Canadian Plastics

Checking the temperature on the TCU market

As Vincent Van Gogh once said, "great things are done by a series of small things brought together." Although the tortured artist probably wasn't referring to injection molding and extrusion, his maxi...

June 1, 2007   By Umair Abdul, editorial assistant



As Vincent Van Gogh once said, “great things are done by a series of small things brought together.” Although the tortured artist probably wasn’t referring to injection molding and extrusion, his maxim could easily be applied to the importance of auxiliary equipment.

Temperature control units (TCUs) play an integral role in a plastics manufacturing facility, and auxiliary equipment manufacturers have introduced a host of added-value features that optimize performance. Newer TCUs are making greater use of steel, reducing the overall footprint and improving user-friendliness. Although there have been no major design overhauls for TCUs in recent years, the latest offerings have some noteworthy benefits.

THE APPEAL OF STAINLESS STEEL

The use of stainless steel in the construction of TCUs is not a new concept: leading equipment manufacturers like Wittmann Inc. have used the alloy in their units for many years. However, North American manufacturers have generally shied away from making extensive use of the material in their TCUs — until now.

Mokon has introduced the new Hydrotherm II, with a pumping capacity of 25 gpm and nine kW of heating capacity. The unit has stainless steel construction, and Mokon claims that it is the first system of its kind with stainless steel as the main component for wetted surfaces.

The traditional Mokon heating design is replicated with a stainless steel heating canister for the Hydrotherm II. With a maximum operating temperature of 120C, the TCU also features a microprocessor-based controller, an easy access cabinet, and a control panel with indicating lights.

Stainless steel is a formidable feature when it comes to the longevity of the unit. For instance, the alloy is less susceptible to corrosion than the materials that have been used in the past, a particularly important consideration for water-based units.

UNDER PRESSURE

Halting production is not a viable option for most plastic processors, but it can often be the only one when a leak appears in your TCU. Repair costs and times can hinder the facility’s operations, and — most significantly — impact the bottom line.

Wittmann Inc., a European leader in the construction of TCUs, is introducing new units that are hybridized versions of American and European TCU technologies. The newer units have a system where the water level in the tank is controlled, allowing the TCUs to have a negative pressure system.

A negative pressure system “enables the unit to also run in negative ways that mean if you have a small leak somewhere you run in vacuum,” explained Wittmann Kunststoffgerate GmbH’s sales manager Peter Weber.

Upon leak detection, the directional flow of the circulating water is reversed to prevent further leakage. The negative pressure system, also known as a “leak stop,” allows the processor to continue with their production job and repair the leak in the system once the work is completed. The negative pressure system’s vacuum feature can also eliminate the need for compressed air for mold purging.

Berg Chilling’s new TCUs, with the new Johnson Controls controller that allows customization of control and integration into the customer’s process, also have negative pressure units available. The standard program for these new TCUs offers an automatic auto-vent on start-up, and a 0-10v input signal to control the set point. The standard units have a selection of ? horsepower to 7? horsepower pumps and 9 kW to 24 kW, and processors can also add a communication module.

SIZE MATTERS

Smaller footprints are a big deal for many processors, and manufacturers continue to strive to strike the perfect balance between unit stability and spatial optimization.

Advantage Engineering, Inc. increased the dimensions of its Sentra TCUs from 27″ x 11″ x 16″ to 27″ x 12.5″ x 19.5″ for Sentra models with ? to 3 horsepower pumps and 10-16 kW heaters. However, the slightly bigger footprint has increased the controller’s stability, and the unit still takes up less shop floor space in comparison to some other commercial TCUs.

Other manufacturers have also placed a focus on their petite products. Colortronic North America, Inc.’s ECU Series boasts a cabinet design with a footprint of 121/8″ x 235/16″. Despite its compact size, the company says the PID controls and Incoloy immersion heater inside is powerful enough to maintain an operating leaving water temperate range of 0-121C. AEC’s off-the-shelf TrueTemp Series controllers are available in two configurations, with compact units measuring 283/8″ x 13″ x 27″ and upright units measuring 48″ x 13″ x 27″. The TrueTemp TCUs come in a range of kW configurations, and have an operating leaving water temperature range of 0-121C. Mokon’s Hydrotherm II systems only take up approximately two square feet of floor space.

WATER OR OIL?

Oil-based TCUs can traditionally achieve higher temperatures than their water-based counterparts, but auxiliary equipment manufacturers seem to be predominantly focusing on water units. The recent advent of high-pressure water-based units has also made them more competitive.

Shini Canada/Hamilton Avtec Inc. have introduced the STM-PW unit series, which can operate to temperatures of up to 160C. All models are equipped with a high-temperature, high pressure Speck pump manufactured in Germany, and accurate temperature control +/-1C is accomplished through indirect water cooling. For the processor, the use of water eliminates the need for “expensive and messy” oil-based units.

“The advantage is that it’s easier to clean up, it’s easier to use water than oil, the contamination between water and oil is always an issue, [and] the disposal of the oil that you use is always a problem because it is environmentally controlled now,” noted Hamilton Avtec’s president Richard Hamilton. “In Europe and the Far East, there is a huge change to move away from oil into high pressure water.”

Wittmann’s Weber notes that oil leaks can be more dangerous and messy, and oil takes longer to cool down than water. Additionally, water tends to heat up faster than oil, thus reducing the startup times.

“You must understand that in injection molding the heating period is essential for the customer at startup,” he explained.

CONTROLS & PANELS

Strong technical specs are very important, but processors are also concerned about operation and ease of use. Many of the leading players in the TCU arena have been utilizing complex systems to make simpler controls and panels.

Sterling’s 6017 Fluid-Circulating Control System is ready to operate once the power and circulation connections have been made, and the M2B+ Microprocessor Controller features PID control for both heating and cooling.

The controller also has a built-in ramp/soak feature, in addition to setpoint, to process, from process and DT displays. The unit comes standard with pumping rates of 90, 150 or 200 gpm; 50 to 200 kW heater size; heat exchangers from 3.9 to 27 square feet; and a temperature range of up to 288C. Sterling also offers models that operate up to 343C, and has made special units with heat exchanger sizes of up to 81 square feet.

Conair’s Thermolator units also come with control and operating features that are most commonly seen in very sophisticated unit. According to Conair’s Heat Transfer product manager Sam Lanza, the control’s four pushbuttons enable all of the operator-specific functions for the units. Additionally, instructions for use are clearly published on the interface panel.

Wittmann will also introduce a special colour-coded panel in its high-end units, such as the Tempro Plus C.

The panel will use blue, green, yellow and red colours to symbolize the status of the mold temperature, and provide a visual cue for operators. In addition to the temperature and setpoint, processors will have the ability to customize their displays to monitor values such as pressure rates and the flow r
ate.

If an error occurs, Wittmann says that TCUs like the Tempro Plus C will allow the operator to address issues through customized data collection.

Resource List

Advantage Enegineering, Inc. (Greenwood, Ind.); www.advantageengineering.com; 317-887-0729

Chillers Inc. (Newmarket, Ont.); www.chillersinc.com; 905-895-9667

AEC, Inc. (Schaumburg, Ill.); www.aecinternet.com; 847-273-7700

Equiplas (Toronto, Ont.); 416-407-5456

Berg Chilling Systems Inc. (Toronto, Ont.); www.berg-group.com; 416-755-2221

Colortronic North America, Inc. (Flint, Mich.); www.colortronicna.com; 810-720-7300

Ontor Limited (Toronto, Ont.); www.ontor.com; 800-567-1631

Conair (Pittsburgh, Penn.); www.conairnet.com; 800-654-6661

Auxiplast (Sainte-Julie, Que.); www.auxiplast.com; 450-922-0282

Industries Laferriere (Mascouche, Que.); www.industrieslaferriere.ca; 450-477-8880

Hamilton Avtec Inc. (Mississauga, Ont.); www.hamiltonavtec.com; 905-568-1133

Mokon (Buffalo, NY); www.mokon.com; 716-876-9951

En-Plas Inc. (Toronto, Ont.); www.en-plasinc.com; 416-286-3030

Nucon Wittmann Inc. (Markham, Ont.); www.nucon-wittmann.com; 905-887-5355

Shini Plastics Technologies (Canada) Inc. (Mississauga, Ont.); www.shini.ca; 905-565-1602

Sterling (New Berlin, Wis.); www.sterlco.com; 262-641-8610

CNSmith Plastic Machinery Sales Inc. (Georgetown, Ont.); www.cnsmith.com; 416-917-3737

Equipment Resources Northwest (Portland, Oreg.); 503-281-3612


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