Drilling Operations Mr. Casper

Objective Students will be able to identify different tooling used in drilling process. Students will be able to safely operate a power drill, drill press, and vertical mill.

Unit Outline Punching & Piloting Tooling Drilling Machines Twist Drills Whole Saw End Mills Drilling Machines Power Drill Drill Press Mill Lathe Drilling Procedure Safety

Tooling Drill bits are cutting tools used to create cylindrical holes, almost always of circular cross-section. Bits are held in a tool called a drill, which rotates them and provides torque and axial force to create the hole. Specialized bits are also available for non-cylindrical-shaped holes.

Pilot Holes A pilot hole is a smaller hole drilled into a material prior to a larger hole being drilled Pre-Drilling is a must on smooth metal Large bits will slip and wonder potential safety hazard Good chance you will damage your piece

Pilot Hole Procedure 1. Mark with a center punch 2. Drill the pilot hole 3. Drill hole to finished diameter 4. Clean up

Twist Drills The most common type of drill bit Can be used for wood, metal, plastic, and other material. The geometry and sharpening of the cutting edges is crucial to the performance of the bit. 118* point angle is standard but may vary (90*plastic vs. 150* steel)

Drill Bit Geometry

Sharpening Twist Drills Three essential characteristics 1. Equal drill point angle 2. Equal cutting edge/lips 3. Clearance behind lips KEEP THE BIT COOL!

1. Equal Drill Point Angles 118* is standard

2. Equal Cutting Edge/Lips A handyman's adjustable protractor can be used to check both the drill-point angle and the lengths of the cutting edge lips.

3. Clearance Behind Lips Visually inspect clearance to 8-12 degrees. Not super critical as long as it’s close. Too Little prevents the cutting edge from producing a chip and the bit will not drill. Too much clearance weakens the cutting edge because too much metal behind the edge is removed.

Sharpening Video http://www.youtube.com/watch?v=pW7kGFcM2sc

Drill Bit Chemistry Used for wood Require frequent sharpening Low Carbon Steel Bits Used for wood Require frequent sharpening Can dull from drilling some hardwoods. High Carbon Steel Bits Used for wood and mild steel Less frequent sharpening High Speed Steel (HSS) Greater durability than carbon Most common Replaced most carbon bits

Drill Bit Chemistry Cobalt Used for stainless steels HSS bit that contains more cobalt Hold hardness at much higher temperatures Tungsten Carbide Extremely hard & can drill through almost any material Expensive to manufacture, usually the tungsten is brazed onto the tips. Polycrystalline diamond (PCD) Hardest of all tool materials Extremely Resistant to wear Commonly used for glass and tile Thin layer (0.02”) of diamond is brazed onto the cutting edge.

Hole Saws The saw consists of a steel cylinder usually mounted on an arbor. Teeth are commonly made from steel, some are diamond tipped. The arbor holds a drill bit which helps centering the bit.

Hole Saw Advantages Efficiency Size Little of the total material being removed is actually cut, which ultimately reduces the overall power requirement. Size Cheaper tooling is required for drilling large holes.

Hole Saw Disadvantages Drilling machine being used must produce lots of torque at low speeds. VERY powerful kickback. Attach side handles to drills. Difficult removal of material from core.

End Mills END MILLS ARE NOT DRILL BITS!!!

End Mills While a drill bit can only cut in the axial direction, a milling bit can generally cut in all directions. End mills are used in milling applications such as profile milling, tracer milling, face milling, and plunging.

CNC Milling Video http://www.youtube.com/watch?v=HfIaISnqHOk&feature=relmfu

Flat End Mills | Ball End Mills

T-Slot Mill Shell Mill

Countersink Performed by using either a countersink or larger dill bit. Required for flat or recessed surfaces. Characterized by tapered underside. Pilot hole is required.

Counterbore Performed by plunging a flat end mill Required for flat or recessed surfaces Characterized by flat underside

Reaming A reamer enters the work piece axially and enlarges an existing hole to the diameter of the tool. A reamer is a multi-point tool that has many flutes, which may be straight or in a helix. Removes minimal material. Often performed after drilling for a smoother finish.

Tapping A tap enters the workpiece axially and cuts internal threads into an existing hole specifically designed for the tap. The tap is selected based on the major diameter and pitch of the threaded hole. Threads may be cut to a specified depth inside the hole (bottom tap) or the complete depth of a through hole (through tap).

Drilling Machines Drill Drill Press Milling Machines Lathes

Power Drills Use corded drills for long drill cycles Caution: Drill may catch & twist near the end of the drill cycle. Don’t lose the chuck key!

Drill Press

Mill & Lathe Used when extreme accuracy is needed. Ideal for deep drilling operations.

Drilling Procedure Use a punch to mark your hole. Tighten bit in ALL locations. Measure bit diameter for precise drilling before drilling! Use cutting fluid during operation Cleanup and de-bur holes with a file or countersink tool

Drilling Safety Do not hold material with your hand, use a vice or clamp. PPE: Safety glasses, no lose clothing, tie hair back, no gloves Stand balanced & never lean toward the machine Make sure the chuck is secure in the shank. Never leave a chuck key in the chuck socket! Line up and set depth BEFORE drilling. Use sharp bits. Adjust speed when the machine is ON! Larger bits = slow RPM Small bits = faster RPM

Drilling Safety Cont. If your piece spins remain calm and shut the machine off. Reduce feed rate near the end. Keep the bed clean, remove scraps, use a brush! Remove your bits when your finished! Put the chuck key back into the bed!

Cutting Fluids Characteristics Cools keeps the work piece at a stable temperature critical when working to close tolerances Very warm is OK Avoid rapid heating and cooling (warping) Maximizes tool life Lubricates & Removes chips Small pieces can weld themselves onto the tooling if they become too hot. Prevents Rust Machine Parts & Tooling

Types of Fluids Mineral Synthetic & Semi-Synthetic Water Petroleum Based Vary from dark heavy oils to light clear oils. Synthetic & Semi-Synthetic Combination of the best properties of oil and water Rust inhibition Compatibility: ability to work with different metals Thermal breakdown Environmental safety Water Pros: Good Conductor of heat Cons: Poor Lubrication & Corrosion

Pastes or Gels Similar to lipstick or beeswax. Popular for Band Saws Periodically apply to the blade Hand Operations Drilling Cutting threads