Introduction
In the world of aerospace hydraulic systems, precision and reliability are everything. Each component of a Permaswage head assembly—including the often-overlooked end plates—plays a critical role in ensuring proper tube-to-fitting connections. In this post, we’ll explore what end plates do, how to inspect them, and why maintaining them correctly keeps your swaging system performing safely and efficiently.
What Are End Plates in a Permaswage Head Assembly?
End plates are key structural components of the DLT Series Swage Head Assembly used in standard Permaswage systems (up to 3,000 psi). Each swage head includes four end plates:
Upper Outboard End Plate (Item 4)
Upper Inboard End Plate (Item 5)
Lower Outboard End Plate (Item 6)
Lower Inboard End Plate (Item 7)
These plates are secured to the yoke and lower die block with MS24671 screws and work together to hold the dies firmly in place during the swaging operation.
Function and Importance
Each end plate has a specific purpose within the head assembly:
The Upper Outboard End Plate acts as a fitting stop, ensuring the tube and fitting align correctly before swaging.
The Inboard End Plates help maintain proper spacing and compression of the die set.
The Lower End Plates provide structural stability and prevent misalignment under pressure.
Because the Permaswage process subjects these parts to extremely high hydraulic pressures (up to 10,000 psi in some systems), end plate integrity directly affects the quality of every swage.
Inspection Criteria
According to the MCP-016 inspection manual, technicians should verify end plate condition and placement during visual inspection. Here’s what to check:
Correct Part Numbers Each end plate must match the head assembly size. Reference Table 2 in MCP-016 for the proper pairing. For example:
DLT30PSHA3012 uses DLT30PSFU4012 (Upper Outboard) and DLT30PSEL4012 (Lower Inboard).
DLT40PSHA3016 uses DLT40PSFU3016 (Upper Outboard) and DLT40PSEL3016 (Lower Inboard).
Proper Installation
Ensure each plate is mounted in the correct location—Inboard and Outboard plates are not interchangeable due to different screw hole spacing.
Secure Fastening Verify that all screws are tight but not over-torqued to avoid warping or cracking.
Visual Condition Look for cracks, bending, gouging, or wear—especially on the Upper Outboard End Plate, since it acts as a fitting stop. Damaged plates should be replaced immediately to avoid improper swages.
Maintenance Tips
To maintain tool performance and safety:
Inspect regularly. Check end plates each time the head assembly is serviced.
Replace worn or cracked plates. Even minor wear can affect fitting alignment.
Keep components clean and lubricated. Debris or lack of lubrication can cause uneven die compression and reduce tool life.
Use only genuine Permaswage replacement parts. Aftermarket or incorrect plates can compromise tool calibration and swage integrity.
Assembling End Plates in the Head Assembly
When reassembling a DLT head:
Install the Upper Outboard End Plate on the yoke first.
Lubricate contact areas between the dies and yoke.
Insert the dies, align with the end plate, and secure with the appropriate screws.
Repeat the process for the Lower Inboard and Outboard End Plates.
Each end plate’s position and function are critical for maintaining die alignment and ensuring repeatable, certified-quality swages.
Conclusion
End plates might be small, but their role in a Permaswage head assembly is crucial. They ensure die stability, precise fitting alignment, and consistent pressure containment during each swage. Regular inspection and proper replacement of these plates can prevent tool failure, protect operators, and maintain aerospace-quality connections.
If you’re looking for replacement Permaswage end plates or complete DLT head assemblies, Top Flight Tools offers factory-new and certified used components—all inspected to manufacturer standards.
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