Achichamire Nouveau Machine Toutils: The Mikron HEM 500U in Practice

The Mikron HEM 500U belongs to the family of five-axis machining centers that position the table and the spindle in a fixed orientation before cutting. Two rotary axes tilt the work into place, then the machine cuts with three linear axes. The rotary axes lock. They do not move during the cut.

That single detail is the whole story. Because the rotary axes hold still, rigidity at the tool tip stays close to what a three-axis machine gives you. You get access to five faces of a part without building a new fixture for each face. You do not get the continuous interpolation that lets a ball nose cutter sweep a sculpted surface in one pass.

For prismatic parts with pockets, holes, slots and faces at compound angles, 3+2 removes operations. A housing that would need four setups on a three-axis mill can often be finished in two. Each setup you delete removes a re-clamp, a re-datum, and the position error that comes with both.

Where it stops being the right answer is freeform geometry. Impeller blades, blisks, and organic medical implants need the rotary axes to move while the tool is engaged. That is a different machine and a different programming effort.

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  Position, then cutRotary axes index to an angle and lock before the tool enters the material.
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  Fewer setupsCompound-angle features can be reached without a dedicated angle plate per face.
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  Rigid by designA locked rotary axis behaves closer to a solid block than a live one.
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  Not for freeformContinuous contouring of curved surfaces needs simultaneous motion.

Start with the feature count, not the part name. If a part has features on three or more faces that must hold position to each other, 3+2 is usually the cheaper route. The classic examples are manifold blocks, gearbox housings, valve bodies, and instrument enclosures with ports on different sides.

Consider the aspect ratio too. A part that is long and thin will deflect under cutting force no matter how many axes you have. On a machine with a Ø400 mm rotary table, you want the work envelope to fit with room for the fixture. Parts that crowd the table edge lose stiffness fast.

Medical instrument bodies are a good fit for a different reason. They often combine a machined pocket, a sealing face, and a set of drilled ports at odd angles. A 3+2 cycle can hold the sealing face flat while the ports are drilled from the tilted position, so the relationship between the two is set by the machine, not by a fixture pin.

Titanium and Inconel parts need a harder look. These alloys push cutting forces up, and a tilted setup moves the load away from the machine's stiffest direction. On TC4 (Ti-6Al-4V) or Inconel 718, we often keep the critical faces in a horizontal orientation and use the rotary axes only for the secondary features.

Small brackets and simple plates rarely justify the setup. If a part fits in one three-axis vise and has features on two faces, run it on a three-axis machine and save the five-axis hour for work that needs it.

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  Good fitHousings, manifolds, valve bodies, ported medical instrument bodies.
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  Marginal fitLong thin shafts, parts that overhang the rotary table edge.
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  Poor fitImpellers, blisks, sculpted surfaces, organic implant geometry.

Every setup you add puts a new number into the tolerance stack. On a 3+2 machine you can cut that stack down, but only if the workholding is planned before the part is programmed. We usually start from the datum the inspection team will use, then work backward to the first op.

A common approach is to machine a soft jaw pocket that matches the raw stock, then cut a reference face and two reference edges in the first operation. Those three surfaces become the datum for everything that follows. When the part is tilted for the second operation, the machine knows exactly where it sits because the datum was cut, not clamped.

Thin-walled parts need support in the tilted position, not just at the base. A wall that is rigid when vertical can sing when the table tilts 45 degrees and the tool pushes sideways. Adding a sacrificial rib or a low-melt fixturing compound is often faster than chasing chatter with feeds and speeds.

For parts that will be anodized or plated, plan the clamping marks now. A witness mark on a cosmetic face is a scrap. We keep clamp zones on surfaces that get masked or machined away in a later pass.

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  Cut the datumMachine reference faces instead of trusting raw stock edges.
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  Support the tiltAdd ribs or fixturing compound where walls thin out.
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  Plan clamp marksKeep them on masked or non-cosmetic surfaces.

GreatLight runs 16 simultaneous 5-axis machining centers alongside 12 four-axis mills and 27 three-axis machines. That mix matters when a job arrives. Not every feature on a part needs five axes, and splitting the work across machine types usually shortens the schedule.

Our largest travel is 4,000 × 400 × 150 mm, with medium envelopes at 750 × 1,150 × 550 mm and 600 × 600 × 600 mm. Compact cells cover 500 × 500 × 450 mm and 500 × 310 × 200 mm. A Ø400 mm rotary table handles the tilted work. Parts are quoted to ±0.005 mm (±0.0002 in), with surface finish held at Ra 0.8–1.6 μm for standard work and Ra 0.2–0.8 μm where a sealing or bearing face needs it.

Materials we cut daily include 6061-T6, 7075, 17-4PH, 316L, TC4 (Ti-6Al-4V), Inconel, and the common plastics such as POM, PEEK and ABS. The material choice often settles the axis question on its own. Hard alloys prefer fewer tilted cuts.

Inspection is 100% before shipment, with raw material checks, in-process monitoring and a final report available on request. For tilted setups, we verify the datum face and the critical compound angle on the CMM before the run continues.

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  16 five-axis centersSimultaneous capability for jobs that truly need it.
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  127 CNC machines totalWork can be split to keep the schedule short.
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  Four plants certifiedISO 9001, IATF 16949, ISO 13485, ISO 27001.