17-4 PH Stainless Steel Medical CNC Machining | Reliable 5-Axis Spinal Surgical Instrument Parts
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产品详情
5Axis CNC Machining 17-4 PH Stainless Steel Surgical Instrument:
At Flow Wing Metal, we specialize in CNC machining for high-precision medical devices, aerospace components, and industrial parts. Our expertise in 5-axis CNC machining allows us to produce complex, monolithic parts with tight tolerances, minimizing assembly and improving reliability.
CNC Equipment at Flow Wing Metal:
Our machine shop is equipped with a range of CNC machining to address diverse part geometries, volumes, and tolerances.
客户： OS Medical (ISO 13485 certified, Germany)
行业： Medical Device (Spinal Surgery)
挑战： OS Medical required a spinal pedicle screwrod reduction instrument used in minimally invasive spine surgery. The part (150mm total length, 12mm maximum diameter)
featured:
A complex, ergonomic handle with undercut finger grooves.
A distal “reduction tab” with a precise 2.5mm × 3mm rectangular slot (tolerance ±0.01mm).
A cannulated (hollow) shaft with a 2.0mm internal throughhole.
A ratcheting engagement interface requiring a 0.15mm radius root (sharp internal corner impossible with standard ball end mills).
Original challenge:
The instrument was previously manufactured as a 3component assembly (handle machined separately, shaft with broached slot, ratchet insert welded in place).
This resulted in:
High assembly labor cost.
Weldment weak points (potential for crevice corrosion after sterilization).
Inconsistent slot positioning (±0.08mm across batches) leading to poor instrument fit intraoperatively.
8 weeks lead time.
OS’s request:
A single piece, weld-free, monolithic instrument machined from 174 PH stainless steel (precipitation hardened, high strength, corrosion resistant), with:
No assembly required.
Slot tolerance ±0.01mm (half of previous tolerance).
Internal ratchet feature with 0.15mm root radii (EDM or 5axis machining).
Lead time ≤ 4 weeks for 200 units.
The Flow Wing Metal Execution:
Step 1: Material Selection & Preparation of CNC Machining
Material: 174 PH stainless steel bar, Condition A (solution annealed – softer for machining), then agehardened to H900 condition postmachining (yield strength ≥ 1,170 MPa / 170 ksi).
Bar size: 16mm diameter × 250mm length blanks.
Certification: Material traceable per ASTM A564 with mill test reports (MTRs) and biocompatibility verification (ISO 109935 noncytotoxicity).
Step 2: CNC Programming & Simulation
CAM Software: Mastercam 2024 with 5axis simultaneous module.
Machine: DMG MORI DMU 65 (5axis machining center with 20,000 RPM spindle, HSK63 tool holder, throughspindle coolant at 70 bar/1,000 PSI).
Workholding: Custom soft jaws with a dovetail fixture providing 5sided access.
Toolpaths:
Roughing: High efficiency dynamic milling (trochoidal toolpaths) with a 10 mm 5 flute carbide end mill.
Semifinishing: 6mm ball end mill (scallop height 0.02mm).
Finishing (grooves/slot): 1.5mm miniature carbide end mill (7flute, necked reach).
Ratchet feature: 0.5mm tapered ball end mill (0.15mm corner radius programmed).
Internal throughhole: Gun drilling (2.0mm diameter, 120mm depth – L/D ratio 60:1) followed by carbide reamer.
Step 3: Machining Process (5Axis Simultaneous of CNC Machining)
Operation Tool Parameters Result:
- Face & turn OD CNMG 432 insert (turning) 200 SFM, 0.1mm/rev 15.8mm diameter
- Drill center hole 1.8mm carbide drill 4,500 RPM, 0.025mm/rev Pilot hole
- Gun drill throughhole 2.0mm gun drill (coolantfed) 8,000 RPM, 0.02mm/rev 2.0mm +0.00/0.02mm
- Dynamic roughing 10mm end mill 8,000 RPM, 2,000mm/min 80% material removed
- 5axis handle finishing 6mm ball end mill 12,000 RPM, 1,500mm/min Handle surface RA 0.8µm
- Rectangular slot (reduction tab) 1.5mm end mill (7flute) 18,000 RPM, 400mm/min 2.5mm × 3.0mm ±0.008mm
- Ratchet feature 0.5mm tapered ball (0.15mm rad) 22,000 RPM, 200mm/min 0.15mm root radius retained
- Ream final throughhole 2.0mm carbide reamer 2,000 RPM, 0.1mm/rev 2.0mm +0.005/0.000mm
Step 4: Post Machining Heat Treatment & Finishing
Heat treat: Age hardening to H900 (480°C / 900°F for 1 hour, air cool). Achieved hardness: 44 HRC (target 43–46 HRC).
Surface finishing:
Electropolishing: 30 minutes in an electrolytic bath to remove a 0.01mm layer, resulting in a bright, smooth (RA ≤ 0.2µm), and passivated surface. This eliminated any burrs from the 0.5mm ratchet tool.
Passivation: Subsequent citric acid bath to ensure chromium oxide restoration (per ASTM A967).
Inspection:
CMM (Coordinate Measuring Machine) for full 5axis dimensional inspection.
Vision system for 0.15mm ratchet root radius verification.
Optical comparator for slot tolerance.
Surface roughness profilometer (RA 0.18µm achieved).
| 要求 | 指定 | 流翼 Result | 及格/不及格 |
| 材料 | 174 PH H900 | 174 PH H900 (44 HRC) | 通过 |
| Slot tolerance | ±0.010 mm | ±0.006 mm (Cpk 1.8) | 通过 |
| Through-hole diameter | 2.0mm +0.01/0.00 mm | 2.003 mm average | 通过 |
| Ratchet root radius | ≤ 0.18 mm radius | 0.152 mm radius | 通过 |
| Surface finish (functional) | RA ≤ 0.4 µm | RA 0.18 µm (electropolished) | 通过 |
| Lead time (200 units) | 4 weeks | 3.5 weeks | 通过 |
| Unit cost (vs. 3-piece assembly) | ≤ 25% | 38% reduction | 通过 |
数控加工 the Result:
Cost savings: 38% lower per unit cost compared to the previous 3 component assembly ($48 → $30 per instrument).
Lead time reduction: From 8 weeks to 3.5 weeks for 200 units (factory to sterile ready).
Quality improvement: Slot positioning tolerance ±0.006mm vs. previous ±0.08mm (13× more precise). No rework or scrap in production run.
Reliability: Zero field failures after 24 months (3,500+ surgical uses). No crevice corrosion, no weld fractures (there are no welds), and the electropolished surface cleans faster in sterile processing.
Clinical feedback: “The single piece instrument feels more solid, engages the pedicle screw with zero play, and the ergonomic handle reduced surgeon hand fatigue by approximately 40%.” – Lead Spine Surgeon, University Hospital Munich
客户感言
“Flow Wing Metal transformed a three part welded assembly into a monolithic 5 axis CNC machining masterpiece. The 0.15mm internal corner on the ratchet feature – achieved with a 0.5mm end mill – is the reason we chose them over five other CNC machining shops. They understand medical quality.”
