Occupation | |
---|---|
Occupation type | Vocational |
Activity sectors | Industrial manufacturing |
Description | |
Competencies | Patience, steady hand, ability to read plans, attention to detail, physically strong |
Education required | Industrial Training Institute, Apprenticeship |
Fields of employment | Industrial manufacturing |
Related jobs | Millwright |
A machinist is a tradesperson or trained professional who operates machine tools, and has the ability to set up tools such as milling machines, grinders, lathes, and drilling machines.[ clarification needed ]
A competent machinist should have a well-developed mechanical aptitude, the ability to correctly use precision measuring instruments and to interpret blueprints, and a working knowledge of the proper parameters required for successfully utilizing the various tools commonly used in machining operations. CNC (computer numerical control) is the modern manufacturing method in which machinist use a form of programming called G-code to make components for a wide variety of industries. CNC programming is a highly skilled position. Programmers are usually machinist as well. A CNC programmer creates programs using software called CAM (computer aided manufacturing). The programmer must be proficient in math, speeds and feeds, machine tooling, work holding, and the different ways various materials react to stress and heat in the machining process.
The machine trade is an extremely broad field with a wide variety of workplaces, job duties, and types of work. Most machinists work in machine shops and factories where they operate machinery that produce precision component parts. In general, the occupation is exacting, and requires extensive knowledge of the tools and processes in order to achieve the tight tolerances and surface finishes that these parts specify.
Many machinists make mass-produced parts using highly automated computer numerical control machines which are common today, but still require such professionals to set up and calibrate the machines. Other more specialised machinists produce custom-made parts for prototyping, repair, or research. A machinist may work on manufacturing something relatively simple like a bracket, or a shaft, or something extraordinarily complex, such as aerospace components accurate to 5 micrometres.
Good machinists are highly sought after and respected skilled trades persons and are generally well-paid. In utility, medical, and military use companies, experienced machinists can earn over $100 000 per year.
Some titles reflect further development of machinist skills such as tool and die maker, patternmaker, mold maker, programmer, and operator. A machinist is one who is called on to fix a problem with a part or to create a new one using metals, plastics, or rarely, wood. Depending on the company, a machinist can be any or all of the titles listed above.
Other related fields include Millwrights, quality assurance, and mechanical engineers.
In Australia, a related profession is a fitter and turner. A fitter and turner is the tradesperson who fits, assembles, grinds and shapes metal parts and subassemblies to fabricate production machines and other equipment. [1]
Under the machinist title are other specialty titles that refer to specific skills that may be more highly developed to meet the needs of a particular job position, such as fitter (assembles parts), turning hand, mill hand, and grinder.
A machinist is usually called upon when a part needs to be produced from a stock material by cutting. Such a part may be unique or may be needed in the thousands. The part could be anything made from metal or plastic, though machined parts are usually ones that require high precision and cannot be produced by other means. Machinists generally start with a saw cut length of stock or a casting. Producing a part will often require several steps and more than one machine tool. Each machine tool plays a specific role in cutting away excess material. When large numbers of parts are needed, production planning is required to plan the most logical workflow through a series of machines. Computer numerical controlled (CNC) machines are computer-driven tools that can machine a large variety of shapes, and whose use in the workflow depends on the part to be machined. [2]
CNC machines are becoming the standard due to their speed, precision, flexibility, repeatability, and reduced downtime while changing jobs. Production runs consisting of large numbers of parts are more cost effective and commonly referred to as production work in the trade. Conversely, small production runs are sometimes referred to as prototype or jobbing work.
Production engineers use blueprints and engineering drawings to produce detailed specifications of the part, especially its geometry (shape), then decide on a strategy to make it. Machine tools are then configured by the machinist and production commences. The machinist works with the quality department to ensure the specifications are maintained in the finished product. [2]
Large commercial organizations often staff machinists on site in a maintenance mode to ensure continuing operations of the production machinery. Such machinists can often make replacement parts the same day. Because of this, the labor cost for this role are significantly lower than costs involved with production shutdowns.
Additive machining means 3D printing to create industrial components, prototypes, tooling, and end-use production parts. Additive machining comes into its own in the manufacturing of very small intricate parts, which could not be produced through any other manufacturing process. There are several processes in additive manufacturing which include direct metal deposition: electron beam melting, fused filament fabrication, select laser sintering, and variations of them.
The most common materials that machinists make parts from are steel, aluminium, brass, copper, and various alloys of these materials. Other less common materials such as vanadium, zinc, lead, or manganese are often used as alloying elements for the most common materials. Materials that machinists work with occasionally are plastics, rubber, glass, and wood products. Rarely, machinists also work with exotic and refractory metals. The term exotic metals is a general term describing out of the ordinary, rare or special purpose metals. A synonym might be space-age. A list of exotic metals might include, but is not limited to, titanium, beryllium, vanadium, chromium, molybdenum and tungsten, as well as special high-temperature metal alloys like Inconel or Hastelloy (superalloys). Very often the meaning of the term suggests the need for specialized handling and/or tooling to machine them effectively. [3]
While the foregoing were primarily the materials that a machinist would be cutting, the cutters that the machinist uses must be harder and tougher than the materials to be cut. The materials in the cutters a machinist uses are most commonly high-speed steel, tungsten carbide, ceramics, Borazon, and diamond. [3]
Machinists usually work to very small tolerances, usually within 0.010" or 0.25 mm (more commonly expressed as ±0.005" (Plus or minus five thousandths of an inch) or ±0.13 mm), and sometimes at tolerances as low as +/-0.0001" (plus or minus one tenth of a thousandth of an inch – or 0.0025 mm) for specialty operations. A machinist deals with all facets of shaping, cutting and some aspects of forming metal, although forming is typically a separate trade. The operations most commonly performed by machinists are milling, drilling, turning, and grinding. There are other more specialized operations that a machinist will less frequently be called upon to perform such as honing, keyseating, lapping, and polishing, to name a few.
The tools that a machinist is expected to be proficient with fall into broad categories:
A lathe is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, sanding, knurling, drilling, deformation, facing, threading and turning, with tools that are applied to the workpiece to create an object with symmetry about that axis.
A machine tool is a machine for handling or machining metal or other rigid materials, usually by cutting, boring, grinding, shearing, or other forms of deformations. Machine tools employ some sort of tool that does the cutting or shaping. All machine tools have some means of constraining the workpiece and provide a guided movement of the parts of the machine. Thus, the relative movement between the workpiece and the cutting tool is controlled or constrained by the machine to at least some extent, rather than being entirely "offhand" or "freehand". It is a power-driven metal cutting machine which assists in managing the needed relative motion between cutting tool and the job that changes the size and shape of the job material.
Metalworking is the process of shaping and reshaping metals in order to create useful objects, parts, assemblies, and large scale structures. As a term, it covers a wide and diverse range of processes, skills, and tools for producing objects on every scale: from huge ships, buildings, and bridges, down to precise engine parts and delicate jewelry.
Machining is a manufacturing process where a desired shape or part is created using the controlled removal of material, most often metal, from a larger piece of raw material by cutting. Machining is a form of subtractive manufacturing, which utilizes machine tools, in contrast to additive manufacturing, which uses controlled addition of material.
In machining, numerical control, also called computer numerical control (CNC), is the automated control of tools by means of a computer. It is used to operate tools such as drills, lathes, mills, grinders, routers and 3D printers. CNC transforms a piece of material into a specified shape by following coded programmed instructions and without a manual operator directly controlling the machining operation.
Metal fabrication is the creation of metal structures by cutting, bending and assembling processes. It is a value-added process involving the creation of machines, parts, and structures from various raw materials.
A grinding machine, often shortened to grinder, is any of various power tools or machine tools used for grinding. It is a type of material removal using an abrasive wheel as the cutting tool. Each grain of abrasive on the wheel's surface cuts a small chip from the workpiece via shear deformation.
The phrase speeds and feeds or feeds and speeds refers to two separate parameters in machine tool practice, cutting speed and feed rate. They are often considered as a pair because of their combined effect on the cutting process. Each, however, can also be considered and analyzed in its own right.
A Tool and Cutter Grinder is used to sharpen milling cutters and tool bits along with a host of other cutting tools.
Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates.
In machining, a metal lathe or metalworking lathe is a large class of lathes designed for precisely machining relatively hard materials. They were originally designed to machine metals; however, with the advent of plastics and other materials, and with their inherent versatility, they are used in a wide range of applications, and a broad range of materials. In machining jargon, where the larger context is already understood, they are usually simply called lathes, or else referred to by more-specific subtype names. These rigid machine tools remove material from a rotating workpiece via the movements of various cutting tools, such as tool bits and drill bits.
An end mill is a type of milling cutter, a cutting tool used in industrial milling applications. They can have several end configurations: round (ball), tapered, or straight are a few popular types. They are most commonly used in "milling machines" that move a piece of material against the end mill to remove chips of the material to create a desired size or shape. It is distinguished from the drill bit in its application, geometry, and manufacture. While a drill bit can only cut in the axial direction, most milling bits can cut in the radial direction. Not all mills can cut axially; those designed to cut axially are known as end mills.
In machining, boring is the process of enlarging a hole that has already been drilled by means of a single-point cutting tool, such as in boring a gun barrel or an engine cylinder. Boring is used to achieve greater accuracy of the diameter of a hole, and can be used to cut a tapered hole. Boring can be viewed as the internal-diameter counterpart to turning, which cuts external diameters.
A machine shop or engineering workshop is a room, building, or company where machining, a form of subtractive manufacturing, is done. In a machine shop, machinists use machine tools and cutting tools to make parts, usually of metal or plastic. A machine shop can be a small business or a portion of a factory, whether a toolroom or a production area for manufacturing. The building construction and the layout of the place and equipment vary, and are specific to the shop; for instance, the flooring in one shop may be concrete, or even compacted dirt, and another shop may have asphalt floors. A shop may be air-conditioned or not; but in other shops it may be necessary to maintain a controlled climate. Each shop has its own tools and machinery which differ from other shops in quantity, capability and focus of expertise.
Tool and die makers are highly skilled crafters working in the manufacturing industries. Tool and die makers work primarily in toolroom environments—sometimes literally in one room but more often in an environment with flexible, semipermeable boundaries from production work. They are skilled artisans (craftspeople) who typically learn their trade through a combination of academic coursework and with substantial period of on-the-job training that is functionally an apprenticeship. They make jigs, fixtures, dies, molds, machine tools, cutting tools, gauges, and other tools used in manufacturing processes.
The cylindrical grinder is a type of grinding machine used to shape the outside of an object. The cylindrical grinder can work on a variety of shapes, however the object must have a central axis of rotation. This includes but is not limited to such shapes as a cylinder, an ellipse, a cam, or a crankshaft.
Grinding is a type of abrasive machining process which uses a grinding wheel as cutting tool.
In machine tools, a spindle is a rotating axis of the machine, which often has a shaft at its heart. The shaft itself is called a spindle, but also, in shop-floor practice, the word often is used metonymically to refer to the entire rotary unit, including not only the shaft itself, but its bearings and anything attached to it. Spindles are electrically or pneumatically powered and come in various sizes. They are versatile in terms of material it can work with. Materials that spindles work with include embroidery, foam, glass, wood, etc.
In manufacturing, threading is the process of creating a screw thread. More screw threads are produced each year than any other machine element. There are many methods of generating threads, including subtractive methods ; deformative or transformative methods ; additive methods ; or combinations thereof.
Milling is the process of machining using rotary cutters to remove material by advancing a cutter into a workpiece. This may be done by varying directions on one or several axes, cutter head speed, and pressure. Milling covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations. It is one of the most commonly used processes for machining custom parts to precise tolerances.