Special Report: Machine-control retrofits provide success at less cost

For blow molders mulling whether to upgrade to new machine controls, retrofitting can deliver dramatic results at a fraction of the price, Steve Schroeder, business development manager, plastics, at Eurotherm by Schneider Electric, Ashburn, Va., said in a presentation last month at the Society of Plastics Engineers' Annual Blow Molding Conference in Pittsburgh. Whether they are seeking ways to better control shape, reduce downtime or scrap, save energy, or limit their consumption of expensive engineered resins, Schroeder said blow molders should consider machine-control retrofits.

Schroeder touted the virtues of retrofitting vs. buying new. Considering that a new two-head blow molding machine can cost $350,000, a retrofit of new machine controls — even units that cost $39,000 each — to an older blow molding machine makes sound economic sense, he said. Return on investment is quicker, too. According to Schroeder, after retrofitting, machines have production capabilities comparable to new machines, thanks to state-of-the-art processing features.

Schroeder said retrofitting provides an option for processors who might otherwise be tempted to replace machines that in every other way still operate well.

"Older machines for the most part are in good overall condition, lacking only the reliability and performance of an updated control," he said. For plants with older machines, even maintaining the original control systems becomes difficult, as parts become obsolete.

Besides Eurotherm, a number of other companies can retrofit new control systems to operate older machinery. Eurotherm, which is marking its 50-year anniversary this year as a supplier of machine control systems to plastics processors and end users, improves manufacturing performance by incorporating updated digital or electronic innovations, Schroeder has told Plastics Machinery Magazine. At NPE, the company, which works with injection molders and extrusion processes, as well as blow molders, displayed the Maco Compact-based retrofit kit it had developed for the Van Dorn HT injection molding machine model. For blow molders, it supplies its Maco Compact integrated machine control and Maco Breeze IIc parison-only control system.

"The upgrading of an obsolete control system to one with the same features that are available in today's new machinery combines the reliability and the repeatability that can result in better overall productivity for many years to come," Schroeder said.

A retrofitted control system can address some of the same concerns as a new unit that is sold alongside a new machine. New and retrofitted systems offer computer architecture that allows users to add or adapt new capabilities, and robust hardware ensures fewer system failures. Those factors — along with the availability of spare parts—ensure that systems purchased either new or as retrofits will enjoy long service lives. Most importantly, in either case, a blow molder can take advantage of advanced features to enhance productivity. Quoting users of such control systems, Schroeder said companies can run more efficiently and troubleshoot problems more easily by retrofitting their control systems. Schroeder said one customer told him that the systems ultimately extend the life cycle of the machinery and demonstrate the firm's commitment to continuous improvement.  

Schroeder cited the example of a shampoo bottle manufacturer. In an effort to trim weight fluctuations in the 34-gram bottle it produced, the blow molding plant ran trials with a retrofitted, fully electronic parison-only control system. Using the control system, the plant was able to reduce the standard deviation of bottle weight from 0.4619 grams to 0.2609 — generating a cost savings of about $43.75 per day on each of the 50 machines it ran, totaling $525,000 in savings over the course of a year. Having spent $9,000 for each control unit, the company reaped a return on investment in just 10 months.

Parison control, which enables processors to optimize the thickness of blow molded parts, is only one of many options that retrofitted control systems can offer, Schroeder said. Other functions include high-speed display updates, Ethernet communications enabling connection to plantwide systems and data analysis and storage of information such as recipes and set-point changes. Systems can provide online diagnostics or automatic switching to a "smart" manual output upon sensor break; issue warnings about failed heater elements or changes in operation; and auto-tune temperature to provide precise control with no user intervention.

The parison-only control system used by the shampoo bottle maker illustrates an alternative to full-function machine controls. Carrying a lower price tag than full systems, parison-only control systems, still offer sophisticated capabilities, Schroeder said. Using older parison-only control systems, operators performed manual adjustments with slide bars or graphs offering an estimate of correct position. Operators got no feedback from the system and had no way to compare actual process values with set-up input. The new, fully electronic parison-only control systems have transformed this process. They offer a parison profile on as many as 100 points displayed on a large touch screen. This allows profiles to be quickly modified and graphically compared to the actual process value. The entered profiles can then be stored internally and, in some systems, saved to removable USB memory sticks, Schroeder said. Operators can view actual tooling performance in comparison to the values entered, and they can create separate settings for weights and die gaps.

Using newer parison-only control systems, Schroeder said processors can create elaborate shapes and designs. By providing precise control during processing and forming, these systems allow processors to make efficient use of the expensive resins often required when producing complex parts. Parison-only control retrofit packages are adaptable to current blow molding machines regardless of existing control systems, as long as the machines have the hydraulics to perform the desired function, Schroeder said. The systems are specifically designed for simple installation and ease of use. This means that in most cases, no changes are needed to the existing machine and no additional programming is required.

In many cases, setting up a retrofitted system is fairly easy. Once ordered, retrofits can be delivered more quickly than many new machines. The company contracted to perform the retrofit conducts the system startup, troubleshooting and basic operator training, Schroeder said. Because operators are familiar with the existing machines, retrofitting controls requires less time for setup and troubleshooting than the setup of new machines would demand. Plants can continue using the hydraulic and mechanical spare parts inventory they have already established to support existing machinery. In addition, Schroeder said, retrofits require fewer expenditures for electrical spare parts.

Typically, Schroeder said, a retrofit package includes the removal of the existing control system and installation of the new system and operator station. In addition, buyers of retrofitted systems can expect drawings showing all of the new systems' control connections. In some cases, the company performing the retrofit includes a warranty of up to three years on parts.

In shopping for a company to perform the retrofit, Schroeder advised that blow molders look for a supplier of cutting-edge control systems. They should seek out a price-competitive system with the advantages of an integrated, total machine control package.

If the system lacks certain functions that the molder anticipates needing in the future, it should have an architecture that allows for expansion, he said. Saying that choosing a compatible retrofitter is akin to buying new machinery, Schroeder recommended making decisions based on the breadth of product lines, available application support and the experiences of plants using similar machines and systems.

Karen Hanna, copy editor

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Contact:

Eurotherm by Schneider Electric, 703-724-7378, www.eurotherm.com