Oblique vs Orthogonal Cutting in Machining Operations

Chip Formation and Machinability

• The chip-compression ratio measures the ratio of the thickness of the chip to the depth of cut.
• The velocity of the chip (Vc) is proportional to the cutting speed (V).
• Ductile materials and high cutting speeds typically form continuous and spiral chips.
• The depth of cut is also referred to as the undeformed chip thickness.
• There are two main types of metal chips commonly observed in practice: continuous and discontinuous chips.

Machining Operations

• The primary goal of a machining process is to produce a desired shape or surface finish.
• Turning involves a rotating cutting tool removing a layer of material from the workpiece.
• Parting involves the cutting tool moving radially inward to separate a piece from the blank.
• Drilling produces a cavity by traveling to a certain depth in the workpiece.
• There are two main types of machining operations: turning and drilling.

Material Properties and Machinability

• The presence of gaseous elements like hydrogen and nitrogen affects steel properties.
• Aluminum combines with oxygen to form aluminum oxide and silicates, causing tool wear and reduced machinability.
• Copper, silver, and tin can be used as substitutes for lead but are not as effective.
• Sulfur plays a key role in free-machining steels.
• Lead contributes to the machinability of steels, but there is a trend towards eliminating its use due to toxicity concerns.
• The four factors that define the machinability of a material are: tool life, surface finish, cutting forces, and chip form.
• The key role of chip control in machining operations is to ensure continuous and efficient cutting.

Cutting and Chip Formation

• Oblique cutting is characterized by a non-perpendicular angle between the cutting tool and workpiece surface.
• The angle at which the chip leaves the workpiece surface in oblique cutting is defined by the inclination angle.
• The effective rake angle in oblique cutting is calculated using the inclination angle and the normal rake angle.
• To calculate the effective rake angle, the normal rake angle and inclination angle are assumed to be equal.
• As the inclination angle increases in oblique cutting, a segmented chip is produced.
• In orthogonal cutting, the chip leaves the workpiece surface perpendicular to the cutting edge.