Casting Technique & Cannons

Year 1563, August, Rudradeva Khurd company branch factory in Badrak

As the prince recalled about all the cast iron and bronze cannon designs of early modern period that he studied in his previous life his thoughts went to the heavy bronze cannons he captured at the battle with count Durani which he has handed over to the royal army brigade to be used at the northern border.Thinking about those cannons and its bulkiness and slow firing rate he decided to design a lighter field artillery which will be easy to move and rate of fire should be higher. Though the process to casting bronze cannon is already known by most of nations surrounding his small kingdom but unfortunately Khurda kingdom being a small state do not have people with such expertise.Hence his father has to import cannon from only power that will lend to them that is the Vijayanagar empire.

Soon the prince thought shifted towards the making of current bronze cannon which is being used by other powers in the vicinity of his kingdom which uses sand molded cores to cast a canon with a hole in the centre and then try to smoothen it with a spinning boring bar. Unfortunately the accuracy suffered because the spinning bar was not super stiff and the inside of the cast part was rough applying uneven loads to the bar causing it to deflect resulting in crude and uneven cannons.

As supervisor Hariharan entered the office and saluted the prince and took his seat the prince handed him the design and notes for the making of cannon which included concepts like sand casting, molding flask, green sand, solid casting and water-powered horizontal boring machine and how this all works together to create a smoothbore 6 pounder cannon.The prince gave a brief explanation of the same. He said

"The green sand is made of silica sand, clay, graphite, water, inert sludge and black coal which is used as molding sand. Most of the minerals mentioned is already being brought from Mayurganj county and talcher area in Angul" 

"Next is the molding flask is divided into two halve the drag which is the top and cope which is the bottom and is prepared to receive the pattern of the cannon which is made of wood. Molding boxes are made in segments that may be latched to each other and to end closures. For a simple object—flat on one side—the lower portion of the box, closed at the bottom, will be filled with a molding sand. The sand is packed in through a vibratory process called ramming, and in this case, periodically screeded level. The surface of the sand may then be stabilized with a sizing compound. The pattern is placed on the sand and another molding box segment is added. Additional sand is rammed over and around the pattern. Finally a cover is placed on the box and it is turned and unlatched, so that the halves of the mold may be parted and the pattern with its sprue and vent patterns removed. Additional sizing may be added and any defects introduced by the removal of the pattern are corrected. The box is closed again. This forms a "green" mold which must be dried to receive the hot metal. If the mold is not sufficiently dried a steam explosion can occur that can throw molten metal about.This process is called sand casting"

"Next, once the casting flask is ready then molten metal is poured to create cannon using solid casting in which the cannon is formed as a solid piece .The trick is with casting a cannon is that the barrel must be cast in a vertical position with the ingate at the muzzle. When molten metal get cold it contracts and must be replaced with hot molten metal or shrinkage defects will occur in the casting. Areas with small volume will freeze before the bigger volumes so a deadhead is provided to supply molten metal to the casting. This is the area above the muzzle on the casting. Being vertical is also good as the weight of the metal pushing down will help to reduce shrinkage cavities forming. If the gun is cast in a horizontal position then the muzzle and the trunions will freeze before the breech volume. The supply of molten meal will stop and cavities will form"

"Next once the cannon is casted the horizontal boring mill is used to drill the cannon in which the solid-cast cannon itself should be revolved horizontally, while the drill remained static. This will result in smoothbore cannon." It is here the prince stopped speaking and waited to see whether Hariharan was understanding his description. As supervisor Hariharan confirmed that he is following prince words, the prince once again started speaking.

He said "The design also specify size and measurements of 6-pounder cannon consisted of a bronze barrel mounted on a two-wheeled frame, weighing about 1200 lbs total. The inside diameter of the gun is 3.5 in."

"Finally I have also provided details of diagrams of a crucible furnace a container made of a heat-resistant material such as graphite, fireclay etc used for melting and casting metals that have a low melting point such as brass and bronze which is also needed to be built before starting on the canon as for now I have decided to use bronze to build cannon instead of cast iron and the canon balls will be made out cast iron which will include canister shot and round shot for now".

"All the details with notes and diagrams and design is provided in the document in your hand, you need to start applying it."

Supervisor Hariharan after listening to the prince words and looking through the documents he couldn't stop himself from smiling as once again the prince has given him new technologies to work with. As he was going through the document he found a design of a weapon called flintlock pistol on pointing it out, the prince replied "Its merely a miniature version of the flintlock musket which my elite cavalry guards will use in combination with there swords in a battle".Listening to the prince explanation Hariharan nodded and was about to depart for his office to study the new design and start applying it. The prince stopped him and said "Elder I am changing your designation to Chief Weapons Officer(CWO) for the branch factory and you will be in-charge of all the foundries and weapons development process within this branch factory". With this the newly minted CWO Hariharan left towards his office. 

Soon his personal attendant Bhimrao entered his office and the prince gave him the details of the designations to be used for different workers and employee within the factory grounds and their standard salary. Prince Viraja wanted to standardise the rank and salary of his company employee just like that of his army personnel. Nodding and taking the document from the prince, Bhimrao handed him the reports regarding the improvement such as drainage system application not only in town but also villages of his barony, building cement wall around the company ground and the residential area where the family of his company employee lives and constructing roads within his barony. It also seems his father has also started applying changes such as drainages and cement roads in the capital city and the towns around it.