manufacturing of weapons

weapons:

Introduction & History

From the axe, which originated in 10000 B.C., to today's killer drones, mankind's use of weapons has been varied and incredibly inventive.

Any object that is designed to inflict physical damage to humans or to any other animal can be categorised as a weapon. Making weapons from the material around has set us apart from other animals, helped us in survival and shaped our history. With this in mind it is important that we as engineers have a brief knowledge of the history and the development of weapons and its manufacturing processes.

Now we will see how the technology and the procedures used in manufacturing these weapons have changed.

The head of the axe is heated and hammered to the desired shape. Next it undergoes heat treatment to remove internal stresses through annealing. It is grinded and polished to make it razor sharp.

Finally the handle is made by choosing an appropriate kind of wood which is shaped according to the axe head.

Similarly, spears and arrows were made.

As humans learn how to melt metal, they started making swords, cannon balls and also shurikens.

Welding and machining also started to become an integral part of weapon manufacturing.

Soon more complex designs using counterweights, chemical, atomic and biological agents, electricity; innovations in design and manufacturing processes have brought about endless possibilities.

For example, the pain ray. A dish like structure made through casting and forging is implanted with a device which sends out directed energy beam. It is then mounted on an armored vehicle. When switched on, this high energy beam burns the skin of the person at whom it is directed and causes pain.   

Manufacture of a Gun

The various processes involved in the manufacture of a gun are:

1 Forging

   It is a process of heating metals and hammering them into desired shape. It can be used for the smaller parts of a firearm such as hammer, trigger or pan. Red hot pieces can be hammered into a die to give them a rough shape of the finished piece. This process compacts the metal making the final product stronger.

  Forging a

  Gun barrel

  with a die

2 Casting

       Small parts can be cast easily from molten metal. Investment or “lost wax” moulding which is almost 4000 years old, is used to make complicated parts which would otherwise involve many machining steps. A wax or plastic model of the part is made in moulds like these or can be machined or carved from a solid block. These parts are connected to form a “tree” enabling the casting of many parts at one time. The “tree” is put in a can and a plaster material is poured around it and allowed to harden. The cans are then placed in an oven and the pattern burned out leaving a cavity identical to the model. Molten steel is then poured into the cavity and allowed to solidify. After the steel cools the plaster is broken away and the parts are cut off in minor finish.

                                          Casting of a series of M14 rifle automatic fire                                              

                                          Selectors.

3 Machining

      In machining, machine tools are used to finish parts that were made using casting and forging. Machining is used in the process of rifling if barrels. Cutting, turning, drilling, polishing etc. are the various machine operations that are utilised. The advantage of this process is that it makes parts interchangeable.

    Parts of a flintlock musket.                             Pistol frames cut from metal stock using

                                                                                   Cutting tools

4 Stamping

   Non critical parts can be fabricated by the less expensive method of stamping and bending to shape. This involves cutting and shaping parts out of sheet metal. The disadvantage is that finishing of such parts is not as fine as machined parts. This process is widely used in making stamped trigger guards and stamping serial numbers.

                           

  Stamping machine                             Stamped trigger guard.   

5 Woodworking

   Gun stock is the part of the firearm to which barrel and firing mechanism are attached.  Back in the days when stocks were made of woods such as walnut, beech, ash, myrtle etc., the art of woodworking was used heavily in the gun trade. A skilled woodworker would take a block of wood and using various tools such as lathes, chisels, planers etc., would carve out gun stocks, to which the barrel and firing action were fitted. On more expensive models, craftsmen would engrave patterns, cross-hatches, inlay precious metals etc. into the stocks.

These days, stocks are made of other materials as well (e.g.) plastic, fiberglass composite, metal etc., where woodworking skills are not as important. However, some of the finest shotguns and rifles still feature wooden stocks carved by very skilled craftsmen.

Grenades

Manufacture of grenades involves the preparation of a shell mould with the desired shape and details. The components are introduced into the mould either separately or as a non-compressed mixture. The mould is then rotated in a tumbling manner to get a uniform casting with simultaneous heating.

Ammunition:

Bullets: Their types and manufacture.

Manufactures need to design bullets that do the best job for their intended purpose

Primarily, there are two types of bullets, which are

1 - Non Jacketed                    2 - Jacketed

The two most common bullet-forming methods are casting and swaging. Hollow points can be formed by either method. Hard (harder than lead) solid bullets can be stamped (a metal punch cuts a bullet-shaped piece out of a bar or sheet of softer metal) and machined from metal stock. Machining includes any process where a machine is used to shape metal by cutting away portions. A typical machine used for bullets is a lathe. A lathe rotates the bullet metal against steel chisels to gradually cut away material.

CASTING A BULLET

1 Casting is pouring molten metal into a mould. This mould is hinged and when closed has a hollow space that is the shape of the bullet. The metal is melted in a crucible (a metal or ceramic pot that can hold molten metal safely) and then poured into the mould.

2 After the metal has cooled, the mould is opened and the bullet falls or is knocked out. Any imperfections are removed by cutting or filing. If the bullet is extremely deformed, it can be melted down and the process repeated.

3 To cast a bullet with multiple sections of different materials, the first material is poured into the mould to partially fill it. After this material has cooled and partially or completely solidified, the second molten material is poured into the mould to fill it partially or completely. This can be done several times, but most often is done twice to create a bullet with a heavier section (for penetration) behind a softer section (for expansion).

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The casting of a bullet.

SWAGING A BULLET

1 Swaging is a cold forming process, which means that it involves shaping metal without heating to soften or melt it. The appropriate amount of material to be swaged (measured in grains) is placed in a die. A die is a harder metal container with a cavity (an empty space) shaped like the bullet without the back end. The die is part of a larger stationary object or is held in place on a platform.

2  A metal punch that fits into the open end of the die is forced into the die to the appropriate depth. As the punch forces the bullet metal into the die cavity, the material takes the shape of the cavity. The pressure can come from a manual or hydraulic press, from repeated hammer blows, or from a threaded punch that is screwed on. Excess metal is squeezed out of bleed holes.

3 The punch is removed from the die and the bullet is pushed or pulled out of the cavity. Any imperfections are removed by cutting or filing.

4  Multiple swaging steps can be used to insert partitions, to create a bullet out of multiple materials, and to further define the shape of the bullet. Sometimes several steps are necessary to add features such as a hollow point.

The bullet jacket

Some bullets have jackets of harder metal surrounding a softer core.

1  A coin-shaped piece of jacket metal is punched out of a strip or a sheet. The punch is usually a round metal cylinder that is pushed through the jacket material into a depression in a table. Some punches are rounded so that the piece of metal is shaped like a cup. Sometimes, tubing is used instead of a coin or a cup of metal.

2   If the jacket material is too hard to be formed easily, it can be annealed. Annealing is heating the metal, often with a gas flame, to soften it and make it more workable.

3  The jacket material is then placed in a die or over a punch and the punch is forced into the die. There may be several different punches and dies used to form specific features in the jacket. One of usual steps is to make sure that jacket is of uniform thickness. The thickness is typically 0.03-0.07 in (0.08-0.17 cm). Some bullets have a thin jacket electroplated onto the core.

MISSILES:

Laser guide missiles:

Laser guided missiles consist of 4 major components which are missile body, guidance system, propellant and warhead.

Two basic types of laser guided missiles exist on the modern battlefield. The first type "reads" the laser light emitted from the launching aircraft/helicopter. The missile's electronic suite issues commands to the fins (called control surfaces) on its body in an effort to keep it on course with the laser beam. This type of missile is called a beam rider as it tends to ride the laser beam towards its target.

The second type of missile uses on-board sensors to pick up laser light reflected from the target. The aircraft/helicopter pilot selects a target, hits the target with a laser beam shot from a target designator, and then launches the missile. The missile's sensor measures the error between its flight path and the path of the reflected light. Correction messages are then passed on to the missile's control surfaces via the electronics suite, steering the missile onto its target.

Manufacture:

Constructing the body and attaching the fins

• 1 The steel or aluminum body is die cast in halves. Die casting involves pouring molten metal into a steel die of the desired shape and letting the metal harden. As it cools, the metal assumes the same shape as the die. At this time, an optional chromium coating can be applied to the interior surfaces of the halves that correspond to a completed missile's cavity. The halves are then welded together, and nozzles are added at the tail end of the body after it has been welded.
• 2 Moveable fins are now added at predetermined points along the missile body. The fins can be attached to mechanical joints that are then welded to the outside of the body, or they can be inserted into recesses purposely milled into the body.

Casting the propellant

• 3 The propellant must be carefully applied to the missile cavity in order to ensure a uniform coating, as any irregularities will result in an unreliable burning rate, which in turn detracts from the performance of the missile. The best means of achieving a uniform coating is to apply the propellant by using centrifugal force. This application, called casting, is done in an industrial centrifuge that is well-shielded and situated in an isolated location as a precaution against fire or explosion.

Final Assembly- The required circuits are soldered onto pre-printed boards. After the assembling the guidance system, it is inserted into the missile body through an access panel. Control surfaces are linked to the circuits by means of relay wires.

Insertion of the warhead is the final step. Simple fastening techniques such as bolting or riveting are used to attach the warhead.

Constructing the missile body, figure also shows

Assembly of guidance system

Final assembly