Straight-line Cutting Machine Technology Developed Slowly

Straight-line cutting can be defined as cutting of squares, rectangles, or trimming edges from the stock size glass sold by glass manufacturers. Surprisingly, it took until the late 1940s before any type of automated equipment for straight-line cutting became commercially available. Until then, straight-line cutting was done on tilting or stationary tables, with hand-cutting tools and straight edges. There was one exception to this… the automation of the cutting (“capping”) of stock sheets from the continuous vertical and horizontal glass ribbons, after the glass was cool enough to be handled. Billco built this type of equipment for glass producers, and I assume other companies did as well.

Sometime in the late 40s, our company started offering what was called Pin‐bar Tables, which were designed to lessen hand-cutting fatigue and produce more accurate cut parts. These Pin‐bar Tables consisted of a large table with a row of pins along the sides of the table surface. These pin‐bars were actually ¼” thick, 2” wide steel strips embedded into the edges of the table, below the surface. The strips had ¼” holes drilled on 1” centers in the middle of the strip. Steel pins were inserted into the holes and only projected up to the surface of the table so that glass could be loaded onto the table without hitting the pins. Using the pins as measurement points, a special cutting bar that spanned the width of the table was inserted into the corresponding pins on both sides of the table. Using this accurately positioned bar, a person could run his hand tool along the bar to accurately score the glass.

This eliminated measuring for each cut and then used a “T” square for alignment of the hand-cutting tool. There were some versions of this table where a cutting head and rail were attached to the bar, and the operator pulled the cutting head across the bridge. The Pin‐Bar Table did not automate straight‐line cutting, but it did speed up the hand-cutting process and make the finished parts more accurate.

In the late 1950s, commercially available, powered straight‐line cutting machines called Strip Cutters were developed. It is important to note that all scores produced on a strip-cutting machine went completely across the glass lite from one side to the other. These strip‐cutting machines were available in three basic designs known as Powered Stip Cutters, Traversing Single-Bridge Strip Cutters, and Dual-Bridge Cutters.

Manual Shape Cutter with Model 55 or 67 Cutting Head

Manual Shape Cutter with Model 55 or 67 Cutting Head

Dual‐bridge cutting machines (also referred to as Block Cutters or X‐Y Cutting Machines):

This machine has a fixed, air float cutting table in general sizes from 48” x 48” to 96”x96”. In two automated cycles, two bridges (one able to pass over the other), with multiple, adjustable cutting heads on each bridge, traversed across the table in each dimension. After the second cycle, the glass has been scored in both the X and Y-axis dimensions. Our company also produced automatic breakout (score separation) machines to accompany this cutting machine. X‐Y Cutting Machines were primarily used by the glass producers, to reduce the large lites cut from the glass ribbons down to stock sizes supplied to their customers.

These three strip-cutting machines were very popular in the glass industry, and actually, some of them are still being used in glass fabricating facilities around the world. There were also some other semi-automated versions of straight‐line cutting machines being used in various glass plants throughout the world… mostly by the companies themselves, to meet their unique needs.

It is also once more important to point out that none of these strip-cutting machines could score a stock lite of glass into a group of random size rectangles or squares.

Dual‐bridge Cutting Machines

Glass Passed Through Several Steps From Producer to End User:

In general, the progression of glass from the glass manufacturers to the finished glass used by the consumer went through one or two different steps before it reached the end user. For residential and commercial building glass, the glass was shipped in wooden cases, in large stock sizes, from the glass manufacturer to a glass distributor located in a large metropolitan area. The distributor cut these large stock sizes down to smaller sizes that the local glass shops could handle. In almost all cases, the glass distributors and shops relied exclusively on tilting or stationary hand-cutting tables for glass cutting.

Vertical, hand-cutting machines were and still are used in glass shops and hardware stores to trim larger lites of glass down to smaller finished sizes for the end user.

For windows, as well as auto glass and mirror producers, the glass manufacturer supplied directly large quantities of stock sizes in boxes or on racks that were close to the actual finished parts they produced. These companies then used their powered strip cutters, and/or shape-cutting machines, to reduce the stock size to the desired finished rectangular or shape parts.

No matter what the end use of the glass part was, in many cases, it had to be processed on more than one type of glass cutting machine.

The Dawn of a New Generation of Glass Cutting Technology and How Glass Was Sold To Consumers:

A meeting at Billco in 1970 started a change in the way glass cutting machines would be designed and controlled. This new technology is still in use on glass cutting machines today.

The purpose of the meeting was to determine if there might be faster and more accurate control methods, as well as machine design, for cutting shaped glass parts for the automotive industry. The meeting was attended by the principals of Billco, the chief engineer, and myself.

Fortunately for our company and ultimately the glass industry, our chief engineer, Hugh Trautmann, was a brilliant mechanical engineer who had extensive machine tool experience, as well as experience in designing and producing aircraft parts for such companies as McDonnell Douglas and Boeing. He also was a person
who didn’t mind acting on hunches he thought might work. He was the right person, at the right time in glass industry history.

Hugh was up for the task. After evaluating Tracer‐type Control and Numerical Control (NC), both of which were in use at the time in the machine tool industry, he settled on NC technology. NC was being used for controlling milling machines in the metalworking industry. There were some obstacles to be overcome with Numerical Control, as it was being used at that time. The greatest problem by far was the machine speed of a standard milling machine…around 100 to 200 inches per minute….much too slow for shape glass cutting. Hugh’s goal was to start out at cutting speeds of possibly 1000 inches per minute. Selecting a standard Mark Century™ NC Control from General Electric, and after much study, he found unique ways to get around this speed problem and make NC useable on a glass cutting machine.

The next step was to design a cutting machine to accept this new control technology. Here Hugh relied on his experience in the aircraft industry by using ball screws to support and move a traversing bridge. These ball screws were similar to those used on aircraft to raise and lower wing flaps and landing gear. The bridge supported a single pneumatic cutting head, holding a standard tungsten carbide cutting wheel. The framework of the machine was built from massive square steel tubing to support both the cutting table and the cutting bridge and ball screw assembly suspended above the cutting table. The reason for the ruggedness of the machine frame was to eliminate the vibration of the machine at the high cutting speeds, which could affect both cutting accuracy and the smoothness of the score path.

The reason for the ruggedness of the machine frame was to eliminate the vibration of the machine at the high cutting speeds, which could affect both cutting accuracy and the smoothness of the score path. After testing and overcoming detractors both in our company and in the glass industry, this prototype machine was sold to PPG at their Greensburg, Pa. auto glass plant…and remained in operation at that plant until it closed in the late 90s / early 2000s.

These NC / X‐Y Axis, Contour Cutting Machines, were sold both in the US and Europe, and served the automotive industry well for many years.

Taking a Bold Second Step in Straight‐line Cutting:

Also in the early 1970s, some decisions were being made in other parts of the glass industry that helped to revolutionize straight‐line cutting machine technology and combine it with NC shape cutting. This new technology is still the norm in glass cutting machine design today.

These decisions included:

Glass Packaging:

Float glass manufacturers decided to make available to glass fabricators large stock glass sizes up to 130” x 204”. The reason this was unique, was that they packaged this glass, not in wooden cases, but rather in 10,000 lb. packs, referred to by one company as StoceTM packs. The packs could be delivered to glass fabricators by truck, on specially designed low‐slung trailers. Using an overhead crane, these packs were moved from the trucks to storage racks using nylon slings.

Tempering:

The glass machine company Glasstech Inc., located in Perrysburg, Ohio, and the leading manufacturer of flat glass tempering furnaces, revolutionized the residential and commercial tempered glass industry, by designing a large-width, batch‐type tempering furnace. Instead of being a very long, high-speed, continuous furnace, this shorter 84” wide furnace was designed to accept a batch of large or small glass parts in random sizes of the same thickness. The batch was processed through the heating chamber on ceramic rollers, and then into a unique quench (cooling) area. In both areas, the batch would oscillate back and forth on the rollers as it progressed through the furnace. Hence, this new furnace came to be known as an oscillating, batch‐type tempering furnace.

A New Way to Offer Tempered Glass to End Users:

Using the above new packaging and tempering technologies, a revolutionary new type of glass industry business was born by the name of Tempglass Inc. The purpose of this business was to supply random (custom) sizes, thicknesses, and quantities of tempered glass to anyone who needed them. The principals of this custom tempering business were the company Indal‐RTZ, a worldwide leader in the construction materials industry, and two of the owners, Norman Nitschke and Harold McMaster of Glasstech Inc. This new venture completely changed the concept of how tempered glass was marketed
and ultimately used in the world. Tempglass Inc. was cloned several times around North America. It also became the template for many other custom tempering operations by other glass fabrication companies.

A New Cutting Machine Design:

Tempglass Inc. asked Billco to build a cutting machine and loading system that could produce random (custom) size glass parts from the very large stock glass sizes they were going to buy from the float glass producers. As I have mentioned previously, up to this point all cutting machines could only produce scores in checkerboard layouts, and thus large quantities of the same sizes. Billco accepted the challenge, and once again called on Hugh Trautmann to design a machine. Using the Numerical Control based technology that he had recently developed for shape cutting, Hugh designed a totally different-looking machine. This machine had a fixed cutting table with conveyor belts and a cutting bridge that spanned the narrow width of the cutting table but was mounted on rails at the side of the table instead of being suspended above the table. The cutting bridge supported a single traversing cutting head.

The exciting thing about this new cutting machine design was that it not only could score the large stock sheet into random size rectangular or square pieces (block sizes), it could also score shapes inside the blocks. The cutting tables started out in 130” x 170” sizes but quickly were upgraded to 130” x 204” in size. This new cutting machine technology became known as NC‐XYZ / Contour glass cutting.

To load the large stock glass onto the cutting machine table, an automatic loading machine was developed. This machine could pick up and tilt single large stock lites from the vertical racks to a horizontal roller conveyor, and then convey them onto the cutting machine conveyor belts. An air float breakout table completed this unique glass cutting system. In 1976, Billco delivered to the Tempglass Inc. location in Perrysburg, Ohio, this revolutionary new glass cutting system, the concept of which is still being used all over the world today.

Needless to say, the 1970s were some very exciting years in the growth of the flat glass cutting machine industry. The above events totally changed the way straight‐line glass cutting was accomplished in the glass industry throughout the world. These machine design concepts are still being used today by many glass equipment builders throughout the world. There have been many upgrades over the years, but the basic, traversing bridge with a single cutting head concept still remains the foundation of all XYZ/Contour machines.

Although the original machine had cutting speeds of 1000 inches per minute, with new magnetic‐linear motor technology current machines are cutting at 7000 to 9000 inches per minute. The original Numerical Control technology became Computer Numerical Control (CNC) and has much more control capability than the original versions first used in 1976. Automatic loading systems from multiple glass racks have been developed and installed to improve the glass loading process. In some cases, automatic score separation machines have been developed to use in place of hand separation on breakout tables.

CNC 2200

Challenges and Solutions of the New Technology:

One of the greatest challenges to operating an NC, and then CNC contour glass cutting machine, was how to program the machine control. This was a two-part problem. First, was how to produce the step‐by‐step control program to cause the machine to move the cutting bridge and head assembly, in such a way that the desired shape was scored on a glass lite that was laying on the cutting table. The method to program the NC control used originally in 1971 for shape cutting was to first digitize the shape part so that it was described in X and Y coordinates. Then, using the coordinates, manually generate a series of movements using a control language specifically developed for Numerical Control. After the program was generated, it was typed into a Teletype machine that produced the program on a punched paper tape. This tape was loaded into the control’s reader and caused the Numerical Control to send electrical commands to the motors on the cutting machine bridge and head to accomplish the desired cutting path. Although laborious, this worked successfully since the number of unique shapes in the automotive industry was relatively small.

A computer software program, using the coordinates, the NC language, and the specific commands unique to the cutting machine, was developed to eliminate manual programming. The paper tape procedure was used for only a few years until computers were merged into Numerical Controls. Within the onboard computer, a CNC software program could produce a cutting program and convert it into machine language, all within a matter of seconds.

The second problem was unique to the XYZ / Contour cutting machine introduced in 1976. Instead of producing a simple layout of X and Y checkerboard score lines on a lite of glass, as automated cutting machines had to do up to this point in time, this machine had to produce X and Y straight‐line scores in a random layout of block sizes, and place shape scores within some of the blocks.

This was a three‐fold programming problem:

Any shapes to be cut had to be digitized and described in X and Y coordinates, then stored in a computer file. All the various block sizes to be produced for a certain time period had to be defined by size, glass thickness, and type of glass and then stored in another program. After sorting the sizes by glass type and thickness, each category of sizes then had to be “optimized” (the process of fitting the blocks onto the large stock sizes in order to get the least glass waste on each stock lite). Borrowing some technology being used at the time in the plywood industry, a rudimentary software program for optimizing was
developed to meet the needs of the first generation of cutting machines. However it took a decade or more, and many software engineers from various companies to develop the very sophisticated Glass optimization software that is being used today.

After generating an optimized layout of random block sizes for each stock lite of glass, a unique NC cutting path program for each lite of glass had to be generated, including placing any shapes to be scored within the blocks. This problem was daunting. Some X and Y score lines went completely across the lite of glass, and others started and stopped between intersecting perpendicular lines. Some scores crossed over each other, while other scores stopped short of intersecting with another perpendicular score. All these individual programs had to be combined and converted into a Numerical Control program to operate the XYZ / Contour cutting machine.

One interesting result of all the above work was the XYZ nomenclature for the cutting machine. While X and Y described all the various straight‐line scores on a layout, an X or Y score line that intersected, but did not cross over a perpendicular score, became known as a Z score. Although using XYZ became an easy way to identify the type of cutting machine and its capabilities, the score identified as Z has always caused some controversy… because a Z movement in Numerical Control language is actually a vertical movement. Cutting machine manufacturers have worked around this issue in various ways by using
different descriptions for their machines and their operation, but in the end when someone talks about an XYZ/Contour glass cutting machine most people in the glass industry know what capabilities the machine has.

Just to complicate this nomenclature issue further… when XYZ/Contour cutting machines first began to be used in the window industry (as you will read in the next section), some newer machine manufacturers referred to the actual cutting machine simply as an “Optimizer”. The words “glass cutting machine” were not used. This really caused some confusion in the already established glass cutting industry, but now most people in the industry have accepted or at least understand that the machine referred to as an “Optimizer” is actually an XYZ/Contour cutting machine.

CNC Cutting is introduced into the Window and Door Industry:

There was another significant development in the 1980s, that made XYZ/Contour machine cutting available to window manufacturers and other glass fabricators. This group of glass users did not have the means to handle the very large sizes and packs of glass being supplied to the temperers and other large glass fabricators.

For the thicknesses used by the window industry, the glass manufacturers began offering shrink-wrapped packs of 72” x 84” glass, weighing in the 3,000 to 5,000 lb. range, and shipped on returnable steel glass racks. These racks could easily be handled in low-ceiling buildings, by fork trucks instead of overhead cranes. In order to load this glass from the racks to the cutting machines, a technique called “free‐fall” was used. This technique had been used in the Australian glass industry for many years.

Auto Free Fall System