Instruments Industry
This group contains establishments engaged in producing various instrumentation. Its industries include:
-Search, Detection, Navigation, Guidance, Aeronautical, and Nautical Instruments
-Laboratory Apparatus, Analytical Optical, Measuring, and Controlling Instruments
-Surgical, Medical, and Dental Instruments
-Opthamalic Goods
-Photographic Equipment and Supplies
-Watches, Clocks, and Clock Operated Devices
Material Formation: The only material formation involved in the instrumentation major is that of high quality glass. Glass is often produced by establishments requiring precision for optical goods such as analytical systems and glasses.
CERAMICS consist of combinations of metallic and non-metallic elements. Compounding is the process used to produce ceramics. They are brittle materials used extensively for their resistance to electricity, wear, and high temperatures. Most ceramics have crystalline structures and can display polymorphism or many crystalline states. For example, silica can exist in three forms; quartz, tridymite, and cristobalite.
Forming: Small, precise formation is often required to accommodate the instrumentation group.
CASTING is one of the oldest and most common methods of forming. It requires the melting of a solid, heating it to the proper temperature, treating it to produce a desired chemical composition, and then pouring it into a cavity or mold for solidification. A wide range of sizes and shapes are possible with casting including large and bulky to small and detailed products. Some common casting processes include:
Some machining is required in casting processes to remove cores, gates, fins, left by air holes in the molds. Casted parts offer the best resistance to working stresses because they are melted for forming and not mechanically worked.
POWDERED METALLURGY is a material formation process that is similar to casting in that some type of mold is used. Fine metal powders are blended, pressed within a mold, and then heated or sintered. Powdered metallurgy is used for its ability to produce many complex shapes in one step. Machining is many times unnecessary for a part produced with powdered metallurgy. Melt atomization and electrolytic deposition are the most common processes used to produce the often expensive metal powder.
Cold working forces require the material to be mechanically worked or deformed cold. Such processes are advantageous because they provide good dimensional accuracy and good surface finish. Greater forces are required to cold work, and there are also losses in strength. However, machining can sometimes be eliminated with proper working.
SQUEEZING is a forming process where the material is forced to compact. It is used to produce features such as sudden tapers, rounded ends, and thinner sections. Common squeezing techniques include:
BENDING requires deformation of the workpiece about a linear axis. It is used to form metal to numerous geometric shapes such as right angles, rounded corners, and tight seams. Common bending applications include:
SHEARING is a mechanical forming process for metal sheets or plates where material is cut
without the formation of chips or the use of burning or melting techniques. Shear forces
are applied to produce dislocations along grain boundaries of the material. Common
shearing applications include:
DRAWING is a forming process where plastic (permanent) flow occurs over a curved axis. A good way to envision drawing is taking a flat sheet of material and using a punch to push a cup-like shape from the sheet. Some common drawing techniques include:
Machining: All of the industries in this major group use machining processes. Machining deals with removing material (usually in the form of chips) so as to obtain a finished product of desired size, shape, and finish. Machining that does not produce chips is classified as non-traditional machining.
SAWING produces chips by a succession of small cutting edges or teeth arranged in a narrow line on a saw blade. Sawing processes cutting off sections of wood to notching metal. Saws can be classified into three distinct types; reciprocating, band, and circular.
FILING requires cutting teeth arranged in succession along the same plane on the surface of a file to remove material chips. Types of files include; single-cuts double-cut, vixen-cut, and rasp-cut. Files are also classified by coarseness and construction. Filing is important to furniture industries in easily removing sharp edges that could cause injury in finished products.
ABRASIVE machining uses very small cutting edges that are integral parts of abrasive particles to produce chips from the material. A good example is using sandpaper to smooth a rough surface. Types of abrasives include; quartz, aluminum oxide, silicon carbide, and diamond. Some common types of abrasive processes include grinding and lapping. Grinding uses a wheel of some shape on which abrasives are bonded. Lapping requires that fine particles be embedded into a soft material (like paper) which serves to finish the part Abrasive machining is limited to small amounts of wood removal. However, it can provide extremely smooth surfaces.
ABRASIVE JET machining removes material through the action of a focused stream of abrasive laden gas. Common abrasives include; aluminum oxide, silicon carbide, sodium bicarbonate, and glass beads. AJM is used to debur plastic parts, deflash small castings, and touch up molds. AJM is very cheap and good for difficult to reach areas. It can machine very hard materials, but it has a slow material removal rate. Stray cutting may occur, along with the embedding of particles in the workpiece.
CHEMICAL machining is classified as non-traditional machining in that it doesn't produce chips. It employs some type of chemical reaction (sometimes enhanced by electrical or thermal energy) to remove material. Chemical machining often take the place of processes such as deburring, grinding, and polishing.
ULTRASONIC machining is a material removal process used to erode holes and cavities in hard workpieces. It uses shaped tools and high frequency mechanical motion. Another form of ultrasonic material removal is the stripping of finishes via underwater ultrasonic wave emission.
Assembly: The actual putting together, joining, and additional finishing of components constitutes assembly. Not many processes define a fashion in which parts and components are put together; it's just done in (hopefully) the fastest, most efficient manner. Assembly in the instrumentation group is a vital task, since many fine parts must often be precisely assembled. Once together, there has to be a means of joining the components.
WELDING is a process where two materials (usually metals) are permanently joined together through localized coalescence. Weld quality and strength depend on a combination of temperature, pressure, metallurgical conditions, and skill of the welder. Various forms of welding include:
SURFACING is the deposition of a layer of metal or other material upon the surface of some base metal. The layer of material can be applied with nearly all gas flame and arc welding methods.
METALLIZING is the surfacing of a base metal by melting and atomizing material in a special torch and spraying the resulting liquid onto a surface. Metallizing is used to protect, harden, reflect, and provide electrical conductivity.
BRAZING is the joining of metal components through the use of heat and filler material whose melting temperature is above 450 degrees Fahrenheit, but below the melting point of the metal to be joined. Common fillers include; brass, bronze, copper silicon, and silver alloys. Brazing is not as strong as welding, but can be used on virtually all metals. Less heat is required than welding, and brazing is good for mass production.
SOLDERING is the joining of metal components through the use of heat and filler material whose melting temperature is below 450 degrees Fahrenheit. Common fillers include; lead alloys and aluminum. Dip type soldering is used extensively when many parts can be joined at once. Soldered joints are weaker than brazed joints, but less heat and effort are required to perform soldering.
ADHESIVE BONDING uses composite systems with several compounds to join two surfaces together. The bonding material may exist as liquids, pastes, solids, tapes, or films. Common types of adhesives include:
The surfaces of all components to be joined must be clean and dry to insure proper bonding.
MECHANICAL FASTENING requires that a joint be formed by mechanically interlocking or interfering with no fusion or bonding present. Fastener types include integral and discrete. Integral fasteners are machined areas of wood such as tabs and seams that fit into other parts. Discrete fasteners are separate pieces such as nails, bolts, screws, rivets, and wires.
COATING is performed to impart certain properties to surfaces such as resistance to weather and wear, different colors, and smoother finishes. Coatings can be classified into organic and inorganic types. Common coatings include paint, enamel, anodization, and plastic laminations.
Inspection and Testing: Most of the processes already described in the instrumentation group occur at only one point in the overall manufacturing path. Inspecting and testing, however, are performed numerously throughout all processes. It can consist of a simple check to see if a piece is present, or a minute measurement of the surface of a finished part Inspection and testing tell whether or not a particular process was performed adequately.
DESTRUCTIVE TESTING does not allow for use of the tested part after inspection because it imparts some type of mechanical deformation. This type of testing is done on a sampling basis. Other types of destructive testing include fatigue, impact, creep, torsion, and shearing.
NON-DESTRUCTIVE TESTING allows for use of the part after inspection. It includes a wide range of optical and mechanical techniques. Mechanical techniques using instruments such as calipers, micrometers, and scales may contact the part, but they leave no significant mechanical deformation. Optical techniques include structured light, triangulation, holography, and interferometry.