Thermal management and fluid conveyance solutions for ICE engines

Internal Combustion Engine (ICE) Technologies 

Necessity for a Cleaner Environment – Gas & Diesel Vehicles getting Cleaner and More Efficient

Senior Flexonics developed a unique metal bellow to create leak-tight exhaust flex systems instead of the ball joint system, the standard practice at the time. This innovation took up the different motions/movements between the engine and the exhaust system while at the same time helping our customers keep a leak tight exhaust to meet emissions legislation.

Commercial vehicles presented a different clean air challenge. While accounting for only 4% of the vehicles on the road, they were responsible for 25% of the emissions. Capturing the heat from wasted emissions and reintroducing this into the engine flow is one method to reduce that impact. Although well intended, earlier EGR Cooler designs were prone to various problems as metals were exposed to extreme temperature ranges and the inherent expansion and contraction.  To address this, Senior Flexonics engineers listened to our customers’ needs, and applied their thermal management and heat exchanger experience to develop a durable, million-mile Exhaust Gas Recirculation (EGR) cooler that would not only reduce emissions, but drastically reduced our customer’s warranty claim burden.


Whether it is a Diesel, Gasoline or Natural Gas Engine, our extensive range of products can be customized to your exact specifications.

  • Exhaust Gas Circulation (E.G.R.) and waste heat recovery for all types of combustion engines (Diesel, Natural Gas and Gasoline).
  • Flexible metal bellow solutions to manage temperature and movement in all types of vehicles ranging from personal transport to on and off highway commercial vehicles.
  • Diesel and gas fuel delivery systems including common rail and liquid conveyance for all types of cooling requirements.
  • Turbo Oil Feed and Drain Tubes.


Senior Flexonics designs, Engineers and manufactures a complete range of metal engine bellows assemblies to match each vehicle’s unique platform. We are an established and trusted OEM supplier and resource to some of the world’s leading brands. Application of our metal bellows can be found in all on / off road vehicle types. We have experience with Commercial Buses, Agriculture, Construction, Forestry, Marine and Mining Equipment. Our Engineers work closely with our client’s Engineering departments to: satisfy emission requirements, reduce the transfer of stress and vibration to the vehicle, improve vehicle noise, vibration & harshness (NVH).

Different flex designs provide different benefits at different costs.

Design constraints that determine drive flex design include:

    • Transverse or longitudinal engine orientation
    • Allowable engine roll & exhaust alignment relative to engine roll axis (displacements, torsion, etc.)
    • Available packaging area in engine compartment
    • Engine temperatures
    • Primary need/function for flex (i.e. durability, NVH, assembly, thermal expansion, etc.)

Our mechanical or hydro formed bellows are Engineered and fabricated with the optimum combination of alloy, diameter, length, convolutions and wall thickness. Add to this our “know how” and capacity to manufacture all related components and you have the convenience and time savings of a “drop-in” type of installation.



Senior Flexonics is a leader in EGR Cooler design and manufacture with design centers in North America, Europe and Asia. We serve the on/off Highway diesel markets with manufacturing centers in USA and Mexico. EGR products include Tube and Shell, Tube and Fin, Plate and our unique Co-Axial EGR Cooler. Our products can be found in light/medium and heavy duty vehicle platforms.

About EGR Coolers

As emissions-related engine components continue to expand both in quantity and complexity, the market is demanding solutions that provide full transparency to the end user. This zero-impact approach when adding complex components leaves no room for compromises in durability or performance. Senior Flexonics has taken this direction seriously and has developed the experience and tools necessary to deliver products that exceed even the most demanding customer requirements.

Among emissions-related components, EGR (Exhaust Gas Recirculation) coolers are some of the most complex and historically unreliable subsystems of a modern engine. Senior Flexonics saw customers struggling with these products nearly a decade ago and moved quickly to adapt existing technologies and expertise to provide a solution. Central to the design of these coolers was the use of thermal compensating tubes utilizing Senior Flexonics’ Bend-a-Flex tube technology.

When evaluating EGR cooler durability, it is crucial to understand the different loading mechanisms and their causes within a general loading category – primarily thermal cycling. Thermal loading of EGR coolers falls into two levels that are typically referred to as thermal fatigue (high cycle) and thermal shock (low cycle).

High-cycle thermal fatigue is a more commonly discussed phenomenon, however it is difficult to understand its impact during the design stage due to the complexity of the structure. To assess damage, the loading cycles are counted throughout the normal application of the product and can often be approximated by looking at peak load swings over a given period of time or distance. The more challenging task is understanding exactly how to accommodate these thermal stresses within the component design. Unfortunately, these design lessons are often learned the hard way, with history witnessing product after product with massive warranty liabilities.

Within the design process, the only savior of the designer is the ability to lean upon robust analysis processes. Senior Flexonics understands this well and has invested heavily in an analysis team dedicated solely to EGR cooler development. This team has developed tools based upon lessons learned from a Bend-a-Flex field population approaching half a million EGR coolers. The modeling techniques are vetted against results of those existing products, as well as results coming from proven rig testing. The application of these analysis tools is the key component of Senior Flexonics’ competitive advantage in fast and robust product development cycles.

The second thermal loading category is low-cycle thermal shock. This mode is experienced by the EGR cooler in non-normal running situations such as broken water pump belts, cooling line failure or aeration of the cooling system. In these situations, the boundary conditions that the EGR cooler is designed for start to break down, often resulting in runaway metal expansion that the structure cannot accommodate. The problem with non-normal operating conditions is that it is normal for most vehicles to experience these conditions over the course of the engine’s life. Since many cooler designs can fail within seconds of coolant loss, it becomes unacceptable to expect an EGR cooler to require replacement after encountering these conditions.

These situations are where the base architecture of Bend-a-Flex sets itself apart from the competition. While stiff-tubed coolers can fail within seconds of coolant loss, Senior flexonics’ coolers have survived events such as these thousands of times. Both rig and field-testing have shown nearly unlimited resistance to any cooling system issues the engine is capable of generating. One test shut off the water flow to the cooler and allowed it to boil dry under continuous hot gas flow. Coolant flow was then restored and subsequently shut off again, replicating an absolute worst-case field scenario. Competitor after competitors’ coolers failed on this test within a handful of cycles; Senior Flexonics’ coolers were pulled off the test after thousands of cycles without any issue.

Other EGR cooler manufacturers have attempted to replicate these results with macro-compensating features such as floating cores or convoluted outer shells. These strategies, however, are fundamentally flawed because cooling systems do not see issues on a macro scale. Any of the above issues will result in non-uniform expansion of the gas tubes (typically starting with the upper tubes) rendering the macro-compensating feature useless. By utilizing individual flexible tubes, every passage within the tube array has micro-compensating abilities and accommodates thermal expansion independently of the rest of the tube bundle. This level of flexibility gives the OEM and the end-user independence from EGR cooler constraints, allowing for engine design flexibility features such as cold-side EGR valves, as well as the equipment uptime necessary to run a competitive business.

This level of thermal shock resistance sets the Bend-a-Flex cooler far apart from the rest of the competition. However, good companies understand the limitations of their products. When looking to smaller displacement applications, power density requirements can make the Bend-a-Flex cooler difficult to package in tighter spaces. In these applications, engine OEMs have been forced to compromise thermal shock resistance in favor of designs such as fin-in-tube coolers with inherently higher power density. While these designs can provide power density benefits, their tube passages are extremely stiff columns that expand without compromise under various thermal shock scenarios.

Senior Flexonics recognized this difficult compromise as an opportunity. The engineering team was able to lean on the company’s 100-year experience with flexible tubing along with extensive heat exchanger knowledge to develop an advanced fin-in-tube product that builds flexible features directly into the finned gas tubes. Through proprietary forming processes, each passage has convolutions formed directly to the tube enabling the same micro-compensation as discussed above on the Bend-a- Flex. This state-of-the-art EGR cooler technology can be found in Senior Flexonics’ newly developed Flex-a-Fin EGRFlexonic coolers.

Within all of Senior Flexonics’ EGR cooler designs, flexibility is the key feature. Metal expansion is a simple fact within the abusive environment EGR coolers are applied in. Senior Flexonics’ engineering team believes that, as with most things in life, it is far better to accommodate change than to resist it.



Senior Flexonics engineers, tests and manufactures turbo oil feed tube assemblies and turbo oil drain tube assemblies to exceed customer guidelines and technical requirements.  We design, manufacture, and supply complex tube assemblies for the world’s leading brands. Our design process includes many stages such as:

Initial Design

During the initial design stage of turbo oil feed tubes or drain tubes, we consider bolt access, clearance, orientation, and assembly to ensure there are no concerns.  Temperature fluctuations and movement frequencies are all analyzed and contemplated so the correct engineering course is taken as well as the correct materials are utilized for a durable final product. Often specialized stainless steel metal bellows are utilized by Senior Flexonics in the final tube assembly to mitigate thermal expansion and contraction as well as inherent engine and external vibrations at high frequencies. This is one of many differentiators in our approach vs. a simple rigid tube supplier.

Knowledge and Expertise  

Senior Flexonics is uniquely positioned in the industry as we have accumulated decades of field data regarding thermal management and movement characteristics.  This valuable information is applied to our products.  We understand metal characteristics and their inherent benefits of one type vs. the other.  Having the necessary on-site testing facilities to do extensive durability analysis including FE analysis to study heat and movement means we can assist you with complex 3D geometries and customize the flexibility vs. stiffness of the tube to meet installation constraints.

Manufacturing Capabilities

Senior Flexonics’ production facilities are equipped with an extensive range of dedicated tooling for bending, forming, and joining complete assemblies including advanced multi-axis Computer Numeric Control (CNC) bending machines, hydroforming and brazing to name a few. Some of these manufacturing cells are augmented by robotics for large production runs of OEM parts.

One Stop Shop

We are familiar with all standard turbo oil feed tube and turbo oil drain tube fittings (i.e. O-rings, heat shields, flanges) and can offer precision custom end fittings as required by the manufacturer. We further understand cleanliness requirements on feed and drain tubes are critical with extremely tight requirements that must be maintained. Our extensive experience with medical devices and strict ISO quality measures affords Senior Flexonics an additional industry leading advantage.



The common rails ensure fuel is readily available for delivery to the engine’s injectors. Sensors on the rail link to the ECU and provide feedback to regulate fuel flow and operating pressure. Senior Flexonics provides many well known manufacturers with full assemblies that may include high pressure connectors, sensors and valves.


Forged Common Rail involves the pre forming and rolling of materials to established specifications. The rail is then forged and trimmed to final tolerances.  Typical applications include On/Off Highway, Heavy Duty Trucks, Construction Equipment, Agricultural Equipment, Mining Equipment, Marine and Industrial.


  • Cost effective solution
  • Forging designed, developed and tested in-house
  • Pressures to 2600 Bar
  • Customize to specific applications
  • Various diameters available
  • Available delivered separately or assembled complete with Pressure Relief Valve and Pressure Sensor


Welded Common Rails are development friendly because the ports are welded directly to the rail body. This allows for ports to be relocated accommodating late design changes.  Typical applications include On/Off Highway, Heavy Duty Trucks, Construction Equipment, Agricultural Equipment, Mining Equipment, Marine and Industrial.


  • Custom designed pressure inserts allow fuel pipe to seal to rail and hold system pressure
  • Pressures to 3000 Bar
  • Available delivered separately or assembled complete with Pressure Relief Valve and Pressure Sensor

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