The processing and forming of food-grade pure titanium cutting boards must balance material properties with food contact safety requirements. The core challenges lie in material handling, thermal processing control, surface precision, structural stability, composite processes, tool compatibility, and quality inspection, requiring breakthroughs through multi-dimensional technological collaboration.
Work hardening of pure titanium and tool wear are primary challenges. During cutting, pure titanium is prone to surface hardening due to plastic deformation. The hardened layer's hardness increases by 30%-50% compared to the substrate, creating a vicious cycle of "the more you cut, the harder it gets." This characteristic demands high hardness and wear resistance from the cutting tool; however, the chemical affinity of pure titanium makes it prone to adhesion to the tool material, accelerating tool wear. For example, when machining pure titanium with traditional carbide tools, the cutting edge easily forms crater-like grooves due to adhesive wear, leading to a sudden increase in cutting force and even chipping. Therefore, cubic boron nitride or diamond-coated tools must be used, coupled with low-speed, high-feed cutting parameters to reduce the contact time between the tool and the material and delay wear.
Oxidation and grain control during heat treatment directly affect the performance of food-grade pure titanium cutting board. Pure titanium readily reacts with oxygen above 600℃ to form a brittle oxide layer, reducing the material's toughness. To avoid oxidation, heat treatment must be performed under an inert gas (such as argon) atmosphere; however, an inert gas environment increases equipment costs and operational complexity. Furthermore, grain growth during heat treatment requires precise control: excessively high annealing temperatures lead to grain coarsening, reducing the strength of the food-grade pure titanium cutting board; excessively low temperatures fail to eliminate processing stress, causing deformation. For example, during recrystallization annealing of TA1 industrial pure titanium, the temperature must be strictly controlled within the 700-750℃ range, combined with short-term heat holding, to obtain a uniform and fine equiaxed grain structure.
Surface smoothness and anti-contamination treatment are core requirements for food-grade materials. Food-grade pure titanium cutting board requires a mirror-like surface finish (Ra≤0.8μm) to prevent bacterial hiding. However, pure titanium's elastic modulus is only half that of steel, making it prone to springback deformation during processing, leading to excessive surface waviness. To address this, rigid fixtures are used to fix the workpiece, combined with a multi-pass, low-reduction rolling process to gradually release internal stress. Simultaneously, the surface needs pickling and passivation treatment to remove the oxide layer and processing contaminants. However, the concentration and time of the pickling solution (such as a mixture of hydrofluoric acid and nitric acid) must be precisely controlled to avoid excessive corrosion and deterioration of surface roughness.
The interfacial bonding strength in composite structure molding is a technical challenge. Some high-end food-grade pure titanium cutting boards use a titanium-plastic composite structure to reduce costs and improve anti-slip properties. However, the significant difference in thermal expansion coefficients between titanium and plastic (titanium 8.6×10⁻⁶/℃, plastic 50-200×10⁻⁶/℃) easily generates interfacial stress during temperature changes, leading to delamination. To enhance bonding strength, sandblasting or chemical etching is required on the titanium plate surface to increase surface roughness. Co-extrusion or in-mold injection molding processes are then employed to allow the molten plastic to fully penetrate the micropores on the titanium plate surface, forming a mechanically interlocking structure.
The balance between tool wear and machining efficiency restricts large-scale production. Although the cutting force of pure titanium is lower than that of titanium alloys, the unit cutting force is still 1.5 times that of steel, leading to increased spindle load and low machining efficiency. To improve efficiency, tool geometry parameters need to be optimized (e.g., increasing the rake angle to 15°-20° to reduce cutting force), and high-pressure coolant (pressure ≥7MPa) should be used to flush the cutting zone and reduce cutting temperature. Furthermore, while non-contact processes such as laser processing or EDM can avoid tool wear, their high processing costs limit their application to small-batch customized products.
The stringent quality inspection standards reflect food-grade requirements. Food-grade pure titanium cutting board requires passing multiple tests: its chemical composition must comply with GB 4806.9-2016 "National Food Safety Standard - Metal Materials and Articles for Food Contact," ensuring that heavy metal migration (such as lead and cadmium) does not exceed the limits; the surface must pass a bacterial adhesion test to prove its antibacterial properties; and the structure must pass a drop weight impact test to verify its impact resistance. These tests require high-precision equipment (such as ICP-MS spectrometers and colony counters) and a strict quality traceability system, increasing production costs and timelines.
The processing and molding of food-grade pure titanium cutting board is an interdisciplinary field of materials science, mechanical engineering, and food safety. It requires collaborative innovation across multiple aspects, including tool design, heat treatment processes, surface treatment, composite structures, processing parameters, and quality testing, to overcome technical bottlenecks and achieve a balance between high performance and high safety.
