Canadian Plastics

Talkin’ ’bout keepin’ cool

The pace of technological change and acceptance is often as rapid as it is unrelenting....

September 1, 2005   By Tom Venetis, editor



The pace of technological change and acceptance is often as rapid as it is unrelenting.

Cell phones were once the toys of the well-to-do, a status symbol of wealth and privilege. Now, everyone has a cell phone. It was the same with computers. First they were big, expensive machines housed behind glass –expensive toys for the perennially geeky. Today, many households have multiple computers and more than a few public schools give computers to children upon enrollment, replacing the traditional lined paper notebook and pen.

The chiller and temperature control unit (TCU) market is no different. More manufacturers are embedding a wide range of communications and control technologies and protocols into chillers and TCUs.

Currently, there are several different communications protocols that are incorporated into these devices. These protocols let chillers communicate with molding machines, molds and peripherals to help regulate such things as temperature. At the same time, these communications protocols allow data about temperature and other critical measurements to be transmitted to a central computer. This enables the machines to be centrally managed, and can trigger alerts so that operators can catch and correct potential problems.

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One of the most common and oldest communications protocols is the SPI Protocol, created in 1987 by member companies of the Society of the Plastics Industries (SPI). The protocol was devised specifically to facilitate communications between processing and auxiliary equipment like chillers and TCUs.

The goal of the protocol was to enable the exchange of information between equipment from different manufacturers. The SPI Protocol accomplishes this by assigning each machine a unique ‘address’ for its device type, and these ‘addresses’ will allow different devices to exchange information over a set data rate.

For example, a mold temperature controller’s address would connect to a chiller’s address, allowing the devices to pass information back and forth and to present this information to the equipment’s operator. This information could include whether the chiller or TCU is running properly and is keeping the temperature at a set level.

Walt Bishop, executive director with the SPI Machinery Division of the SPI in Washington, D.C., said the SPI Protocol can be used to set ‘safe-machine’ operating parameters. For example, during the processing of a part, the machine should not run bellow and above a certain temperature. The chiller or TCU then monitors that temperature to ensure the machine operates within the set specified temperatures.

“As long as the (machine) functions within those parameters it goes merrily on its way,” Bishop noted. “If it falls below or spikes above those set parameters, an alarm will sound and a supervisor will be able to immediately identify where the problem is, what the problem is and reset the parameter.”

Jon Gunderson, national sales and marketing manager for Advantage Engineering Inc. in Greenwood, Ind., added that having a cooling system and a machine, which communicates back to a supervisor through a protocol ensures a high-quality product. Advantage is a provider of TCUs, liquid chillers, evaporating cooling towers and pumping systems.

“A temperature variation can quite possibly spoil the part or impact the quality of the part,” Gunderson explained. “So it is important to make sure temperatures are maintained correctly by the (cooling system). If the temperature is supposed to be 160 degrees but the system finds that it actually is 170 degrees, we may be making bad parts and that is something critical to know.”

Since this kind of information must be quickly acted upon to eliminate a bad part run, some cooling systems are set up so that this data and other information can be transmitted directly to a central computer system. It is even possible to use a central computer to monitor several primary machines, and their chillers or TCUs, in real-time, and to communicate back remotely to fix problems automatically without sending a supervisor to the shop floor. This could help reduce maintenance and personnel costs as companies would not need to have several people conducting rounds of the machines throughout the day to ensure they are functioning properly.

Advantage Engineering has been incorporating various communications protocols into its chillers and TCU systems since 1990, making it a standard feature on many of its machines. Advantage’s newest Sentra Series 300 hot water temperature controller is made to regulate temperatures up to 300F, and can be used in the manufacturing of engineering grade materials require precise temperature control. The Sentra Series 300 uses the SPI communications protocol to monitor process temperature requirements and help regulate temperatures.

Because the SPI protocol is some 15 years old, it tends to be a bit slow in how quickly it gathers and presents information. Because of that slowness, chiller and TCU manufacturers are turning to faster control and communications protocols, one being the Modbus TCP/IP (Ethernet). This protocol is based on the same protocol used to establish connections over the Internet between systems, networks and computers. TCP/IP is a proven, reliable and fast means to facilitate communications between the molding machines and the chiller or TCU. Additionally, this protocol can communicate with a central computer system over an internal company network making it easy to monitor and control multiple machines and cooling systems from a single location in a plant.

Advantage will integrate Modbus TCP/IP protocol into its systems if requested by the customer.

Don Berggren, president of Berg Chilling Systems Inc. in Toronto saidtoday many larger plastics manufactures are asking for SPI, Modbus and other kinds of communications protocols to be embedded in the chillers and TCUs they purchase.

While larger plastics processors have taken the lead in using communications protocols and other high-tech solutions — even going so far as networking the many different cooling and primary manufacturing systems to centrally control them — smaller plastic processors have been slower to adopt the technology.

The reason is that a communications protocol like SPI, Modbus or any other is really just a means of connecting the machines together so they can communicate. Really, it is a simple handshake that says, ‘Hello, can we talk?’ But what actually gets passed between them and what finally gets presented to a supervisor or plant manager is another matter entirely.

Because these protocols can present a wide range of information, the key to using them successfully is ensuring the protocols transmit information that is relevant to a processor. Temperature is certainly one type of data, but there are others like flow rates, for example. The key to getting the right information and presenting it in a meaningful way can be tricky. However, many chiller and TCU manufactures can program and customize the protocols to present information in ways that are meaningful to specific customers.

Berg Chilling, for example, will customize its communications protocols for customers at an added cost, Berggren said.

Yet the cost of using these communications protocols depends on the level of customization. A complex set of communications controls can increase the cost of a chiller or TCU, which is why many smaller processors don’t bother.

Roger Lambert, president of Temperature Corporation in Markham, Ont. said a barrier to widespread adoption of these protocols, is that there is no one standard protocol used by all manufacturers in the industry. One manufacturer may use a certain protocol, and another may employ a different set of protocols. As a result, each machine would present information differently and have difficulty communicating with devices using different protocols.

Another problem is that many older primary plastics processing machines were not embedded with communications protocols, so they can’t
communicate with a chiller or TCU that has been built with one.

Berg Chilling’s Berggren added while many smaller companies may feel the investment in such sophisticated communications and control is not something they can afford, he suspects that over time many will adopt the technology as it becomes increasingly obvious how it can help maintain product quality and reduce operating costs.

“Companies will use this technology to do such things as record and trend temperatures during a manufacturing process, how many alarms happen and how good the flow is,” Berggren added. “If you can use these technologies to provide consistent temperature and trend information, you could use that information to run the machine at its maximum and peak performance, 365 days a year, which will increase the operating efficiency of the plant in general. So from a plant manager’s perspective, there is now a move to know what your machines are doing.”

CONAIR ADDS HYBRID LOGIC TEMPERATURE CONTROL IN TCUS

The Conair Group Inc. has incorporated a combination of temperature-indicating controls (TIC) with programmable logic controllers (PLC) into its most recent line of low-cost Thermolator temperature control units. Conair said this hybrid represents a significant technical advance over previous entry-level controls.

The control’s four push buttons enables the set-up, operational and troubleshooting functions, and the instructions are clearly presented on the user interface panel.

The large LED display shows the set-point and actual temperatures from the “to process” and “from process.” The Thermolator TCU can control the process from either of these inputs, as well as the “centre” of the process (the average of the “to process” and “from process” sensors). If the sensor being used should fail (out of range alarm), the system will automatically cascade to control from the “to process” sensor.

The Conair Group Inc., Pittsburgh, PA www.conairnet.com

Auxiplast Inc. (Sainte-Julie, Que.) 450-922-0282 Stephen Sales Group (Markham, Ont.) 905-940-5577

THERMAL CARE TC SERIES CHILLER

The TC Series of central chillers from Thermal Care Inc. uses frictionless, magnetic bearing compressors to deliver optimum chiller performance and energy efficiency. The TC Series of Chillers come with centrifugal compressors featuring variable speed direct drives motors, computer-controlled liquid refrigerant cooling of electronic, mechanical and electro-mechanical components, as well as a compressor and monitoring control through Modbus communications protocol.

The Modbus communication protocol can provide alarm displays, general operational information, electronic expansion valve display information, bearing display information and motor display information.

Thermal Care Inc., Niles, IL www.thermalcare.com Dier International 905-474-9874


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