Air Plug Gauge to Check ID Bore
Precision Internal Diameter & Bore Measurement with Setting Rings
Linear Resolution: 0.1 µm (0.0001 mm)
Repeatability (Gage R&R): ≤ 0.5 µm (< 10%)
Operating Line: 3–4 bar Regulated Pneumatic
Master Calibration: ISO 17025 / DIN 2250
Product Overview
AKIRA Air Plug Gauges are high-precision non-contact pneumatic gauges engineered to inspect inside diameters (ID), taper, and ovality across high-volume precision manufacturing. Sourced with hard chrome plating for extreme durability and supplied for through, blind, and step bore applications.
Technical Definition & Operating Principle
An air plug gauge is a non-contact pneumatic comparator designed to measure the internal diameter (ID), taper, and ovality of high-precision machined bores from 2 mm to 200 mm. Operating on the back-pressure differential principle, compressed air regulated between 3 and 4 bar (45 psi) passes through calibrated diametrical nozzles. As the clearance between the gauge body and the workpiece bore changes, the resulting back-pressure variation is converted into linear dimensional readings with sub-micron resolution up to 0.1 µm. Manufactured with high-wear-resistant hard chrome plating or tungsten carbide bodies, air plug gauges prevent contact scratching on super-finished automotive cylinders, bearing sleeves, and hydraulic valve bodies. The system utilizes double-master comparative calibration, requiring minimum and maximum setting master rings traceable to ISO/IEC 17025 standards. Available configurations include through-bore, blind-bore (with jets positioned near the leading edge), and stepped-bore designs equipped with adjustable mechanical depth stops.
Technical Review & Specification Sign-off
Technical specifications reviewed and verified by Kalidoss, Lead Metrology Applications Engineer at AKIRA Precision Automation. Calibration methodologies certified traceable to ISO/IEC 17025:2017 and DIN 2250-C setting standards.
Key Features
- Can be supplied for through bore / blind bore applications
- Adjustable depth collars can be provided for checking a specific depth
- Standard measurement range: 2 mm to 200 mm
- Hard chrome plated construction for long life
- Precision manufactured to partner with AKIRA display units
- Two setting rings ensure precise comparative zero and span setting
Technical Specifications
| Specification | Parameter |
|---|---|
| Diameter Range | 2 mm to 200 mm |
| Bore Applications | Through bore, Blind bore, Step bore |
| Surface Treatment | Hard chrome plated |
| Depth Control | Adjustable depth collars available |
| Master Requirements | Two setting rings required (Double Master Calibration) |
| Principle | Pneumatic back-pressure differential measurement |
| Wear Resistance | High-wear resistant hard chrome plating |
Frequently Asked Technical Questions
- How do air plug gauges inspect blind bores without jamming at the bottom?
- For blind-bore applications, AKIRA positions the pneumatic measuring nozzles close to the leading edge of the plug body (as close as 1.0 to 1.5 mm from the tip). This allows full-depth diameter inspection without mechanical interference or bottoming out.
- What calibration masters are required for an air plug gauge?
- Air plug gauges require two certified setting master rings (Minimum and Maximum) manufactured to DIN 2250-C Grade standards. This double-master calibration sets both the zero datum and linear magnification span across the measuring range.
- What is the expected operating life of a hard chrome plated air plug gauge?
- Because pneumatic gauging maintains an escaping air cushion between the plug body and workpiece bore, mechanical contact is virtually zero. Hard chrome plated bodies typically exceed 300,000 inspection cycles, while tungsten carbide bodies exceed 1,000,000 cycles under proper air filtration.
- Can an air plug gauge detect bore out-of-roundness and taper simultaneously?
- Yes. By rotating the air plug 90 degrees or scanning axially along the bore, operators can detect ovality and taper. For automated stations, multi-jet plugs (with 4 or 6 nozzles across multiple planes) measure diameter, taper, and ovality in a single stationary stroke.
Industrial Applications
- Automotive engine cylinder and liner bore inspection
- Precision bushing, sleeve, and bearing ID checks
- Through bore, blind bore, and step bore quality control
- Hydraulic valves, pumps, and pneumatic actuators