Metal Roofing: February 2009

Torch Down Roofing - A Cautionary Tale

Don't spend a dime on torch down roofing until you've read this cautionary tale. While the names and places change, this tragedy is a common occurrence. It goes something like this...

Two roofers are installing a small flat roof over a lanai while the homeowner is at work. The tear off goes well. Perhaps there's a little rotted wood to fix but that, too, is no problem.

Then they start installing the new roof system. It is a type commonly referred to as "torch down roofing". The official name is "modified bitumen" (pronounced buy-TOO-men). It is a rolled roofing product that consists of a tough membrane embedded in a thick layer of asphalt. Rubbery additives in the asphalt allow the roofing to expand and contract, where other roofing systems just crack. The roofing can bond tightly to metal flashings and move with them, while maintaining the bond. This flexibility is the main benefit of modified bitumen and is a big factor in its success.

Some types are applied with an adhesive, some types are self-adhering and some types are hot mopped as the cap sheet in built-up roofing systems. But it is the type applied with a propane torch that is referred to as "torch down roofing". It is also one the most dangerous of all roofing products...

One of the roofers gets a little careless with the torch and starts something smoldering in the attic. And they don't notice the small wisp of smoke coming out of the soffit vents. Just after the roofers go to lunch, the smoldering turns into a fire that spreads quickly in the dry, dusty attic.

With nobody home, the fire is going pretty good before the mailman notices the black smoke billowing up from the back of the house. He dials 911 and the fire trucks are there in a matter of minutes. But they have trouble putting the fire out because it is mostly contained within the attic. Finally they chop a big hole in the roof so they can put lots of water on the raging inferno. They get the fire out, but not before the home suffers extensive smoke and water damage, in addition to the actual fire damage.

One of the neighbors calls the homeowner, who rushes to the scene to find that the lovely home she had a few hours before, is now pretty much destroyed. About that time, the roofers come back from lunch... and wish they had taken up plumbing instead of roofing!

Fortunately, this scenario is completely preventable. For a good discussion of the alternatives to torch down roofing, check out: "Roofing Secrets: How to Avoid Leaks and Save Thousands of Dollars!" by John C Bishop. It will make the job easier and help you avoid big mistakes.

Emergency Roof Repair - Six Tarping Tips

If you're looking for "Emergency Roof Repair" information, you've come to the right place. Here are some pointers for tarping your own home.

1. First off, you need some good tarps. If you are in an area devastated by a hurricane, look for a FEMA assistance trailer. They may be able to get your home tarped for you. If not, they might have tarps you can use to do it yourself. Although they have been criticized in the past for various things, I WILL say this about FEMA -- they have HEAVY DUTY tarps. They probably pay $800 a piece for them and chose them after a five-year multi-million dollar study, but they are really good. Try to get those if you can.

2. The problem with most of the cheap blue tarps you get at the home improvement stores is that they just don't hold up very long in the sun and wind. It may be months before you can get a new roof. Go for the heavy-duty ones or you may find yourself doing this emergency roof repair twice.

3. Wood battens will help to secure the tarps in place. The size to get is 1" x 2" and they come with or without pressure treating. Either one is fine. Get enough so you can run them VERTICALLY about every four feet apart from the eave to the ridge. Don't run the battens horizontally if you can help it, as that tends to trap water that can get in at the nail holes.

4. You will also need nails to hold the battens on. Although a framing nail gun makes short work of this emergency roof repair, a hammer and eight-penny common nails will do just fine. Drive the nails about two feet apart and keep them at least a foot away from the valleys.

5. Don't tarp any more than you need to. Areas that have been tarped usually need to be re-roofed because of all the nail holes through the roofing. If only the back of your home is torn up, just tarp the back. But you do need to make sure the tarp is "counter-flashed" to make sure water can't run under it. That means tucking it under the roofing or running the tarp all the way to the ridge.

6. A word to the wise... Some tarps are slippery to walk on and especially treacherous when wet. Plan your work so you can avoid walking on them as much as possible. You should also be tied off to the roof with a rope and harness. If you can't do it is safely, don't do it. It's better to wait for FEMA or a roofing contractor than risk life or limb.

Understanding Sheet Metal Fabrication and How It Works

Sheet metal fabrication is the manipulation of metal to create any type of component that will be used in an end product. It can be used in almost any manufacturing field including medical, computer, electronics, or appliances.

Any product that contains metal components will go through some form of sheet metal fabrication.In sheet metal fabrication, several processes are used to reach an end product. These include cutting, forming, and finishing.Aluminum, stainless steel, and others forms of metal are utilized to create a component for a larger piece, something that can be used to create an end product, or the end product itself.

The Cutting Process

Sheet metal cutting involves a number of ways to cut a piece of metal into smaller pieces. These small pieces of metal can then be molded or formed into a final piece. One form of cutting is called shearing, which is used to cut larger pieces into smaller ones using the process of shear stress on a cutting machine.Another process is called Electrical Discharge Machining, or EDM, in which conductive materials are melted with an electrode spark from a thin, charged electrode that is surrounded by iodized water.

In abrasive cutting, grinders or saws are used to cut through sheet metal.

Sometimes water jets are used. These generate no heat while cutting, but instead use high pressure water from 20,000 to 60,000 psi. There is also laser cutting where lasers are used for complex, or precise, cutting.

The Forming Process

Once the sheet metal has been cut, it will be formed into its required shape to create a component before finishing. There are several forming techniques. Rolling is used to shape flat pieces of metal over and over by the use of roll stands. In bending and forming, the sheet metal is manipulated basically by hand to form a desired shape.

Stamping involves tools and dies that are used to stamp designs into the metal. The designs might also be 3-D designs. A method called punching is used to punch holes in the metal. Welding is used to join pieces of sheet metal together by forming a bond between the metals. To add latches or handles to the sheet metal, hardware and fastener creation methods are used.

The Finishing Process

After cutting the sheet metal and then forming it into the shapes needed, it must go through a finishing process. In finishing, the sheet metal is sharpened to eliminate or polish rough spots and edges using an abrasive.After the finishing process, the sheet metal goes on to fulfill its next purpose. It is either shipped out as an end product, or if it is a smaller piece, it might be used on a larger component or product.

Saving Money on Sheet Metal Fabrication

There are companies today that specialize in the sheet metal fabrication business. Their customers are usually companies that sell or use an end product that is made of sheet metal, or a part of it is made of metal.Instead of opening a factory to create their own metal products, a company might hire a sheet metal fabrication specialist to do the work for them.

This gives the company more time to focus on marketing and promotion and can also save money.

Methods for Forming Sheet Metal

Since the dawning of ancient civilizations, people have sought out ways to make life easier. Even humans today attempt to find ways to complete more work in a shorter amount of time. Ancient people had the same desire and thus tools were developed to aide in the completion of daily tasks. With the discovery of metal ore, and the process of applying heat to extract the metal from the ore, the complexity of tools significantly increased. Even today tools constantly become increasingly complex with new advances in engineering. Throughout the years of progress, increasing demand prompted the development of more efficient and precise ways of manipulating metal. Modern metalworkers use a variety of different metal forming machinery to reshape metal into varies parts and components.

Different shapes and forms of metals may require the application of different methods in order to shape the metal into something intended and useful. For example, specific processes are typically used to form sheet metal. Rollforming is an example of one such process that is typically used to shape sheet metal.

The art of sheet metal forming refers to the variety of ways used to shape sheet metal into a variety of forms. For example, sheet metal is used to make automobile panels and aluminum cans. Machinery has been developed to bend the sheet metal into new forms. An important word to know when discussing the forming of sheet metal is the word ductility. Ductility refers to the ability of the sheet metal to allow itself to be manipulated without fracturing. In other words, the level of ductility of the metal is the level to which pressure can be applied to reshape the metal without the metal breaking. Examples of highly ductile metals include silver, gold, copper and aluminum. These metals can be easily shaped without cracking or breaking.

Once the level of the metals ductility has been determined, its use can also be decided. Once a person decides what to use the metal for, the forming process can begin. Bending, drawing and the roll form process are all examples of methods for shaping sheet metal.

Roll forming refers to the process of continually bending a piece of sheet metal until the desired cross-section profile is obtained. Basically, each roll forming stand is developed to bend a small section of the metal. This allows each stand to be responsible for an incremental part of the bend. A roll forming machine consists of several stands. The metal is fed through the roll forming machine and gradually bent consecutively by each stand. Roll form is an ideal method to apply when shaping sheet metal because it is long and can be easily formed by passing through the stands.

A Look at Sheet Metal Stamping

Sheet metal stamping is the system wherein metal sheets are used for producing final products. When a metal sheet is inserted into the die or the press, it is molded into the required shape and size. Metal sheets of only a certain thickness can be inserted into metal stamping machines. The maximum limit for most metal stamping machines is ¼ inch. However, machines can be designed to accommodate sheets of greater thickness also. Even the kind of metal sheets that can be processed in metal stamping are also specific. Only certain metals or alloys can be used like aluminum, brass, steel (hot rolled or cold rolled), galvanized steel, stainless steel, copper, zinc and titanium.

Before the metal sheet is inserted into the machine, the customer provides the prototype or at least a diagram of the final product. In case the customer doesn’t have a clear idea of what the final product should look like, most metal stamping producers also offer engineering services for designing the products as well. Even some secondary services such as deburring and plating are provided by the metal stamping companies after the metal sheet is stamped.

There are three main components in sheet metal stamping -- the die, the punch and the binder/blank holder. The sheet is kept between the blank holder and the die and the punch is driven into the die wherein the sheet spreads over the die because of the drawing and stretching. The blank holder provides the restraining force that is required to control the sheet flow into the die. This force prevents wrinkling and tearing of the sheet as the quantity of material going into the machine can be controlled. For some processes where the blank holder force is too high for the material, draw beads are used to create the restraining force.

Sheet metal stampings are also known as thin stampings. Sheet metal stamping is used most primarily in the case-building process. It is also the most important part as each of the panels has to be stamped one by one. First the motherboard tray is stamped, then one-side panels on the right and left from bottom to top and back.

Planning the Custom Automotive Sheet Metal Project

A custom sheet metal fabrication project should always start with a concept, or an idea of what you want built, and how you'd like it to look, and this by itself can take days, or even weeks, because it's best if you make your mistakes during this stage, here they won't cost you money.

You don't want to make mistakes that waste the sheet metal, or a lot of your time, so during the first stage of this venture, take a lot of measurements, and draw up a lot of concepts, and make them out of cardboard if you need to, but take your time here.

Once you have a solid concept, you can plan out how much sheet metal you need to complete the project, and then double it, you can't go wrong with extra sheet metal, now that you have your metal, you can lay out your project on it, using the cardboard cut out that you made, trace around the outside edge after it's laying on the sheet metal.

Once you have that done you can cut it out and begin to make your bends, get the basic idea bent in the metal, you can fine tune it from here, bending more in some places, and less in others, making bends sharper, or more round, adding body lines or crowns in the metal.

After you have a basic idea bent in to the sheet metal, you can finalize things a bit more and get it ready to put on your car, if you need two of the same part, you should make the second part now so you can just go to town and get the entire job done at one time.

Now it's time to put the parts on your car, and this can be nerve racking, so make sure that you do it right, take perfect measurements, this is the part of the process that will make or break the entire project this part is absolutely crustal to the out come of your project, so take your time here.

Precision Sheet Metal Fabrication

Metal fabrication is a process of producing a metal component by modifying a raw piece of material in a machine shop. These materials are processed on different temperatures and depending on the range of temperatures; the process is classified as cold, warm and hot. Precision sheet metal fabrication describes various different processes that form sheet metal into finished products. Objects that are fabricated and used for machinery and other instruments are among the daily used objects like paper clips, computers, bolts, nails, automotive parts and many more.

There are various factors like rate of production, desired geometry, and other physical requirements that influence the fabrication process. The benefits of the metal fabrication process are far and wide because it is used by all industries. Every precision sheet metal fabrication process undergoes three primary processes that include forming, cutting and finishing. Forming is a process that alters the form of the flat metal sheet. Forming can be done using various different processes like annealing, bending, cold rolling, drawing, forging, mechanical working, press forming, roll forming and welding. After forming, a metal sheet is cut to alter the shape by removing some unwanted material. The cutting process includes stamping, shearing, sawing, drilling, blanking and punching. Finally, the last stage is the finishing process. In this process, the shaped metal sheet is given a finished and soft surface using sanding and vibration techniques. Aesthetic considerations like painting and visual design applications are also few of the method applied to give the finishing touch. Some of the latest techniques in metal fabrication involve laser cutting, electro discharge machining, water jet cutting and wire cut EDM. In some cases CNC machining is also used.

There are various products that are created during precision sheet metal fabrication. The most common objects produced are metal cabinets, enclosures, ventilation shafts, hoods, exhaust systems, tanks and prototypes. Metal fabrication is also used by various other industries for food dispensing, food storage, communications, automotive, computer, medical, electronics, aerospace, telecommunication, pharmaceutical, residential and construction.

Some of the types of Precision Sheet Metal Fabrication include processes like Annealing (heating), Bending (straining), Cold forming, Cold rolling (shaping sheet metal using rollers), Drawing (material is forced into a die with a punch to form a cup-like shape), Forging (hammering or pressing), Rolling (reducing thickness of the material), Extrusion (producing cylindrical bars or hollow tubes by forcing round billets through one or more dies) and Spinning (forms axially symmetrical shapes).

Why Choose a Metal Hammer?

Depending on what type of a job you have to do, choosing a metal hammer over a regular hammer may be the way to go. Here are some examples of situations where a hammer that is made for jobs involving metal may be your best bet.

One excellent example is when you are working with sheet metal. A hammer that is manufactured for working with metal will be lighter in weight, usually around eighteen ounces or so. The result is that you have plenty of force to drive a nail into the sheet metal, but not as much to damage the product if you happen to miss. These types of hammers are just gentler with the sheet metal, which means your finished product will look more professional, even if you did take a wild shot or two.

Working with metal flashing on a roof is another example of a time when a metal hammer is a good idea. Just as with the sheet metal, you have the power and ease of use you need to get the job done, but have less of the ability to bang up the flashing while you are working with it. The result is that the flashing will lie more evenly, making it easier to create a seal when you have everything in place.

Putting up aluminum siding is another example of a time when this type of hammer comes in very handy. Siding made of aluminum is notorious for showing every little ding. Using the right kind of hammer helps to minimize the chances that you will have to toss out a section of siding because of a few random missed shots. By using a hammer made for use with metal, you end up saving money that would have gone to replace those sections that were messed up during the installation process.

Having a metal hammer on hand to work with various types of metals is a good idea, not only for the professional but also the weekend do it yourself home owner. Check out the hammer at your local hardware store today.

Safety Tips for Sheet Metal Workers

Sheet metal is used to produce a wide variety of items like automobile panels, rain gutters, restaurant equipment, road signs and heating ducts, fabricating. As a result, installing and maintaining these items can be a hazardous job.

Sheet metal workers are subject to frequent cuts, scrapes, burns and falls from scaffoldings or ladders. Many times, the sheet metal production process itself requires repetitive heavy lifting, bending and squatting, putting workers at risk for back, neck and muscle injuries. Knowing the proper safety procedures can help keep sheet metal production workers safe on the job.

Safety Equipment is everyone's Friend

While safety equipment may feel like a cumbersome, frivolous waste of time, safety gear is designed to prevent and limit injury should an accident occur. Accidents can happen in a matter of seconds.

During an accident, safety equipment must already be in place in order to be effective. Hard hats, gloves and safety glasses left in a truck or tool box are useless during an accident.

Sheet metal workers can be subject to flying debris and tiny shards of metal shavings, cuts from sharp metal edges, crushing injuries from presses and other sheet metal forming equipment, and burns from metal heated during production, installation or repair.

Many of these injuries have the potential to be life threatening unless safety equipment is worn when working around sheet metal.

Preventing Back Injury in Sheet Metal Workers

Back and neck injuries are one the most common causes of Worker's Compensation claims. A serious muscle injury can keep a sheet metal worker from the job for months while muscles, tendons, tissue and bones heal.

Learning to lift with the large, strong muscles of the legs instead of the muscles of the neck, back and arms is crucial to preventing back injuries. A 100 pound woman can easily pick up a 150 pound weight with proper body mechanics.

Heavy lifting requires lowering the body's center of gravity. Bending at the knees improves balance and provides a stable, lowered center. Lifting is only begun after the neck and back muscles are relaxed. Upper body muscles should not bear the weight of the object being moved; they should only be used to hold the object near the body.

If at all possible, sheet metal workers should plan and position their workstations and materials so that heavy items can be lifted from waist high in a standing position. Feet should be placed shoulder width apart, directly under the hips.

The body can also be positioned to take advantage pivoting movements that can reduce the chance of falls or improper body alignment during transfers of heavy objects. These lifting techniques can reduce muscle strain and prevent neck and back injuries in sheet metal workers.

Corrugated Metal Roofing

When you build a house, you need to put a roof over your head. If you haven't decided yet what to use, why don't you consider getting corrugated metal roofing.

Corrugated metal roofing is basically a choppy metal sheet used commonly for barns and industrial buildings. Each sheet has a wave like pattern similar to that you see in a corrugated cardboard. While some consider it a functional eyesore, if you see what it can do, you won't feel bad about having this installed.

The price of it is much cheaper in terms of price and lighter in weight when compared to a double layer of ordinary metal roofing because you get the same strength without any additional expense.

The biggest downside though is that it is prone to rust. To answer this problem, steel manufacturers decided to make galvanized corrugated metal roofing. This happens when the metal undergoes a chemical process to prevent it from corroding. The key ingredient in this process is zinc which results in the fabrication of a coat over the original metal.

After the metal is coated, you get to have zinc on top, the metal in the middle and zinc again in the bottom. It is like making a sandwich and instead of eating it, this is what you buy and put on your roof so water does not drip in the house when it rains.

You will notice that it is not that noisy outside when you use it for your home. Surprisingly, it only produces the same amount of noise as asphalt, clay or wood.

The basic installation of it is simply by fitting these sheets over the wooden roof. It will overlap and how each fits into place is decided by the pitch of the wooden roof.

Should you consider getting a corrugated metal roof? If it is galvanized, definitely the answer is yes. Rust won't be able to destroy it and with proper maintenance, this can last up to 50 years or more.

If you want to do your share in protecting the environment, you will be happy to know that it is recyclable. Once throw away, this can be melted and a new sheet can be used to roof another home.

Corrugated metal roofing is available in various colors. You can treat each sheet with different solutions like polymers to make them stronger and long lasting. Lower in cost compared to other types of roofing and better in quality, this is surely good value for your money.

How To Install Metal Roofing In 6 Easy Steps

If you are planning to replace your old roof with new metal roofing, it would be very cost-efficient if you do it yourself. After all, anyone can learn how to install metal roofing. All you need is to learn the basics of tool-handling and pay attention to detail.

Now, to begin learning how to install metal roofing, we strongly recommend that you read through these very easy steps:

1. Get rid of the old material.

The initial task in how to install metal roofing is getting rid of the previous roofing, including all the nails. You can do this by using a pitchfork or shovel. Upon clearing the roof surface, you have to sweep the entire area with a broom to prepare it for the next step.

2. Roll out the roofing felt.

A 30-lbs. roofing felt needs to be laid out on the entire roof surface. Make sure the each sheet overlaps the previous one by a couple of inches, and that you leave about 3 inches hanging over each edge.

3. Create guidelines on the felt.

Draw parallel lines going from the crown of the roof to the gutter at two feet intervals from one another. You can do this using a chalk line. These straight lines will serve as guidelines when you are placing your metal sheets on the roof.

4. Attach the metal sheets.

If you feel you are confident enough and really know how to install metal roofing, then get ready because this is the biggest and most exciting part of the construction - installing the metal sheets. First, you have to cut a length of metal roofing equal to the distance from the crown to the edge of the roof, adding a couple of inches for the overhang. If you really want to learn how to install metal roofing, you also need to learn to measure accurately.

Lay down the first metal sheet on the leftmost side and attach it to the roof frame with screws every two feet. Repeat the same procedure for the next sheets until you have covered the whole roof. Make sure that each metal sheet overlaps the one beside it by about 2-3 inches.

5. Plug up the gaps.

Use a rubber strip to plug the lines where the metal sheets overlap. This will keep insects and other small animals from burrowing into your roof.

6. Attach the metal edging and cap.

The final touches of how to install metal roofing are installing the metal edging around the roof's perimeter and fastening the metal cap on the crown of the roof.

If you understand these six steps and find them all very doable, then you have already learned how to install metal roofing. The only thing left is to actually go out and do it.

However, there is one more thing to remember. Even if you already know how to install metal roofing, there may still be some unexpected situations during your actual installation, in which case you have to consult with experts in order to set things straight.

What is Sheet Metal Assembly?

This is the process of joining two or more separate components into a finished product. These components can be made of any variety of metal including steel, copper, plated materials, aluminum, or whatever metal best suits the project at hand.

There are numerous methods for assembling sheet metal, and what method is preferred depends on the materials being assembled, the function of the finished product, the environment the product is being installed into, and the desired durability of the finished, assembled product.

Welding is a very common technique used to assemble sheet metal. Multiple kinds of welding have been developed as the metals industry has grown and evolved, and the selection of welding technique relies heavily on the kind and size of the materials being used. Arc welding, oxy-fuel welding, resistance welding, laser beam welding, and electron welding are the primary types of welding being used today. Arc welding uses an electrical current to create a bond between materials.

Different categories fall within arc welding and include submerged arc welding, which is commonly used in shipbuilding; gas metal arc welding, which is used for non-ferrous materials; shielded metal arc welding, which uses a consumable electrode; flux-cored welding, which revolutionized the speed at which welders could work. All of these methods are just to name a few.

Resistance welding is a method that uses the material’s resistance to the electrical current to create the heat needed to bond the materials. Spot welding and seam welding are both forms of resistance welding as well as flash welding, projection welding, and upset welding.

Oxy-fuel welding, or oxyacetylene welding uses a gas to generate the heat to bond the materials together. Most commonly oxyacetylene is used, but other gases can be used depending on the material being welded. Whatever other gas is used, it is always passed through a steam of oxygen in order to create the combustion process that creates the weld. Laser beam welding uses laser beams as a concentrated heat source to join the two metals, and electron beam welding uses an electron beam as the heat source.

Besides welding there are numerous other techniques to joining sheet metal.

Riveting, bolting, screwing, and clipping are all potential assembly routes, and the efficacy of each technique will depend on the finished product itself. There are even some sheet metal components that are designed to fit together in a slot-A/tab-B configuration without the help of any major assembly process.

How to Design a Roof - The Best Rafter Tail Detail

If you're looking for information on "how to design a roof", you probably know that a "rafter tail" is the end of the rafter that overhangs the wall. What you may not know is that the design you choose can determine whether you have a leaky roof edge or not. If you're going to attach a fascia board, you basically have two choices...

How to Design a Roof -- Plumb Cut Rafter Tails

Plumb cut rafter tails have a vertical fascia board. That's handy for installing gutters because the back side of most gutters is also vertical. But without gutters, much of the water coming off the roof runs down the fascia, where it can rot the wood over time, especially at the joints.

But a far bigger problem is the angle of the fascia to the sloped roof. It varies with the slope of course, but standard drip edge comes with just one angle, which is 90 degrees. Of course the roofer could have custom drip edge fabricated, but more often than not, he "makes do" with the standard stuff, trying to bend it by hand on site to accommodate the angle.

The typical result is a drip edge that not only sticks out at an unsightly angle, but creates a little "dip" at the very edge of the roof. Water lays in the dip, coming in at the seams in the roofing. With the leaks coming through vinyl or aluminum soffits outside the house, they can go undetected for years, resulting in a significant amount of rotted wood.

How to Design a Roof -- Square Cut Rafter Tails

Square cut rafter tails are perpendicular to the rafter. That slopes them down and away from the drip edge. I'm not a big gutter fan, but if you want them, brackets are available to provide a plumb mounting surface. And when gutters aren't used, water can run off the drip edge without ever touching the fascia board.

But the biggest advantage with square cut rafter tails is they accommodate standard 90 degree drip edge perfectly. The face of the metal is flush up against the fascia board and the flange lies flat on the roof, just like it should. That makes it easier for the tradesman to do a good job, which is an important principle when learning how to design a roof or anything else.

For more information on "how to design a roof", check out "Roofing Secrets: How to Avoid Leaks and Save Thousands of Dollars!" by John C Bishop. Chapter one is about how to save a small fortune by choosing a sensible roof design.

For details, go to: http://www.roofingsecrets.com

Sheet Metal In The Automotive Industry

Historically, sheet metal has been used extensively to produce automotive body panels. Although sheet metal use has decreased with the advent of fiberglass body panels, sheet metal is still the most popular material for manufacturing automobiles today. The addition of lasers and robotics to the automobile manufacturing process has further expanded the way that sheet metal is processed.

Lasers

Lasers have been used in production facilities since the 1960's. Today, they are used to cut, form holes, engrave, weld or heat treat sheet metal for use in automotive production.

Lasers are used in applications that rely on precise measurements and exact alignments.

The adjustment of lasers is measured in micrometers, or millionths of a meter.

There are many different types of lasers used to alter sheet metal and plastics in the automotive industry.

Carbon dioxide laser- uses a mixture of carbon dioxide, nitrogen and helium to produce a continuous laser output

Continuous-wave laser- this type of laser produces light beams continuously rather than in controlled pulses

Excimer laser-emits light in a UV spectrum that is used for producing high quality edges on parts that are prone to cracking or thermal damage; it falls into the category of pulsed-gas lasers

Gas laser-any laser that uses a gas mixture as the lasing medium; common gases are argon and carbon dioxide

Pulsed laser-emits light in controlled pulses and is preferred for thin materials ; it can be used to create intricate details and work in tight corners without burning

Ruby laser-a solid state laser that uses a synthetic ruby crystal with a chromium impurity as the lasing medium

Solid-state laser-a type of laser that uses a crystal or glass as the host for an impurity to produce the lasing action; especially useful for precise measuring and spot welding

Yttrium aluminum garnet (YAG) laser-ranges in power from a few milliwatts to more than 400 watts; used for cutting, drilling, heat treating and welding operations

Robotics

Robotics are often used for repetitive tasks, monotonous jobs or those parts of the manufacturing process that are physically difficult or take place in environmentally unpleasant conditions. They are directed by computer programs and perform precise operations without human intervention.

Lasers and robotics have significantly increased the speed at which sheet metal can be processed in the automotive manufacturing process. Continued technological advancements in these two areas will further increase the cost effectiveness and productivity of automotive manufacturing facilities.

How Plasma Cutters Work

Plasma cutters cut metal using a plasma torch. For it work, plasma (the fourth state of matter) has to be created. Plasma is a super-heated (15,000 degrees Celsius) substance that is a gas and a liquid at the same time. Two things are required to create plasma, a gas and a heat source.

Plasma cutters use inert gases (often compressed air) and electricity to create plasma. The plasma cutting equipment is set up so that it creates an electric circuit with the metal that is being cut. When the end of the torch is touched to the metal, the circuit is created and a spark flashes through the nozzle of the plasma torch. This spark travels to the negative electrode in the torch handle and meets with the rapidly flowing inert gas. When the gas comes into contact with the electricity it is heated to around 15,000 degrees Celsius and becomes plasma. The plasma surges out of the tiny nozzle and onto the surface that you want to cut. The tiny opening in the nozzle focuses the plasma flow and causes it to speed up. It is the speed, temperature and focus of the plasma that enables it to cut metal almost as well as a laser.

As long as everything is set up properly, the cuts can be very clean with little noticeable affect on the rest of the work piece.

Since a plasma cutter's function requires an electric circuit they can cut pretty much anything that conducts electricity including copper, aluminum and stainless steel.

There are two methods used to create the plasma for plasma cutting.

HF (High Frequency) Contact. This method is generally used in low budget equipment since it cannot be used for CNC (Computer Numeric Control) Plasma Cutting operations. To generate plasma, this method uses a high frequency, high voltage spark. When the plasma torch touches the material to be cut, thereby closing the circuit, the spark fires into the torch head and plasma is created.
Pilot Arc. This method is a little more involved since it produces plasma in two cycles. Cycle one: inside the body of the torch a low current, high voltage circuit creates a high intensity spark. This spark creates a small volume of plasma (the pilot arc). Cycle two: the pilot arc remains static until the torch head is touched to the metal at which point a trigger allows the pilot arc to light the main flow of gas and plasma cutting begins.

The old versions of plasma cutters (plasma cutting was invented during World War II) started the arc with high frequency, high voltage circuits. This means that the operator risked electrocution if they were not careful. Also, these old machines are difficult to repair and maintain.

A plasma cutter can cut metals of different thicknesses. The size of the machine is what determines the sever cut. "Sever cut" is the standard used to define the thickest possible cutting potential for a given plasma cutter. The thicker the metal to be cut the easier it is for a CNC plasma cutter to operate. You have to watch out though, the closer the metal thickness comes to the sever cut rating of a plasma cutter the messier the cut may be. This means you may have to clean up the edges after you are finished cutting.

Since CNC plasma cutters are computer controlled they are very precise. For very repetitive projects or industrial applications a CNC plasma cutter is must. These machines can do the same thing over and over and over all day long.

When you are using plasma cutters please make sure that you follow safety guidelines.

Used Plasma Cutters

You can find used plasma cutters online and in the real world. If you find a used plasma cutter you have to make sure that it is in good condition and, more importantly, you have to find out if the unit meets your needs. Use the following list of questions to assess any used plasma cutter that you find. When you have the answers, you will be in a much better position to make an educated buying decision.

Is the cable insulation worn down from use?

Does the sever cut, rated cut, and quality cut of the match what I need?

Are the cuts still clean?

Has the machine ever been repaired or serviced?

Is there still a factory warranty?

Is there a power source at my business or home that matches the power requirements of the machine?

What is the duty cycle of the unit?

Are the diagnostic lights and controls functioning properly?

If I buy the machine do I get any consumables?

What is the condition of the internal components (if they are in good condition then the owner probably took good care of the machine)?

It is most important that all of the cables are in good condition. Electrocution is no joke and no matter how safely you operate the machine, if there are exposed cables you are in danger. It is better to spend a few dollars more than to put yourself in a dangerous situation.

You may find it to be a pain to try to answer all of these questions, but it will be worth it. I would rather put in the time to find the right machine on the first try as opposed to kicking myself for buying a piece of junk.

Methods for Forming Sheet Metal

Different shapes and forms of metals may require the application of different methods in order to shape the metal into something intended and useful. For example, specific processes are typically used to form sheet metal. Rollforming is an example of one such process that is typically used to shape sheet metal.

The art of sheet metal forming refers to the variety of ways used to shape sheet metal into a variety of forms. For example, sheet metal is used to make automobile panels and aluminum cans. Machinery has been developed to bend the sheet metal into new forms. An important word to know when discussing the forming of sheet metal is the word ductility. Ductility refers to the ability of the sheet metal to allow itself to be manipulated without fracturing. In other words, the level of ductility of the metal is the level to which pressure can be applied to reshape the metal without the metal breaking. Examples of highly ductile metals include silver, gold, copper and aluminum. These metals can be easily shaped without cracking or breaking.

Once the level of the metals ductility has been determined, its use can also be decided. Once a person decides what to use the metal for, the forming process can begin. Bending, drawing and the roll form process are all examples of methods for shaping sheet metal.

Roll forming refers to the process of continually bending a piece of sheet metal until the desired cross-section profile is obtained. Basically, each roll forming stand is developed to bend a small section of the metal. This allows each stand to be responsible for an incremental part of the bend. A roll forming machine consists of several stands. The metal is fed through the roll forming machine and gradually bent consecutively by each stand. Roll form is an ideal method to apply when shaping sheet metal because it is long and can be easily formed by passing through the stands.