Hydroforming

Hydroforming forms sheet or tube metal using high-pressure fluid against a die, producing smooth, complex shapes with fewer seams and good repeatability.

Overview

Hydroforming uses pressurized fluid to push sheet metal into a die cavity (sheet hydroforming) or expand a tube inside a die (tube hydroforming). It supports deep draws, smooth contours, and large radii while reducing wrinkling compared with many conventional forming methods. Parts often come out with good surface finish and fewer joints because shapes that would require multiple stampings and weldments can be made as one piece.

Choose hydroforming for moderate to high volumes when you need complex, lightweight shells or tubular structures with consistent geometry, minimal weld seams, and clean exterior surfaces. Tradeoffs: tooling is specialized and not cheap, cycle times are longer than simple stamping, and feature definition for sharp edges, embossing, and small pierced details is limited—secondary trimming/piercing is common. Material thinning and springback still apply, so early forming simulation and prototype trials help de-risk the design.

Common Materials

  • Aluminum 5052
  • Aluminum 6061
  • Stainless steel 304
  • Stainless steel 316
  • Mild steel
  • Titanium Grade 2

Tolerances

±0.010"

Applications

  • Automotive exhaust components
  • Chassis and subframe tubular members
  • Bicycle frames and handlebars
  • Aerospace ducting and manifolds
  • Architectural handrails and curved tubing
  • Appliance and HVAC enclosures

When to Choose Hydroforming

Hydroforming fits parts that need complex curvature, smooth surfaces, or variable cross-sections without seams, especially in tubes or large panels. It makes sense when volume can amortize tooling and you want repeatable geometry with minimal weld distortion. Plan for secondary trim/pierce operations and validate thinning and springback early.

vs Cutting

Choose hydroforming when the job is primarily shape creation, not just perimeter definition. Hydroforming forms 3D curvature and cross-section changes that cutting alone cannot produce, while still allowing post-trim cut features where needed.

vs Forming

Choose hydroforming when conventional press forming would require multiple hits, complex draw beads, or segmented operations to avoid wrinkling and tearing. Hydroforming can consolidate operations into one forming step and improve surface quality on large, smooth shapes.

vs Punching

Choose hydroforming when the primary requirement is a formed 3D geometry and holes/features can be added after forming. Punching excels at fast 2D hole patterns and louvers; hydroforming is better for deep contours where in-die piercing would be difficult or distort the part.

vs Welding (Sheet Metal)

Choose hydroforming when a welded assembly would drive distortion risk, leak paths, or cosmetic rework. Hydroforming can replace multi-piece weldments with a single formed shell or tube, reducing joints and improving consistency.

Design Considerations

  • Specify material, thickness, and temper up front; small changes can swing formability and thinning
  • Avoid sharp corners and tight reverse radii; use generous radii to reduce thinning and improve die life
  • Place critical holes and slots away from high-strain zones and plan for post-form trimming/piercing
  • Control section expansion and depth with realistic thinning limits; request forming simulation for aggressive geometry
  • Define datums and inspection points on stable, repeatable surfaces; freeform areas can vary more part-to-part
  • Call out surface finish expectations and cosmetic sides; hydroformed parts often need secondary trim marks managed