CNC Spin Press: How the QK63-350CNC Three-Rotary Wheel Works

• 1
  What a cnc spin press actually does to the metal
• 2
  Why 350 kN longitudinal and 240 kN transverse matter
• 3
  Closed-loop control of four axes on the spin press
• 4
  Rotary seat drag plate and tailstock rigidity
• 5
  Which metals spin well and which fight back
• 6
  Where a cnc spin press stops being the right call
• 7
  Spin press vs machining vs deep drawing

Spinning is not cutting. A flat or pre-drawn blank is clamped between a spindle and a tailstock and turned at speed. A roller then pushes the material against a mandrel, and the blank wall thins and stretches as it wraps the mandrel profile. On a cnc spin press the roller path is programmed, so each pass is repeatable instead of depending on a hand wheel.

The metal does not melt and it does not shear. It deforms plastically at the contact point, roughly 20–40 mm wide under a roller nose radius of 6–15 mm. That contact patch sees high local pressure, so the surface hardness rises and the grain structure aligns with the flow direction. A spun 6061-T6 wheel can read 10–15 HV harder at the surface than the parent sheet, though the ductility drops.

Because the wall thins, you cannot spin a part thicker than the starting blank at any point. If the finished wall is 2.0 mm on a cone with a 1.8:1 draw ratio, the blank must start near 3.6 mm. Engineers who treat spinning like machining get caught here. The blank thickness sets the ceiling, and the mandrel sets the shape.

The three-rotary layout on the QK63-350CNC means a longitudinal roller head plus transverse roller heads that can swing in and out of the work zone. That lets one setup form a flange, a cylindrical body and a closing radius without re-chucking. The tailstock slides on a drag plate so the tail position follows part length, which matters once you pass 600 mm.

• 1
  Flow, not removalMaterial moves along the mandrel; chip volume is near zero.
• 2
  Blank thickness is the limitFinished wall is always thinner than the starting sheet.
• 3
  Surface work-hardensHardness rises a little, ductility drops a little.
• 4
  Mandrel defines geometryEvery profile change is a new mandrel, lead time included.

The QK63-350CNC carries 350 kN of longitudinal rotation pressure and 240 kN of transverse rotation pressure. Those numbers are not marketing figures. They tell you what wall thickness and what material you can push through a single pass before the roller stalls or the blank wrinkles.

As a working rule, mild steel and 300-series stainless need roughly 1.5–2.0 kN per millimeter of wall thickness per pass at a 1.2:1 draw ratio. Aluminium 6061 needs about a third of that. So 350 kN longitudinal is comfortable for a 6 mm stainless wall in two or three passes, and tight for a 10 mm wall.

The transverse heads see less force because they work the flange and the closing radius, where the contact area is smaller and the draw ratio is lower. 240 kN is enough for flanging a 3 mm stainless disc up to a 90° bend without tearing, provided the roller nose is not too sharp. A 3 mm radius nose tears; a 10 mm nose does not.

Force alone does not decide the pass schedule. Spindle speed, feed per revolution and roller radius all trade against each other. Slow the spindle and you can push harder, but the part cools and the surface marks get deeper. Speed it up and the metal heats, which helps flow but risks galling on stainless.

• 1
  Longitudinal head350 kN. Does the main body draw and wall thinning.
• 2
  Transverse heads240 kN. Flanges, beads, closing radii, trimming support.
• 3
  Pass countTwo to four passes is normal; one pass rarely holds tolerance.
• 4
  Roller nose radius6–15 mm. Too sharp tears thin stainless.

The machine uses an electro-hydraulic control system with a Siemens 840C control and closed-loop feedback on four axes. In plain terms, the controller knows where each roller actually is, not where it was told to go, and corrects in real time. That is what keeps wall thickness even around the full 360°.

Open-loop spinning depends on the operator watching the part and adjusting by feel. It works, and it is how a lot of shops still run. The cost shows up as wall thickness variation, often ±0.15 mm on a 300 mm diameter cone. Closed-loop control pulls that into the ±0.05 mm range on the same part, because the roller follows a programmed path regardless of springback.

The human-machine interface runs on a high-resolution TFT color monitor. Programs are written as roller paths with pass-by-pass depth, spindle rpm and feed. An engineer can edit one pass without rewriting the whole cycle, which is useful when a trial run shows wrinkling at pass three.

This is not the same as a CNC lathe control. There is no tool offset table in the usual sense. The reference is the mandrel, and the roller position is measured against it. Setup time lives in mandrel mounting and first-article adjustment, not in tool presetting.

• 1
  Four axes closed loopRoller position is measured and corrected continuously.
• 2
  Wall variationAbout ±0.05 mm closed loop vs ±0.15 mm open loop.
• 3
  Program structurePass depth, spindle rpm, feed per revolution.
• 4
  Reference is the mandrelNo conventional tool offset table applies.

The rotary seat drag plate carries the upper tail system. It is built to raise rigidity and stability and to cut the pressure on the guide rails. When you spin a long part, the tail can slide along the drag plate to match part length instead of hanging out on an overhung quill.

That matters for vibration. A 900 mm long spun tube with an unsupported tail will chatter around 40–60 Hz, and the chatter shows as a spiral mark on the outside diameter. Moving the tail onto the drag plate and locking it close to the part raises the natural frequency and kills most of that mark.

The transverse power supply uses three servomotors, each driving a cylinder piston rod that moves the transverse sliding body. Fixing the cylinder block instead of the rod improves rigidity and reduces the momentary reaction when the roller hits the blank. In practice the first contact is smoother and the part is less likely to walk off the mandrel.

None of this replaces a proper mandrel. If the mandrel runout is over 0.05 mm, no amount of machine rigidity will hold wall thickness. Check mandrel TIR before you blame the machine.

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  Drag plate tailTail position follows part length; less overhang.
• 2
  Chatter controlLong parts need the tail close, not far out.
• 3
  Three servomotorsTransverse motion with reduced first-contact shock.
• 4
  Mandrel TIRKeep under 0.05 mm or wall thickness drifts.

Aluminium 6061, 5052, 5083 and 6063 spin easily. They work-harden slowly, so you can take bigger passes. 2024 and 7075 spin but crack if you push the draw ratio past about 2.0:1 without an anneal between passes. For a wheel hub in 7075, plan two anneals.

Stainless 304 and 316 spin well when the roller nose is generous and the feed is steady. 316L work-hardens faster than 304, so pass depth drops by roughly 20%. Stainless also galls the roller, so lubricant choice matters more than on aluminium. 17-4PH spins in the annealed condition only; after aging it tears.

Copper and brass spin like butter. C110 copper needs a soft roller or a polished nose because it picks up on tool steel. Titanium TC4 (Ti-6Al-4V) can be spun hot, around 600–750 °C, which is outside the normal setup and needs a heated mandrel and shielding. Most shops outsource that.

High-strength steel above 700 MPa yield is where spinning stops making sense. The force required climbs past what 350 kN can deliver at a reasonable wall, and springback ruins the final radius. For those parts, machining or forging is the honest answer.

• 1
  Easy6061, 5052, 5083, 6063, C110, C36000.
• 2
  Needs care2024, 7075, 304, 316, 316L, 17-4PH annealed.
• 3
  Hot spin onlyTC4 (Ti-6Al-4V) at 600–750 °C with heated mandrel.
• 4
  Do not spinSteel above 700 MPa yield; springback wins.

Spinning cannot make a part with a wall thicker than the blank, and it cannot hold a sharp internal corner. If your drawing has a 1 mm internal radius on a 4 mm wall, spinning will not deliver it. Add a machined insert or switch to turning.

It also struggles with non-round features. A wheel with three bolt bosses on the face needs those bosses machined after spinning. That is normal, and it is why spun wheels often go to a mill-turn center for the second op. On our floor that is a 16-station simultaneous 5-axis cell or a mill-turn center, depending on the feature count.

Tolerances follow the mandrel and the machine. Wall thickness holds around ±0.05 mm with closed-loop control. Diameter holds ±0.1 mm on a good mandrel. If you need ±0.005 mm on a bore, spin it oversize and finish it on a CNC lathe. That is the standard two-step route.

Volume matters too. Below about 10 pieces, mandrel cost dominates and machining is cheaper. Above 10,000 pieces with a simple profile, deep drawing usually wins on piece price. The spin press sits in the middle, and it is a wide middle.

• 1
  No internal sharp cornersMinimum internal radius tracks wall thickness.
• 2
  Non-round featuresBosses, slots and holes are machined after spinning.
• 3
  Tolerance splitSpin oversize, then finish bores on a lathe.
• 4
  Volume windowAbout 10 to 5,000 pieces; outside that, compare.