MGC 110 - Manufacturing Methods Lecture 20: Machining Operations

Flashcards covering machining operations including turning, milling, drilling, related engineering analysis, and automated machining centers based on MGC 110 Lecture 20.

What is the general definition of machining operations?

Processes in which a piece of raw material is processed accurately into a desired shape and size by means of a carefully controlled material removal process, usually using a form of cutting.

How is the machining process of 'Turning' characterized?

It is used for circular components symmetric about a rotational axis; shapes are generated by rotating the work part and moving a cutting tool.

How is 'Milling' defined as a machining operation?

A machining operation in which work is fed past a rotating tool with multiple cutting edges (called teeth or a milling cutter) on a milling machine.

What is the primary difference between Peripheral Milling and Face Milling regarding the cutter axis?

In peripheral milling, the cutter axis is parallel to the surface being machined; in face milling, the cutter axis is perpendicular to the surface.

What are the common types of peripheral milling operations?

Slab milling, slotting, side milling, straddle milling, and form milling.

What are the common types of face milling operations?

Conventional face milling, partial face milling, end milling, profile milling, pocket milling, and surface contouring.

Distinguish between Up Milling and Down Milling.

Up milling involves cutting against the feed, while down milling involves cutting with the feed, which is known to increase tool life.

What is the formula for calculating the feed rate ($f_r$) in milling?

$f_r = N \times n_t \times f$ where $N$ is rotational speed ($rpm$), $n_t$ is the number of teeth, and $f$ is the chip load ($mm/tooth$).

What is the formula for calculating approach ($A$) in peripheral milling?

$A = \sqrt{d(D-d)}$ where $d$ is the depth of cut and $D$ is the cutter diameter.

What is the formula for calculating machining time ($T_m$) for a single pass?

$T_m = \frac{L + A}{f_r}$ where $L$ is the workpiece length, $A$ is the approach, and $f_r$ is the feed rate.

How does 'Drilling' differ from 'Boring'?

Drilling creates a new round hole in a workpart, whereas boring is used to enlarge an existing hole.

What is the standard diameter range for holes produced by the drilling process?

Mostly ranging from $0.15\,mm$ to $75\,mm$ in diameter.

Define the following drilling-related operations: Reaming, Tapping, and Counterboring.

Reaming: Enlarging a hole a small amount to a specific diameter/close tolerance; Tapping: Cutting a spiral inside a hole for fasteners; Counterboring: Creating a sunken flat surface to yield a hidden bolting platform.

Define the following drilling-related operations: Countersinking, Center drilling, and Spot facing.

Countersinking: Making a cone shape at the hole end for shaped fasteners; Center drilling: Starting a hole at a specific location to improve accuracy; Spot facing: Cleaning up a part surface to provide an accurate surface for fasteners.

What are the three types of workholders used in drill presses?

1. Vise: General purpose with two jaws. 2. Fixture: Custom-designed for a particular part. 3. Drill jig: Similar to a fixture but also guides the tool during drilling.

What is a 'Gang Drill'?

A platform with more than one drill machine so that various holes may be drilled sequentially on the same part.

What is a Machining Center?

A highly automated machine tool that can perform multiple machining operations (typically milling and drilling) under CNC control in one setup, often featuring automatic tool-changing and pallet shuttles.

What is a Mill-Turn Center and what are its 'live tools'?

A highly automated tool that combines turning, milling, and drilling in one setup. ‘Live tools’ are rotating cutting tools (like milling cutters) used to machine features into the outside surface of a cylindrical part while it is held at a specific angle.

What does a Through Hole differ from a Blind Hole in drilling?

A through hole passes completely through the workpiece, while a blind hole reaches a specific depth without exiting the other side.