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How to avoid some problems with U-drill in CNC machining?

The difference between U drills and ordinary drills is that U drills use inserts - a peripheral insert and a central insert. In this respect, the relationship between U drills and ordinary hard drills is in fact similar to that between chucking and welding turning tools, and U drills can be replaced directly without resharpening when they wear out.

After all, using an indexable insert still saves material compared to an integral hard drill, and the consistency of the insert makes it easier to control the size of the part.

SO, the U-drill is a good choice for you!

The U-drill can drill holes in surfaces with an inclination angle of less than 30° without having to reduce the cutting parameters.


▲The U drill's cutting parameters can be reduced by 30% to enable interrupted cutting, such as machining intersecting holes, intersecting holes and interpenetrating holes.


▲The U drill enables drilling of multi-step holes and the ability to bore, chamfer and eccentrically drill.


▲U drill drilling chips are mostly short chips and can use its internal cooling system for safe chip removal without cleaning chips from the tool, which is conducive to product machining continuity, shortening machining time and increasing efficiency.


The U-drill can be used to drill holes without the need for chip evacuation under standard L/D conditions.


The U-drill is an indexable tool that requires no sharpening when the insert wears out, making it easier and cheaper to replace.


The U-drill has a small surface roughness value and a small tolerance range, which can replace some of the work of boring tools.


The U-drill does not require a pre-drilled centre hole, and the bottom surface of the blind hole is straighter, eliminating the need for a flat bottom drill.


The U-drill technology not only reduces the number of drilling tools, but also allows the U-drill to have more than ten times the cutting life of an ordinary drill because of the way the head is set with carbide inserts, while the inserts have four cutting edges, which can be replaced at any time when the inserts wear out.


Common problems with U-drills


❶ Blades break too quickly and are prone to breakage, increasing machining costs.


❷ Harsh whistling sound during machining and abnormal cutting condition.


❸ The machine shakes, affecting the machining accuracy of the machine.


Points to note when using the U-drill


▲ The U-drill must be installed in a positive and negative direction, which blade is up and which blade is down, which faces in and which faces out.


The centre height of the U-drill must be corrected, according to its diameter to require control range, generally control within 0.1mm, the smaller the diameter of the U-drill, the higher the centre height requirements, the centre height is not good U-drill two sides will wear, the hole diameter will be large, shorten the life of the blade, small U-drill, it is easy to break.


▲ The U-drill has high requirements for coolant. It must be ensured that the coolant is ejected from the centre of the U-drill and the pressure of the coolant should be as high as possible, and the excess outlet of the turret can be plugged up to ensure its pressure.


▲ The cutting parameters of the U-drill are strictly in accordance with the manufacturer's instructions, but it is also necessary to consider different brands of inserts, the power of the machine tool, and the size of the load value of the machine tool can be referred to during processing to make appropriate adjustments, and generally adopt high speed and low feed.


▲ U-drill inserts should be checked frequently and replaced in time, and different inserts should not be installed in reverse.


▲ Adjust the feed according to the hardness of the workpiece and the length of the tool overhang, the harder the workpiece, the greater the tool overhang and the smaller the tool travel should be.


The harder the workpiece, the greater the tool overhang and the lower the travel. ▲ Do not use excessively worn inserts, and keep a record of insert wear in relation to the number of workpieces that can be machined in production and replace them with new inserts in a timely manner.


▲ Use adequate and correctly pressurised internal coolant. The main purpose of coolant is chip evacuation and cooling.


▲ U-drills should not be used for machining softer materials such as bronze, soft aluminium etc.


Tips for using the U-drill in CNC machines


1. The use of the U-drill requires high rigidity of the machine tool and the alignment of the tool with the workpiece, so the U-drill is suitable for use on high power, high rigidity and high speed CNC machine tools.


2. When using the U-drill, the central insert should be a good tough insert and the peripheral insert should be a relatively sharp insert.


3、Processing of different materials, should be used with different groove-shaped inserts, in general, small feed, small tolerances, U drill length and diameter ratio of large, choose a smaller cutting force groove-shaped inserts, on the contrary, rough machining, large tolerances, U drill length and diameter ratio of small, choose a larger cutting force groove-shaped inserts.


4、U drill must be used to consider the machine tool spindle power, U drill clamping stability, cutting fluid pressure and flow, while controlling the U drill chip effect, otherwise it will largely affect the hole surface roughness and dimensional accuracy.


5. When clamping the U-drill, make sure that the centre of the U-drill coincides with the centre of the workpiece and is perpendicular to the surface of the workpiece.


6、When using the U-drill, choose the appropriate cutting parameters according to the different part materials.


7. When using the U-drill for trial cutting, be sure not to reduce the feed or lower the speed at will because you are afraid of being careful, and break the U-drill insert or damage the U-drill.


8. When using the U-drill for machining, if the insert is worn or broken, carefully analyse the cause and replace it with a tougher or more wear-resistant insert.


9. When using the U-drill to process stepped holes, be sure to start processing from the large holes first, and then process the small holes.


10. When using the U-drill, pay attention to the cutting fluid to have enough pressure so that the chips can be flushed out.


11. The inserts used in the centre and edge of the U-drill are different and must not be used incorrectly, otherwise the U-drill shank will be damaged.


12. When drilling with a U-drill, the workpiece can be rotated, the tool can be rotated and the tool and workpiece can be rotated at the same time, but when the tool is moving in a linear feed, the most common method is to use the workpiece rotation.


13. When machining on a CNC lathe the performance of the lathe should be taken into account and appropriate adjustments made to the cutting parameters, generally a lower speed and a lower feed.

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Contact: Jacky Wang

Phone: +86 14714816052

Tel: +86 14714816052

Email: [email protected]

Add: Floor 1, Shixi Industrial area, Canton, Guangdong, China. 510288

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