Lighting Technologies – Are They Lamps? (Part 3.4 of an 8 Part Series)
Welcome back to our Lighting Technologies series! The lighting industry has embraced new technologies to reduce costs while delivering fresh experiences. To understand the technologies used in lighting design, we must know the properties of the common and uncommon materials used in the manufacturing process.
Manufacturing is already becoming more automated with robots, and it is become quicker and more affordable to develop prototypes through Stereo Lithography or Rapid Prototyping machines. Fixtures and lighting systems may become more widely available with modifications and tweaks for smaller quantities at a minimal up charge because of these changes in how we build things.
Properties of materials: physical property, mechanical properties, type of materials
I. Physical property
Melting point, magnetic, optical gravimetric, thermal, electrical, acoustic
II. Mechanical property
Tensile strength, ductility, hardness, heat distortion, PV limit, yield strength, toughness, fatigue, creep resistance, compression strength, fracture toughness, proportional limit
III. Type of materials
The versatility of metals attests to the very wide range of properties of the more than 70 metals on the periodic table. A description of all of these properties and the applications in which they are used is well beyond the scope of this section. The following therefore provides an introduction to some of the more prominent properties.
Single polymer molecules typically have molecular weights between 10,000 and 1,000,000 g/mol–that can be more than 2000 repeating units depending on the polymer structure! The mechanical properties of a polymer are significantly affected by the molecular weight, with better engineering properties at higher molecular weights. The softening point (glass transition temperature) and the melting point of a polymer will determine which applications it will be suitable for. These temperatures usually determine the upper limit for which a polymer can be used. For example, many industrially important polymers have glass transition temperatures near the boiling point of water (100C, 212F), and they are most useful for room temperature applications. Some specially engineered polymers can withstand temperatures as high as 300 C (572 F).
A ceramic is often broadly defined as any inorganic nonmetallic material. Examples of such materials can be anything from NaCl (table salt) to clay (a complex silicate). By this definition, ceramic materials would also include glasses; however, many materials scientists add the stipulation that “ceramics” must also be crystalline. For years, ceramic materials were only useful in the making of pottery and other artwork. This was a result of their brittleness and difficulty of manufacturing. However, people’s demands for microelectronics and structural composite components have created a high demand for ceramics. Silicon, a semiconductor but also a ceramic material, has been THE material which has made computers possible. Ceramic fibers such as graphite and aluminum oxide with their extremely high stiffness have led to the production of fiber-reinforced composites. These materials are only a few of an ever-growing list of industrially important ceramics.
A glass is an inorganic nonmetallic material that does not have a crystalline structure. Such materials are said to be amorphous. Examples of glasses range from the soda-lime silicate glass in soda bottles to the extremely high purity silica glass in optical fibers. Some of the useful properties of ceramics and glasses include high melting temperature, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance. Many ceramics are good electrical and thermal insulators. Some ceramics have special properties: some ceramics are magnetic materials; some are piezoelectric materials; and a few special ceramics are superconductors at very low temperatures.
Ceramics and glasses have one major drawback: they are brittle. Glasses have historically been used for low technology applications such as soda bottles and window panes. However, glasses, like ceramics, have recently found new application in high technology fields, particularly the semiconductor microelectronics industry where silica is widely used as an insulator in transistors and the fiber optic cable industry where high purity silica glass has made advanced telecommunications possible. As with ceramics, the list of industrially important glasses also continues to grow.
Pure metals are elements which come from a particular area of the periodic table. Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans. There are three main categories for metal; ferrous, non-ferrous, and alloy. Ferrous metals are metal that contains iron. They have the highest melting temperature among metals which makes them difficult to machine but very reliable as machining tools such as dies. Non-ferrous metal are the metal that does not contain iron. Metal alloys are metal that contain some other metallic substances to increase performance for required application.
Ferrous metal: Steel and iron (metal that contains iron)
Non-ferrous metal: Aluminum, brass, copper, lead (metal that does not contain iron)
In metal, tiny imperfections within the crystalline structure control whether it bends, stretches, or ultimately breaks in response to stresses produced by heavy physical loads.
It would be misleading to suppose that all the atoms in a piece of metal are arranged in a regular way. Any piece of metal is made up of a large number of “crystal grains”, which are regions of perfect regularity. At the grain boundaries atoms have become misaligned.
Becoming more automated with robots
Quicker and cheaper to develop prototypes through stereo lithography or rapid prototyping machines
Fixtures and lighting systems may become more widely available with modification for smaller quantities at a minimal upcharge