The Isobar System from Acrolab...

Transcription

1 The Isobar System from Acrolab... Temperature scale C F Traditional Heat Transfer The Isobar System Effective, affordable heat transfer technology that has the industry talking. ISO 9001:2000 Since 1948 For the design and manufacture of Isobar and heat transfer systems, temperature sensor assemblies and calibration services for industry. Isolab division is also successfully assessed to ISO 10012:2003 HEAT TRANSFER TECHNOLOGY WORLDWIDE

2 Applying Effective Heating to the Mold Acrolab Ltd Canada Acrolab s Isobar super-thermal conductors are based on heat pipe technology and have been in use in heat transfer and thermal linearisation applications in production environments for over 20 years. Enhancing thermal conductivity and heat distribution can offer substantial benefits to molders in terms of improved cycle times, cure rates, mold temperature uniformity, start-up times and recovery rate. Isobar super-thermal conductors, used in conjunction with Isoplatens, permits each core molding surface to be held at the optimum uniform molding temperature and provide high thermal efficiency. Isobar heat transfer technology can be incorporated into any application involving the management of thermal energy. This article focuses on applications in the fields of rubber and thermosetting elastomer molding and processing. Isobars have their roots in thermosyphons. Thermosyphons, as shown in Figure 1, function as a super-thermal conductor only in a vertical or near vertical plane. In a thermosyphon, a small quantity of working fluid is placed in an evacuated tube. Heat is applied to the base of the tube, causing the temperature of the working fluid to rise as this fluid heats, it vaporises. This vapor then migrates to the colder end of the tube where it is condensed. The condensate (liquid) is returned to the heated tube end by gravity. Since the latent heat of evaporation is large, considerable quantities of heat can be transferred with a very small temperature difference from end to end. The thermosyphon is limited in application because the evaporator region must be situated lower than the condenser region. The Isobar (Figure 2) differs significantly from the thermosyphon in that it incorporates a sophisticated solid-state pump to return the condensate to the evaporator site. This pump takes the form of a fine metallic wick that resides tight to the inner wall of the Isobar. This wick, through its capillary action, returns the working fluid to the evaporator without regard to orientation. In a normal environment, the wick permits equal function in vertical and horizontal planes. In applications where the evaporator site is above the condenser, the performance of the Isobar is controlled by the capillary action of the wick structure. Isobar super-thermal conductors have the capacity to transfer large amounts of heat at high speeds in both heating and cooling applications. In fact, Isobars have, in some applications and orientations, a thermal conductivity in excess of 20,000 times the rate of a solid copper bar of the same geometry. Figure 1: Traditional thermosyphon Figure 2: The Isobar concept

3 the steady state temperature of the Isobarinfiltrated core is 40 percent higher than the solid steel core. The installation of Isobars in standing cores, either singly or in multiple arrays, allows the molder to resolve difficult processing problems such as uneven core heating and low-temperature recovery that directly effect cycle time and uniform cures. Figure 3: Standing core thermal performance Figure 4: Heating of corepins to steady state Isobars are also high-speed superthermal distributors. The working fluid constantly changes phase due to the low vapor pressure inside the unit the device is innately isothermal. Temperature uniformity along the entire length from the evaporator to the condenser is typically in the range of ±1 C while transferring large amounts of energy. Isobars can be designed or retrofitted into many molding applications to improve efficiency related to cycle times, cure rates, mold temperature uniformity, start-up times and recovery rate. Isobar technology works equally well with tools drawing their energy from heated platens and with integrally heated molds. Energy sources such as oil, steam or electric heaters may be used. Isobar in standing cores Isobar super-thermal conductors provide a high-speed isothermal path for thermal energy to travel. Figure 3 shows thermal performance in standing core applications, measured by a test jig developed by Acrolab. An Isoplaten provided a common heat source for two identical corepins 25mm in diameter and 150mm long. One core pin was made of solid steel and the other was bored out to accept a 16mm Isobar. A thermocouple was mounted on the top of each core pin and the Isoplaten was heated to a temperature of 180 C. Figure 4 illustrates two results of the test. First, it can be seen that the Isobar-infiltrated core reached steady state in approximately half the time required for the solid steel core. Secondly, Figure 5: Tree-bars installed in parallel cartridge heaters CORE PIN TREE BAR ISOBAR HEATER Figure 6: Heating along core length The Isoplaten s unique thermal uniformity permits the use of one single-zone temperature controller for the entire platen no special multizone controls and multiple thermocouplers are required. Isobars provide the thermal linearity necessary to achieve uniform molding conditions on all molding surfaces. Deep cavities and standing cores will become much easier to cure uniformly with the installation of Isobars. The entire cure cycle will be exposed to isothermal conditions. Installation of Isobars may result in recovery of old face temperatures in up to half the time when compared to traditional heating and conduction methods, as shown in Figure 4. Tree-bar technology Isobars resolve the difficulties in achieving thermal uniformity within a core and from core to core in complicated multicavity molding. Installing Isobars in tree-bars to parallel cartridge heaters (Figure 5) assures that the tree-bar itself is isothermal. The tree-bar can now provide a common temperature to the base of each core pin mounted onto it. These cores, in turn, achieve an isothermal condition along their molding face when Isobars are installed in them. Figure 6 illustrates the temperature variation along the length of a core mounted in a tree-bar orientation with and without Isobars installed. With Isobars

4 C o 160 o 155 o 150 o 145 o 140 o 135 o 318 o 308 o 298 o 288 o 278 o 268 o C o 160 o 155 o 150 o 145 o 140 o 135 o 318 o 308 o 298 o 288 o 278 o 268 o isobar heaters on heater off thermocouple isobar heaters on heater off thermocouple Figure 7: Temperature distribution for Isoplaten with all heaters and Isobars Figure 8: Temperature distribution for platen with heaters only installed in both the tree-bar and the attached cores, each core molding surface may be held at an optimum uniform molding temperature without complex multizone temperature controls and the complex wiring associated with large numbers of thermocouples and heaters. The Isobar system reduces maintenance costs by reducing the overall complexity of the mold heating system. Isobar heat transfer systems permit the molder to maintain optimum processing temperatures with a high degree of mold face thermal uniformity and with an increase in energy throughout. This results in faster cycle times with consistent, optimal cures. Isoplaten technology Acrolab s Isoplatens provide high levels of thermal stability to press platen applications and can be designed for electric, oil or steam heating (the standard Isoplaten is electrically heated). Integral water cooling lines for fast process temperature changes are available on all models. The standard Isoplaten has an operating range of ambient to 250 C. These units utilize an engineered bi-level array of Isobar super-thermal conductors to redistribute and uniformly apply heat provided to the platen either by oil or steam channels or through a series of standard electric cartridge heaters. Isobars in the lower level of this array linearise the typical non-linear output of the electric heaters. The upper array provides a further uniforming of the energy residing in the platen. The combination of the two levels of the Isobar array ensure that the random point-to-point temperature of the Isoplaten is ±3 C at typical operating temperatures. Isoplatens are pre-engineered to fit all new press models manufactured by most of isobar heaters on heater off thermocouple Figure 9: Temperature distribution for platen with heaters only (one heater disconnected) isobar heaters on heater off thermocouple Figure 10: Temperature distribution for Isoplaten with heaters and Isobars (one heater disconnected) C o 160 o 155 o 150 o 145 o 140 o 135 o the leading press builders in North America and Europe. Isobars engineered in a bi-level grid pattern maintain a temperature of ±3 C over 90 percent of the platen surface (Figure 7). These results allow a substantial improvement in cycle times, start-up times, thermal recovery rates and improved part quality. The Isoplaten s unique thermal uniformity permits the use of one single-zone temperature controller for the entire platen no special multizone controls and multiple thermocouples are required. 318 o 308 o 298 o 288 o 278 o 268 o C o 160 o 155 o 150 o 145 o 140 o 135 o Isobars accept energy inputs from any location along their length and redistribute these inputs uniformly at high speed, they therefore provide a unique advantage to the Isoplaten over traditional press platens (the temperature distribution for a traditional platen is shown in Figure 8). If one heating element fails in a traditional platen as shown in Figure 9, a cold area immediately becomes apparent on the platen surface adjacent to that heater. When a heater fails in an Isoplaten, the distributive properties of the Isobar array super-conduct energy to the cold region caused by the failed heater, quickly compensating for the loss of energy in that region. The result is a slight reduction in the amount of heat being generated 318 o 308 o 298 o 288 o 278 o 268 o in the Isoplaten but no significant change in the thermal uniformity of the Isoplaten face (Figure 10). Existing platens may sometimes be retrofitted as Isoplatens when enough free space is available. Acrolab s Isobar and Isoplaten technology provides the molder with the first major breakthrough in processing high-quality molded parts at a lower cost. This is achieved through faster cycle times, applying more uniform cure rates at optimum processing temperatures, reducing maintenance and lowering energy requirements. Returns on initial investment vary from application to application, however as a general rule, the Isobar and Isoplaten are reported to return investment in less than six months.

5 Acrolab Isoplatens : worth looking into Inexpensive, ultra-even heat distribution Isobar Superthermal Conductors: Last the life of the platen** A crolab s Isoplatens are ingenious in their simplicity. Their straightforward design a bi-level matrix of Isobar superthermal conductors (shown in gold above) redistribute the energy generated by standard cartridge heaters with unparalleled evenness. With Acrolab s Isoplatens, your tools operate with reduced energy demands, produce better quality molded parts and allow you to use faster curing compounds with narrower thermal processing windows. Acrolab s Isoplatens cost only marginally more than conventional platens, and the technology can be quickly and easily retrofitted to existing tools. The completed platen is controllable with a single thermocouple; there is no need for multi-zoned temperature controls. Standard cartridge heaters make on-site maintenance of Acrolab s Isoplatens quick and easy Another important benefit: All platens require periodic heater replacement. Acrolab s Isoplatens use standard heaters available through your local supply house or through Acrolab s Warranty Parts and Service Department. This minimizes costs and reduces downtime, so you can be back in business faster, more profitably. To learn more about how Acrolab s Isobars and Isoplatens can help streamline your rubber processing operations, call Acrolab today. C o This Thermographic* profile, from an actual testing sequence, demonstrates the unique Isothermal properties of Acrolab s revolutionary Isoplatens. *Data was obtained under steady state laboratory conditions with the test platen resting on ceramic stand off. **Isoplatens have a temperature limit of 250 C (500 F) See back panel for your nearest Acrolab Representative. ISO 9001:2000 For the design and manufacture of Isobar and heat transfer systems, temperature sensor assemblies and calibration services for industry. Isolab division is also successfully assessed to ISO 10012:2003 Since 1948 HEAT TRANSFER TECHNOLOGY WORLDWIDE

6 Want to make your molding processes more profitable? Rapid, uniform heating of the core allows for increased productivity on rubber parts such as this one. Superthermal Isobars conduct heat up to 20,000 times better than tool steel and vastly improve the uniformity of the core s surface temperature. T Typical molded rubber part he 6 copper coloured pins in the above illustration are called Isobars. They represent an extraordinary and proven opportunity for rubber molders to reduce cycle times and increase profitability. Here s how: Acrolab s Isobars are thermal superhighways that conduct heat up to 20,000 times faster than tool steel. They transfer heat from the base through the length of a core with exceptional uniformity and speed, allowing you to heat and cure cores with a productivity increase of at least 10%. The temperature gradient along the core s working face is all but eliminated, permitting The core of a more profitable operation Low-cost retrofit, proven results! previously unheard-of core temperature uniformity. And you reduce energy consumption! Best of all, Isobar technology can be easily retrofitted into existing molds or cores, without wires or external support systems. Small wonder why Acrolab s Isobar technology is finding its way into the most profitable molding operations. Isn t it time you considered the reduced cycle times and increased profitability of Acrolab s Isobar technology in standing core and tree bar C o applications? Contact Acrolab Ltd. directly or your nearest Acrolab agent for a free appraisal of your savings potential. ISO 9001:2000 For the design and manufacture of Isobar and heat transfer systems, temperature sensor assemblies and calibration services for industry. Isolab division is also successfully assessed to ISO 10012:2003 Since 1948 HEAT TRANSFER TECHNOLOGY WORLDWIDE CANADA (ACROLAB LTD.) 7475 Tranby Ave., Windsor, Ontario, N8S 2B7 Phone: (519) Fax: (519) Internet: info@acrolab.com U.S.A. (ACROLAB INC.) 1423 Franklin St., Unit F143, Taylor, MI Phone: (313) Fax: (519) POLAND (WPT SP. ZO.O) ul.burzaki 17, Lublin, Poland Phone: +48-(81) Fax: info@wpt.lublin.pl WORLD WIDE For a list of Acrolab agents world-wide, please go to TOLL FREE IN NORTH AMERICA: Phone: , Fax:

7 Applying Effective Cooling for Thermoplastic Molders Benefits checklist Acrolab Ltd Canada Within the context of thermoplastic molding, the unique heat transfer characteristics of the Isobar super- thermal conductor, when designed into the mold, ensure that energy build-up on the mold face is rapidly directed to the mold s cooling channels. The result is faster, more uniform cooling to the entire mold surface, which allows for shorter molding cycles. Rapid, uniform surface cooling also eliminates hot and cold spots on the working face, which in turn results in molded parts that are free from short shots, irregular shrinkage, and molded-in residual stress and warp. It is not necessary to have the Isobar in direct contact with a waterline to effect cooling; although Isobars can be incorporated into the cooling channel, in may cases they need only be in proximity to a water line to promote effective cooling. This capacity allows the mold designer greater flexibility for positioning cooler lines in locations remote from complex core and cavity inserts, thus simplifying tool design and eliminating seals required to prevent coolant leakage. Water lines that are uninhibited by bubblers and bafflers also permit faster Efficient super-thermal cooling No o-rings, fluid leaks, complex water channels or bubblers Achieves uniform temperature distribution on the cavity surface Significantly reduces maintenance downtime No calcification/waterline build-up Significantly reduces pressure drop and improves coolant flow rate Simplifies mold design and reduces construction costs Pays for itself as fast as it cools Easy to install A typical Isobar cooling system within a core designed to produce parts made from high-temp plastic. Whether you are molding proprietary high-temp plastics, acrylic or poly-carbonate, Acrolab s Isobar cooling systems can help make your process more consistent, more reliable, and more profitable. turbulent flow that minimizes mineral deposits and promotes a higher level of effective heat removal. The result: more efficient and effective cooling. Further, because Isobar systems eliminate the need for bubblers and baffles which are associated with such problems as o- ring leakage, mineral build-ups, pressure drops, uneven cooling and complex water line designs, maintenance requirements and problems which can result in unscheduled downtime are significantly reduced or eliminated. Isobar super-thermal conductors are manufactured in many diameters and lengths (see chart on back) and can be custom built, when necessary, to precisely fit your application. Acrolab engineering Acrolab s applications engineering team can assist you in designing simplified, highly effective mold cooling systems for your mold. Our applications specialists will recommend optimum sizing and placement, and will provide all the requisite details regarding drill sizes and installation requirements. All engineering drawings, electrical schematics, heating elements, Isobars, thermocouples, wiring, terminal boxes, electrical connectors and control cables are provided with Acrolab s Isobar systems, and field installation can always be arranged to meet your specifications and requirements. Competitive advantage If the potential for improved part quality and profit-building efficiency of your molding operation rests, as most do, in the effective management of temperature control, Acrolab s Isobar heating and cooling systems are an excellent, affordable and maintenance-free way to gain a competitive advantage. We would be pleased to assist you and we welcome your inquiry.vapor pressure inside the unit the device is innately isothermal. Temperature uniformity along the entire length from the evaporator to the condenser is typically in the range of ±1 C while transferring large amounts of energy.

8 Isobars can be custom manufactured to any size! Diameter Inches 3/32 1/8 5/32 3/16 7/32 1/4 5/16 3/8 1/2 5/8 3/4 Millimeters 2mm 3mm 4mm 5mm 6mm 8mm 10mm 12mm 15mm 16mm 18mm 20mm 25mm 30mm Standard Isobar Sizes Length Tolerances: / inches / millimeters - Stocked Isobars - Available Non-stocked Isobars Hole drilling tolerances for paste installation Diameter Drill Tolerance High 3/32 1/8 5/32 3/16 7/32 1/4 5/16 3/8 1/2 5/8 3/4 Diameter Drill Tolerance Tolerance (inches) (inches) (inches) (millimeters) (millimeters) (millimeters) Tolerance Low 2mm 3mm 4mm 5mm 6mm 8mm 10mm 12mm 15mm 16mm 18mm 20mm 25mm 30mm High Low ISO 9001:2000 Since 1948 CANADA (ACROLAB LTD.) 7475 Tranby Ave., Windsor, Ontario, N8S 2B7 Phone: (519) Fax: (519) Internet: info@acrolab.com For the design and manufacture of Isobar and heat transfer systems, temperature sensor assemblies and calibration services for industry. Isolab division is also successfully assessed to ISO 10012:2003 U.S.A. (ACROLAB INC.) 1423 Franklin St., Unit F143, Taylor, MI Phone: (313) Fax: (519) HEAT TRANSFER TECHNOLOGY WORLDWIDE POLAND (WPT SP. ZO.O) ul.burzaki 17, Lublin, Poland Phone: +48-(81) Fax: info@wpt.lublin.pl Acrolab s worldwide business is expanding, and we are working to add to our list of worldwide agents. If interested, address inquiries to the Managing Director of Acrolab Ltd. (Canada). WORLD WIDE For a list of Acrolab agents world-wide, please go to TOLL FREE IN NORTH AMERICA: Phone: , Fax: