2. Outline
Machinability
Tolerances
Types of Machining (Descriptions)
Types of Machining (Illustrations)
Machine Speeds and Feeds
Machine Finishes
Conclusion: Selecting the right machine supplier
3. Machinability
Machinability refers to the ease with which a material can be
machined.
The below table provides a summary of common materials and their
machinability difficulty rating:
Material Easy Moderate Difficult Very Difficult
Aluminum X
Steel X
Thermoplastics X
Composites X
4. Tolerances
General Machined Materials
have tolerances in the
thousandths or .001
Precision Machined Materials
have tolerances in the tenths
of thousandths or .0001
$0
$20
$40
$60
$80
$100
$/Hour
Labor Rate/Hour
Precision General
5. Types of Machining (Descriptions)
• Boring: These are typically used as finishing equipment to enlarge holes
previously cut into the material.
• Cutting: Devices such as saws and shears are typical examples of cutting
implements. They are often used to cut material with predetermined
dimensions, such as sheet metal, into a desired shape.
• Drilling: This category consists of two-edged rotating devices that create round
holes parallel to the axis of rotation.
• Grinding: These instruments apply a rotating wheel to achieve a fine finish or
to make light cuts on a work piece.
• Milling: A milling tool employs a rotating cutting surface with several blades to
create non-circular holes or cut unique designs out of the material.
• Turning: These tools rotate a work piece on its axis while a cutting tool shapes
it to form. Lathes are the most common type of turning equipment.
7. Machine Speeds and Feeds
Speed is the rotational speed of the tool measured in revolutions per minute
or RPM
Feed is the rate the machine tool moves through the part measured in inches
per minute or IPM
Harder materials require slower speed and feed rates to avoid damage during
machining so it is important to select your material carefully:
8. Machine Speed and Feed Chart
Optimal Speed and Feed Chart (MRR = Maximum Material Removal Rate)
Take-Away is: Harder materials = more machine time and Higher Costs!
9. Machine Finish Videos
Anodizing Plating Passivation
As a technique, passivation
is the use of a light coat of
a protective material, such
as metal oxide, to create a
shell against corrosion.
Electroplating is a process
where a coating of metal is
added to a conductor using
electricity via a reduction
reaction.
Anodizing is a process that
thickens and toughens the
naturally occurring
protective oxide. This
coating is part of the metal,
but has a porous structure
which allows secondary
infusions
10. Conclusion
Selecting the right machine supplier
Determine the material (aluminum, steel, composite)
Determine the tolerances (general, precision)
Determine the operations (mill, turn)
Determine the finishes
Example: If the part has precision tolerances and is turned, you
would not want to put it in a general milling machine house.
Match the part with the supplier’s capability.
