J - Hand Tools Flashcards
What process requires the use of Tools?
Material Removal Processes
Machining
Subtractive Manufacturing
Portable tools that are powered manually (by human muscles)
Hand Tools
Examples: Hacksaw, Files
Portable tools that use a supplementary power source like mains electricity, batteries, compressed air, or even fuel.
Power Tools
Examples: Electric Drill, Angle Grinder, Reciprocating Saw
Static (non-portable), large, stiff, heavy units usually employed in machine shops. These are usually electrically powered and may use 220VAC or 3-phase supply.
Machine Tools
Examples: Lathe, Vertical Stand Drill
This performs the actual cutting of metal and must provide the necessary hardness and geometric configuration to facilitate the cutting action.
Cutting Tool or Tool Bit
Tool Bits that have an essentially circular cross-section, must be rotated, and involve a number of individual cutting edges or teeth.
Multi-point cutting tools
A tool bit that uses a square cross-section cutter, which doesn’t rotate, and only has one cutting edge. Examples include Lathes, Shapers, Planers, and Boring machines.
Single Point Cutting Tool (SPCT)
Cleaving
Wedging
The geometry of a SPCT is dominated by _____ angles that stop the tool rubbing on the workpiece and provide clearance for cutting debris, and _____ angles that create the wedge.
Relief; Rake
Two examples of the effect tool positioning (at any compound angle) can have on the cutting action.
Orthogonal (cutting edge at 90°) and Oblique (inclined cutting edge) Cutting
The cutting debris from the SPCT
Chips (Swarf outside the USA)
Optimal cutting (characterized by low tool wear, low energy consumption, low heat, and good surface finish) is indicated by the production of
Continuous Chips
Chatter
Vibration
Very poor inefficient cutting, even with ductile material, results in _____. These are characteristically short and fragmented, and are associated with noise, heat, and bad surface finish.
Discontinuous Chips
These are an intermediate type of chips that are generated in a continuous form but with toothed edges. They produce all the same bad outcomes as discontinuous chips, while being sharp and hazardous.
Serrated chips
Continuous chips are desirable, and can be achieved through the manipulation of
Cutting Speed, Feed Rates, SPCT Angles, and Tool Presentation Angle
These are employed to achieve the “best of both worlds”, where chips are initially generated as continuous (with all the benefits), but then are subsequently broken up into a discontinuous form for better packing and cleanup.
Chip Breakers
The two types of chip breakers.
Obstruction-type and Groove-type
This chip breaker type is more popular as it is more rugged, less prone to wear, and won’t fail under high temperature/load/friction.
Groove-type Chip Breaker
Adjustments are made to _____, ______, and ______ until continuous chips are generated.
Speed, Feed, and Angles
Small particles of workpiece material detach from the chip as it rides the tool face and fuse themselves to the tool due to the high temperatures and pressures involved.
BUE (Built Up Edge)
The cure for BUE, which is a mixture of lubricant and coolant that reduces temperature and friction.
Cutting Fluid
The most common Cutting Fluid is comprised of what which has a milky-white appearance.
Soluble Oil (lubricant) and Water (coolant)
A Cutting Tool Material must be harder than the workpiece material, but must also be able to maintain that hardness at elevated operating temperature. This ability is called
Hot Hardness
Cutting Tools are also subject to impact/shock loading and must possess sufficient
Toughness
The rule-of-thumb to select a tool material is
Select a tool material that is just slightly harder than the workpiece, but no more, so as to preserve as much toughness as possible.
One of the first cutting tool materials developed, which is very poor by today’s standards, and should no longer be used. It has low hardness at room temperature, which drops off dramatically as it heats up.
Carbon Tool Steel
An excellent material for general purpose use, and has replaced carbon tool steel. When used for twist drills it usually has a black appearance as a result of the black oxide developed during heat treatment.
High Speed Steel (HSS)
A slightly harder cutting tool material than HSS
Cobalt Alloy
Twist drills made of cobalt alloy are heat treated to a ____ _____ temper, which gives them their characteristic appearance.
Light-Straw
A material with even greater hardness than cobalt alloy. This slate-gray colored material is very easily chipped because of low toughness, and cannot be resharpened.
Tungsten Carbide (WC)
The most common type of Coated Cutting Tool. This material combination has a bright gold-colored appearance except on areas such as the shank of drills where the underlying HSS is left exposed.
Titanium Nitride (TiN) on HSS
The hardest material known, but is expensive (in large pieces) and very brittle. However it is useful for cutting very hard workpieces such as glass or ceramic.
Diamond
Since SPCTs only cut at their nose, any use of harder material need only be applied in that one locality, while the rest of the tool can remain HSS. This locality is called
Cutting Tool Insert
Inserts are often constructed of ______ ______ coated in ________ _________ and thus have a gold appearance.
TUNGSTEN CARBIDE; TITANIUM NITRIDE
A material that is second only to diamond in hardness. This material can be made and shaped into a form suitable for a SPCT, but is rather expensive. To keep cost manageable, it is offered as a small INSERT on one corner of an INSERT.
Cubic Boron Nitride (CBN)
