Machine Bridge / Gantry for CMM - Component Overview

Q: 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.

Q: 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.

Q: 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.

Q: 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.

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.

Application & selection

Application Fit & Sizing Matrix

Operational Limits

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)

Media Compatibility

✓ Clean room environments ✓ Temperature-controlled manufacturing facilities ✓ Low-vibration industrial labs

Unsuitable: High-particulate or corrosive atmospheres (e.g., foundries, chemical processing)

Sizing Data Required

Maximum measurement volume (X, Y, Z dimensions)
Required positioning accuracy and repeatability
Maximum permissible structural deflection under probe load

Risk, maintenance & compliance

Reliability & Engineering Risk Analysis

Failure Mode & Root Cause

Structural fatigue cracking

Cause: Cyclic loading from repeated lifting operations, vibration from moving components, and stress concentrations at weld joints or connection points leading to crack initiation and propagation.

Guide rail and wheel wear/misalignment

Cause: Inadequate lubrication, contamination buildup (dust, debris), improper installation/alignment during setup, and uneven loading causing accelerated abrasive wear and loss of precision movement.

Maintenance Indicators

Visible cracks or deformation in structural welds, beams, or connection points
Abnormal grinding, scraping, or knocking sounds during bridge/gantry movement, especially at start/stop

Engineering Tips

Implement regular laser alignment checks and thermal growth compensation for guide rails to maintain precision and reduce uneven wear forces
Establish a preventive lubrication program with contamination control (sealed systems or clean grease points) and conduct periodic non-destructive testing (ultrasonic or magnetic particle) on high-stress weld areas

Indicative industry ranges for design and RFQ preparation. Confirm the exact figures and applicable standard with the manufacturer before specifying.

Compliance & Manufacturing Standards

Applicable Standards

ISO 230-1:2012 (Test code for machine tools - Geometric accuracy of machines operating under no-load or quasi-static conditions) ANSI B5.54 (Methods for Performance Evaluation of Computer Numerically Controlled Machining Centers) CE Machinery Directive 2006/42/EC (Essential health and safety requirements for machinery)

Quoted from the published standard.

Manufacturing Precision

Bridge parallelism to guideways: ≤0.02 mm/m
Positioning repeatability: ±0.005 mm

Quality Inspection

Laser interferometer geometric accuracy verification
Ball bar test for circular interpolation accuracy

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

Compare the published product scope and source details, then include your specifications and quantity in an enquiry.

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

Listed there as: “Welding Machine Bridge Rectifier”
View source page ↗ electronic-diode.com · recorded 2026-08-29

View profile Send enquiry

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

Listed there as: “Cnc Machine Bridge Drag Chain”
View source page ↗ yacaijm.com · recorded 2026-08-27

View profile Send enquiry

Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.

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.

Related equipment

Applied To / Applications

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

Coordinate Measuring Machine

View system integration details

Industrial Ecosystem & Supply Chain Structure

Complementary Systems

Downstream Applications

Specialized Tooling

Industry Taxonomies & Aliases

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

Data Basis

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

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review · Page last updated 13 October 2026

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