GENERAL QUALITY INSPECTION AND ASSESSMENT OF CNC MACHINE

Accuracy error in machining is the cause of product failure, reducing quality and productivity that any manufacturer or manufacturer does not want to encounter

.There are many causes of accuracy errors in machining such as:

– Subjective: The way of setting the workpiece, setting the knife of the operator, the selection of cutting tools, the cutting mode of the CNC machine programmer is not reasonable, …

– Objective: Initial accuracy error due to low-quality CNC machine, due to selection of machine structure not suitable for product, machine operating for a long time without maintenance/maintenance or maintenance/maintenance. Improper maintenance leads to the following numbers in the mechanical system, … or because the control part is old also makes the accuracy error in machining.

Precision machining error correction is the foundation of CNC machining process control. Modern industry must meet stricter tolerances and demanding customer schedules and the requirements of international quality standards.

With the pressure to reduce costs, device performance has never been more important. Measuring and calibrating using technological equipment can provide many benefits:

♦ Benefits for machine and service providers:

• Test and diagnose the machine before reaching the consumer.
• Build and refine machines with higher precision to meet Customer demand.
• Reduce machine repair and installation cycle time.
• Provide professional maintenance service.
• Show conformance to specification.

♦ Benefits for Customers:

• Compliant with ISO, JIG,…
• Properly evaluate machine performance, to choose the best machine for every job.
• Plan and minimize machine downtime by tracking wear and tear.
• Win high precision machining contracts from your competitors.
• Improve productivity.
• Extend the life of the machine by identifying its source of failure early.

Due to the outstanding development of the high-tech industry and due to the strict requirements on the quality of processed goods, it is required that the quality and working efficiency of CNC machines must achieve the error index in machining. absolute best.

Therefore, in order to help customers evaluate the quality of the machine before starting to process and produce, as well as predict the possibility of machine failure in order to have a suitable plan for maintenance/repair, we always wants to build solutions to help customers always be assured of the best quality of goods, the lowest machine downtime and the most appropriate repair costs such as:

I. CHECK THE Axis ACCURACY WITH A BALLBAR DEVICE.

The Renishaw QC20-W Ballbar Tester offers you the perfect solution. It is the fastest, easiest and most effective way to monitor CNC machine status.

The heart of the system is the ball bar itself, a very precise linear sensor with precise balls at each end. During use, the balls are kinematically placed between precision magnetic cups, one is attached to the table and the other to the BT in the spindle. This arrangement allows the rod to measure variations in radius as the machine follows a programmed circle (see main illustration below).

Collected data are used to calculate overall measures of accuracy (roundness, roundness deviation) according to international standards such as ISO. Data is displayed graphically as well as in digital format to aid diagnosis and assistance. Supplied as a complete kit, the ballbar kit provides a powerful and portable solution – just add a PC and you’re ready to start the audit process.

This ballbar device helps the process of checking and evaluating the machine’s status in the fastest way and gives the most accurate results to:

• Customers can choose the right machine according to the requirements of the product.
• The engineering department can calibrate the machine in the fastest and most efficient way.

Test items:

• Circle Error Check (Backlash X, Y, Z)
• Check for reversal errors (Reversal spikes X, Y, Z)
• Check servo load and power (Servo mismatch)
• Check the straightness of the axis (Straightness X, Y, Z)
• Check the shaft ratio (Scale mismatch)
• Calculated federate check

II. TEST, EXCEPT POSITION ALREADY WITH LASER DEVICES.

Laser interferometry provides the most accurate and repeatable calibration method.

The basic principle of using the wavelength of light as a unit of measurement dates back to the 1880s. It has since been developed but it is still based on measuring the interference of light waves, hence the name. (Laser interferometry).

The light waves emitted by the laser have three main properties:

• The wavelength is known for its high accuracy, allowing for precise measurements.
• The wavelength is very short, allowing for precise or high-resolution measurements.
• All waves are in phase, allowing measurement from a known reference.

Laser interferometry is a measure of relative motion (measured from the initial position) and not an absolute measurement (measured of a specific location). Different optical choices transmit the laser beam through different paths, allowing measurements with multiple measurement modes (e.g. linear, angular, straight) taken from a single laser unit.

With the errors that all CNC machines encounter such as: the guide rails (ball bearings) and lead screw are worn, the coupling is loose over time, which will lead to errors and unfortunate defects in the product. products and manual inspection also help only a small part in inspection and repair.

Therefore, correcting the accuracy by using a LASER measuring device can fine-tune and compensate for errors straight into the controller of the CNC machine. Help to improve the error in machining is absolute.

Test items:

• Progressive and iterative error (linear).
• Angular error.
• Straightness error.
• Direct pitch error compensation.

III. MAINTENANCE MEASUREMENTS

The CNC milling and turning spindle plays an important role in machining processes because it provides the cutting speed for the tool and is part of the power transmission chain between the CNC machine and the tool or part. Depending on the type of machine, the spindle has different characteristics. Therefore, the periodic inspection and correct assessment of the actual status of this part also greatly contribute to improving the machine’s life as well as stabilizing the machining quality during the production process. Understanding the concerns that most customers have been using CNC machines for processing and manufacturing with the criterion of always accompanying and sharing difficulties with customers, we have also Equipped with all the equipment and tools that are considered the most advanced to help diagnose the possibility of machine failure early as well as respond quickly and accurately during the repair process:

1. MILLING MACHINE MANUAL RUNCHING TOOL (BT TEST BAR HEAD)

The tapered hole of the CNC milling machine spindle is the type that is often damaged by wear due to direct contact or by impact during product processing. Therefore, it greatly affects the quality of the product after processing, so checking the wear with paint marks in contact between the hole and the taper caliper or using the test bar to check the run out and run out of the shaft. CNC milling machine itself to detect damage early and take early remedial measures to reduce repair and replacement costs.

2. MANUAL VIBRATION MEASUREMENT (DYNAMIC BALANCE MACHINE)

Machining machines that require high precision such as lathes, milling, drilling, boring, grinding, CNC machining centers or rotors or motors when newly manufactured, installed, old machines are used for a long time or are being used. Repair and maintenance are often shaken, causing manufacturing errors. The reason is that the center of gravity of the rotating object does not coincide with the center of rotation or the mass is unevenly distributed, leading to unbalance when rotating, especially the higher the speed, the greater the vibration. Dynamic balancing machine is used to overcome this phenomenon.

Principle and operation of dynamic balancing machine (dynamic balancing method).

Thanks to the combination of vibration sensor mounted on 1 to 4 positions, speed sensor and balancing algorithm, the dynamic leveling machine will automatically calculate the correct position, weight of material at that position is increased or decreased to bring the machine back to balance.

3. MAJOR CLEANING DEVICE (DYNA FORCE MEASUREMENT EQUIPMENT)

SAFE CONTROL – Equipment for spindle repair and maintenance work on CNC machines. Serves for measuring clamping force and deflection of the main shaft. Measurement deviation is only 0.5% (accuracy is 0.5 kN) in measuring range from 2-100 kN with all common taper sizes such as BT, HSK, PSK and SK.

=> Ensure machining quality and improve accuracy.
=> Test technology 4.0, allowing users to connect wirelessly to the device.
=> View results via smartphone, store results on software.
=> An effective tool for the maintenance team to quickly detect the machine’s disease, ensuring the machining progress.
=> Increase machine life, reduce new purchase cost.

4. EQUIPMENT FOR MEASUREMENT OF ENCOURAGEMENT IN THE MAIN (SO – DIAL TEST INDICATORS)

A dial gauge is a commonly used device in the mechanical industry. Is a device mounted on the measuring head of a height ruler, specialized in measuring straightness, flatness, … Or used to compare positions in terms of parallelism, perpendicularity, taper, inversion, deviation, …

Thanks to the low error, accuracy is from 0.01mm to 0.001mm. Comparators are used for locations requiring high sensitivity, providing the most accurate data.

5. MANUAL TEMPERATURE MEASUREMENT EQUIPMENT (TEMPERATURE MEASUREMENT EQUIPMENT)

Temperature management and monitoring while the machine is in operation or during spindle repair is a rigorous process that must be followed throughout the process, helping to detect possible abnormalities early. Let the technical team fix it earlier before the damage occurs, helping to prevent the risk of severe damage leading to too much expense for recovery and repair.

So using the right equipment, in the right way and at the right time is your companion to always serve your customers the best.

6. SMALL SPIN SPEED MEASUREMENT

The actual speed of the spindle greatly contributes to the accuracy and aesthetics of each product made, so it is important to check and evaluate the actual spindle running speed at the programmed speed. in the program is a mandatory element to perform before processing products.

Therefore, the introduction of the device to measure the rotational speed of the spindle motor is extremely useful, helping people a lot, bringing great efficiency as well as ensuring safety for users. . Different types of machinery, equipment, and engines will have different measurement methods, using different speedometers. So how do we distinguish and use the right measuring equipment?

=> Let us help you!

Please contact Hotline: 0902 419 483 – 0911 122 122

7. OTHER TESTS