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Laser Calibration

CMTI offers services for on-site calibration of Conventional and NC/CNC machines, Measuring machines and alignment of large machines like Roll Grinding Machines, Plano Millers and Floor type boring machines, diesel engines and structures like Rails, Guide tracks, etc. CMTI pioneered calibration of machine tools more than three decades ago, with the first Laser Measurement System in the country. Since then this activity has achieved phenomenal growth and has been extended to levelling and alignment work.
 
All calibrations and measurements carried out are traceable to National/International standards as traceability is an essential and mandatory requirement of ISO 9001/QS 9000 series certification processes. The Laser laboratory is accredited by NABL for on-site calibration of Machine Tools, Coordinate Measuring Machines and other measuring machines.
 
LASER MEASUREMENT SYSTEM – A Tool for Calibration of Machines and CMMs 
Laser is a powerful measurement tool and has now become an industry standard for various type of linear and angular measurements. With wavelength of Laser light as the basis, Laser interferometer enables measuring distances down to submicron levels. With appropriate optics, a complete check on a machine can be made for positional and geometrical accuracy checks like linear positional errors, repeatability, reversal errors, pitch, yaw and straightness errors in slide motion and squareness among axes. In conjunction with a Rotary calibrator, Laser Measuring System can be employed to calibrate Rotary axis also.
 
Dynamic Measurements and Analysis Using Laser Measurement System 
Dynamic measurement and analysis is a solution for testing precision machine tools and measuring machines. The Laser laboratory is equipped with Laser Measurement Systems having higher data capture speeds (up to 5000 Hz), which are used for dynamic measurements like Velocity and Acceleration of slides, which reveal drive errors and stick slip motion. These systems can also be used for monitoring various machines elements for their performance.
 
On-line Evaluation and Analysis of Data 
All the Laser Measuring Systems are equipped with latest Computers. On-line usage of computer has made possible immediate presentation of results in numerical and graphical forms conforming to standards like ISO, NMTBA, VDI-DGQ, JIS & CMMA. The instant availability of results immensely helps in effecting immediate mechanical adjustments on the machine and software compensation in the control system.
 
Laser Measurement System for Alignment 
The Laser Laboratory also offers services in the activity of Alignment using Laser Measurement/Alignment System. Alignment of the machine prior to calibration is necessary before starting the calibration exercise. The services include, alignment of guide ways, guide rails, bores, guide tracks, etc.
 
Alignment and Calibration of Roll Grinding Machines 
The exercise of levelling, aligning and checking of Roll Grinding Machines (RGMs) used in Paper making industries, needs technical expertise and precise equipment to monitor the refinements achieved. The technical expertise has been developed by the laboratory to monitor various parameters during and after levelling and alignment exercise. The laboratory possesses Laser Measuring Systems, Laser Alignment System, electronic levels, Auto collimators, rotary calibrator, Alignment telescope, etc. to assist in the above work. Perhaps CMTI is the only organization in the country providing such a systematic service.
 
Calibration Of Laser Measuring System
The Laser Laboratory maintains a Reference Laser Measurement System with traceability to International Standards as a Master. Using this system, other Laser Measurement Systems are calibrated by comparison. The calibration covers the overall accuracy of the system along with the individual accuracies of Laser head and Sensors.
 
Evaluation Of Contouring Accuracy
The Laboratory is equipped with a Telescopic Ball Bar System and Grid Encoder with analysis software is used for quick evaluation of contouring accuracy of CNC Machines.
 
Ball Bar System 
Ball Bar System with its software is used to measure geometrical errors present in the CNC machines and detect inaccuracies induced by its controller and servo drive systems. A Ball Bar Test is performed in which a circle is scribed by the machine. Small deviations in the radius of this movement are measured by a transducer and are captured by the software. If machine has no errors the plotted data will show a perfect circle. The deviations from perfect circle give us the inaccuracies like Reversal error, Straightness of slides movement, Relative Squareness of axes, Lateral play in the axis, Positioning accuracy, reversal spike, servo system lag and lead error, etc.
 
Grid Encoder:
Grid Encoder is used for dynamic testing of the contouring accuracy of CNC machines (Non contact measurement) at very high feed rates up to 80 m/min.
 
This equipment is used to carry out free form or corner test, step response test and also measures static positioning accuracy and Guide way (linear) error. This instrument is used as a measuring system for the machine tool inspection and acceptance as per ASME and ISO standards. The accuracy, specifications and software/measurement features of the system satisfy the requirements of ASME and ISO standards (of ASME-B5 and ISO 230-4) for machine tool performance evaluation.
 
Instrumentation Available in CMTI for Machine Tool Calibration and Alignment
Grid Encoder is used for dynamic testing of the contouring accuracy of CNC machines (Non contact measurement) at very high feed rates up to 80 m/min.

  • Laser Measurement Systems
  • Rotary Calibrator
  • Laser Alignment System
  • Ball Bar
  • Grid Encoder
  • High Precision Autocollimator with plane and Polygon mirrors
  • Alignment telescope
  • Electronic levels
  • Quick check ball bar
  • Precision Granite Measuring Aids like Straight edge and Squares of various sizes
  • Precision Step Gauge

 

 

Contact: Girish Kumar M, Sc-C
E-mail : girishkumar.cmti@nic.in

 

 



by Dr. Radut.