with a refined deadband capability to match extruder requirements.

In addition to the 1/4-DIN 10Q, the series includes a 1/8-DIN 10E. Models 15Q and 15E will also be available, offering faster response time and greater accuracy. List price of the 10Q is $300-340.

A new spring-type "Varidepth" thermocouple improves on the standard Varidepth model by using a lock cap that adjusts on a spring. Two spring lengths are offered, 6 in. and 12 in., in six different wire configurations, type J or K thermocouple, and single or dual element.

A new low-cost IR50 series of infrared sensors has a temperature range from 0 to 500 C (32-932 F). It has standard output of 4-20 mA but can provide other outputs as well as simulate a thermocouple. List prices start under $1000.

Also on hand will be two relatively new, low-cost power controls--CC50 (zero-fired) and CC60 (phase-fired). Soon to be added to the line is a 70-amp CC70 zero-fired model. Zero-fired controls are less expensive to manufacture and also provide less electrical interference than phase-fired.

Also, Barber-Colman now offers individually certified test disks for its Impressor hand-held hardness tester, allowing users to keep these testers calibrated in-house.
COPYRIGHT 1994 Gardner Publications, Inc.
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Author:De Gaspari, John
Publication:Plastics Technology
Date:Apr 1, 1994
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