Machining and Machining Operations: Part A

What fluid is always needing in machining?

Cutting fluid

What are some benefits of cutting fluid?

• Reduces heat

• Lubricates

• Reduces tool costs

• Controls chip flow

• Improves surface finish

What are the three main categories of cutting fluids?

• Cutting oil

• Emulsifiable oils

• Chemical cutting fluid

What is cutting oil?

A mixture of oils which are used on low speed operations to provide lubrication a improve machining.

What are emulsifiable oils?

Oils blended with emulsifying agents (soluble oils and soaps) that can be mixed with water to form an emulsion which lubricate as well as cool the parts being machines.

What are chemical cutting fluids?

A mixture of inorganic chemicals and water which lubricate and cool the parts being machines as well as resist extreme pressures.

What are the three main risks of cutting fluids?

• External (skin) irritation like Dermatitis

• Internal irritation (inhalation)

• Bacterial infection

What are the 5 types of drilling machines?

• Sensitive drill press

• Upright drill press

• Hand drills

• Magnetic drills

• Radial drills

What is a sensitive drill?

A small drill press that has no power feed and is operated by hand.

What is an upright drill press?

A large drill press that has power feed, tapered shanks, a t-slot table, and typically has integrated lubrication and coolant systems.

What are electric hand drills?

Small hand held battery powered drills.

What are magnetic base drills?

Small portable sensitive hand drills with magnetic bases which can drill precise holes.

What is a radial drill press?

A large drill press with power or manual feed which uses a movable spindle (radial arm) to drill in difficult positions.

What are the two methods to size a drill press?

• Radius from column to tool

• Diameter sized by the largest diameter workpiece that can be centered under the tool.

What are the three kinds of drill bit?

• Twist drills

• Specialty drills

• Reamers

What is a twist drill?

A twist drill is the most common type of cutting drill bit which uses twisted helical flutes to drill in a work piece.

What is a drill bit margin?

The narrow, raised strip running along the outer edge of a drill bit’s body that guides and stabilizes the bit inside the hole.

Where should you measure a drill bit?

Across its margin (widest cross section)

What are the parts of a drill bit?

• Point

• Body

• Shank

• Tang (only on tapered bits)

What are the parts of drill bit point?

• Web (center)

• Lip (cutting edge)

• Chisel edge (portion between flutes)

• Heel (back side of the cutting edge)

• Land (area between cutting edge and heel edge)

• Lip clearance 8-12 degrees (heel lower than cutting edge)

• Flute (empty space)

What is a specialty drill bit?

A drill bit designed for specific applications, materials, or hole profiles where a standard twist drill would be insufficient. (high helix drill, Core drill, oil hole drill, straight fluted drill, step drill, hole saw, center drill)

What is a reamer?

A reamer is a precision rotary finishing tool designed to enlarge and smooth an existing hole to an exact diameter with a high-quality surface finish.

What is the rule for feeds and speeds with reamers?

Half the speed, twice the feed!

What are the 4 sizes of drill bit?

• Fractional size (1/64”- 4”)

• Metric size (.04mm - 80mm)

• Number size (#97 (.0059) - #1 (.228))

• Letter size (A (.234) - Z (.413))

(remember numbers come before letters)

What are the two types of shank?

• Straight shank (typically smaller or 1/2” and smaller)

• Tapered shank (morse taper shank and typically larger than 1/2”)

What is a drift?

a wedge-shaped steel tool used to remove taper-shank tools, sleeves, or sockets from a tapered machine spindles.

What is a drill chuck?

A device with three adjustable jaws which grip the shank of a drill bit and secure it to a drilling machine.

What are drill sleeves and sockets?

tooling accessories used to adapt Morse taper cutting tools to the spindle of a drill press, lathe, or milling machine.

What is a quick change tool holder?

A socket mounted tool which is installed into a quick locking collar

What is a power tapping attatchment?

A tool with a slip clutch and floating head that holds a tap into a drilling machine

What is a floating reamer holder?

A device which holds a reamer and allows it to float/self center in order to maintain accuracy.

What is a work holding device?

Any device that holds a workpiece. (vice, clamp, jig, v-block, angle plates, etc)

What is a drill press vice?

A tool with precision ground base that holds flat, square, or rectangular objects in a movable lever operated screw jaw and is has mounts to be fastened to the table of a drill press.

What is an angle vice?

A vice that has a hinged base to swivel to be set and an angle.

What are C-clamps?

Clamps made up of a c shaped jaw and screw clamp which is used to hold a workpiece during layout, assembly, and drilling.

What are v-blocks?

Precision ground blocks which accurately clamp and hold square, rectangular, circular, and octagonal work pieces during layout and machining.

What is a jig?

A work holding device which holds a workpiece and has a drill guide to accurately locate and drill a hole.

What are the three inputs when drilling?

• Feed

• Speed

• Depth of cut

What is cutting speed?

The rate at which the cutting tool moves through metal and is measured in m/min or sfpm.

What is the peripheral speed?

The fastest moving part of a rotating object

What edge is cutting speed based on?

The outside edge (largest diameter)

What is feed?

the rate at which the drill (tool) is fed into the work and is measured in inches/mm per revolution

What is the most efficient process for removing material?

Drilling

What is peck drilling?

stopping and restarting the feed in order to break long chips.

What is the most common way to hold a workpiece on a drill press?

Using a vice

True or False: The Center punch must be as large or larger than the chisel edge of the drill bit?

True, otherwise the drill bit will wander.

What are three good practices when using a drill press?

• Always use cutting oil

• Use parallels to prevent drilling holes into the vice

• Use a soft/dead blow hammer to tap the workpiece flat against the bottom of the vice

• Clamp/secure the vise on the work table or position stops when drilling

What should you always do before you drill a large hole?

Drill a pilot hole

What are the three methods for drilling holes in mating parts?

• Twist drill method (transfer hole with drill bit)

• Transfer punch method

• Transfer screw method

What is most helpful when drilling a hole on round work?

A deep center punch mark

How must round materials be clamped in a vice?

At or above the center line.

What is reaming?

using a special drill called a ream to drill an accurately sized hole with a good finish.

What are some general guidelines when using a reamer?

• Half the speed/twice the feed

• Use cutting fluid

• Only use in forward rotation direction

What is countersinking?

Cutting a bevel at the top of a hole so the hole can accept the head of a flat head screw.

What is counterboring?

Enlarging the top of an existing hole to allow it to accept the head of a bolt or screw. The hole must have a flat bottom and the bolt must sit below or flush with the surface of the work.

What is tapping?

Cutting threads into a drilled hole

What are the two components used for tapping?

The tap and tap wrench

What are the three kinds of taps?

• Spiral fluted tap (pull chips out)

• Spiral point tap (push chips out)

• Straight fluted tap (break chips in hole)

What must be true about a drill bit point for it to properly drill?

It must:

• Have equal length cutting lips

• The point angle must be even

• It must have clearance behind the cutting edge

• The chisel edge must be as thin as possible

What is the standard included angle of a drill bit point?

118 degrees

What are three common angles for drill bit points?

• 60/90 degrees for soft materials

• 118 degrees for general drilling

• 150 degrees for hard materials

What are the parts of the point on a drill bit?

• Web

• Chisel edge

• Cutting edge

• Margin

• Clearance

• Heel

• Flute

• Land