To guarantee quality output one has to ensure geometrical accuracy, meaning the straightness, perpendicularity and levelness of axles. Proper geometrical accuracy is a starting point for the machine’s measurement accuracy, meaning the measurement and adjustment of dynamic accuracy of both the axles and positioning accuracy. We have several specialized measurement devices developed for selected geometric parameter measurement and leveling.
The difference in the positional coordinates to which a machine actually moves and the theoretical coordinates.
ou have commanded the machine to move to position X = 10.581 mm. When the machine moves, it actually reaches 10.57 mm. so the positional accuracy in this case is difference between actual and theoretical values, i.e. 10.581 – 10.571 = 0.010 mm. Generally, positional accuracy is not calculated by a single measurement. Multiple readings are taken when a machine moves to multiple programmed points and all deviations recorded. The statistical average value all these deviations is the positional accuracy of the machine.
It is the reproducibility of the values when the machine is asked to move to a targeted point multiple times and the difference in various values is the repeatability.
You ask machine to move to target point 10.58 mm, 5 times. The actual values to which the machine moves are 10.570, 10.568, 10.571, 10.567 and 10.572 mm. Repeatability in this case is difference between two extreme positions, i.e. 10.572 – 10.567 = 0.005. In reality, repeatability is calculated using multiple readings over multiple points.
Repeatability is more important than positional accuracy for consistant results.
Positional accuracy and repeatability is measured separately for each individual axes of the machine (X, Y, Z etc.).
This measurement is done by an instrument called Laser Interferometer.
Ballbar is a precision measurement tool that collects axis movement when moving in circular motion. The Ballbar test will measure any deviation the machine makes from a perfect circle, recording data as the two axes work together. Errors such as Backlash, Squareness, Servo Mismatch, Reversal Spikes, Lateral Play, Squareness and other errors can be determined. Users can be useful in determining what feed rate delivers the best accuracy by running the test at different feed rates. A longer length may be used to increase sensitivity to geometry errors, such as Squareness ; while a very small radius may be used to highlight errors such as servo mismatch.
Ballbar is used for primarily preventative, predictive maintenance and for determining problems which are hard to tell by the use of indicators. Plots are usually compared at looking for some change in the plot and can hopefully catch the problem early.
The term used today in the world of business is ‘Customer Delight’. In the era of ‘Six Sigma’, the best way to keep your customers delighted is to deliver goods on time with Quality that conforms to the requirements. While taking care of customer, one should also take care of his machine productivity and consistency.
The accuracy of machined components depends mainly on the machine tool healthiness in terms of positioning accuracy and repeatability.
To know the machine tool health, Geometrical Accuracies, positioning accuracies and interpolation relations needs to be periodically ensured by performing Laser calibration and Ball Bar Test of all the CNC machine tools. Once positioning accuracy and circularity between axes is known, one can decide, which component can be loaded on which machine to achieve optimum output.
These are very essential machine tool tests for the Tool Room and Production machines like CNC lathe, VMC, VTC, VTL, Drill-tap centers, Wire EDMs, CNC Die Sinking Machines, Laser Cutting Machine etc. This will assure the production team on achieving Cp & Cpk of the process will help the team to pass Production Part Approval Process (PPAP).
It is suggested to perform above tests of the CNC machines once in a year to understand & plan the machine work table usage in future to manage Ball screw wear.
We are in the field of on-site calibration of Conventional, NC & CNC machines, Universal Measuring Machines and Coordinate Measuring Machines by means of Ball Bar and Laser Interferometer.
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.
We provide detailed calibration report containing measurement data, graphical presentation of data and analysis of result as per VDI / ISO / JIS / ISO- 230 Standards. We also provide compensation values required to correct the positional accuracy and the backlash error.
We have got experience of more than 30 years in the field of high precision CNC machine tool building and after sales support. We analyze the laser calibration results and give important tips regarding further machine operating style to achieve better laser calibration results of the same machine next time. We also help our customers by suggesting remedial measures, if required and preventive measures to avoid any damages in future.
We look forward to work with your esteemed organization to keep your CNC machine tools and CNC measuring machines up and performing as per norms.
1. Laser interferometer XL 80, Renishaw, U.K. (For Linear and Rotary axis Measurement.)
Range: 0-40 Meter. Least Count: 0.000001 mm., Beam Accuracy: ±0.5µm per meter
- Positioning error (A)
- Positioning repeatability (R)
- Systematic positioning error (E)
- Reversal (B)
- Mean reversal
- Range of mean bidirectional positioning error (M)
2. Ball bar QC 20 –W, Renishaw, U.K.
Radius 600 mm, Least Count: 0.1 Μm, Accuracy: (0.7 + 0.3% L) μm
- Reversal Spikes
- Lateral Play
- Cyclic Error
- Servo Mismatch
- Scaling Error
- Scaling Mismatch
- Cyclic pitch
- Calculated feed rates
- Center offset
- Positional tolerance
- Best fit radius
3. Geometrical Accuracy measurement :
Precision Sprit Level: RSK – 0.02 mm / meter
Precision Straight Edge: 1000 mm
Precision Square Master: 500 x 300 mm
Plunger Type Dial Gauge: 0.001 mm
Lever Type Dial Gauge: 0.001 mm
- Machine Leveling.
- Straightness of Axis movement.
- Flatness of Work Table.
- Parallelism of Work Table.
- Squareness of Axis Movement.
Experience of more than 30 years
We have got experience of more than 30 years in the field of high precision CNC machine tool building and after sales support.View Gallery
Microcheck Guarantee Quality Output
To guarantee quality output one has to ensure geometrical accuracy, meaning the straightness, perpendicularity and levelness of axles.View Gallery
We are in the field of on-site calibration of Conventional, NC & CNC machines, Universal Measuring Machines and Coordinate Measuring Machines by means of Ball Bar and Laser Interferometer.View Gallery