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Toolmark Identification
retrieved April, 2020
https://firearms-examiner…
Toolmark Identification
retrieved April, 2020
https://firearms-examiner.training.nij.gov/
Module 13
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Cutting Operations
Metal-forming operations, using conventional machine tools, involve the removal of metal using a cutting tool of a greater hardness than the workpiece
Lathe Operations
those in which the exterior of a workpiece rotates against a cutting tool controlled by an operator or by automation
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boring - a single-point cutting tool enlarges a hole beyond the capability of a drill or reamer and works the interior of a piece
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Milling
Milling involves the use of rotating multitoothed cutters moved into the workpiece, allowing for a wide variety of cutting operations
Milling involves the use of rotating multitoothed cutters moved into the workpiece, allowing for a wide variety of cutting operations
Peripheral milling (slab milling) - the surface being machined is parallel to the (often helical) cutting teeth in the periphery of the tool
End milling - fluted cutting edges are arranged on the circumference and end of a rotating shaft that is vertical to the workpiece
Other Cutting Operations
Shaping - a single-point cutting machine cuts in a straight line by repeated parallel strokes, gradually moving across a flat surface.
Planing - similar to shaping, but the workpiece moves under a stationary cutting tool
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Reaming - a cutting technique that it is sometimes used after drilling to produce accurate finely finished holes
Broaching - multitooth cutting tool that moves against a stationary workpiece. It can remove metal on both interior and exterior surfaces
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Abrasive machining - thousands of tiny cutting edges made up of individual abrasive grains and used as a finishing operation
Metal-Forming Techniques
Metal forging involves using great pressure and/or heat to squeeze metal into a particular shape in a die
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Physical Characteristics
striated and impressed toolmarks may contain several levels of marks resulting from tool use on softer objects
Pattern Identification
process of determining whether or not the details of striated marks or impressions on two objects correspond
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