Frequently Asked Questions (FAQ) about CNC Machine Tools

• When purchasing a CNC machine tool, how to match the machine bed structure and guideway type according to the characteristics of the workpieces to be processed?

  It is necessary to make a comprehensive judgment based on the workpiece material, size and precision requirements. For high-speed cutting of lightweight materials such as aluminum alloy, priority should be given to an integrally cast machine bed (with good shock absorption) matched with linear guideways (low friction coefficient and fast moving speed). For heavy cutting scenarios such as hardened steel processing, a welded machine bed (strong rigidity) matched with box-way guideways (wear-resistant and high load-bearing capacity) is recommended. If the maximum processing size of the workpiece exceeds 1.5 meters, the integrally cast machine bed has better anti-deformation ability, which can avoid processing precision drift.

• For small-batch and multi-variety production, how to select the tool magazine and tool changing device of a CNC machining center?

  The tool magazine capacity should be determined according to the number of processes of frequently processed workpieces. If a single workpiece requires 5-8 tools, a tool magazine with a capacity of 24 tools is recommended, with a 30% redundancy reserved to cope with product variety switching. For tool changing speed, the "tool-to-tool" time is the core indicator; for small-batch production, it is recommended to control it within 1.5 seconds to improve tool changing efficiency. For such scenarios, models equipped with an Automatic Tool Changer (ATC) should be preferred, which can reduce manual tool changing time and human errors. If there are plans for future capacity expansion, models that support tool magazine capacity expansion can be selected.

• How does the selection of CNC system brand affect the operating cost? How to balance performance and budget?

  Imported systems such as Fanuc and Siemens have higher spare parts prices (e.g., the replacement cost of an encoder is about 2-3 times that of domestic ones), but they have strong stability and low failure rates, making them suitable for high-precision and continuous production scenarios. Mitsubishi and domestic systems such as Huazhong CNC and GSK have low maintenance costs and abundant training resources, and their initial purchase price is 15%-25% lower than that of imported systems, which are suitable for medium-low precision and intermittent production needs. Balance suggestion: Select imported systems for core processing procedures and domestic systems for auxiliary procedures. At the same time, require suppliers to provide a 1-3 year spare parts package to lock in long-term maintenance costs.

• When purchasing a 5-axis CNC machine tool, what performance indicators should be focused on besides precision?

  Focus on three core indicators: First, the indexing accuracy of the rotary axes (A/C axes) ≤ 10″ and repeat indexing accuracy ≤ 5″ to ensure the angular processing accuracy of complex curved surfaces. Second, spindle power and torque: for processing difficult-to-cut materials such as titanium alloy, a spindle with power ≥ 37kW and torque ≥ 1500N·m should be selected. Third, the dynamic response characteristics of the machine tool: the surface waviness (required to be ≤ 0.8μm) can be observed by test-cutting "impeller" workpieces, and at the same time, confirm whether the system supports the 5-axis linkage error compensation function.

• When the workshop power capacity is limited, what electrical parameters should be verified before purchasing a CNC machine tool?

  Priority should be given to verifying three key parameters: First, the rated power of the machine tool (the total power of the main motor + servo motor should be clearly defined, such as 30kW) to avoid exceeding the load capacity of the workshop lines. Second, starting current (usually 3-5 times the rated current) to confirm whether the workshop transformer can support short-term overload. Third, voltage level (380V three-phase AC is common); if the workshop uses 220V, communication and modification should be carried out in advance. It is recommended to ask electricians to issue a workshop power load test report and compare it with the electrical parameter sheet provided by the machine tool supplier. If the gap exceeds 20%, the power capacity expansion and transformation should be planned in advance.

• To adapt to future capacity expansion, what expansion space should be reserved when purchasing a CNC machine tool?

  Reserve space from three aspects: First, hardware interfaces: confirm whether the machine tool has reserved 4th/5th axis interfaces and tool magazine expansion interfaces, and the worktable load margin should be ≥ 20% (e.g., if the current processed workpiece weighs 500kg, select a worktable with a load capacity of 1000kg). Second, system compatibility: select a system that supports CAD/CAM software upgrading and data networking functions to facilitate subsequent access to the MES production management system. Third, workshop adaptability: the machine tool size should be 30% smaller than the reserved space in the existing workshop, and at the same time confirm the foundation bearing capacity (e.g., a 10-ton machine tool requires a foundation bearing capacity ≥ 15 tons) to avoid space constraints during future capacity expansion.