Blow molding controls gain in speed & flexibility.

The venerable MACO 8000 control system has been the blow molding industry standard for a decade, with more than half the U.S. market. It's a distributed control system consisting of a series of separate control modules, each of whichmonitors a certain number of temperature or pressure zones, and each module "talks" to the others.

Almost exactly 10 years after the MACO 8000 was introduced in late 1983, Barber-Colman Industrial Instruments, Loves Park, Ill., plans to introduce soon a new MACO 6000 high-performance blow molding controller, which contains

all    modules in a central control rack. Where the MACO 8000 modules were in
a        distributed architecture and talked to each other over a
communications link,   control modules in the 6000 system speak directly to a
data bus. Company        spokesmen say the change was made possible by the

continuing miniaturization of electronics, which allows more components to be packed into a single box. The new controller uses the same "Alpha" hardware platform as Barber-Colman's MACO 4000 injection molding controls and MACO 5000 extrusion controls. It comes standard with a flat-panel electroluminescent display (monochrome), though a less expensive LCD screen is optional.

Barber-Colman provided PLASTICS TECHNOLOGY with this preview of the product, which is targeted for availability in the first quarter of 1994.

HIGHER PERFORMANCE

The new system does not replace the MACO 8000, which "will be available through the year 2000 and beyond," says Barber-Colman marketing programs manager Randy Brian.

Rather, the new 6000 system is a higher performance alternative. It answers the company's need for faster, more flexible control of parison programming, hydraulics, and machine motion--all in a smaller hardware package--in order to answer the challenge of competitors like Moog Inc., Aurora, N.Y.; Siemens Energy& Automation, Inc., Roswell, Ga.; Allen-Bradley Co., Highland Heights, Ohio; andEurotherm Controls, Reston, Va.

The new controller offers more than 10 times faster computing speeds. It also isbetter able to integrate configurable automatic control features. For example, in closed-loop control of a multi-head blow molder, each head has a discrete parison-tooling loop that closes every 100 microsec and may have its own unique parison program of up to 100 points. This allows a double-sided shuttle machine,for instance, to mold two different kinds of parts. "You can

configure two      different parison profiles and alternate them. The 8000
didn't have the         capability to go back and forth between part sizes,"
says MACO product-line     manager John Searle.

The reason is increased processing capability. The new parison module has multiple microprocessors and digital signal processors dedicated to parison, head, and accumulator control functions. These allow more flexible and customized control. "In extrusion blow molding, the control could monitor melt temperature and melt pressure and use those data to regulate extruder speeds," Brian says. "The value-added features of the new system won't be just in the number of control loops but also in the increased performance of parison control. In the MACO 8000 you have master parison points for which you enter x,ycoordinates. With the new MACO 6000, you'll sketch a continuous parison profile on the display and it will be turned automatically into defined points." As a further illustration of the new system's speed, Searle says, "When a machine makes 80 bottles a minute with 100 parison programming points per bottle, the controller is checking thousands of points a minute," integrating a multitude of pressure, speed and temperature signals from sensors and position signals from linear and rotary transducers.

The new controls also have faster response time for servo valves and for new non-servo, directional-proportional valves, which have been used in injection molding and are now being tried in blow molding.

Although the new MACO 6000 flat-panel, electroluminescent operator station is half the size of the CRT on the MACO 8000, the MACO 6000 EL can display more information on each screen. EL screens can be customized with Barber-Colman OptiGrafix software (IBM-compatible). The EL display is monochrome because flat-panel color displays are still too expensive, the company says. (The EL display is also available for the MACO 8000.)

A TOTAL SOLUTION

The initial release in the MACO 6000 series will be the MACO 6500, a single control rack plus a separate operator station, capable of controlling small to intermediate-size machines. Ultimately, multi-rack controls will also be available for larger machines, where two or more expansion racks will communicate with a master rack.

The 6500 is a total control system: up to 96 zones of auto-tuned heat/cool control, sequence logic, velocity or position control of clamp and mandrel, and parison programming of up to 12 heads with shared or independent programs. The MACO 6500 stores up to 16 job recipes internally and accepts Insta-Set cartridgestorage of another 40 machine setups, depending on their complexity. Twenty-fourmachine function keys, programmable screen-display path keys (which let an operator pull up any screen by title, rather than having to scroll through the "tree" structure of the displays), and LED indicators on the EL operator stationreplace the touchscreen that's standard on the MACO 8000. SPC screens can also be displayed. RS-232C and RS-485 communication ports are optional, allowing multiple MACO 6500s to be linked to a supervisory control and monitoring PC in aCIMAC 8000 network.

As a retrofit to an existing machine, a MACO 6500 system with EL display will cost in the range of $15,000-20,000.

COMING TO NPE

At press time last month, Barber-Colman had completed testing the MACO 6500 using test fixtures to simulate machine movements. Beta-site test shipments willcommence to a number of OEMs in January. The new system is not yet for sale and won't be until it is fully tested on several machines.

Barber-Colman says MACO 6500 controls will be seen on many blow molding machinesat NPE '94 in Chicago this June.