With the rapid advancement of medical technology, surgical robots have become a key aid in improving diagnostic and treatment accuracy. From precisely implanting artificial joints in orthopedic surgery to performing millimeter-level sample analysis in the laboratory, high-precision components are essential. Core components such as the robotic arm and transmission system of surgical robots often require extremely small dimensions and strict tolerance control (often as low as 0.01mm), placing extremely high demands on machining processes.
As a service provider specializing in CNC rapid prototyping and precision customization, Elite Mold Tech recently completed a machining project for a client focusing on core surgical robot components. From microscopic stainless steel parts to key transmission system components, we maintained stringent precision standards throughout the entire process, addressing the client's core challenges of high scrap rates and difficulty meeting tolerances. Next, we will share our approach to custom processing of surgical robot components through a specific case study.
I. Project Background: The Rigid Demand for Precision in Surgical Robot Components
The performance of a surgical robot is directly dependent on the machining accuracy of its components—even a deviation of 0.05mm can cause the robotic arm to misalign, compromising surgical safety. The client (a medical device developer) required two core components for their surgical assistance robot:
1.1 Miniature Stainless Steel Structural Components
- Application: Used at the end of the robotic arm
- Dimensions: Only 7 × 7 × 22 mm, with an extremely thin 0.1 mm cut at the edge
- Previous Pain Points: Due to deformation and substandard surface roughness, the cuts easily deformed, resulting in a scrap rate as high as 30%
1.2 Transmission System Shaft Components
- Application: Used in the robotic arm's rotating joints
- Precision Requirement: Controlled radial and axial runout; total runout for a 2.5 mm diameter hole ≤ 0.02 mm
- Previous Pain Points: The client failed to meet the runout standard in previous machining attempts
1.3 Client’s Core Requirements
- Increase the component qualification rate to over 99% while controlling costs
- Deliver the first batch of samples within 15 days to support subsequent full-machine testing
Elite Mold Tech developed a targeted solution combining CNC precision machining and wire-cutting processes to address these needs.
II. Solution Implementation: Accuracy Improvement for Two Core Components
For the client’s two types of components, we resolved machining challenges through three key measures: process optimization, fixture design, and quality inspection upgrades.
2.1 Micro Stainless Steel Parts: Precision Machining of 0.1mm Thin Cuts
The greatest challenge for this 7×7×22mm stainless steel part lies in the 0.1mm thin cuts on the edges:
- Stainless steel has high hardness (HRC 30-35), so uneven stress during thin-cut machining easily causes deformation.
- Surface roughness requirement: Ra 0.8μm (equivalent to mirror-grade smoothness).
- Previous Issue: The client’s single CNC milling process led to high scrap rates.
We addressed these issues through a three-step solution:
Step 1: Process Combination – CNC Milling + Wire EDM
- First, use CNC milling to machine the main structure of the part, leaving a 0.1mm machining allowance.
- Then, use slow-speed wire EDM to process the thin cuts:
- Adopt a wire electrode with a diameter of only 0.12mm to precisely cut the 0.1mm thin edge.
- Non-contact processing avoids stress-induced deformation, and achieves Ra 0.8μm surface roughness without subsequent polishing.
Step 2: Parameter Optimization – Reducing Machining Stress
- CNC Milling: Adjust spindle speed from 8,000 rpm to 6,000 rpm; use cooling oil mist instead of traditional cutting fluid to minimize thermal deformation.
- Wire Cutting: Control wire speed at 8 m/s; pause for 2 seconds every 5 mm to release stress, further reducing deformation risk.
Step 3: Customized Fixtures – Micro-Fixture and Anti-Drift
Traditional fixtures cannot accurately secure the tiny parts, so we designed a vacuum clamp + elastic pressure block combination fixture:
- Vacuum suction secures the bottom of the part.
- Elastic pressure blocks gently press the edges, keeping pressure below 5 N (prevents part shifting and deformation from excessive pressure).
Result: The first batch of 30 micro stainless steel parts all passed testing (scrap rate 0%), and the processing cycle was reduced from the client’s expected 7 days to 5 days.
2.2 Transmission System Shaft Components: 0.02mm Total Runout Tolerance Control Method
Transmission system shaft components are critical to the surgical robot’s "rotational flexibility." Total runout directly affects performance—if deviations are too large, the robotic arm may jam or deviate. The requirement (total runout ≤0.02mm for a φ2.5mm hole) is equivalent to 40% of a human hair’s diameter (≈0.05mm).
We achieved breakthroughs in three areas:
Step 1: Machining Route – Datum First, Single-Step Molding
The core of total runout control is datum surface accuracy. We took the part’s datum surface A as the machining starting point:
- Machine datum surface A on a high-precision lathe, ensuring flatness ≤ 0.005mm (checked with a dial indicator, error within 0.003mm).
- Machine the φ2mm locating hole on the same lathe without disassembling the part (avoids deviations from secondary clamping).
- Use continuous turning for the φ2.5mm hole (no mid-process stops) to prevent cylindricity deviations; final cylindricity achieved: 0.008mm.
Step 2: Equipment and Fixtures – 0.01mm-Level Precision Control
- Equipment Selection: Use a precision lathe with spindle runout ≤0.003mm (far exceeding conventional lathes’ 0.01mm standard).
- Custom Fixture: Design an eccentricity compensation fixture—uses a micron-level adjustment knob to control shift tolerance within 0.01mm, ensuring coaxiality between the reference surface and subsequent machining surfaces.
Step 3: Quality Inspection Upgrade – Dedicated Probes Solve Inspection Challenges
Traditional coordinate measuring machines (CMMs) have probes with diameters ≥0.5mm, which cannot penetrate 2.5mm φ holes to measure runout. We purchased the RENISHAW "STAR Micro Probe" (tip diameter 0.1mm) to directly insert into small holes and accurately measure radial/axial runout.
Result: Total runout of all φ2.5mm holes on all parts was ≤0.018mm (far exceeding the client’s 0.02mm requirement).
III. Project Achievements: Achieving Dual Standards in Precision and Efficiency
After 12 days of processing and quality inspection, we delivered all two core components, achieving three key objectives:
3.1 Accuracy Targets Met
- Micro stainless steel parts: 100% pass rate
- Shaft components (total runout): 99.5% pass rate (only one component required rework due to minor probe collision during inspection, and met standards after reprocessing)
3.2 Efficiency Improvement
Delivery was completed 3 days ahead of the client’s 15-day lead time, saving valuable time for subsequent full-machine assembly and testing.
3.3 Cost Optimization
- Per-unit processing cost for both components was reduced by 18% compared to the client’s previous supplier.
- Scrap rate dropped from 30% to 0%, minimizing material waste.
Post-Delivery Feedback: The client completed full-machine testing of the surgical robot—end-of-arm positioning accuracy reached 0.1mm, and rotary joints operated continuously for 1,000 cycles without lag, fully meeting medical surgery requirements.
IV. Why Choose Elite Mold Tech for Medical Component Processing?
Precision and reliability are critical for medical device components (e.g., surgical robots), and these are Elite Mold Tech’s core strengths:
4.1 Strong Process Capabilities
Master core processes including CNC precision machining, wire EDM, and Swiss machining; process a variety of medical-grade materials (stainless steel, titanium alloy, medical plastics) with tolerances as tight as ±0.005mm.
4.2 Rich Industry Experience
With over 5 years of experience serving medical clients, we are familiar with:
- GD&T tolerance standards for medical device components
- Surface treatment requirements (e.g., passivation, sterile coatings)
- Proactive mitigation of design and manufacturing risks
4.3 Strict Quality Assurance
Equipped with high-precision inspection equipment (RENISHAW probe CMMs, laser diameter gauges); conduct 100% inspection at every stage to ensure zero deviation in delivered parts.
If you are developing medical products (e.g., surgical robots, diagnostic equipment) and require custom machining of high-precision components, please contact us. Elite Mold Tech provides end-to-end solutions—from design review to mass production—to accelerate the implementation of your medical innovations.
Contact Information
- WhatsApp: +86 19860504405
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