Super Long Screws
We take an M10×250 mm super long screw as an example. The total length straightness is ≤0.4 mm. It can easily go through a 250 mm long stacked part hole. The hole diameter is φ10.5-11 mm. The single side gap is only 0.5 mm. For M10×250 mm, grade 8.8, the proof load is ≥30 kN.
Reach Through Many Layers with Our Super Long Screws
Do you need to go through many layers of parts? Lengths over 200 mm. Length to diameter ratio over 15:1. Regular screws cannot be made that long. Or they come out bent. Our Super Long Screws solve this problem. They go through a stator and end cover. A nut locks on the other side. We are a Shanghai factory. We have made fasteners for 20 years.
Check Our Straightness Data and Tensile Strength
We take an M10×250 mm super long screw as an example. The total length straightness is ≤0.4 mm. It can easily go through a 250 mm long stacked part hole. The hole diameter is φ10.5-11 mm. The single side gap is only 0.5 mm. For M10×250 mm, grade 8.8, the proof load is ≥30 kN. The failure load is ≥38 kN. Following ISO 3800, at a stress range of 80 MPa, the fatigue life is ≥5,000,000 cycles. The material is carbon steel SWRCH35K, SCM435, or 45#. Or stainless steel SUS304 or SUS316. Carbon steel grades are 4.8, 8.8, or 10.9. Thread precision is 6g. We can make partial thread or full thread. The key to a long screw is straightness control. Length can reach 300 mm or more. The length to diameter ratio can reach 20:1. The straightness per 300 mm length is ≤0.5 mm. This ensures it goes through multiple part holes. For shorter lengths, we use cold heading and thread rolling. For super long and big diameters, we use hot forging, turning, and thread rolling.
|
Parameter |
Standard / Value |
|
Straightness (M10×250mm) |
≤ 0.4 mm total length |
|
Proof Load (M10, 8.8 grade) |
≥ 30 kN |
|
Failure Load (M10, 8.8 grade) |
≥ 38 kN |
|
Fatigue Life (8.8 grade) |
≥ 5,000,000 cycles (ISO 3800) |
Why Our MOQ and Special Packaging Work for You
Cold headed parts start at 50,000 pieces. Machined parts depend on the size. Free samples are ready for stock items. Mass production takes 2-3 weeks for standard parts. Custom products take 4 weeks. Repeat orders are even faster. Typical uses: stator to end cover through bolts (4-6 bolts, 150-300 mm long, grade 8.8 or 10.9). Brush holder fixing bolts (long and thin, need high straightness). Housing flange connection bolts (go through the whole motor body). Surface finish includes zinc plating, black oxide, or Dacromet. Dacromet gives 500+ hours of salt spray. Stainless steel comes in natural color. We suggest using a nylon lock nut or double nuts for vibration areas. We use individual cartons or strapped packing for super long screws. This stops bending during shipping.
The entire product line is fully customizable.
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