Glass Cutting

View A Video on Glass Cutting - A Quick Introduction

Glass Cutting is used for every glass function, such as clear float glass (flat glass), decorative and obscure glass used by window manufacturers and framers for building construction and art housing; many types of building window glass and automotive windshield glass are laminated glass panes which have been tempered for use as shatter-proof safety glass. Highly demanding glass window and panel applications may call for wire glass, which is glass that has been reinforced with an embedded wire net. Most glass tubes, sight glass and precision optical products are made from borosilicate glass, the same heat resistant and shatter-proof material from which Pyrex products are manufactured. Sight glass is a type of tubular or lens-shaped optical glass manufactured for the transparent observation and level gauging of liquids within manufacturing processes. The most heat resistant type of glass is quartz glass, which looks like standard glass but is made of pure silicon and is transparent to UV rays. Glass bottles and containers are made by hand or automated glass blowing, and glass fabricators provide a range of custom molding, glass cutting and glass etching services. Coated glass and laminated glass have had elements added in the manufacturing process which increase specific features of the glass making it ideal for certain applications.

Glass is a unique material unlike plastics, metals or ceramics. Glass products are common in many industrial, commercial and consumer applications, including decorative architecture, electronic devices, medical equipment, laboratory equipment and household containers, but their most crucial applications can be found in building construction, automobiles and optical equipment. As an inorganic amorphous solid, glass retains a rigid, brittle structure without crystallizing and may be blown, formed and molded with relative ease at temperatures above 1800°F. The shape, heat resistance and thickness of glass are crucial elements to be considered for accurate viewing and measurement, just as eyeglass lenses, microscope and telescope lenses are manufactured with precision thickness and curvature. Nearly all types of glass used in automotive windows or as architectural safety glass undergo precision tempering, coating and laminating processes to reduce brittleness, increase strength and to cause the window, if shattered, to break into small, rounded pieces rather than dangerous shards.

Silica is the main ingredient used in glass fabrication. Pure sand is often used as raw silica material, which is usually mixed with other inorganic compounds such as soda ash, or sodium carbonate, which lowers silica's melting point from 2300°C to a more manageable 1500°C; lime, or calcium oxide, which increases chemical durability; and other carbonate minerals such as magnesium oxide, aluminum oxide, gypsum and dolomite. Glass made primarily of silica, soda ash and lime is referred to as soda-lime glass, while glass made of silica and boron oxide is referred to as borosilicate glass. Soda-lime glass is a cost-effective option and is typically used in commodity items, glass containers and standard windowpanes. borosilicate glass, also known as Pyrex, is more costly yet is a highly durable, heat resistant material used in laboratory beakers, test tubes, cookware and optical lenses. Once raw materials have been melted and refined in a furnace, the liquid glass may be molded or blown. Flat glass is float glass that has been formed by channeling melted glass into a bath of molten tin; the less dense glass floats on top of the tin's even surface while rollers smooth the top surface and move the glass along. The glass panel cools as it exits onto a conveyor, where it is cut, heat treated and laminated. Glass containers for use in beverage and product storage may be formed by blow or press procedures depending on the necessary output. Molten drops of glass called gobs are formed into parisons and are plunged or blown into molds where the glass solidifies. Glass products such as glass blocks may also be poured and pressed into molds then slowly cooled at controlled temperatures. Glass products then need to go through the process of annealing to balance the inner and outer stress of the product and remove potential areas of weakness.

Hand blown glass products take a high level of skills and are most often used for costly decorative pieces. Some manufacturers still use hand blowing techniques to manufacture containers and other pieces, although hand processes are far less cost effective than automated glass blowing, molding or float fabrication. Technologies developed within the last fifty years have increased the safety, durability and functional capabilities of glass products far beyond that of traditional glass making. Manufacturers of glass panels and products fabricate fire proof glass, heat resistant glass, safety glass and bullet proof glass that have been able to replace or enhance metal or ceramic materials, as well as a spectrum of precision optical equipment. Other developments have been made in glass manufacturing through tempering and laminating, including the fabrication of UV-blocking glass, reflective glass, non-reflective glass, insulating glass and one-way mirrors. The raw materials, mainly silica, used to fabricate glass are widely available, and glass may be completely recycled, making glass highly cost-effective to fabricate.

Glass Cutting and Glass Cutting Services Image Provided by S&S Optical Company

Glass Cutting Services Image Provided by Pegasus Glass.

Glass Cutting Types

• Blown glass is glassware shaped and created by air pressure; this has commonly been done by mouth in the past or by compressed air through a metal pipe. Pieces are often made in mass quantities such as bottles, via a highly automated system, which both moves and injects air into the glass gob to form the finished piece.
  
• Cut glass is any glass object decorated by cutting or grinding facets and is for purely decorative purposes, like decorative plates or other assorted knick knacks.
  
• Flat glass is a wider classification of glass that includes wired and tempered glass. The main processes by which flat glass is made are the rolled and float glass procedures: rolled glass is made when a continuous stream of molten glass is poured between water-cooled rollers, while the float glass process is the most widely used process and consists of the glass being held in a chemically controlled atmosphere at a high temperature for a long enough time for the surface to become flat and parallel.
  
• Glass blowing is the process of shaping glass with air.
• Glass cutting includes various methods, including diamond saw cutting, thermal or hot cutting, score and break cutting, and laser cutting.
• Glass rods are long, cylinder-shaped pieces of glass.
• Glass tube is a cylinder made of glass material.
• Heat strengthened glass is exposed to a heating and cooling cycle and is typically doubly strong as standard annealed float glass of equal measurements.  Breakage of this glass results in larger pieces than with completely tempered glass.
  
• Precision optics offer superior clarity and precision to meet the very specific demanding needs for high-tech lenses, prisms, medical internal visual systems, etc.
  
• Quartz glass is the result of melted silica, and it can resist extreme or quickly changing temperatures and is typically transparent to ultraviolet radiation. This product is utilized in fiber optics, analytical instruments, semiconductor technologies and casting processes.
  
• Specialty glasses include any number of glass products fabricated for specific purposes, including bent, bulletproof, silk screened and colored glass and glass parts for industrial and commercial uses.
  
• Tempered glass is a type of safety glass that is heat treated and approximately five times stronger than similarly measured glass standard annealed float glass; breakage results in small, rectangular-like pieces, beneficial for general and safety glazing like storm doors, building entrances, sliding doors and bath and shower doors.
  
• Textured glass is a product with various patterned and uneven surfaces.
• Wired glass is created by inserting a wire mesh into sheets of glass, which has a resistance to impact forces like normal glass, but wire holds broken pieces in place. This has customarily been accepted as inexpensive fire safety glass.

Glass Cutting Terms

Annealing - The procedure of controlling the cooling of glass in the manufacturing of float glass; doing it in a lehr prevents residual pressures in the glass. Annealed glass from the manufacturer typically has a breaking strength of 500psi.
 
Annealing Lehr - An apparatus in the float glass production line subsequent to the tin bath and prior to the cooling conveyor, which controls the cooling and heating. It relieves pressure from the flat glass product to permit ordinary cold end-of-line processing.

Anti-Walk Blocks - Blocks of elastomer that restrict lateral movements of glass as it travels through the glazing channel caused by seismic, thermal, building movement, wind load effects or any other applicable force.  
 
Autoclave - A container using heat and extreme pressure in the glass industry that creates a bond between glass and PVB or urethane sheet, resulting in laminated glass.
 
Bent Glass - A glass product that has been shaped from a flat shape into the desired curved shape during the molten state.
 
Beveling - The procedure of putting a bevel edge on finished cut glass.
 
Bow/Warp - An imperfection in flat glass that is a bend, curve or any other alteration.
 
Bubbles - Imperfections that occur in laminated glass as a pocket of air or gas between the interlayer and the glass. The parameter is any inclusion higher than .8 mm (1/32") in diameter in float glass.
 
Chemically Strengthened Glass - The strengthening of glass through ion-exchange to create a compressive pressure layer at the treated surface.
 
Chipped Edge - A flaw resulting from breakage of tiny pieces off of the edge of cut glass; typically, it is only significant for heat absorbing glass.
 
Cullet - Waste or broken glass. Can often be remolded for later use.
 
Double Strength - Float glass that measures approximately three mm thick (1/8").
 
Flare - A protrusion on the edge of a lite of glass.
 
Flat Glass - A general term that describes float glass, sheet glass, plate glass and rolled glass.
 
Float Glass - Glass formed on a bath of molten tin. The surface in contact with the tin is known as the tin surface or tin side. The top surface is known as the atmosphere surface or air side.
 
Gob - The portion of hot glass delivered by a feeder or gathered on a punty or a pipe.
 
Heat Absorbing Glass - Glass designed to absorb significant quantities of solar energy.
 
Laminated Glass - The bonding of two or more panes of glass (lites) with one or more interlayers; the interlayer is composed of plastic. The glass lites could be various colors and thicknesses, mirrored or stenciled, and the intermediary plastic material choices are many depending on the preferred effect.
 
Lite - An industry term for pane of glass, spelled differently to differentiate from perceptible light.
 
Moil - The left-over glass remaining on a punty or blowpipe after a piece has been completed and cut off.
 
Polished Wired Glass - Wire glass with both sides polished and ground.
 
Punty - A device to which ware is attached for holding during fire polishing or finishing.
 
Quartz Glass - Glass that is composed almost entirely of silica.
 
Seam - The mark on a glass surface resulting from joint of matching mold parts.
 
Temper - A reference to the degree of enduring stress found in annealed glass.