The Tool Centering Instrument and Tool Measuring Instrument: The Key Technology of Improving Precision Machining

Introduction

In the cutthroat competition of modern manufacturing, the precision and efficiency of machining centers directly determine a company's core competitiveness. As critical equipment in CNC machining, tool setting instruments and tool measuring instruments significantly enhance processing quality and production efficiency by accurately measuring tool parameters and promptly compensating for machining errors. With the growing demand for high-precision and high-efficiency machining, these measuring devices have become indispensable components of modern machining centers. This article will delve into the principles, classifications, and practical applications of tool setting instruments and tool measuring instruments in machining, providing professional references for manufacturing enterprises.

I. Basic Concepts of Tool Setters and Tool Measuring Instruments

The tool setter, also known as an in-machine tool setter or automatic tool setter, is a standard accessory in CNC machine tools. It fundamentally differs from the tool pre-adjuster: the tool pre-adjuster is a standalone tool measurement instrument that requires manual operation and measurement before tool installation. In contrast, the tool setter is integrated into the machining center, enabling real-time tool detection and monitoring during the machining process.

Tool measuring instruments are versatile equipment for tool measurement, including different types such as tool setters, tool pre-adjusters, and measurement centers. Their core function is to accurately measure tool geometric parameters like length, diameter, and radial runout, providing precise tool offset data for CNC machining. In high-precision machining, these instruments not only measure basic dimensions but also inspect complex parameters like rake angles and flank angles, meeting the stringent requirements of precision machining.

The tooling system achieves intelligent and automated machining through seamless integration with the machine tool's CNC system. Before processing, it automatically measures tool parameters and sets up the workpiece coordinate system. During operation, it monitors tool wear in real time. After processing, it performs preliminary quality inspection on the finished product. This comprehensive tool management significantly enhances the machining center's intelligent capabilities.

II. Classification and Technical Principles of Tool Setters

1. Contact-Type Tool Setter

The contact-type tool setter is currently the most widely used tool alignment device, featuring repeatability accuracy within 1μm and a service life exceeding 6 million cycles. Operating on mechanical contact triggering, it activates a high-precision sensor when the tool contacts the measuring head. The system instantly records the position data of each axis, then automatically calculates the tool's offset value by comparing it with the reference position.

Contact-type tool setting instruments are categorized by signal transmission methods. Cable-based models offer optimal cost-performance per unit, though their cable drag limits application scenarios, primarily for small-to-medium three-axis milling machines and machining centers. Infrared-based instruments typically transmit signals within 6 meters, utilizing encoded HDR infrared technology to eliminate cable drag. These devices can be removed from the worktable post-setting without occupying machining space, making them suitable for medium-sized and large CNC lathes. Radio-based instruments achieve signal transmission distances exceeding 10 meters with minimal environmental interference, ideal for heavy-duty and large-scale machine tools.

2. Laser Tool Setter

Laser tool gauges operate on a non-contact measurement principle, detecting trigger signals generated when rotating tools partially block laser beams. The BLUM machining center laser tool gauge from Germany exemplifies this technology. Its working mechanism involves: when rotating tools obscure 85% of the laser beam, the system generates trigger signals transmitted to the NC system. The NC system then records positional data and calculates tool parameters through macro programming.

The laser tool setter demonstrates exceptional capabilities in measuring ultra-fine tool diameters (down to 0.008mm) with repeatable precision of 0.2μm. By rotating the tool at high speed during measurement, it achieves near-identical conditions to actual machining, significantly enhancing practical accuracy. Additionally, the system performs contour scanning, profile measurement, and edge wear monitoring for multi-edged tools.

3. Tool Measurement Center

The tool measurement center is an advanced tool measurement device that employs autofocus technology to capture depth information, enabling the calculation of parameters such as rake angle and flank angle that are unmeasurable by conventional instruments. For instance, the Zoller Genius3 measurement center utilizes a sensor system comprising two CCD cameras, a linear encoder, and a rotary encoder. Its mechanical system includes three linear motion worktables and two rotary motion pairs, with position sensors installed on each axis. The CNC system drives the motor to achieve four-axis synchronization, automatically completing the entire measurement process.

The measurement center's software system integrates advanced features including automatic focusing, edge detection, and data fitting. The automatic focusing function uses a motor to drive the lens forward and backward, capturing images from various positions and determining the optimal focus point through image clarity analysis. The edge detection function identifies tool boundaries by analyzing image pixels. The data fitting function employs algorithms such as B-spline interpolation to enhance computational accuracy.

III. Application Value of Tool Setters in Actual Processing

1. Improve Machining Precision

The tool setter significantly enhances machining accuracy through precise measurement of tool parameters. Unlike traditional methods that rely on manual trial cutting with substantial subjective errors, this instrument achieves micron-level precision in length and diameter measurements. More importantly, it measures tools under actual machining conditions, accounting for factors like spindle thermal deformation and tool clamping force, ensuring results that closely reflect real-world processing scenarios.

In practical applications, tool compensators effectively mitigate errors caused by thermal deformation in machine tools. During operation, machining centers may experience structural deformation due to environmental temperature fluctuations and internal heat generation, which compromises machining accuracy. Regular tool parameter monitoring through these compensators enables real-time adjustment of tool offsets to counteract thermal effects. Research demonstrates that implementing thermal compensation with tool compensators can elevate a machining center's Cycle Performance Index (CPK) to over 2.95, achieving exceptional process quality standards.

2. Improve Production Efficiency

Statistics reveal that in a single workpiece machining process, pure machine time accounts for approximately 55%, while auxiliary time for tooling and tool setting makes up 45%. The implementation of a tool setter significantly reduces auxiliary time and enhances equipment utilization. For CNC machines without tool setters, each tool's offset value must be determined through trial cutting, measurement, calculation, and compensation—a cumbersome process prone to defective products. In contrast, tool setters enable automatic measurement and configuration of tool parameters, reducing tool setting time from several minutes to just a few dozen seconds.

Furthermore, the tool damage detection feature of the tool setter significantly reduces downtime. During machining, operators often fail to promptly identify tool wear—particularly with small-diameter drill bits—which could lead to further tool damage or even workpiece rejection. The tool setter automatically measures tool length after processing and triggers immediate alarms upon detecting wear, effectively preventing mass production of defective products.

3. Reduce Production Costs

The tool alignment system reduces production costs through three key approaches: First, it minimizes scrap rates by implementing precise tool alignment and damage detection, preventing workpiece rejection caused by tool inaccuracies. Second, it extends tool lifespan through wear monitoring and optimized replacement schedules, avoiding both premature and delayed tool changes. Third, it lowers technical requirements for operators, reducing training costs and workload for skilled technicians.

The economic benefits of tool compensators are particularly pronounced in mass production. For instance, in manufacturing complex automotive components like engine blocks and cylinder heads, these devices enable automated tool compensation to ensure consistent product quality. Case studies demonstrate that implementing tool compensators can elevate a production line's process capability index (CP) to 3.24 and its CPK to 2.95, resulting in significant quality improvements.

4. Implement Intelligent Production

The tool setter is a critical component enabling intelligent and automated production in machining centers. By integrating seamlessly with CNC systems, it provides essential data support forFlexible Manufacturing Systems (FMS) and Computer Integrated Manufacturing Systems (CIMS). In modern smart workshops, the tool setter's measurements are transmitted to the central management system, allowing comprehensive monitoring and intelligent management of tool life cycles.

The tool measurement system is integrated with the in-machine measurement system to form a complete machining quality control system. This system not only monitors tool parameters but also performs automatic alignment and compensation for workpieces and fixtures, achieving comprehensive control throughout the machining process. For instance, in automotive engine cylinder block machining, the system uses a probe to measure cylinder height and automatically calculates milling parameters, ensuring the precision requirements of the cylinder liner installation plane.

IV. Selection and Use of Tool Setters

1. Selection Principles of Tool Setters

When choosing a tool setter, several factors should be considered. First, the processing requirements: for small and medium-sized machining centers, cable contact tool setters offer good cost-performance; for large machine tools, infrared or radio transmission tool setters are more suitable; for high-speed processing and micro tools, laser tool setters are the best choice.

Secondly, the precision requirements vary by industry. For high-precision applications like mold manufacturing and aerospace, laser or high-end contact-type tool gauges are required, whereas standard contact-type gauges suffice for general component processing.

The compatibility between the tool setter and the machine tool control system is also a key consideration. Seamless integration between the tool setter and the machine tool's CNC system requires that the tool setter's interface protocol matches the control system. Most tool setter manufacturers provide compatible interfaces for mainstream CNC systems, including FANUC, SIEMENS, and HEIDENHAIN.

2. Precautions for Installation and Use of Tool Setters

The installation position of the tool setter should be considered according to the actual situation of the machining site. It should be installed in the place where the iron chips are less on the worktable as far as possible to avoid the influence of the iron chips on the measurement accuracy. At the same time, the position of the tool setter should be convenient for operation and not easy to be collided by the workpiece or fixture.

During operation, observe these key points: The tool must maintain a vertical contact surface with the tool setter, ensuring downward orientation. Settling speed should be controlled between 50-200mm/min. The tool diameter should not exceed 20mm. After setting, lift the tool vertically away from the surface to prevent lateral movement that could damage the tool setter.

Regular maintenance of the tool setter is also crucial. Clean the contact surfaces of metal debris and inspect all components for integrity. For infrared and radio transmission models, periodically check the battery status to ensure stable signal transmission.

3. Calibration and Accuracy Guarantee of Tool Setters

The precision of the cutting tool tester directly affects the machining accuracy, so regular calibration is essential. The calibration cycle depends on usage frequency and environmental conditions. Professional calibration is generally recommended every six months or annually.

The calibration should be performed with standard reference tools and in accordance with standard procedures. For contact-type tool gauges, the repeatability of the probe and the force of contact should be checked; for laser tool gauges, the parallelism and intensity of the laser beam should be checked.

The environmental conditions have a significant impact on the calibration results. The working temperature of the knife instrument should be between -25℃ and 70℃, and the voltage should be stabilized within the range of DC10-30V. At the same time, adverse factors such as vibration and electromagnetic interference should be avoided.

V. Technological Trends and Prospects

Tool measurement technology is advancing toward higher precision, intelligentization, and integration. On one hand, measurement accuracy continues to improve, with emerging technologies like laser measurement reaching sub-micron precision. On the other hand, measurement capabilities are expanding from basic geometric parameter analysis to advanced functions including tool contour scanning, wear analysis, and service life prediction.

Online measurement and real-time compensation technologies have emerged as key research priorities. With the advancement of Industrial Internet of Things (IIoT) technology, the integration between cutting tools and machine tool numerical control systems has significantly increased, enabling real-time optimization and compensation of machining parameters. Meanwhile, intelligent tool management systems based on big data analytics are gaining widespread adoption. By analyzing historical data, these systems predict tool lifespan and optimize machining parameters.

Although the technology of domestic tool alignment instruments started relatively late, it has made remarkable progress. Domestic enterprises such as Harbin Measuring and Cutting Tools Group and Tianjin Tianmen Precision Machinery have already launched their own brand of tool pre-adjustment instrument products. With the transformation of China's manufacturing industry towards high-quality development, the technical level of domestic tool alignment instruments and tool measuring instruments will continue to improve, and the market prospects are broad.

Epilogue

As core components of modern machining centers, tool setting instruments and tool measurement devices play an irreplaceable role in enhancing machining accuracy, production efficiency, and intelligentization. With manufacturing industries raising quality standards, these measurement tools are expected to see wider adoption. Manufacturers of machining centers should fully recognize the importance of tool setting instruments, select and configure them appropriately based on their specific needs, leverage their technical advantages, and ultimately boost product competitiveness.

For manufacturing enterprises, investing in high-quality tool gauges and instrument measurement devices is not merely an upgrade of equipment, but a strategic move for future development. In the wave of Industry 4.0 and smart manufacturing, companies mastering advanced measurement technologies will gain a competitive edge in the market and secure a head start in growth.