cutting tools knowledge-drill
DESCRIPTION
Basic knowledge about drillsTRANSCRIPT
Different type of drill’sStepped drill
Gun drill
Center hole drill
Burnishing drill
(Drills and chamfers holes at the same time)
(Used for opening deep holes)
(Used to open center holes in shafts)
(Used to open high-precision holes in aluminum)
Different type of drill’s
Throwaway drill
Twist drill
Formed flat drill
Flat drill
(Regular drill with good swarf removal)
(An insert is set in the end of the tool. Used primarily for finishing holes)
(Used for finishing stepped holes and shaped holes)
(The angle on the end is between 120 degrees and 100 degrees, !while the end can be separately attached or shaped like a spade drill)
The structure of drill
Margin: This is the diameter of the drill, and improves the progress of the hole. Chisel edge: This part joins the cutting edges at the ends of the webs. Thinning: This feature reduces cutting resistance. Shank: This is the part that is used to hold the drill, and is either straight or tapered. Cutting edge: Used to actually cut with the drill. Tang: Used to hold the drill and stop it from turning. Inserted into the sleeve socket. Back taper: In order to prevent friction with the hole wall, drills have a smaller diameter closer to the back end.
Margin
Chisel edge
Cutting edge
Thinning
Drill diameterPoint angle
Back taperTang
ShankNeck
Web
DrillingCharacteristics of drilling
Simple mode of processing
Extremely difficult processing
Friction with the hole wall
Cutting usually occurs deep in the hole
Not very rigid
Cannot see the point during processing
Characteristics of drilling
Swarf is ejected from
the flute
- Characteristics of swarf generation -
Because the cutting edges are not outside, the swarf has to work its way out. However, there are
limitations to the swarf ejection route.
The purpose of each typeStructure Type How it is used
Solid drill
Carbide brazed drill
Drill with replaceable carbide tips
Optimum for finishing holes 20mm in diameter or smaller
Appropriate for processing holes between 8mm and 40mm in diameter. If the required hole precision is low, the “NEW POINT” drill is suitable. If it is high, the “KEY POINT” drill is suitable.
Suitable for holes between 12mm and 56mm in diameter. It is also suitable for low-precision holes, and because the tip is replaceable, it does not need to be reground.
Different types of carbide gun drillPrimary characteristicsType
Gun drill for machining centers
Regular gun drill
SAMMIKA gun drill
ARROW JET gun drill
Diameter 6 to 20mm; L/D = 10, 15, 20; for cast irons, ductile cast irons, and aluminum alloys
Diameter 2 to 30.3mm; L/D = up to 150; for carbon steels, alloy steels, stainless steels, cast irons, ductile cast irons, aluminum alloys, and copper alloys
Diameter 5 to 30.3mm; L/D = up to 150; for carbon steels, alloy steels, cast irons, ductile cast irons, and aluminum alloys. Excellent for cutting swarf; high feed rates are possible.
Diameter 6 to 30.3mm; L/D = up to 150; for cast irons, ductile cast irons, aluminum alloys
Carbide drill: components & operation
Margin
Drill diameterPoint angle
Web
Groove
(1) Groove: There are two helical grooves that guide the swarf back and eject it. (2) Point angle: Generally 118 degrees for high-speed steel and 140 degrees or 150 degrees for
carbide. (3) Web: Tapered to make the drill shaft rigid. (4) Back taper: To prevent the outer edge of the drill from contacting the hole wall, the drill is
tapered so that it narrows toward the shank. (5) Margin: The part of the drill that contacts the wall of the hole in order to produce the
required dimension.
How to lock at cutting edge
シンニング不良切れ刃の欠け マージンの欠け シャンクの傷
Lip height difference for drills
0.05 or less
Lip height difference for reamers
0.02 or less
Excessive land wear
Excessive wear
Residual wear
Secondary angle
Chipped cutting edge Chipped margin
Damaged shank
Good
Thinning defects
Asymmetry Too deep Too shallow
Off-center (runout) Discontinuity in cutting edge No cutting edge
Troubleshooting of drill’s(1) Drill problems caused by swarfDuring drilling, swarf can cause the following types of problems, so sufficient care is required.
(1) Swarf winding around the drill (2) Swarf ejection problems (3) Damage caused by too little cutting fluid
These can lead to damaged drills and problems such as abnormal wear.
(2) Typical methods for addressing swarf removal
(1) Workpiece material: Change to a more brittle material (e.g. use free-cutting steel)Doing this makes it easier for fan-shaped swarf particles to form, making it easier to manage.
(2) Change the feed rateThis depends on the workpiece material and the processing conditions, but changing the feed speed can change long pieces of swarf into flakes, strips, or short pieces.
(3) Step feed Mainly used for twist drills used for drilling deep holes. With twist drills, step feed is considered for deep holes with a depth that is 4 to 6 times the hole diameter.
Number of steps (guideline)
For steels, there should be one step per hole depth multiple. For cast materials, no step feed is required for FC23. For the FCD series, there should be one step every 5 to 6 hole depth multiples. For aluminum, there should be one step every 5 to 6 hole depth multiples.
Troubleshooting of drill’s(4) Drills with a chip breaker or nicked drills
As a countermeasure for swarf issues that are done on the drill itself, some drills have a chip breaker that breaks the swarf up, as well as drills with nicks in the cutting edge that divides up the swarf. However, these features must be put in every time the drill is re-ground (resulting in increased man-hours) so these methods are not common at Toyota.
Breaker Nick Nick
Drill with chip breaker Nicked drill
–Fran Noto
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