Deep Hole Drilling and Reaming

12 Questions

What is the purpose of the hole in the middle of a deep hole drill?

To inject coolant

What is the main difference between a drill and a reamer?

Drills cut from the front, reamers cut from the side

What is the purpose of a reamer?

To remove uneven surface created by a drill

What is a gang broach?

A tool that cuts all grooves at the same time

What do you see in a groove area from a gang broach barrel?

Multiple small grooves

What is the main advantage of a reamer over a drill?

Reamers overwrite all drill marks

What is the byproduct of the hook, scrap, and gang broach method?

Chips

What is the purpose of ball burnishing in metal finishing?

To remove sharp edges

Which metal treatment process involves heating and rapid cooling to make the metal harder?

Hardening

What is the primary function of a punch in metalworking?

To make a hole in a substrate

What is the main difference between alloy steels and plain steel?

Alloy steels are made by adding specific elements to obtain specific properties

What is the purpose of using files in metalworking?

To remove unwanted metal

Study Notes

Drilling

Deep hole drilling may cause the drill bit to wobble and create an uneven surface
As the drill bit gets smaller, the web (front part of the drill) also gets smaller
Chamber drilling is a shorter version of deep hole drilling
The drilling surface must stay cool, so a deep hole drill has a hole in the middle to inject coolant

Reaming

Reaming has less flexibility than drilling
A reamer removes uneven surfaces created by a drill and requires a guide hole
A reamer is a few thousandths of an inch larger than the guide hole
It overwrites all drill marks and has an injection point for coolant
Reaming needs a lot of powder and cuts from the side, unlike drills which cut from the front

Rifling

Hook and scrape methods were the earliest methods in rifling, cutting one groove at a time
The gang broach method cuts all grooves at once using sequential cutters
Square and rectangular broaches are used for machine flat surfaces
The gang broach method produces chips as a byproduct
The button method uses a carbide button to push metal out of the way, creating a barrel with perpendicular lines

Finishing

Ball burnishing removes sharp edges by running a lead ball with abrasive powder down the barrel
Firing hundreds of rounds through a barrel can also remove sharp edges
Heat treatment colors indicate that a process has taken place
A Parkerizing finish is used for the worst expected terrains

Tool Functions

Gripping: holding or grasping an object (e.g. pliers)
Cutting: dividing an object into two parts (e.g. scissors)
Prying: using a tool to open or move an object (e.g. crowbar)
Threading: creating threads on a rod
Scraping: removing material from a surface (e.g. scraping paint)
Punching: creating a hole in a substrate using a hydraulic or mechanical punch

Metals

Types of metals: aluminum, copper, brass, bronze, iron, plain steel, alloy steels (listed in order of hardness from least to greatest)
Metal treatments: hardening, tempering, annealing
Hardening: making an existing piece of metal harder through heat treatment and rapid cooling (requires carbon)
Hardness scales: Rockwell and Burnel (highest number on Rockwell scale is 10, equivalent to diamond)

Steel

Steel is an alloy of carbon and iron, making iron hardenable
Alloy steels are made by adding specific elements to obtain specific properties (e.g. molybdenum, chromium, nickel)
Molybdenum: impenetrable to fast moving objects (used in tanks)
Chromium: reduces rust
Nickel: used in alloy steels

Files

All files have a different degree of roughness (grades)
A worker uses files in a proper sequence to remove unwanted metal