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In lean times like these, manufacturers and component makers like you need to stretch your equipment investment dollar.
To keep your production facilities running, a systematic and calibrated programme of preventive maintenance for your CNC machine tools like CNC lathes and machining centres is needed. This will ensure that your equipment continue to function well despite frequent and prolonged use.
In this article, you will learn some of the best practices in checking, maintaining, and cleaning your CNC machine tools to keep them in optimal condition years after they are installed in your shop floor.
Why CNC Machine Tool Maintenance is Needed
CNC machine tools are not just durable heavy-duty performers – they also need to be extremely accurate to excel in their machining roles on your factory shop-floor.
Machine tools like lathes, milling machines, and multi-axis machining centres often perform multiple machining tasks. Many of these cutting, shaping and drilling tasks are highly complicated, and require specially designed software and hardware to execute. They require long uninterrupted periods of production to suit the unique manufacturing needs of factories – often these stretch for days and nights.
Because of the high levels of performance and long hours of operating and cutting needed for different metal parts and components, regular and preventive maintenance is needed. This will help your CNC machine tool to last longer, remain serviceable for a longer time frame, while maintaining the accuracy and quality of your machined parts.
The Benefits of Regular Maintenance for CNC Machine Tools
Are there any benefits in incorporating a programme of preventive and regular maintenance for your machine tools?
Let us list some of them down for you:
- Help to steadily increase the profitability of your company
- Prevent and reduce machine and production downtime
- Improve and keep the productivity of the machine tool
- Extend the lifespan of both your machines and cutting tools
- Minimise or eliminate crashes or accidents that can be dangerous for operators
- Increase efficiency by using less material and reducing scrap materials
- Reduce and avoid hefty repair costs from unexpected break down of your machines
Now that you’ve learned what the benefits are, let us look at the steps you need to keep your machine tools in prime running condition.
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Daily / Weekly Preventive Maintenance Checklist for Machine Tools
Most of the daily and weekly preventive checks and maintenance tasks are performed by your machine operators.
These routine maintenance procedures are needed to ensure that your production rate is not slowed by simple errors such as the following:
- Stopping of machine due to the failure to top up lubrication oil (or worse, have insufficient stocks of the oil)
- Blockage of production as chips – especially aluminium chips – are not cleared, resulting in chips overflow
- Poor air-supply (volume and quality), which may result in costly damages. Dirty or humid air can affect production quality.
- Drop of coolant levels below the limit, resulting in overheating and damage
Rather than blame the manufacturer, you should institute a simple daily or weekly care and maintenance programme. Here are some steps you or your operator can take:
Check on levels of coolant
Check on the cutting tool at ATC
Check on hydraulic systems for any leakage
Check on air supply to make sure that it is clean and dry
Check for any leakage or strange sounds
Lubricate machine’s moving parts
Ensure that spindles, chucks and any moving parts are cleaned by brushes or flushed with coolant.
Check on pneumatic pumps and chucks.
Note : This is very important as the pneumatic operated chucks are highly sensitive, and work best when they’re regularly maintained. Damages to the sealing and a lack of lubrication can be very costly to repair.
Ensure that chips are cleaned but not blown off to prevent damage.
Note : For CNC machines, the clearance of chips, dirt or coolants should not be done by blowing them away with an air-gun. This is because an air-gun may push chips and coolant in areas where the machine manufacturer actually spends effort to prevent them from reaching (using expensive covers with wipers for example).
Quarterly / Semi-Annual Maintenance Checklist for Machine Tools
On a quarterly or six-monthly basis, check that your coolant tanks, air reservoirs, pumps, and drainages for oil work smoothly. You can do so by making sure that they are clean and free to operate.
For example, your coolant tank may collect sludge over time if it isn’t cleaned regularly. Over time, this may not only reduce your overall tank capacity for coolant – it may affect the purity of your coolant and be detrimental to the performance of your spindle. This is particularly damaging if a CTS (Coolant Through Spindle) system is used. Fine chips and particles will be sucked through your CTS Pump, damaging it in time. Your machine’s toolholders and spindle cones may also be damaged.
To prevent such mishaps from happening, do the following every quarter or half-yearly:
Have the coolant tank cleaned of sludge, chips, and oil
Have the chuck and jaws taken off the machine and cleaned
Have the levelling of your machine checked and adjusted if necessary
Have the radiator cleaned while making sure that the radiator fins are straight and not damaged
Have all way wipers inspected for any damage – clean and replace any wipers that are damaged
Have the hydraulic tank drained, and replace the hydraulic oil with fresh hydraulic oil. Do also ensure that the line filter and suction filter are changed.
Have the lubrication unit drained and cleaned out – thereafter you should add fresh way lubricant
If your machine is equipped with a cooling unit, have the cooling unit drained and refilled
Yearly Maintenance Checklist for Machine Tools
What about your annual maintenance schedule? How do you keep your machine tool in prime condition year after year?
First you need to note that the more axis your CNC Machine Tool has (like a 5-axis Machining Centre), the more critical it becomes to keep it aligned and calibrated. For such complex machine tools, you’ll need to check on the status of your machine beds, hydraulic systems, and spindle lubrication systems. You should also test to ensure that your machine tool accuracy and machine tool level can meet your requirements.
Here are some must-dos for your machine tool every year:
Have the spindle checked for radial and end play issues
Have the chuck cylinder checked for run out
Have the tailstock checked for misalignments and quill function
Have the turret parallelism and inclination checked
Have the whole machine checked for leakage of oil or air
Have the headstock checked for any damage or misalignments, and the spindle taper at milling machines
Have your distributor / supplier check the X, Y and Z axis gibs and adjust if necessary. Check in the same way the function of your 4th axis table
Have your distributor / supplier run a backlash program to check the backlash in X, Y and Z axis and adjust if necessary
On an annual basis, it is recommended to have a CNC machine check overall done in respect of levelling, accuracy and functionality. This should be done by the machine manufacturer service engineers or at least by well trained and factory certified dealer engineers. These qualified professionals would know what to do and what to look out for – they will also have the equipment at hand to do the job properly.
As the saying goes, prevention is better than cure. Just like a human body, keeping your CNC machine tool in healthy running order will ensure its longevity, accuracy and productive use over the long-term.
Incorporating a regular maintenance schedule is thus a must for shop floors that deploy CNC machines for their production processes.
Beyond keeping your machine in good running order, it is important to invest in high quality CNC machine tools that are easy to maintain, and which comes with good after-sales support.
Hwacheon’s machine tools are built with a rigid, top quality, and long-lasting mechanical design. However, like your precious bodies, you need a programme of regular maintenance and care to keep them optimally running for a long time.
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