Basic Fabrication Skills

I haven't had the time to go through all of this, but there's got to be something in here about metal fabrication. [Online Education Database http://oedb.org/library/features/236-open-courseware-collections]

[wikipedia metal fabrication http://en.wikipedia.org/wiki/Fabrication_(metal)]

[wikipedia metalworking http://en.wikipedia.org/wiki/Metalworking]

Using Tools website

"Satisfactory work cannot be done with tools in poor condition." -from using-tools.com

Tools

Storage of Tools

"...regardless of where they are stored, each tool should have its own individual place so that it will be readily accessible...Idle tools on a bench top or on the floor are a hazard to anyone working there or passing by, and to one another."

Use of Tools

"You should learn what each tool is designed for and how it should be used." -from using-tools.com

Conditioning of Tools

"Tools should be kept clean and free of rust...Lubrication of the moving parts of various tools is also a necessity...A sharp tool seldom causes an accident. In most cases where a worker cuts himself, the tool is dull." -from using-tools.com

Metalworking

"...imagine the results if suddenly we were prevented from using metals of any type in our various daily activities. What would happen to our factories, our transportation and communication systems, our homes, our buildings, amusement, and education?" -from using-tools.com

Stock Forms

• Sheet metal, "The form most often used by industry is sheet metal, such as sheet topper, brass, steel, and aluminum."
• Plate metal, "...comes as tin plate and steel plate. Tin plate is steel covered with a protective coat of tin..."
• Bands, "...are narrow, heavy strips of steel plate, sometimes called band iron or strap iron."
• Bars, "...may be round, half-round, square, flat, or many other shapes in cross section. Cold-rolled steel bars have harder texture and greater stiffness than bars of hot-rolled steel."
• Wire, "...is generally made by pulling, or drawing, various metals in the form of round bars through small holes in thick, hard pieces of metal called draw plates."

Metals

Ferrous metals

• Cast iron, "...belongs to the group of metals called the ferrous metals — metals that are made largely of iron...It is the presence of graphite that distinguishes cast iron from the other ferrous metals...Automobile engines are made mostly of it. Tools such as lathes, planers, and milling machines are more than ninety per cent cast iron by weight. The making of gray-iron castings is one of the great branches of industry."
• Steel, "If all the carbon and impurities are removed from cast iron and then an amount of carbon up to 2 per cent added in such a way that it combines with the iron, steel will be produced...This steel of low-carbon content is the steel used in building bridges and making the frames of skyscrapers. It can be forged, rolled, or welded. If more carbon is added, the steel takes on a new property; it can then be made very hard by heating it to red heat and cooling it quickly. It is then called tool steel. This is the steel used for making files, chisels, and cutting tools. It has a remarkable property in that after it has been hardened it can be tempered to intermediate degrees of hardness...Tool steel, because of its properties, has become one of the most useful materials employed in industry. It can be annealed so that it is easy to work with files or other metal-cutting tools."
• Alloy steels, "Tungsten, vanadium, nickel, chromium, and other metals have been alloyed with steel, both separately and in combination. The high-speed steels used in making lathe tools, drills, reamers, and other tools are examples of these steels. Chromium has been used to make steel resist corrosion. New alloys are being developed constantly to meet special needs."

Nonferrous metals

• Copper, "...can be worked hot or cold. It can be drawn through dies to produce wires so fine that the eye can hardly see them. It is easy to solder. Copper presents some difficulty in welding because when hot it absorbs gases. When it is hammered or rolled it becomes quite hard. When this occurs, it may be heated and then plunged into water to soften it."
• Aluminum, "The metal which we commonly call aluminum is really an alloy of aluminum and copper or zinc. When alloyed with manganese or magnesium, aluminum has special properties. It can then be forged, and by special heat treatment can be given great tensile strength; it is then used in airplane construction. Aluminum alloy castings are made in sand and in metal molds. They can be machined very rapidly. Sheet aluminum can be stamped and drawn into intricate shapes."
• Brass, "Brass is an alloy of copper and zinc, with lead added to make it machine easily. Brass is easy to solder; in sheets it can be formed and stamped; and when hammered or rolled, it becomes hard. Brass wire is rolled to make it suitable for use in making springs. If you should wish to soften brass that has been hardened by hammering, you could heat it and then plunge it into water."

Hydraulic Systems

Assembly

• Keep the area and parts clean.
• All openings should be sealed after cleaning.
• No grinding or welding operations should be done in the area where hydraulic components are being installed.
• All open connections should be sealed and/or capped until just prior to use.
• All pipe and tubing ends should be reamed.
• When installing pumps or motors, always align coupling halves as closely as possible, within 0.007 inch.
• When using flexible couplings, follow the manufacturer’s recommendations or allow 1/32 to 1/16 inch clearance between the coupling halves.
• Do not drive couplings on pump or motor shafts. They should be a slip fit, or shrunk on using hot oil.
• Always use a dry spray-on lubricant on splines when installing.

Pipes

• pipes have numbers from 10 through 160. The larger the number, the heavier the wall thickness. The outer pipe diameter stays the same for a given pipe size, while the inside opening becomes smaller as schedule number increases.
• In many cases, flanges are welded to the pipe ends and gaskets or “O” rings are used to seal the connections.
• Pipe fittings can be threaded or welded in place for routing. Threaded connections are used in low pressure applications and welded connections are used if high pressure, high temperature, or a severe mechanical load exists.
• All piping should be secured with clamps to prevent vibration and excessive stress due to the weight of the fluid. Do not weld the clamps to the pipe as it may weaken the pipe and cause a stress crack.

Tubing

• Don’t take heavy cuts on thin wall tubing with a tubing cutter. Use light cuts to prevent deformation of the tube end.
• Ream tubing only for removal of burrs.
• DO NOT over ream tubing as it can weaken the connection.
• Do not allow chips to accumulate in the tubing. They can be difficult to remove after bending.
• Don’t overtighten the feed screw handle on a compression type flaring tool.
• Bend tubing instead of cutting and using a fitting. The minimum radius of a tubing bend should be at least three times the inside diameter of the tube. Larger bends are preferred.
• Sketch the optimum tubing route before beginning the bending process. Be sure to use tubing with the proper temper to prevent wrinkles and flattened bends.
• The standard flare angle is 37 degrees from the centerline.
• For best results, heavy wall tubing should be cut, deburred, and flared and bent using power equipment.

System Design

• One inadequately sized/spec'ed component can cause problems that cascade through the whole system.
• Lines must be big enough and have gentle enough bends.
• Some parts have to maintain a certain orientation either with other parts or with gravity.
• Consider integrating adequate test points into the system from the beginning
• Don't load things beyond their operating pressures. If unknown, then use the lowest pressure that allows adequate system performance and is below maximum ratings.
• When system is functioning properly, make a note of important measurements like pressure and electrical power levels.
• If sound is a problem, the pump should operate at or below 1200 RPM.
• Noise can be reduced by mounting the pump/motor with rubber isolation mounts and connecting with rubber hoses. However, long lengths of hoses generate sound, instead use short lengths of hoses to join long lengths of tube/pipe.
• Mechanical isolation is more effective than acoustic isolation.
• Acoustically isolate a pump by enclosing it completely in a non-porous shell >=10kg/sqmeter without any openings.
• You don't want bubbles. Suppress their formation by keeping inlet lines short and/or large, keeping the reservoir at or above the pump, and use inlet filters that signal a low pressure drop.
• Oil leaving the reservoir should be 120 to 150*F.
• Water-based fluids should be 100 to 120*F.
• A reservoir should have baffles that force the liquid to take a twisted path and be large enough to hold 2 to 3 minutes of maximum pump flow, with room to spare.
• Fluid contamination is marked by oxidation, gummy deposits, sludge, bubbles and noise. Not to mention premature wear and/or failure.
• If operating in noticeably dusty conditions the system should have heavy duty breathers and chrome plated piston rods.

Fluid/Oil

• Fluid and filter replacement schedules should be determined by having the fluid tested periodically.
• Viscosity should probably be changed in spring and fall.
• To drain the fluid, run the system to get it hot, then drain from the lowest point.
• Use a light viscosity fluid with a rust inhibitor to flush out deposits.
• When adding fluid, use a 25 micron filter or a 200 mesh metal screen.
• If the system becomes dramatically contaminated then drain and clean the reservoir, inspect all valves, cylinders, lines and hoses for wear and/or particles, flush all components, replace filters, dispose of the contaminated fluid. Change filters after 50 hours of operation on clean fluid.