Machining Aerospace Couplers for Defense Applications

 Couplers are critical components in aerospace for defense applications. Couplers serve as connector points that join two separate parts, allowing for the transmission of fluids – hydraulic, fuel, air and electrical.  Machining aerospace couplers for defense applications must meet stringent requirements for safety, reliability, and performance. Intrex Aerospace has been producing precision aerospace couplers for over 40 years. The couplers produced are incorporated into fuel, air, electric systems for major aerospace/space commercial and defense manufacturers. Producing these precision components requires state-of-the-art equipment, in-house engineering, machining knowledge, ITAR experience, and a robust integrated software system.

Aerospace metals are selected for functionality and efficiency

In aerospace coupler applications many different metals are used. The metals are selected for structural integrity, specific purpose and strength-to-weight ratios.  Using different metals allows flexibility in producing lighter aircraft without compromising strength and durability. These characteristics contribute to overall performance and also help increase fuel savings.

Typical raw materials used in the manufacture of aerospace couplers are:

 Aluminum is the most common. It has several characteristics that lend itself to coupler applications. It is light weight, has good machinability is corrosion resistance using added secondary special processing (anodizing, etc).

The most common types of aluminum alloys used in aerospace applications:

• 2000 Series: High strength due to copper additions.
• 6000 Series: Excellent formability and weldability, suitable for non-load-bearing structures.
• 7000 Series: This series is very strong due to zinc additives.

Another advantage for aluminum alloys is they are generally affordable and readily available.

Stainless Steels: There are many different formulations of stainless steel—each one with its own unique characteristics, but common to all are:

• A high resistance to corrosion thanks to a protective oxide layer
• Are heavier than aluminum (3X) but have a higher tensile strength
• Have a much higher melting point than aluminum making them more robust for high temperature applications

Titanium alloys boast a remarkable synergy of high strength and low weight compared to most other metals.

• Allows for creating lightweight yet incredibly strong components capable of withstanding significant stresses encountered during flight operations.
• Titanium naturally forms an oxide layer, granting it exceptional resistance to corrosion across diverse environments
• High-Temperature Performance: Certain titanium alloy formulations exhibit good performance at elevated temperatures. This translates to extended service life and reduced maintenance requirements

Manufacturing Couplers for Defense

 All of the aerospace couplers that Intrex manufacturers require machining. Many have complex shapes and precision tolerances are the norm. Most are machined from raw stock, but Intrex also has considerable experience machining parts from forgings and castings (i.e. TZM).

The coupler manufacturing process begins with the raw stock (usually from a round bar/slug or casting/forging), being released to our production floor. Our engineering department generates CNC programs which are then electronically downloaded to the appropriate machine on our shop floor. The programs are matched with tools that have been kitted for that specific part and CNC program. The machine is then setup, with the provided tools. The machine runs through a dry cutting run simulating the program, spindle speeds and tool movement. A sample (setup) part is then machined. The setup part is then measured, adjustment to the program and machine offsets are made. Once the machine movements are verified (confirming no tool or slide interference), and the part meets dimensional requirements and tolerance, production can begin.

The production machining usually involves the turning of both the outside diameter (OD) and the inside diameter (ID) of the raw stock. Many of the parts also require milling and drilling of the workpiece. Most of the parts require the turning to a near net finish diameter (both OD & ID), and many also require some amount of milling/drilling and tapping. Previously we performed these operations using multiple setups on multiple machines, but now most of this work is now achieved on multiple axis twin spindle CNC turn/mills. The twin opposing spindles, make the part transfer from one spindle to the other easy with no operator intervention. The part transfer allows machining access to all sides of the work piece. Our newest machine have 5 axis simultaneous capability to machine our complex shapes. The advantageous of these multi-axis, twin spindle types of CNC machine are:

• Greatly reduce the number of setups
• Minimize fixture requirements
• Reduce floor space requirements
• Reduce error stack up due to less part movement/simplified fixturing
• Minimizes operator intervention during the machining process
• Lower scrap rates

Special Processing

 Most aerospace couplers require some “special” processing – post machining. Some of the most common special processing is:

• Anodize
• Passivation
• Dry film lube
• Particle inspection

At Intrex we have relationships with multiple NADCAP approved sources that provide special processing services. In addition, many of our customers direct us to their own approved sources (ASL). It is customer preference directed. We can provide either.

Quality Control

 In aerospace manufacturing, quality is “everything”. Nothing moves through our shop until quality specifications are addressed. We continue to make significant investments in quality hardware. Recently we purchased multiple Zeiss coordinate measuring machines (CMM) for our shop floor and have CMM’s in our quality lab. We have coupled our very robust Epicor ERP/MRP systems software with our inspection processes. Our inspection processes and supporting documentation are fully integrated into our Epicor system.  We are ISO 9001 and AS 9100 certified and ITAR compliant.

 Conclusion

 Intrex has been machining aerospace couplers for defense applications for over 40 years. Successfully machining the complex shape of the couplers (most are very thin wall) requires machining knowledge, experience with difficult materials and a skilled work force. In addition, we continue to make significant investments in state-of-the-art production and support equipment. As the aerospace/defense/space industry continues to innovate, designs change and improve, materials are updated, part tolerances tighten, we are in position to meet the most demanding future standards

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