RESISTRON & CIRUSsystem components
We at ROPEX see ourselves as a supplier of system solutions. When you purchase a ROPEX sealing system, various other system components are also needed in addition to the heat sealing bars and the temperature controllers. These system components are individually dimensioned by our support team and described in detail in the ROPEX Application Report. The ROPEX Application Report provides the foundation for all ROPEX sealing systems. It contains all important sealing parameters and connection diagrams for your particular application as well as a bill of material or parts list for all of your system’s complementary components.
Our system components are developed on the ROPEX premises, and they interact with one another optimally. Absolute reliability and high, repeatable quality are thus guaranteed.
Gauges and adjusting devices
The ATR-3 (+300°C) and ATR-5 (+500°C) analog temperature gauges show the temperature of the heat sealing band at a glance. In combination with a temperature controller, these instruments respond sensitively to even the smallest change in resistance. They are therefore also very useful when it comes to locating faults in the external control loop, e.g. loose or poor contacts, wire breaks etc.
The PD-3 (+300°C) and PD-5 (+500°C) digital potentiometers can be used to specify the set temperature. They are optimized for ROPEX temperature controllers and can be adjusted to exactly the required temperature with the fine adjustment knob.
ROPEX boosters can be used as external switching amplifiers in addition to the temperature controller. They allow a higher current to be present on the primary side of the current transformer. Two different boosters are available:
- B-075415 for 75 A peak current and 25 A continuous current
- B-100400 for 100 A peak current and 50 A continuous current
Heat sealing bands
Straight heat sealing bands (strips) are the most widespread.
Their thickness, width, profile, length and alloy vary according to the application. Heat sealing bands can have a thickness of 0.1 mm to 0.4 mm and are usually between 2 mm and 10 mm wide. The length ranges from a few centimeters to several meters.
The part of a flat band facing the film is generally wedge-shaped (tapered), to ensure that a sufficiently strong sealed seam is also created at the edges.
The design of the heat sealing band ends also varies considerably. A reliable connection must be guaranteed between the band and the bar end block. Easy handling and freedom from contact resistances are also important. Sleeves, eyelets and brass end pieces are used for this purpose.
Parts of the heat sealing bands that don't need to be heated for sealing – especially the free ends – are passivated by suitable types of coating. This prevents them from overheating, which is also vital for precise temperature control.
Heat sealing bands play a functional role in the impulse heat sealing process, which means we – as the supplier – have no room to compromise on quality.
The general description above is equally applicable to contoured heat sealing bands in 2D or 3D:
- The contour of the heat sealing band must be matched to the required seam and to the contour and geometry of the substructure.
- Bar end blocks and wedge-shaped edges are also required here.
- The ends of the heat sealing band should have a low-impedance coating of copper, silver or nickel.
- The electrical connections should be adequately sized to prevent measuring errors due to temperature rises when determining the resistance.
All contoured heat sealing bands supplied by ROPEX are designed using a 3D CAD tool. The files created in this way are used for further processing, e.g. laser cutting or anti-stick covers. The technical specifications are carefully documented and kept together with a reference sample, which can be used again for follow-up deliveries.
Heat sealing bands can also be supplied with a 3D contour to match our sealing bars. This is necessary for sealing applications featuring a spout, for instance. The heat sealing band corresponds exactly to the contour of the closure. One particular challenge here is that instead of simply sealing the film, it must be sealed with a closure.
Many applications require highly customized heat sealing bands. We can provide exactly the right solution – from bands with multiple temperature zones to circular heating tools. With our longstanding experience and our 3D CAD system, even the most complex geometries are not a problem.
Heat sealing band underlays
The underlays for our heat sealing bands are adapted to the requirements of each individual application. Both flexible silicone underlays with various Shore hardnesses and non-flexible underlays are available. In addition to ensuring electrical and thermal insulation, underlays also compensate mechanical and closing tolerances, so that a homogeneous contact force is easier to achieve.
Hard, non-flexible underlays are ideal for cut-and-seal applications.
The control loop also includes an impulse transformer, which is connected between the temperature controller and the power supply terminals for the heat sealing band. It supplies the band with the required power and is individually tailored to your application. If necessary, we can provide several secondary voltages, so that the transformer can be used for several different applications.
Our impulse transformer is specially designed for impulse sealing and is adapted to interact optimally with our temperature controllers. All impulse transformers have reinforced insulation between the primary and secondary sides.
We can also offer you several suitable cables with different cross sections which are optimized for our control loop. The cables you need are described in the ROPEX Application Report along with the ideal cross section. Complicated wiring calculations are no longer necessary as a result.
The following cable types are available:
- C-HF-xx: Highly flexible high-current cable with silicone sheath
- C-TC-xx: High-current cable suitable for cable carriers
- UML-1: Twisted cable for voltage measurements
All ROPEX temperature controllers require a line filter in order to comply with EMC directives and ensure CE conformity. Line filters damp the reaction of the phase control on the line and protect the temperature controller against line disturbances. Two different line filters are available:
- LF-06480 for up to 6.0 A continuous current
- LF-35480 for up to 35.0 A continuous current
PTFE and cover strips
PTFE fiberglass is widely used as an anti-stick covering and insulating material. It therefore makes a perfect interlayer between the heat sealing band and the underlay. It allows the heat sealing band to slide in case of linear expansion without sticking to the underlay. The PTFE is adhered directly to the underlay, which is made of silicone, for instance.
Cover strips are PTFE fiberglass with a non-adhesive zone which are used directly on the heat sealing band. The non-adhesive zone is located above the heat sealing band, which can be fastened to the bar with the adhesive zone. Once again, the heat sealing band can slide in case of linear expansion but the film is prevented from sticking to it.
Special silicone retainers are available from ROPEX to hold the silicone profile. They are equally suitable for both flat and trim profiles. As long as the width of the silicone profiles is the same, you can switch easily between flat and trim without having to change the silicone retainer.
Cut-and-seal profiles allow you to simultaneously cut and bond several layers of film. Two cut-and-seal profile types are available. Profile type 1 is the classic trim wedge, which is used if the foil layers simply need to be sealed and cut. Profile type 2 combines a flat seal with the actual trim wedge. This profile is chosen if a short flat seal needs to be produced in addition to cutting the film. Once again, different widths as well as smooth or textured surfaces are possible.
Bar end blocks
Bar end blocks made from a special material and with a special geometry are employed in medical applications or whenever space is scarce. PEEK, the thermoplastic we use for this purpose, is resistant to high temperatures.
PEEK bar end blocks are readily machinable. Various different designs are therefore possible depending on the application.
Bar end blocks are attached to the ends of a heat sealing bar. Their function is as follows:
- To fasten the heat sealing band
- To connect the high-current and measurement cables
- To allow the hot heat sealing band to expand due to spring force
- To prevent the heat sealing band from bending or warping
Screwed electrical connections are essential here. Plug-in connections are not allowed because even minimal contact resistances will distort the temperature measurement. Since these connections are generally at one end, there is always a left and right-hand bar end block. Bar end blocks have different technical characteristics depending on the dimensions of the heat sealing band or the end pieces.
The current transformers are an integral part of the control loop. They are used to measure the current, so that the temperature controller can determine the temperature of the heat sealing band. Three different current transformers are available:
- PEX-W4 standard version with additional UL certification (will be replaced by the PEX-W5 on the 01st July 2019)
- PEX-W5 standard version with additional UL certification
- MSW-2 as a monitoring current transformer
- Accessories: HCB-1 high-current busbar with M8 screws for connecting large cable lugs
The RESM-5 monitoring device is an optional add-on for the control loop that enables even greater reliability. It is connected to an existing control system. The RESM-5 measures the resistance of the heat sealing band and indicates the temperature in parallel operation using a separate current transformer.
A variable limit function is used to monitor the maximum temperature; an alarm is indicated at the fault output if this temperature is exceeded, giving you a redundant system.