An Overview of the Milling Machine, Its Processes, and Components

The process in which allows the creation of the variety of features on a part from cutting the unwanted material, such process is known as “Milling Process”. Milling is an important form of machining. Milling process requires tools like a milling machine, workpiece, cutter, and fixture. The workpiece is a pre-shaped material that joins to the fixture, attached to a platform on the milling machine. Along with this, there is a fixation of a cutter in the milling machine, the cutting tool has sharp teeth that rotate at high speed. The machine cuts away the material from the workpiece in the form of small chips by feeding the workpiece into the rotating cutter that allows the creation of desired shape.

As far as the construction of the machine is concerned, the parts of the milling machine are not axially symmetric; they have many features, such as slots, holes, pockets, and three-dimensional contours. Some parts can be completely fabricated by the help of milling process; as components of these parts are used in limited quantity, like prototypes, custom designer fasteners or brackets. One of the most common applications of milling is the fabrication of tooling for other processes. For example, milling the three-dimensional molds. The parts manufactured by using a different process applies to add or refines features of these parts by using milling as a secondary process. The milling process can offer high tolerance and surface finish. Therefore, for that reason milling is an ideal for adding precise features to a part whose basic shape has already been formed.

Components of Milling Machine

Milling machines can be available in several of sizes and designs. However, they have the same components that enable the work performed on three-dimensional that is about the tool. The components of the milling machine include the following sub-parts:

• The base is a simple platform that provides support to the machine, normally fixed on the ground surface. A column attached to the base connects to the other components.
• A table has “T” shaped slots along its surface. The milled workpiece is mounted onto the table surface.  The workpiece can be joined in a fixture called a vise. The vise has fixation into the T-slots, or they can be clamped directly into these slots.
• The saddle is a platform that provides support to the table and allows its longitudinal motion. The saddle is also able to move and provide the horizontal motion of the workpiece in the Y-direction by sliding along another platform.
• There is another platform that supports to saddle and table is called “Knee.”

All of the above-given components of milling machine can operate on both orientations either in vertical or horizontal which allows the creation of two distinct form of the milling machine. Horizontal milling machine sometimes called arbor milling because horizontal milling machine uses a cutter that is mounted on a horizontal shaft, which is called an arbor. On the other hand, a vertical milling machine orients the cutter vertically. It has cutter fixed inside a piece, which is called collet, and then it is attached to a spindle that is orients vertically. The spindle is located inside the milling head, which attaches to the column. On the vertical milling machine, all the milling operations performed to remove the material by using both the bottom and sides of the cutter.

For more information about fabrication and machining, you can visit http://millenniumind.com/

Pressure Testing: Purpose, Regulation Requirements and Its Risk Factors

Pressure Testing has a great importance among industrial processes, as it is a non-destructive test that verifies the system’s integrity of pressure shell on new or old installed tools and equipment; this mechanism also has the ability to detect tightness of a system against leakage.

Pressure Testing has equally importance in the fabrication process, and it is a last physical quality test that performs in a controlled environment. Most of the piping codes require this test, to ensure that repaired or a new piping system is capable to maintain its safety against rated pressure and leakage. 

Most of the regulatory and enforcement agencies compliance to piping codes that mandates for the construction of the system. Nowadays, Pressure testing is mainly preferred due to good safety considerations, whether Pressure Testing is legally backed or not, it serves constructively by protecting works and public.

Pressure Testing establishes a pressure rating for required components. It may also be used to establish a safe rating by calculating various special systems. Before start-up of new systems, Pressure Testing is performed to confirm the integrity of vessels and to obtain relevant certification.

Regulation Requirements for Pressure Test

Pressure Testing is also demanded by the regulation requirements. The important points of these regulation requirements are given below:

• By using the hydrostatic method, all the pressure piping leak tests must be conducted.
• A pressure piping system will not test at a temperature that is colder than its minimum allowed temperature.
• When conducting a Pressure Test, a contractor must considered the ductile-to-brittle transition temperature and the possibility of brittle fracture.

The biggest advantage of Pressure Testing is that it can be performed at low working pressure. The fatal disadvantage of pressure testing, exposure to aged equipment with poor toughness could result in the brittle fracture.

From the above discussion, it can be concluded that the pressure test procedure confirms safety. The purpose of such procedure is to ensure pressure tests are conducted safely and effectively. They apply to mechanics, supervisors, inspectors and subcontractors responsible for pressure tests. Pressure tests are performed to verify the reliability, and leak tightness of pressure systems. A pressure test is required for a new pressure system before use or an existing pressure system after repair or alteration.

Understanding The ASME Standards

ASME (American Society of Mechanical Engineers) is technological association that maintains standardization of equipments for the industries of processing & mining, which involves with items like pressure vessel, boiler and inspection piping. The role of the society is to maintain checks and balances for industrial inspection by the help of volunteer engineers, which are entitled to monitor about predefined aspects of standard for manufacturers and operators operating those mechanical equipments in machining shop. Manufacturers tend to acquire ASME U-Stamp certification, so they could reveal to their consumers about the maintenance of standards while using modern equipment, and they can acquire their services without any hassle. Moreover, it further reflects that firm endows a healthy reputation among industry wide professionals, and certification has bound the company to adopt standards of optimal safety in the production of their products or services.

The certification of ASME U-Stamp also assures that manufacturing company is using pressure vessels and boilers in the synthesis of industrial process are not threat to life. Such kind of industrial apparatus contains excessive pressure & elemental wear and tear, so their usage needs to adopt those standards and protocols of certification, useful in reducing the aspect of malfunction & optimization of productive efficiency of equipment. The welding or other technical equipments that use pressure vessels and machinery must be capable of regular refurbishments, repairs and parts replaceable.

Maintenance Of Quality Assurance:
To achieve optimal operation of welding, there is more than one factor that supervises the whole process from preliminary point to production of product. To get into the listing of certified welding shops, the two levels i.e. machine operation refurbishment and repair must be adopted for future mechanical upgradation of apparatus, so manufacturers or retailers of such an equipment caters to include reusability factor in the machinery. For that sake, pressure vessel manufacturer as well as engineering board of ASME U-Stamp certification inspects the equipment for optimal output.

Generally, physical magnitudes of industrial equipment aren’t small, the large welding machineries comprise of small components which need to be refurbished during different phases of production. Having engineered at component level enables these machines to undergo raw and hard materials in rough condition. The process of excavation and production demands different mechanisms, capacities and orientations. The mechanical operation of these large machines may get damaged during completion of required processes, so machining and repair at component level becomes more easy. Concisely, certification benchmarks ASME U Stamp companies for optimal function of equipment involved in the industrial synthesis.

The achievement of ASME U-Stamp Certification doesn’t involve complex procedure, the inspection to monitor about standards is conducted by respective field experts. The professionals and engineers constituting this association, utilize their skills to prove durability and capability in technology related industrial processes involved in machining shop. Maintaining these procedures for machinery ensures continuity in production and optimal return of investment for the costs along with safety measures for workers.

Metal Fabrication: Its Processes & Applications

A process in which metal structure undergoes the cutting, bending and assembling processes is known as Metal Fabrication.

Processes of Metal Fabrication

Now we will discuss one by one of each process in detail:

Cutting

Metal cutting is done with the help of different automated and manual tools such as saw, chisel or shear. It also includes process of torching that completes by use of torches and via Computer Numerical Controls (CNC) cutters.

Bending

Metal bending is done with the help of manual or powered hammering. It can also be done with the use of pressure brakes. Most of the CNC-Controlled backgauges utilize hard stops to position cut parts, in order to place bend lines in the correct position. As technology is getting advance, now there are several offline programming software, which can configured to make program for any CNC controlled press brakes machines.

Assembling

The process of assembling joins the pieces of metals through welding and binding with adhesive materials. Sometimes, metal bends appear in the form of crimped seam. For fabrication, structural steel and metal sheets are the usual starting materials.
These materials are mostly present along with welding wire, flux and fasteners that can be used to join the pieces. Human labor and automation manufacturing processes are commonly used products of fabrication, and the shop that specializes in these types of metalwork is called Fabrication Shop.
Most of the end products are not classified as fabrication, either they have similar shape and function. The end products of metalworking, such as machining, metal stamping, forging and casting are not classified as fabrication.

Difference between Fabrication Shop and Machine Shop

Fabrication work overlaps with various metal working specialties. Machine and fabricationshops have overlapping capabilities, but in conceptual manner, fabrication and machine shops are different from each other. In fabrication shop, manufacture deals with metal preparation and assembling processes. Whereas, machine shop enables cutting of metals, but they mostly deal with the parts of machining on different machine tools. Most of the companies, involves in both types of activities that includes in fabrication and machine work.

Practical Applications of Fabrication Work

Blacksmithing Process is the core of fabrication work.  From different aspects, welders, boilermaker, millwrights is also included in fabrication work.

Metal fabrication is one of most the important process in field installations. It involves in the construction of machines as well as structures made from different types of raw material. Fabrication shop may involve in most of the processes like welding, cutting, forming and machining. These large fabrication shops offer additional value to their customers by limiting the need for purchasing personnel to locate multiple vendors for different services.

A general overview to Pressure Vessel and its Components

What is a Pressure Vessel?

A Pressure Vessel is a closed container that holds liquids and gases, in which pressure is builds by the application of heat from an indirect or direct source, a direct or indirect source of heat builds the pressure in the chamber. It is designed in such a way that pressure at which it holds liquids or gases is different from the surrounding pressure. Difference in pressure can be very dangerous, as it is evident from history that pressure vessel development and operation caused many fatal accidents.

Components of the pressure Vessel

The components of the pressures vessels are as follows:

• Shell
• Head
• Nozzle
• Support

Shell: Shell is the primary component of the pressure vessel, which contains pressure. Shell of pressure vessel is in the form of different plates, welded together to form a specific structure that has common rotational axis. In most of the vessels, the shell is a component that provides the longitudinal length of the vessel. The thickness of the shell based on the pressure and on any additional loads that created by the supports, nozzles and other attachments. Shells are available in cylindrical, spherical or canonical in the shape. Most of the shells have circular shapes, so due to their circular form the equal distribution of forces applies on it.  Horizontal drums have cylindrical shells and constructed in a wide range of diameter and length.

Head: Head is another component of the pressure vessel. All pressure vessels must be closed at the ends by another shell section or by head. Heads are made in the shape of curved rather than flat because the curved configuration of head is stronger, which allows the heads to be thinner, lighter and less expensive than the flat heads. When heads are used inside a pressure vessel, then they are known as “intermediate heads”. These intermediate heads are separate sections of the pressure vessels that permit different design conditions.

Nozzles: Nozzles are also one of the major components of pressure vessel that has insertion in the shell, which later connects to the process pipe. Depending on the design of nozzles, they can also connect to flanges or threaded fitting. Depending on the following given factors manufactures design nozzles:

• Manufactures must consider the metallurgy of the shell and nozzle.
• They must checks the internal and external projections of the nozzle.
• Before designing, they must consider the orientation of nozzle & internal and external forces that acts on the nozzle, such as pressure and piping forces.

Supports:  Support is also a component of pressure vessel that can be used to bear all the loads like, earthquake and wind loads. Depending upon the orientation and size of the pressure vessel, different types of supports are available in market. The design of this component deals with external forces (wind forces and seismic zones) and physical dimensions of the vessel such as weight, length etc.

What are the Advantages of Pressure Vessel?

Pressure vessel has the following given uses in different manufacturing industries:

• Pressure vessels are used in different industries like Petroleum refining, Chemical, Power, Food & beverage and Pharmaceutical.
• They can be used as storage of high-pressure gas, gas scrubbers, two and three phase separators and some other functions.
• They can be used in different types of boilers such as steam boilers etc. 

For more information about fabrication and pressure vessel design you can visit   http://millenniumind.com/

Oxy-Fuel Welding (OFW)

Oxy Fuel Welding (OFW) is a metal joining process, used to join metal end pieces by heating. This process is commonly used to join mild steel. Oxy-Fuel welding is also called oxyacetylene welding because in this process mixture of acetylene and oxygen burns at intense flame of 3500^oC. Oxyacetylene gas welding consists of a group of welding processes, which joins different type of metals by heating them whether it is used with gas flame or without filler metal. When the gas flame combined with metal, it melts the surface to molten form, by allowing the welding process to take place. Oxy-Fuel welding can be used for shaping metal, cutting and brazing of metals. Oxy-fuel welding is mostly used for prefabrication of tubes, steel sheets and plates.

Oxy-FuelWelding process includes welding operations that make use of oxygen, which can also be combined with fuel gas as a heating medium. In this process, gas, fuel and oxygen are mixed in a mixing chamber with proper proportion that also a part of the welding assembly. This welding process involves a filler metal and the melting of the base metal, which can be used by means of the flame produced at the tip of welding torch.

Oxy-Fuel Welding Processes

There are following three processes that involves in Oxy-Fuel Welding.

• Oxy-acetylene welding
• Oxy-hydrogen welding,
• Pressure gas welding.

Oxy Fuel welding also known as air acetylene welding because of its industrial significance, in which combustion of air and acetylene heat is obtained. Welding with Methyl acetone- propadiene gas (MAPP gas) also uses same procedure like Oxy-fuel welding.

Advantages of OFW

There are following given advantages of oxy Fuel welding:

• A welder can control temperature of weld zone, heat input and the oxidizing or reducing potential of the welding environment that controls the welding process.
• Welding process also controls the shape, weld bead size and weld puddle viscosity as it independently adds a filler metal of the welding heat source.
• Oxy Fuel Welding is used for welding of tubes, thin sheets and small diameter of pipe.
• OFW is also used to repair welding joints, welds of thick sections. However, its repair work is not very economical, so its use is not feasible at commercial level.

Oxy fuel welding process is used in welding shops, it is mostly used for torch brazing, soldering, and many other types of operations, where its heat transfer rates and flame characteristics are not the same like that of welding.

Inspection Overview Of Pressure Vessel

Simply, a pressure vessel appears as a storage container, fabricated to accumulate pressure more than 15 p.s.i.g. In several inspections of pressure vessels at workplaces, usually numerous cracks and damages are observed on their surface. Such cracks and damages on the surface of pressure vessel result in the form raptures & leakages, even they can be risky to health and safety measures in workplace due to air poisoning, suffocation, explosion and fire. In severe case, damages in vessel can result fatal and can bring harm to ecology and property assets. Therefore, to ensure safety & health of workers, the design, manufacture, operation and maintenance of pressure vessel should be according to designated procedures & standards.

Below, the techniques & technologies handy in pressure vessel repair after inspection, by preventing premature failure and shutdown of facility:

Inspection Techniques Of Pressure Vessel:
To ensure safe operation of pressure vessel, online inspection is in the benefit of plant processing as well as surrounding environment. To find out the thickness of vessel surface, ultrasonic testing is widely conducted over industrial level. The purpose of such testing is to check regularly the thickness of metal of suspected areas with necessary equipment, if thickness of surface reaches at minimum allowable limit, then precautionary measures should be taken in order to keep plant working.

Notably, the other inspection techniques incorporate designing & maintenance of pressure relief valves along with installation of corrosion coupons & sentinel holes.

Real Time Example:
A. J. Warner, a senior engineer, who works for a refinery plant in Texas, quotes an example "Consider, for example, that a key Gulf coast refinery develops a serious problem in a pressure vessel. This will likely cause a shutdown of that unit, lasting anywhere from one day to several weeks or longer. This causes a disruption or shortage in the supply of gasoline to the market, which will drive up the cost at the pump. Therefore, it is in the best interest of everyone that pressure vessel technology remains a key focus area for the refining industry and beyond."

Keeping it in same way, Millennium Industries, a pressure vessel manufacturer at industrial scale maintains health and safety measures at its facility. Company aims to provide those industrial solutions, which have less affect over environment, impact over employees’ health, control risk factors and safe work practices.

Hydraulic Pumps

Hydraulic pump is a mechanical device which is used to converts the mechanical power of the system into hydraulic energy. To overcome the pressure which is induced by the load hydraulic pump generates high power flow.

A hydraulic pump performs basic two functions when it operates:

• A mechanical action which creates a vacuum at the pump inlet, it permits atmospheric pressure to force liquid from the reservoir into the inlet line to the pump.

• The second function which is performed its mechanical action that delivers liquid to the pump outlet and then forces it into the hydraulic system.

Why we need Hydraulic Pumps?

We need hydraulic pumps because they are the main sources of power for different dynamic machines. Hydraulic pumps have the power to push large amount of oil through the hydraulic motors and cylinders. In returns, the pump converts the mechanical work of energy into the hydro static energy.

Principle on which Hydraulic pumps operates

According to the displacement principle the hydraulic pump operates. In this principle the existed mechanically sealed chambers in the pump may involves. The purpose of these chambers is to transport the fluid from suction port (inlet) of the pump to the pressure port (outlet). These sealed chambers also ensure that no direct connection between the inlet and outlet port of the pump. This is the main reason that these pump suitable to operate at very high pressure and they are also ideal for Hydraulic systems. The mechanism of pump is shown in the figure below:

Mechanism of a pump

Types of Hydraulic Pumps

Depending on their different functional and other system requirements such as range of pressure or flow, operating medium, type of drive etc. hydraulic pumps are manufactured. Hydraulic pumps may have large range of design principle and configurations. All pumps can’t fully meet the requirements of the system. So for that reason different types of hydraulic pumps exists which are given below:

Hydraulic Gear Pumps

External gear pump

Internal gear pump

Gear ring pump

Screw spindle pump

Hydraulic Vane Pumps

Single chamber vane pump

Double chamber vane pump

Hydraulic Piston Pumps

Axial piston pump

Radial piston pump

Uses of Hydraulic Pumps

Hydraulic pumps are used in hydraulic machines. While selecting a hydraulic pump it must have good frequency, pressure and temperature capabilities. Hydraulic pumps are used to do different type of works such as open, close, lower and to lift components.They are also used in field services like machining and assortment of construction

A pump produces liquid flow or movement which is necessary for the development of pressure. This is a function of resistance to fluid flow in the system. For example, the pressure of the fluid at the pump outlet is zero for a pump not connected to a system (load). Further, to overcome the resistance of the load, pressure will rise to the level for a pump delivering into the system.

For more information about field services and hydraulics machines you can visit http://millenniumind.com/

Shielded Metal Arc Welding (SMAW)

SMAW is a process of welding that uses a fragile electrode coated in flux. SMAW have many names this process is also known as stick welding, Manual Arc Welding or flux shielded arc welding. In SMAW process as the weld is laid, the external coating of flux on electrode disintegrates, providing a layer of slag and a shielding gas. These elements protect the weld area from infectivity until the area cools. The external flux coating also performs more functions such as it provides control bead shape or arc stability.

Equipment & Operation for SMAW

The following equipment and operations are necessary for SMAW process.

• Welding power source
•  Electrode holder
• Ground clamp
• Welding cables and connectors
• Accessory equipment (It includes wire brush, chipping hammer)
• Protective equipment (It includes gloves, helmet etc.)

Welding Power Sources

Shielded Metal Arc Welding circuit we can use either Direct Current (DC) or either Alternating Current. In some specific cases, the power source must use constant current type. In this type, power source will deliver relative welding current or constant amperage. As it will remains constant so the weld beads which are produced will be uniform in shape and size.

Electrode Holder

The use of electrode holder is to connect different welding cables and ducts to the electrode. Electrode holder is available in different sizes and capacities. The purpose of insulated handle is to guide electrode over the weld joints.

Ground Clamp

The purpose of the ground clamp is to connect the ground cable to the work piece. A good ground clamp having the characteristics of carrying more electric current without overheating.

Welding cables and connectors

Electrode cable and ground cable plays an important role in the SMAW circuit. So different welding cables and connectors are also necessary components for the SMAW circuit.

Coated Electrodes

In Shielded Metal Arc Welding various types of coated electrodes are used. For different types of welding specific electrodes are used according to their types. For example, electrodes used for low allows and stainless steels will quite different from the coated electrodes which are used for mild or carbon steel.

For information about the Fabrication or welding you can also visit http://millenniumind.com/

Welding Repair

Weld repair is a process in which remove the damages of a metal. Metal damages removes from the use of Oxy fuel welding and by using carbon arc gouging or plasma cutting. For a good metal weld repair we must follow the steps which are involves in weld repair process.

Welding Procedure

For the use of welders a logical procedure of welding is to be applicable. In this procedure use special metal fillers and preheat the metal. In most of the construction companies, we can successfully weld a steel metal by using the following three steps which are:

•  In first step, Cutting the metal into the parts and removed the defected Components.
• In second step, prepare the new metal weld joints
• In third step, welding and cleaning the metal.

Step 1: Cutting metal into the parts and removed the defected components.

In the first step of welding repair removes the damages of a metal. This step can complete with the use of different welding techniques. Plasma and oxy-fuel are used for cutting a metal. We can also use carbon arc gouging which is well suited for removes the cracks from metal without harming the other parts of a metal.

With the help of different tools we can repair a metal. One of the most commonly used for cutting a metal is Oxy-fuel torch. Another tool which is used for cutting a metal is plasma cutters. By using plasma cutters welders can cut small parts width of metals. Plasma cutters are faster than the Oxy-fuel torches because by using plasma cutter welders can also cut electrical conductive metals but with the use of oxy-fuel torch welders can’t cut the stainless steel or aluminum metals. One of the most other common tools is carbon arc gouging which is used for welding generators. In using a carbon arc gouging uses an electrode which is made up of a carbon. By using this electrode welder can remove the defected parts. In result high pressure stream of air will released.

Step 2: prepare the new metal weld joints.

In the second step, welder will choose the filler material and replace all the parts with selected material which is better and have more power strength of the previous original material. According to their different mechanical properties such as tensile strength, wear resistance and ductility etc they have different applications. For avoiding long term failure of welding must ensure the quality and remove the unwanted downtime defects. When you will choose the right alloy then cut the steel and bevel the edges. After this preheating is required this is to be done by the use of oxy fuel torch.

Step 3: Welding and cleaning the metal.

In the third and last process, welders choose the welding process which they will follow to weld a metal. There are two most commonly used processes are:

•            Shielded Metal Arc Welding (SMAW)
•            Flux Cored Arc Welding (FCAW).

This article is all about the welding repair process. Millenniumind industry will offer the all these services.

For more details you can also visit at http://millenniumind.com

Safety Practices For Fabrication Shop Work

Fires blown up due to welding are avoidable, if workers follow those safeguards & practices prescribed by workshop administration before stepping into it, then precious lives could be saved from loss. 1.4% residential fires & 10% commercial fires reported in Irving – Texas due to welding accidents in 2002. Negligence in preventive measures give rise to such incidents, workers could overcome them by adopting prescribed standards of protection.

It is necessary for welders whether they are professional or unprofessional to know about potential threat of catching fire on fabrication shop, as work at high currents during make and break of connections.

Must do Checkups:
First thing first, before getting into work you should examine:

• Equipment’s health, 
• Working & surrounding area, 
• Available items to minimize hazards and 
• Measures that can ensure safety.

Checking of Equipment:
In order to avoid any accidents, the installation of the welding equipment should be done by qualified technicians, which can ensure about the connectivity as well as operation of apparatus according to manufacturer’s instructions. However, installed equipment correct operation i.e. cable, electrode holder and coupling devices is verified at welder’s end, he should be competent enough to identify, recover or report about the defects. The welder should make sure each time he uses the equipment, the external connections are clean & tight, clamp of wire has firm grip to grab the workpiece and appropriate distance between welding point & workpiece.

Reduction of Electric Shock Risk:
In arc welding, the major hazard that you might come across is the arc radiation and electric shock, it may occur due to appearance with live parts i.e. electrodes and workpiece of welding circuit. Certified welding shops use proper safety & protection system, as voltage seepage during rainy season increases as compared to normal.

More than One Welding Operations at One Workpiece:
There is a huge risk of electric shock when more than one workpieces have physical or electrical connection. Complete isolation of workpieces should be observed, else it will increase the probability of electrocuted in case of simultaneous connection.

Outdoor Working:
While working outdoor welding repair the possibility of moisture increases, it also increases voltage leakage. In such case, system requires sufficient level of waterproofing, for enclosures the ingress protection (IP) codes should be:

• IP 23 protection against water spray <60 degrees from vertical
• IP 24 protection against water spray from any direction

In case of rainfall, welder, equipment & workpiece should have complete protection from moisture.

Some Safety Practices to Avoid Tragic Situations:
The safety practices are as follows:

• The welders should takeoff ornaments like rings and metallic straps before getting started with work.
• The clothing like gloves, boots & overalls should be used to protect from electric shock.
• The external connection of the welding apparatus should be checked on daily basis, whether connections clean and fixed or not.
• The electrode of manual metal arc welding (MMAW) should have insulation for protection, to change the electrode.
• High frequency (HF) can make welder feel electric shock, HF could affect even through small hole in glove.

What Is CNC Machine, Types & Troubleshooting?

The word CNC is the derivation of NC meaning ‘Numerical Control’, whereas CNC means ‘Computer Numerical Control’. Obviously, CNC is numerically controlled device attached with the element of digital computing. In order to do so, machine tools are controlled by means of computer instructions, which are predetermined to perform each function of machine. Punched Tape is the clear example of machined controlled by computing device.

Overview:
Both NC & CNC enables greater ratio of productivity for tools of machine, as they are automatically controllable and require less human intervention. Before the innovation of CNC, Hydraulic Tracer Systems were less capable of automation element, due to the usage of hydraulics in cutting tools of lathe & template of mill. Moreover, such systems require taper attachments, which were used for many manual lathes indifferently capable of hydraulic tracer, as tracer had greater capability for the elaboration of templates rather than simple tapers.

Classification of CNC Machines:
As CNC involves usage of computers, so it increases the no. of machines, which could be brought under such classification.

• Retrofitted Machines – The machines that don’t have CNC installed by default or during manufacture.
• Custom Built Machines – The custom-built machines to perform CNC operation.

Types of CNC Machines:
Here we will mention some of the widely used at industrial level:

Milling Machine:
Milling Machine is used to cut different materials driven by computer controls, which translates programs containing instructions in the form of digits and letters to move the spindle of machine at specified dimensions. The standard programming language of all CNC machines is G code, while some manufacturers use customized propriety languages, which are simpler than standard language & easy in transfer.

Lathe Machine:
Lathe is a retrofitted CNC machine mostly used for cutting metal objects rotating with a fast speed. Basic feature of Lathe Machines is that they are capable to cut the metal by the help of indexable tools & drills with extreme precision in a quick manner that is not possible on manual lathes. Usually machine comprise of twelve tool holders, along with coolant pumps that cut down on tool wear. The field installation & control specification of Lathe Machine is similar to Milling Machine as it allows G code as well as proprietary programming language.

Troubleshooting of CNC Machine:
To troubleshoot a CNC machine, here are the key steps to follow:

• Environmental Issue: The issue may arise due to increase in temperature. Temperature of machining shop should be maintained with respective measures.
• Mechanical Issue: The problem may exist in flatbed guideway, ballscrews, & spindles that affect the tools and job under machine.
• Electrical Issue: At major level, it could be heating of cable, or it could be at miniature level that could be traced by trained CNC engineer through milling machine schematics.

Fabrication classes

Fabrication classes

Metal fabrication shops includes many processes of producing metal elements by ever-changing the raw metal material exploitation varied tools. The processes are classified as cold, heat and hot operating betting on the temperature at that the fabric is processed. Most of the objects around USA like paper clips, computers, bolts, nails, automobile components, components used for instruments and machinery and myriad alternative merchandise are remodeled by metal fabrication processes like bending, punching, drilling, turning, grinding, threading etc. The factors influencing the method enclosed the kind of fabric being machined, the speed of production, the specified pure mathematics, and alternative physical needs of the half.

Fabrication is divided into the subsequent classes. 

Metal Forming:

• Bending: All through bending, the work piece is bent to make flanges, contours, curls, seams, corrugations and alternative geometries by means that of applying force through hydraulic, gas and electrical machines. 

Shearing
• Conventional shearing: cutting off could be a metal cutting method through that flat surfaces cut employing a scissors-like action, typically in straight lines.

• Turret Punching: Turret Punching creates shapes in sheet material by in turn punching a series of basic shapes. Edges are cut by the cutting off action of a punch and die.

Material Removal

• Sawing: Sawing could be a variety of cutting within which the cutting implement could be a blade that incorporates a series of teeth, with every tooth removing a tiny low quantity of fabric. Sawing is usually wont to form stuff to the approximate size of the half, before further processes. 

• Sound: Tapping produces internal threads within the work. This involves use of a tool with multiple cutting teeth.

• Boring: Boring produces circular internal profiles in hollow work or on a hole created by drilling or another method.

• Turning: Turning rotates the work concerning its axis whereas applying cutting tools to form a desired form.

• Drilling: Drilling produces holes in an exceedingly work employing a fluted cutting implement.

• Edge: Milling removes little chips employing a rotating cutter that moves in 3 axes. 

• Grinding: Grinding could be a chip removal method within which the cutting implement is associate abrasive grain wheel. Differing kinds of grinding embrace Surface grinding, Cylindrical grinding, Internal grinding and Center less grinding.

Advanced strategies

• Optical device cutting: Laser cutting involves focusing a beam of high density energy on the surface of the work. The beam evaporates parts of the work in an exceedingly controlled manner.

• Electro Discharge Machining: Electro discharge machining is predicated on erosion of metal by spark discharges. This method is used for machining associate material that is an electrical conductor. 

• Wire EDM: The wire EDM or Electro Discharge Machining produces half shapes by cutting a metal work piece with a endlessly moving wire by means that of fast, repetitive spark discharges.

This method is employed to chop skinny and thick metal and is commonly wont to create punches, tools and dies from laborious metals. 

• Water jet Cutting: during this method, the force of a water jet is employed to chop material. The water jet acts sort of a saw and cuts slim kerfs within the work. Most of metals, plastics, fabrics, wood merchandise, and rubber, building material, leather, brick and composite materials are cut exploitation the water jet method.

Pressure Vessel Repair Safety and Precautions

Pressure vessels create a huge and significant hazard to those that work around them. They can critically wounded and kill. For this cause, hazards must be minimized when treating with or working pressure systems.

It is officially the owner’s accountability to supply a secure functioning setting, even as every person from the designer to the installer, to the user and owner has responsibilities to achieve to stay the pressure vessel repair harmless.

Within the USA, pressure vessels meet ASME Boiler and Pressure Vessel Code (BPVC) standards (Section VIII, Division 1) to guarantee an extended, functional service life.

The ASME Boiler and Pressure Vessel Code (BPVC) groups regulations of safety — connecting just to pressure reliability — prevailing the design, fabrication, and inspection of boilers and pressure vessels, and nuclear power plant components while production. The purpose of the regulations is to offer a periphery for corrosion in service. Encroachment in design and material and the proof of experience are continually being added.

Pressure vessels are usually harmless, it's only when a deprived loom or negligent approach is taken that tribulations lean to happen. The chief grounds of incidents are as follows:

·         Deprived design or equipment

·         Deprived maintenance

·         Hazardous operational practices

·         Operator error

·         Meager training/management

·         Derisory repairs

The frequent line in all these belongings is human fault. With the accurate systems prepared the hazard can be compacted noticeably, and accidents prohibited.

Some of the focal customs to decrease menace are includes the following:

·         Providing safe and suitable equipment

·         Being aware of the operating conditions

·    Fitting suitable protective devices and ensuring they work correctly

·         Carrying out suitable maintenance

·         Making sure all staff are trained to a good appropriate standard

·         Having equipment involved examined regularly

·         Using safe working practices and procedures

Non-destructive testing can successfully complete some of these necessities (suitable continuation and examining equipment), which is why it is extensively worn to examine the clause of pressure vessels repairs across the USA.

Non-Destructive testing employs a range of techniques to check equipment lacking mortifying it in any way, or having to scratch or smash it apart, such as for lab testing. It utilizes principles such as radiography, magnetism, eddy currents and acoustics to gather information in a non-invasive approach.

LFET (Low Frequency Electromagnetic Technique) can be used to examine the wall plates, while current technique can be used for welds. Additional techniques frequently used are dye penetrant, magnetic particle and ultrasonic depending on the necessities of the check, plus the aptitude of the company performing the examination.

During usual testing, the state of pressure vessels can be observed, and tribulations can be vetoed previous to they crop up. The outlay of check is always insignificant in perception, compared to costs earned after a foremost breakdown has occurred.