The internal diameter gauge is a precision measuring tool that plays a crucial role in the quality control of mechanical
processing. According to statistics, over 90% of precision processing enterprises are equipped with internal diameter
gauges, and the measurement accuracy usually reaches 0.001 - 0.01mm. However, the failure of internal diameter
gauges occurs frequently during use, with a failure rate of approximately 5-8%, which directly affects the measurement
accuracy and production efficiency. Common failure phenomena include abnormal pointer oscillation, unstable readings,
stuck measuring heads, and loose scale plates. In-depth analysis of these failure causes and mastering the correct
prevention and solution methods are of great significance for ensuring measurement accuracy, extending service life,
and reducing maintenance costs.
I. Failure Issues Caused by Mechanical Structure Wear
1. The wear of the measuring rod and the guide sleeve is the most common cause of failure. The reciprocating motion
of the measuring rod within the guide sleeve will result in wear. When the wear exceeds 0.005mm, significant
measurement errors and shaking will occur. The measuring rods of high-quality internal diameter micrometers are
treated with quenching, with a hardness of HRC 58-62. The guide sleeves are made of bronze or engineering plastics.
The criterion for judging the degree of wear is that the radial clearance of the measuring rod within the guide sleeve
should not exceed 0.008mm, and the axial displacement should not exceed 0.003mm.
2. The wear and damage of the gear transmission mechanism affect the accuracy of the pointer rotation. The internal
gear module of the internal diameter micrometer is usually 0.3-0.5mm, and the gear ratio is 10:1 or 20:1. The gear
accuracy is required to reach grade 6-7. After long-term use, the tooth surface wear will cause an increase in the
transmission gap, resulting in pointer jumping and return error. The typical manifestations of gear wear include uneven
pointer rotation, increased zero-return error, and poor measurement repeatability. At this time, the gear assembly needs
to be replaced.
3. The fatigue failure of the spring components can cause unstable measurement force. The design life of the measuring
spring of the internal diameter micrometer is usually over 1 million times, and the measurement force is controlled within
the range of 1.5 - 2.5 N. After the spring becomes fatigued, its elastic modulus decreases, and the reduced measurement
force can lead to poor contact between the measuring head and the workpiece. The method to determine the failure of
the spring is to check whether the measurement force is within the standard range. Using a force gauge can accurately
measure the spring force value.
II. Performance Degradation Caused by Environmental Factors
1. The influence of temperature changes on the accuracy of internal diameter micrometers cannot be ignored.
The standard operating temperature is 20 ± 2℃. For every 1℃ change in temperature, the measurement error
is approximately 0.001 - 0.002mm. When the workshop temperature fluctuates greatly, thermal expansion and
contraction will cause changes in the length of the measuring rod and deformation of internal components.
Temperature compensation measures include manufacturing key parts with low expansion coefficients, conducting
precise measurements in a constant temperature environment, or using temperature compensation algorithms
to correct measurement results.
2. Humidity and corrosive environments will accelerate the rusting and aging of metal parts. When the relative humidity
exceeds 80%, internal metal parts are prone to rust, especially precision gears and spring components. Corrosive
substances such as cutting fluids and acidic gases can damage the surface coating and lubricating grease.
The significance of protective measures lies in choosing products with a waterproof and dustproof rating of IP65
or above, regularly replacing anti-corrosion lubricating grease, and avoiding long-term use in harsh environments.
3. Vibration and shock can cause significant damage to precision measuring instruments. When the vibration frequency
of the machine tool is within the range of 50-200Hz, it will affect the stability of measurement and the service life of parts.
Accidental drops or impacts may lead to severe damage such as deformation of internal parts and bending of pointer
shafts. Anti-vibration measures include using vibration-absorbing pads, avoiding measurement in high-vibration
environments, and adopting measurement heads with damping design. Special packaging boxes should be used
for transportation and storage to protect the instruments.
III. Damage Caused by Improper Use
1. Exceeding the measurement range is the main human factor leading to the damage of the internal diameter
micrometer. Each specification of the internal diameter micrometer has a clearly defined measurement range,
such as 50-160mm, 100-300mm, etc. Measuring beyond the range will damage the measuring mechanism.
Excessive measuring force can also cause the measuring rod to deform or get stuck. The normal measuring
force should be controlled within the design range. The correct usage method requires the operator to be familiar
with the equipment's specification parameters and check whether the workpiece size is within the measurement
range before measurement.
2. Incorrect zeroing and calibration methods will affect the measurement accuracy. The internal diameter gauge
needs to be calibrated using a standard ring gauge or gauge blocks. The calibration environment requires stable
temperature and no vibration interference. During zeroing, ensure that the measuring head is in full contact with
the standard part, and measure multiple times to confirm the stable reading. The determination of the calibration
cycle should be based on the usage frequency and accuracy requirements. Generally, it is recommended to calibrate
once every 6-12 months, and for high-precision measurements, it is recommended to calibrate once every 3 months.
3. Improper cleaning and lubrication can accelerate the wear and aging of parts. Clean the outer surface with alcohol
or dedicated cleaning agents, and avoid using strong acid or strong alkali solvents. For internal lubrication, use the
specified type of lubricating grease. Excessive lubrication will affect the motion accuracy of the parts. The
standardization of maintenance and upkeep includes formulating detailed maintenance plans, using specialized tools
and materials, and recording maintenance history, etc.
IV. Faults of Electronic Components and Display Systems
1. The failure rate of electronic components in digital internal diameter measuring gauges is relatively high.
The service life of the liquid crystal display of the digital gauge head is approximately 5-8 years, and the lifespan
of the backlight is approximately 1-20,000 hours.Moisture in the circuit board or temperature shock can cause
component failure, resulting in display abnormalities, data jittering, automatic shutdown, and other phenomena.
The reliability design of the electronic system includes using low-power devices, adding electromagnetic
compatibility protection, and using enclosures with good sealing properties.
2. The stability of the sensor system directly affects the measurement accuracy. Capacitive or inductive sensors
are prone to be affected by electromagnetic interference and temperature drift, resulting in an increase in
measurement errors. The non-linear error of the sensor is usually controlled within ±0.001mm, and if it exceeds
this range, re-calibration or replacement is necessary. The key factors for sensor selection include resolution,
stability, response speed, and anti-interference ability, etc.
3. Failures in the data processing and communication module can affect the output and recording of measurement
results. Problems such as wireless transmission failure, damage to the data storage device, and abnormal
communication interface can lead to data loss or transmission errors. The software system needs to be updated
regularly to fix known vulnerabilities and compatibility issues. Data security and backup measures include regularly
exporting measurement data, using cloud storage for backup, and establishing a data recovery mechanism, etc.
V. Preventive Measures and Maintenance Solutions
1. Establishing a comprehensive preventive maintenance system is the fundamental measure to avoid failure.
Develop detailed maintenance plans, including daily inspections, regular calibrations, and parts replacements.
Operators should receive professional training to master the correct usage methods and basic maintenance skills.
The economic benefits of preventive maintenance are significant, reducing equipment failure rates by 60-80%
and extending service life by 2-3 times.
2. The ability to quickly diagnose and repair faults is crucial for ensuring production continuity. Establish a table
correlating fault phenomena with their causes, and equip with common spare parts and maintenance tools.
Simple faults such as cleaning, lubrication, and adjustment can be handled by oneself, while complex faults
require professional maintenance services. The control of maintenance costs should comprehensively consider
factors such as equipment value, severity of the fault, and maintenance expenses, and formulate reasonable
maintenance decisions.
3. Upgrading and equipment renewal are effective ways to enhance reliability. For outdated equipment, consider
upgrading to digital display systems, replacing with wear-resistant materials, and adding protective functions, etc.
When the maintenance cost exceeds 60% of the equipment value, it is recommended to consider updating the
equipment. The trend of new technology application includes wireless data transmission, intelligent diagnosis,
and cloud management, which can significantly improve measurement efficiency and management level.
