Machine Bridge / Gantry for CMM - Component Overview

Product Specifications

Technical details and manufacturing context for Machine Bridge / Gantry

Definition

In a Coordinate Measuring Machine (CMM), the Machine Bridge or Gantry is the critical structural component that forms the moving axis system. It typically consists of a rigid, often box-shaped, beam that spans the measurement volume. This bridge moves along one axis (commonly the X-axis) on precision rails or air bearings, while carrying the carriage (Y-axis) and Z-axis ram that holds the probing system. Its primary function is to provide a stable, vibration-dampened platform that ensures the probe can be positioned with extreme accuracy and repeatability anywhere within the machine's working envelope, directly impacting the CMM's overall measurement precision and volumetric accuracy. The bridge is driven by a servo motor or linear motor coupled with a precision ball screw or linear drive system. It moves along hardened and ground guideways or on a cushion of air (air bearings). Position feedback is provided by a linear scale (e.g., glass or reflective) mounted along its travel path. The rigidity and low thermal expansion of the bridge structure minimize deflection and distortion during acceleration, deceleration, and probing, ensuring that the geometric relationship between the probe and the measured part remains constant. Materials commonly used include granite, aluminum alloy (e.g., 6000 series), ceramic composite, and carbon fiber reinforced polymer, each offering different trade-offs in stiffness, weight, and thermal stability. The bridge's performance is characterized by parameters such as measuring range (500×400×300 to 2000×1000×800 mm), maximum payload (500–5000 kg), positioning accuracy (±0.001–±0.01 mm per ISO 10360-2), repeatability (±0.0005–±0.005 mm per ISO 10360-2), maximum traverse speed (300–600 mm/s), and operating temperature (15–30°C). It requires a servo motor drive, air bearing guide system, and air supply pressure of 0.4–0.6 MPa. The bridge is available with IP ratings from IP54 to IP65. When selecting a bridge, verify model-specific values and standards with the legal manufacturer or supplier.

Working Principle

The bridge is driven by a servo motor or linear motor coupled with a precision ball screw or linear drive system. It moves along hardened and ground guideways or on a cushion of air (air bearings). Position feedback is provided by a linear scale (e.g., glass or reflective) mounted along its travel path. The rigidity and low thermal expansion of the bridge structure minimize deflection and distortion during acceleration, deceleration, and probing, ensuring that the geometric relationship between the probe and the measured part remains constant.

Common Materials

Granite, Aluminum alloy (e.g., 6000 series), Ceramic composite, Carbon fiber reinforced polymer

Technical Parameters

Parameter	Typical range	Notes & selection driver
Measuring Range (X×Y×Z)	500×400×300–2000×1000×800 mm	Select based on workpiece size.
Maximum Payload	500–5000 kg	Includes workpiece and fixture weight.
Positioning Accuracy	±0.001–±0.01 mm	Higher accuracy for precision measurement.ISO 10360-2
Repeatability	±0.0005–±0.005 mm	Critical for consistent measurements.ISO 10360-2
Maximum Traverse Speed	300–600 mm/s	Higher speed improves throughput.
Drive System	Servo motor	Servo motor for precise control.
Guide System	Air bearing	Air bearing for frictionless movement.
Material	Granite	Granite for thermal stability and damping.
Operating Temperature	15–30 °C	Temperature affects accuracy.ISO 10360-2
Humidity Range	40–60 % RH	Avoid condensation and corrosion.
Power Supply	220/380 V AC	Three-phase or single-phase as required.
Air Supply Pressure	0.4–0.6 MPa	Required for air bearing systems.
Weight	2000–15000 kg	Affects installation and floor loading.
IP Rating	IP54–IP65	Protection against dust and water.IEC 60529

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Bridge Beam
The primary load-bearing spine of the structure, designed for high stiffness and low mass.

Material: Aluminum alloy or composite
Guideway Rails Part
Precision-hardened rails that provide the smooth, straight reference surface for bridge movement.

Material: Hardened steel or ceramic
Carriage (Y-Axis Saddle)
The component mounted on the bridge that moves along the Y-axis, carrying the Z-axis ram.

Material: Aluminum alloy
Drive System (Motor & Screw)
Converts rotary motor motion into precise linear motion of the bridge.

Material: Steel (ball screw), rare-earth magnets (linear motor)
Linear Encoder Scale Part
Provides high-resolution positional feedback to the machine controller for closed-loop motion control.

Material: Glass with chrome plating or reflective tape
Air Bearings Optional
Support the bridge on a cushion of air instead of rolling on the guideways.

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Machine Bridge / Gantry.

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Coordinate Measuring Machine

View system integration details

Manufacturers of Machine Bridge / Gantry

2 companies list this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.

Rugao Lian Tuo Electronics Co.,Ltd

Jiangsu, CN

Also makes: Bridge Rectifier, Junction Box, Photovoltaic Panel and 4 more

Listed on the company's own website · profile compiled by CNFX from public sources

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Wuxi Yacai Precision Machinery Co., Ltd

Jiangsu, CN

Also makes: Magnetic Separator, Screw Conveyor, Chip Conveyor and 5 more

Listed on the company's own website · profile compiled by CNFX from public sources

View profile Send enquiry

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Frequently Asked Questions

What is the primary function of the Machine Bridge in a CMM?

The Machine Bridge provides a stable, rigid platform that supports and guides the probe head, enabling precise three-dimensional movement within the measurement volume. It directly influences the CMM's accuracy and repeatability.

Which materials are commonly used for the bridge structure?

Common materials include granite, aluminum alloy (e.g., 6000 series), ceramic composite, and carbon fiber reinforced polymer. Each material offers different properties in terms of stiffness, weight, and thermal stability.

What are typical positioning accuracy and repeatability values?

According to ISO 10360-2, positioning accuracy ranges from ±0.001 to ±0.01 mm, and repeatability from ±0.0005 to ±0.005 mm. These values are reference ranges and must be confirmed for the specific model.

How does the bridge achieve precise movement?

The bridge is driven by a servo motor or linear motor with a precision ball screw or linear drive. It moves on hardened guideways or air bearings, with position feedback from a linear scale. This setup minimizes deflection and ensures accurate positioning.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification

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pressure:	N/A (structural component, not pressure-rated)
other spec:	Max acceleration: 0.5-2.0 m/s², Max velocity: 0.5-1.5 m/s, Positioning accuracy: ±0.5-5 μm, Environmental vibration tolerance: <0.5 μm amplitude
temperature:	15°C to 25°C (operational), 10°C to 30°C (storage)

Machine Bridge / Gantry

Product Specifications

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