Choosing a CNC bending machine is a significant investment decision, requiring comprehensive consideration of technology, processes, cost, and service. Below is a systematic selection guide, covering key steps from needs analysis to final evaluation, designed to help you make an informed decision.
Step 1: Define Core Needs (Selection Basis)
Before starting your research, you must clearly define your needs:
Processing Materials:
Type: Ordinary steel plate, stainless steel, aluminum, copper, or other special materials.
Maximum thickness and maximum length (determine machine tonnage and table length).
Material strength (e.g., tensile strength σb, directly affects tonnage calculation).
Typical Workpieces:
Maximum/minimum bending dimensions.
Most common bending angles and shapes (e.g., polygonal boxes, complex curved surfaces).
Product accuracy requirements (e.g., angular tolerances, straightness).
Production Mode:
High-volume, low-variety production: Emphasis on efficiency, stability, and automation.
Low-volume, high-variety production: Emphasis on flexibility, quick mold changeover, and ease of programming.
Future Planning: New materials or products that may be involved in the next 1-3 years will be considered, with sufficient capacity margin reserved for the equipment.
Step Two: Core Technology and Configuration Selection
This is the core technology selection.
Drive Method (Key Selection):
All-Electric Servo Drive:
Advantages: High precision, high speed, energy saving (30%-60% more energy saving than hydraulic), clean and maintenance-free, low noise.
Suitable for: Applications requiring high precision, cycle time, and environmental protection; particularly suitable for medium and thin plates and high-frequency bending. This is the mainstream trend for the future.
Hydraulic Drive:
Advantages: High power, stable force, strong load adaptability, mature technology, and potentially slightly lower initial purchase cost.
Disadvantages: Higher energy consumption, risk of oil leakage, and the need for regular hydraulic oil maintenance.
Suitable for: Thick plates, large tonnage (e.g., over 300 tons), and traditional manufacturing where energy consumption is not a primary concern.
Electro-hydraulic Hybrid/Servo-hydraulic: A compromise solution, using servo control on critical axes (e.g., sliders), balancing power and some precision energy consumption advantages.
CNC System (The Machine's "Brain"):
Brand and Maturity: Choose internationally renowned brands such as Delem (Netherlands) and Cybelec (Switzerland), or leading domestic brands such as Estun and Raycus. The system should be mature, stable, and have a user-friendly interface.
Functionality and Ease of Use:
Graphical Programming: Supports direct import of CAD drawings and 3D graphical simulation, greatly simplifying programming.
Automatic Calculation: Automatically calculates bending steps, pressure, and springback compensation based on materials and molds.
Diagnostic Functions: Powerful self-diagnosis and prompting functions for faults.
Precision and Compensation System (The Core Determining Quality):
Key Indicators: Positioning accuracy (e.g., Y1/Y2 axis repeatability), parallelism.
Mechanical Structure: The rigidity and stability of an integrally welded machine body are superior to that of cast parts.
Compensation Mechanism: Must be equipped with a real-time deflection compensation system (such as Delem's RDC from the Netherlands). Through multiple hydraulic or electric wedge blocks under the worktable, it dynamically adjusts the table deformation during bending to ensure consistent angles along the entire length of long workpieces. This is one of the essential differences between high-end and mid-to-low-end equipment. Backgauge System:
Number of Axes: At least X (back positioning), R (backgauge rise), and Z (independent left and right adjustment) axes are required. High-end applications require more axes (such as independent X1/X2, additional Y-axis, etc.) to achieve complex positioning.
Precision and Rigidity: High-precision ball screws and linear guides are fundamental to ensuring positioning accuracy.
Step 3: Automation and Flexibility Considerations
The degree of automation is determined by the production mode.
Basic Automation:
Automatic Die Changing System: For multi-variety production, it can significantly reduce die changing time (from hours to minutes).
Front Support Rack and Backgauge Feeder: Assist in loading and unloading, reducing the labor intensity of workers.
Advanced Automation (Robot Bending Unit):
Bending Robot: Suitable for high-volume or heavy workpieces. Considerations must be made for collaborative control between the robot and the bending machine, collision avoidance, and high-precision gripping.
Integration Solution: Select a supplier that can provide a complete solution of "bending machine + robot + programming software".
Step 4: Supplier Evaluation and Service
Equipment is used long-term, making service crucial.
Supplier Strength:
Brand and Reputation: Industry reputation and market share.
Technical Support and Training Capabilities: Does the supplier provide system operation, programming, and maintenance training?
Localized Service: Service network distance, response speed, and spare parts inventory.
Trial Bending and Reference:
On-site Trial: Bring your typical workpieces (especially the most difficult to process) to the supplier's facility for on-site bending tests to verify accuracy, efficiency, and ease of use.
Visit Existing Customers: Visit factories using this brand's equipment to understand long-term usage.
Step 5: Comprehensive Cost Analysis (TCO)
Don't just look at the initial purchase price.
Purchase Cost: The price of the equipment itself.
Operating Cost: Power consumption (servo-based power saving), hydraulic oil replacement, and the cost of wearing parts.
Maintenance Cost: Regular maintenance costs and spare parts prices.
Efficiency Benefits: Increased production capacity due to faster bending speeds and shorter mold changeover times.
Quality Benefits: Higher precision and consistency lead to reduced scrap rates and increased product premiums.
Quick Checklist for Selection:
* Does the tonnage and working length meet current and future needs?
* Does the drive method (all-electric/hydraulic) meet production cycle time and environmental requirements?
* Is the CNC system user-friendly, powerful, and supports offline programming?
* Is it equipped with a real-time deflection compensation system?
* Do the number of back gauge axes and their precision meet workpiece requirements?
* Are automation options (such as automatic die change, robotic) needed?
Is the supplier's local service and support reliable?
Is the Total Cost of Ownership (TCO), not just the purchase price, reasonable?
Summary and Recommendations:
* For high-efficiency, high-precision, and green production: Prioritize high-end all-electric servo bending machines, equipped with advanced CNC systems and compensation technologies.
For heavy-duty plate and heavy-duty processing with a limited budget: Consider high-performance hydraulic servo bending machines, but pay close attention to their compensation systems and stability.
High-variety, low-volume production: Automated mold-changing systems and graphical programming software are key investment areas.
High-volume, low-variety production: Robotic bending units should be planned to achieve automated production.
Finally, trial bending with material is an essential step, as it provides the most direct verification of how well the equipment matches your needs. Investing time in thorough preliminary research and testing will bring you stable returns for decades to come.