Steel 3D Welding Fixture Table

Complete Manufacturing Process for Standard Steel 3D Welding Fixture Tables (Primarily using Q355 steel):

• 1. Plate Cutting: Large steel plates are cut using plasma, flame, or laser-with an allowance left for final machining. Laser cutting is preferred for thicker plates to minimize thermal deformation at the cut edges.

• 2. Base and Stiffener Assembly: The base plate is welded together with longitudinal and transverse stiffeners. The density of these stiffeners directly determines the table's load-bearing capacity and resistance to deformation.

• 3. Primary Stress Relief (Artificial Aging):

Welding creates significant internal stress within the base; if not released, the table will warp when subjected to heat during CNC machining.
- Artificial Aging: Natural aging (storing for 15–30 days) or low-temperature tempering.
- Premium Option: Vibratory Stress Relief (VSR)-offers faster turnaround, ideal for high-volume orders.

• 4. Rough Milling (First CNC Pass): The top surface and four vertical sides are rough-machined, leaving an allowance for finish milling.

• 5. Secondary Aging (Applied only to high-end, "Grade 0" robotic-grade tables): Performed after rough milling to further release machining-induced stress; essential for meeting ultra-high flatness requirements (e.g., ≤0.05mm/1000mm or ≤0.02mm/1000mm).

• 6. Finish Milling (Multiple-pass finishing-a key differentiator):

While many lower-cost alternatives involve only a single milling pass, our process utilizes multiple finishing passes. This minimizes deformation caused by heat generated during cutting, ensuring consistent hole spacing and superior flatness.

• 7. CNC Drilling and H7 Reaming:

Holes are not simply drilled and left as-is; the process involves drilling, enlarging (boring/counterboring), and precision reaming to achieve an H7 tolerance. Hole edges are chamfered (C2/C3) to prevent damage from locking pins and to avoid the accumulation of weld spatter.
The surface finish of the hole walls directly impacts the ease of inserting/removing locking pins and the accuracy of repeatable positioning.

• 8. Surface Pre-treatment: Shot Blasting / Sandblasting

Removes scale, oil, and welding spatter, while enhancing the adhesion of the nitrided layer.
❗ Skipping shot blasting before nitriding: The nitrided layer may peel or flake off, and welding spatter will easily break away upon impact.

• 9. Plasma Nitriding

- Types: Gas nitriding vs. plasma (ion) nitriding. Plasma nitriding results in less deformation and more uniform hardness, making it the preferred choice for 3D welding tables.
- Hardness Range: HV 550–900. A high-hardness version (HV 870) is available upon request (requires a different base material, such as mold steel; standard Q355 steel cannot achieve such high hardness).
- Standard Nitrided Layer Thickness: 0.3–0.5 mm. The layer should not be too thick, as excessive thickness increases surface brittleness, making it prone to peeling if struck or bumped.
- Benefits: Prevents welding spatter adhesion, improves wear resistance, and provides mild rust protection.

• 10. Cleaning, Rust Prevention, Quality Inspection, and Marking

Clears iron filings from the holes and applies anti-rust oil. Laser marking is used to indicate the model, hole pattern, flatness grade, and serial number.