How to make a hole and Tips for machining 1. YES drill point has 140 degree self-centering point with below 0.4mm thickness on the thinned web. This enables to place center position properly and to control chips flow better.

2. How to make centering(pre-drilling) in worse machining environment. - All the traditional machinings had always required to process a centering before high performance drill was developed. Modern high performance drill like YES point is designed with thicker web along with below 0.4mm web thinned point. This drill construction eliminates such a centering process up to 5 x diameter. Deep hole making over 5 x diameter is still required centering process for YTDI Indexable drill as this tool combines with two different materials of Carbide insert and tool steel body. Below methods are helpful tips for such a deep hole drillings A. When center drilling, select the same drill dia.(shorter length drill less than 3xD.) as required hole diameter and then drill the depth with 1 x hole dia. as initial pre-drilling. This process is to help main drilling placed well at the hole entrance. (See below sketch NO.1) 17.5mm(1xD) dia.=ø17.5 Sketch NO.1 : ø17.5mm Hole, 7xDia. or over depth required

B. Precaution when Center drilling in conventional method - Milling : higher feeding tends to make off-center trouble - Lath : when use with conventional center drill, chattering( or vibration) may be found at the former drill trace and this will be effected on chipping trouble on the cutting edge.( This method should not recommended especially in drlling with Milling machine.) 3. Concentricity(run-out) and Lip-height - Keep run-out less than 0.04mm in the machine spindle. - Bad run-out is affected to make lip-height difference,->to produce unstable chip's thickness and bad chip's flow -> oversize hole -> chipping on the cutting edge -> break the drill finally. - In the lath machining, drill is not rotated but work-piece rotates. Off-center positioned drill will bring scratching trouble on the drill body, chip evacuation will be slow and then break the drill. - Milling : keep run-out 0.03mm or less - Lath : run-out 0.03mm, off-center 0.03mm

4. How to control chip formations A. Broken chips, round shaped(not folded) chips production means a good machining condition. B. If run at proper cutting condition, chips control( chip form, evacuation and constant thickness) looks good in normal 3xDia. depth. Deep hole 5xDia. or over requires higher coolant pressure.(refer to our catalog page NO. 55) C. In case the machine can not increase coolant pressure, operator need to drill with wood-pecker method(step drilling) in order to ease chip evacuation. D. When wood-pecker drilling, operator need to adjust where to pick up spindle before load-meter shows high level. E. The reason to show higher load in the machine is that chips build up on the flute, high friction between built chips and hole surface. If higher load continues, this will be affected to break the drill.

5. Make sure machine's power and jig & fixture - check machine power requirement(refer to catalog page NO.62) A. Even though machine's stability or run-out looks good, bad or weaker clamping will cause chattering or vibrating. (ex, big steel plant material) B. Some machine has powerful in main motor, but shows Z-axis spindle motor weak. Weaker spindle motor is affected on weak feeding -> unstable machining -> bad chip control -> failure. C. In special automatic machine, feeding method may rely on air-supply or hydraulic system, Air supplying feeding system can be found low air-pressure of feeding system which causes failure. D. Hydraulic feeding system will get better pressure than air, but this may show unstable feeding condition, especially in multi-spindle. Make sure if feeding rate is controlled in stable condition.

6. Clearance of chip ejection on the flute length A. Flute clearance length requires normally 1.5 length to diameter(1.5xDia.) in order for chips to eject, but 2xDia. is recommended to perform it in safety. B. If flute clearance length is insufficient or too close, chips clog inside hole and it causes a reason to break drill. C. Side lock holder : check if the fastening screw is enough size (hydraulic chuck will be good for End mill, but inferior for drilling.) 7. Major reasons to break drill A. Bad Chip evacuation or ejection. B. Dull or excessive worn cutting edge->need to change new drill C. Bad chip controlled by bad run-out D. Off-center positioned in lath machine

8. Factors to perform good machining A. Enough machine power to perform desired drilling ? B. Secure clamping method of jig & fixture C. Good run-out and concentricity both machine spindle and drill commodity D. Coolant pressure is enough E. Operate with proper cutting speed & feed 9. Symptoms in bad machining A. Scratching on the drill body B. Bad chip formation and folded chips C. Slow or late chip's ejection D. Hole oversized E. Scratched or bad hole surface F. Higher load meter in machine controller

10. Symptoms in proper machining A. No scratch on the drill body B. Round shape chip and broken chip formation C. Regular or higher speed of chip's ejection D. Hole within tolerance E.Good hole surface(this varies by material) F. Lower load meter in machine controller