Titanium Alloy VS Stainless Steel: How to Choose Materials for CNC Machining? Check These 4 Key Indicators

1. Indicator 1: Mechanical Properties – Match Core Functional Requirements

• Strength-to-Weight Ratio: Titanium alloy (e.g., TC4) has a tensile strength of 860MPa and a density of only 4.5g/cm³ – half the weight of stainless steel (304: tensile strength 520MPa, density 7.93g/cm³) but stronger. It is suitable for "lightweight + high-strength" scenarios such as aerospace and medical devices (e.g., aircraft frames, artificial joints);
• Corrosion Resistance: Stainless steel (316L) has excellent corrosion resistance in ordinary acid-base environments but is prone to intergranular corrosion at temperatures above 300℃ or in strong corrosion environments (e.g., seawater, strong acids). Titanium alloy maintains unattenuated corrosion resistance between -253℃ and 600℃, making it more suitable for deep-sea exploration and chemical equipment parts;
• Toughness: Stainless steel (304) has an impact toughness of 200J/cm² and is not easily brittle at low temperatures, suitable for low-temperature storage tanks and food machinery parts. Titanium alloy has slightly lower low-temperature toughness (TC4: 50J/cm²) and should be avoided in extremely cold working conditions.

2. Indicator 2: Machining Difficulty – Control Production Efficiency and Precision

• Cutting Performance: Stainless steel (304) has severe work hardening, and "built-up edges" easily form during cutting, resulting in surface roughness Ra exceeding 1.6μm. Coated tools (e.g., TiAlN) and reduced feed rates (≤300mm/min) are required. Titanium alloy has low thermal conductivity (only 1/5 of stainless steel), so cutting heat concentrates at the tool tip, causing rapid tool wear (service life is only 1/3 of that for stainless steel). Frequent tool changes or high-pressure cooling systems are needed;
• Deformation Control: Titanium alloy has a low elastic modulus (about 110GPa, vs. 193GPa for stainless steel) and is prone to deformation due to excessive clamping force during machining, requiring special flexible fixtures. Stainless steel has higher rigidity and can be clamped with ordinary vices, with a deformation rate only 1/4 of that of titanium alloy;
• Precision Stability: Stainless steel has a higher thermal expansion coefficient (16.5×10⁻⁶/℃) than titanium alloy (8.6×10⁻⁶/℃). In high-temperature machining environments, stainless steel parts face higher risks of dimensional deviation, requiring strict workshop temperature control (20±1℃).

3. Indicator 3: Cost Control – Balance Performance and Budget

• Raw Material Cost: Titanium alloy (TC4) costs about 200 yuan/kg, 10 times that of stainless steel (304: about 20 yuan/kg). For non-critical parts in small batches (fewer than 100 pieces), stainless steel can significantly reduce material costs;
• Machining Cost: Titanium alloy has low machining efficiency (only 1/2 the processing volume per unit time of stainless steel) and fast tool wear (tool cost for processing 1kg of titanium alloy is about 50 yuan, vs. 10 yuan for stainless steel). Cost-effectiveness must be evaluated first for mass production;
• Post-Processing Cost: Stainless steel surface treatment (e.g., wire drawing, electroplating) is low-cost (about 5 yuan/piece). Titanium alloy usually uses anodizing, costing about 30 yuan/piece, but it improves biocompatibility and is a priority for medical scenarios.

4. Indicator 4: Scenario Adaptation – Lock in Final Application Needs

• Aerospace: Titanium alloy is preferred to meet "lightweight + high-temperature resistance + fatigue resistance" needs (e.g., aircraft landing gear components);
• Medical Field: Titanium alloy is used for implantable parts (e.g., artificial bones, dental implants) due to good biocompatibility and no rejection. 316L stainless steel is used for ordinary medical device housings (e.g., surgical instrument handles) to balance corrosion resistance and cost;
• Industrial Equipment: Titanium alloy is used for chemical pipelines and seawater treatment equipment (strong corrosion resistance). 304 stainless steel is used for food processing machinery and household kitchenware (safe, non-toxic, easy to clean);
• Daily Products: 304 stainless steel is used for thermos cups and tableware (low cost, easy to process). Titanium alloy is an option for high-end outdoor products (e.g., trekking poles, watch cases) due to lightweight and good texture.