Wunf 400 -

Tie-bar nuts on large-tonnage injection molding machines (1,000 tons or more) often utilize the WUNF 400 standard. When clamping the mold halves together, even a micron of slack results in flash (plastic leakage). The precision of the WUNF 400 threading ensures consistent mold closure pressure across thousands of cycles.

If you have the physical item in hand, follow this checklist:

  • Measure dimensions: A 400A device will be heavy (over 20 lbs) and roughly the size of a shoebox or larger.

    • If you have installed a WUNF 400 and it fails prematurely (weeping oil, torn lip, excessive heat), investigate these three root causes: wunf 400

    If the cylinder rod has a damaged chamfer or sharp edge at the end of stroke, it will literally chisel the lip off the WUNF 400. Solution: Deburr the rod end or add a sacrificial wear ring.

    No UNF thread has 400 TPI — but if a drawing specified #0 UNF is 80 TPI max. 400 TPI would be specialty micro-threads for optics or fine adjustment screws. Measure dimensions: A 400A device will be heavy

    Guide for identifying UNF threads:

    How does the WUNF 400 stack up against alternatives like the ISO 4762 standard high-tensile bolt or the standard UNF 400 series? If you have installed a WUNF 400 and

    | Feature | Standard UNF 400 | ISO 4762 (12.9 grade) | WUNF 400 | | :--- | :--- | :--- | :--- | | Thread Form | Sharp root radius | Metric sharp V | Modified wide radius | | Axial Load Capacity | 380 kN (max) | 400 kN | 440 kN (tested) | | Vibration Loosening | Moderate resistance | Low resistance | High resistance | | Corrosion Protection | Zinc plating (basic) | Black oxide | Electroless nickel | | Price Index | $$ | $ | $$$ |

    While the WUNF 400 typically commands a 20–30% price premium over standard fasteners, the total cost of ownership is lower due to reduced downtime, less frequent replacement, and superior safety margins.