Spinal Pedicle Screw Tulip Head

Specifications

Key features

• Near-net-shape silica sol casting reproduces the U-shaped saddle, rod seat and anti-splay geometry in one piece, cutting machining time and tool wear.
• Internal buttress or V-thread produced by thread milling or form tapping on the machined bore, verified with go/no-go gauges for set screw fit.
• H900 hardening gives a strong, wear resistant head that resists deformation during rod reduction and final tightening.
• Concentricity between the screw seat bore and the tulip axis held within 0.03 mm to keep the rod seated squarely.
• Electropolished and passivated surfaces reduce crevice corrosion risk and remove free iron and embedded media.
• Consistent saddle width tolerance across the lot supports interchangeability with mating rods and set screws.
• Cast part numbers, size codes or lot marks can be integrated into the casting for downstream traceability.

Applications

• Polyaxial and monoaxial pedicle screw systems for thoracolumbar fixation
• Posterior spinal fusion constructs and degenerative disc revision sets
• Minimally invasive and percutaneous screw extension tulips
• Trauma fixation and sacroiliac joint screw assemblies
• Instrument sets and surgeon training and demonstration models
• Prototype and validation builds during design freeze and cadaver testing

Quality & compliance

Ningbo Ruican is not an ISO 13485 registered contract manufacturer; we operate as a casting and machining supplier under the customer’s Quality Agreement and supply project-level ISO 13485 documentation (material certification, heat lot records, inspection reports, process control records) for each release. Typical material routes are 17-4PH H900/H1025, AISI 420 and AISI 316L, with biological evaluation data available against ISO 10993-5 for cytotoxicity when the customer specifies the test protocol. Full dimensional records, heat treatment charts and traceable raw material certificates ship with every lot.

FAQ

Q1. Can you cast the tulip head to net shape and only machine the thread?
Yes. Most tulip heads are cast near net shape with machining stock of 0.2-0.4 mm left on the thread bore, saddle faces and rod seat. This keeps cycle time and carbide cost down while holding the critical interfaces within tolerance.

Q2. What is the typical minimum order quantity for a new screw system?
Prototype runs start at 20-50 pieces per size for design validation; production casting lots normally start at 500 pieces per part number because tooling and gating are shared across the pattern cluster.

Q3. Do you supply 17-4PH H1025 instead of H900?
Yes. H1025 is often selected when the design needs more toughness and stress corrosion resistance. We certify the actual hardness and tensile values from the heat lot for either condition.

Q4. How do you control thread quality on such a small part?
Threads are machined on rigid CNC equipment with sharp form tools, then checked with calibrated go/no-go gauges and optical thread measurement on a sampling plan agreed in the control plan.

Q5. Can you work from a sample part instead of a drawing?
Yes. Send a sample and we will reverse engineer it with 3D scanning, CMM measurement and material analysis, then produce a drawing for your approval before tooling.

Q6. What surface treatment do you recommend for implant instrument contact surfaces?
Electropolishing followed by nitric or citric acid passivation per ASTM A967 is our standard recommendation; alternative finishing to your specification is available.