Metallic

Tie Rod and Control Rod

AvetchTyee manufactures a large range of Tie Rods, Push-Pull Rods, and Control Rods assemblies in Aluminum, Titanium, or Stainless Steel. With one of our leading market specialties, rotary swaging for tie and control rod tubes has the capability of sizes up to 4.5-inch diameter and over 12 feet in length. Swaged tubes is by far the most cost to weight effective while exhibiting excellent fatigue strength.

Struts

Structural struts are manufactured by using aluminium, titanium or stainless steel and are swaged in a cold forming process. This style of rod produces a highly fatigue resistant strut and comparatively light weight for it’s strength. The Ends can be flange or plain bushings as needed to attach to the mating surface. This type of strut is used for structural support, landing gears, engine mounting, HTP and VTP support structures.

Swaged Rods

AvtechTyee produces numerous rod designs that rely on a process called Rotary Swaging.  Rotary Swaging is a mechanical form of forging that applies the power and speed of rotary machines to the blacksmiths manual method.  In manual swaging, the swage (or die) is placed in the hardy hole of the anvil, and the blacksmith holds the hafted upper die in one hand while he slowly turns the work piece with the other.  A helper meanwhile strikes the upper die with a sledge.  In a rotary swager, the die and hammer blocks are held in a cross-slot in the end of the rotating spindle, and are thrown open by centrifugal force.  The outward travel is limited by opposing pairs of rollers that are caged like in a roller bearing.  The rollers turn freely against the outer race that is pressed into the frame of the machine.  As the hammer blocks pass under the rollers, they cause the dies to strike the work piece.  Rotary swaging increases the mechanical properties of the material being worked, and allows for high rates of production to close tolerances.  AvtechTyee maintains in-house capability to develop dies for custom angles and shapes in forming.

Swaged Materials

Swaging metals requires some amount of ductility.  Materials having less than 10% elongation are less useful.  Many high strength alloys that otherwise would have desirable characteristics in the finished part may not be easily swaged.  Swaging produces an increase in wall thickness, but results in progressive loss of cross section due to the elongation of the material.

2024 aluminum tubing is the most common structural aircraft material.  In the “0” condition, it is ductile and swageable.  Although is requires heat treatment, straightening, and a protective finish, it remains a readily manufactured material.  6061 aluminum alloy can also be swaged.  High strength steel tubing that is ductile can also be swaged.  Processing is usually less for corrosion resistant materials.  AISI 321, 347, 15-5, 17-4 stainless and carbon steels in the 4130, 4340 families have been used as swaged rod body materials at AvtechTyee.  Many other alloys can be swaged, including titanium alloys.  AvtechTyee maintains a wide library of material process models to design swaged tube design efficiently with tight tolerances and performance.

Metallic Rod Design Considerations

Metallic rods for aircraft control or structural support typically have design requirements for fatigue and static strength, with resistance to corrosion at a minimum weight.  Rod assembly designs must meet calculated ultimate loads, both in compression and tension, but often the critical design parameter is fatigue loading.  A design that optimizes fatigue strength of the original material through careful manufacturing processing is key.

Corrosion and stress can seriously shorten the life of a mechanical assembly.  Most tubes are exposed to a corrosion inducing environment.  Tubes exposed to the low temperatures and low air pressures of altitude cause air to evacuate.  Then, returning to warmer humid air at ground level, the tube refills with moist air that may condense into liquid.  The most corrosive location on aircraft applications is adjacent to the landing gear, where sprays from the runway and ground equipment contact exposed assemblies.  Moisture is basic to galvanic action, and conductive to corrosion between any steel and aluminum.  Good design will preclude the contact of dissimilar materials.

Assembly weight and size is also a key consideration.  Fittings should be only of sufficient diameter to support required loads.  Movable or articulated rods, are often in close contiguity with other structures, and need to avoid interference with any mating surfaces or parts.  Tube thickness, end fitting type, and materials all play key roles in space and weight of control or structural rods.

Integrally Formed Clevises

Metallic assemblies can reduce weight and complexity in some applications through the use of a integrally formed clevis.  This offers a good solution for redundancy paths on control systems, and saves weight.  A bushing or other mount can be fitted into the “ears”, with any “clocking” arraignment possible between ends.

Snubbers

Historically, linear motion arresting devices, known as Snubbers, have used a closed hydraulic system to achieve the required braking action.  However, some applications, especially in extreme aerospace environments, cannot use hydraulic oils.  This is where AvtechTyee provide a novel design solution with purely mechanical braking action in proportion to the load applied.  These designs are lighter weight and less complex than most hydraulic solutions, and meet extreme temperature, humidity, altitude, and flammability requirements.

The mechanical snubbers are designed to operate while extending or compressing, and may be used as a support at the end of the stroke.  Parts currently designed support loads as low as 75 pounds, all the way up to 1 inch diameter snubbers supporting 1000 pounds.  Snubbers may also be designed to control rotary motion in a similar controlled manner.

Snubber Design Considerations

To design a custom snubber, AvtechTyee requires the following information:

Closed Length:
Minimum Travel:
Operating Load Range:
Static Loads:
Time Envelope:
Maximum Working Diameter:
Method of Operation:
Connection Requirements.
Tube bodies can be metallic or composite, with a variety of threaded or formed end fitting inserts.