SCIENCE MARCHES ON
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THE wide range of mechanical properties that can be imparted to steels as a result of small variations in chemical composition and the heat treatments subsequently accorded to them has been responsible for a method being developed for choosing them on the basis of the extent to which they can be hardened. A range of steels, known as I-1 steels, has been developed, the "as-cast " composition and later treatment of which have been regulated according to the specified,hardenability data
By this means of control, unwanted mechanical properties, occasioned lay excessive or inadequate percentages of alloying elements, can be avoided. There are, in all, five methods of indicating hardenability, and any one of these may prove effective.
High-magnetic Alloy
A new high-magnetic alloy has been developed containing 35 per cent, cobalt, 64 per cent. iron, and I per cent. chromium. It gives the highest magnetic saturation point of any known material. For most applications a thickness of : ',proximately 0.05 in, is suitable, but this can be reduced to 0.02 in. if desired.
As a result of persistent research by the British Cast Iron Research Association, a method of treating pig iron, so as to give it properties equal to those of modern high-duty cast irons, without any need for special compositions or treatment, and without spoiling the casting and machining properties, has been introduced. The new process results in iron castings which have a much higher tensile strength and resistance to shock.
To counteract the high temperatares to which the road vehicle oil engine piston is subjected, special means for cooling is being used. A pipe is taken up through the connecting rod, and oil . is pumped through this to the underside of the piston. A cleaning medium for small parts has been developed which removes accumulated deposits of carbonized oil, grease and dirt. It can also be employed as a paint stripper. It will degrease rapidly at room temperature, but cleaning can be quickened by heating the degreaser to 70 degrees C.
Cold-tank Cleaner
Another development is a non-inflammable cold-tank cleaner, with a liquid seal to eliminate odour. Its chief feature is speedy action in the stripping of carbon, paint, varnish, dirt, oil and grease, from engines and components.
A powder, hard-facing installation consists of a metallizer and a welder in combination. A gun is first used to apply evenly an overlay of powdered hard-facing alloy, and then as a conventional welding torch to fuse this sprayed overlay to the base metal. A , rather similar principle is used in a portable equipment. Finely powdered metal is charged into a pressure pot, and air is blown through, thus carrying a blast of powder into the gun.
The powder emerges through the gun's muzzle, surrounded by a ring of flame of blow-torch intensity. By proper air control,-flame and powder can be brought together at the point of maximum heat, and melting takes place in mid-air in front of the gun. The equipment can be used to spr lead, tin, aluminium, brass, and other metals.
New horizons have been opened up for engine designers as the result of the use of hard facing as a means for providing a hard, wear-resistant surface for cylinders and liners that take advantage of the high thermal. conductivity of aluminium. Light weight, greater power, and better performance have been obtained with an engine having, first, a cast-iron cylinder liner and then a chromium-plated aluminium liner. The aluminium sleeve reduced the temperature by 80 degrees C. at the hotspot in the head end, and the temperature of the piston, behind the top ring. was 25 degrees C. levier at fun load.
Corrosion Pits Measured A tool has been designed which detects and measures corrosion pits. It makes use of an electrical instrument such as is used for measuring the thick ness of non-ferrous castings. A new exploring head was designed for it, and by means of this the location and presence of serious pitting is detected. One man moves the head steadily through, say, a tube, while another watches a micro-ammeter.
Steel lorry-body-members are being standardized for mass production. A method is used which employs standardized, stamped, lorry-body members and a simple welding technique. Flexibility of design enables the body builder to meet individual truck or lorry-owners' needs, using mass production facilities.
The flash welding of aluminium, using the standard machines for weld ing steel, is being carried out. For this a special machine with a fastmoving head is used. -By suitable modifications in welding conditions, all the newer, high-strength aluminium alloys can be satisfactorily spot-welded.
An interesting product is an arc welding compound in the form of a paste. This is thinned with water and brushed or sprayed into the seam. It is intended to stabilize and quieten the welding arc, improve fusion, and prevent adhesion of weld spatter. After welding has been completed, the spatter and the compound are quickly wiped off with a dry cloth.
Thtee new methods have been intro duced for cutting stainless steels and other metals, difficult to cut by standard oxygen methods. In one of these processes, a combination of an electric are and a stream of oxygen is utilized. The arc is established between the material to be cut and a coated, tubular, low-carbon steel rod, through which oxygen is fed. The rod is consumed as it cuts.
Cutting with Powder
The second is a powder-cutting process. A finely ground, iron-rich powder is introduced at the nozzle of the blowpipe. It Mims in the cutting oxygen stream, creating an extremely high temperature that melts and washes away the oxides that prevent cutting at the lower temperature of the standard process.
The third method can also be either hand or mechanically operated, and consists in injecting powdered flux into the cutting oxygen in chosen amounts, automatically and directly to the point of cut.
An aluminium solder is now being manufactured and distributed, and was first developed in Switzerland. A ruben solder, recommended for filling and soldering aluminium where tightness is essential, but strength unimportant,, is being made. It is applied without flux at low temperatures, and can be used to repair cracks and build-up worn surfaces on aluminium castings. .
• A silver brazing-paste, that can he applied with a few strokes of a soft brush, is another new product, and has been developed specifically for brazing carbide tips to tools.
Carbon Content Reduced Treatment of parts in the solid carburizing compounds in general commercial use, gives carbon concentrations in the hardened case of 0.9 per cent. and over. These high concentrations are sometimes advantageous, hut in other applications surface-hardness is required, together with good ductility and toughness. This led to the belief that the carbon content of the case could be reduced by modifying thee carburizing compound.
A decrease in maximum carbon content was eventually obtained by usingmixtures of a chloride and a siliconbearing material. Either nickel or chromium chloride and ferro-silicon proved the most potent mixtures from this point of view. It has been found that magnesium can be coated with its own oxide silicate. The coating can be dyed, acts as an anti-corrosive, and forms a base for paints and enamels. Sealing caps, sleeves and tubing of vinyl Material, which can be shrunk over, the ends of metal tubing, threaded pipes, and 'precision surfaces as a protective coating, are being extensively used. The vinyl material is not affected: by most common alkalis, acids and solvents, and by only a few chemicals.
Jumbled stocks of alloys can be recognized and reclassified by means of the small current generated when dissimilar metals rub together. Small changes of structure arising from different heat treatments can be detected. An electronic version of the spectrometer will determine the chemical composition of a specimen in 45 seconds.
. Shrinking Machine Parts
High-purity, inert, non-toxic liquid nitrogen, is now being employed commercially for shrinking machine parts requiring expansion fits. Pre-cooled by gas passing around them to exhaust at the top, the parts are fed down through the liquid; then they rise to an ejection trap at the right. Valveseat inserts are being dealt with in this way.
Using a moulded nylon insert as the locking element, a new self-locking nut has been invented, and has already been proved, it is claimed, to withstand up to 200 removals without losing its effectiveness. A new battery connector, without nut or bolt, is electrically tight, non-locking and nonfreezing. It fits any size of post, and has an adjustable stainless-steel screw, fitted with a special bush. It moves two cams to provide equal pressure around the post, and lasts as long as the battery.
A corrosion inhibitive pigment, of the barium potassium-chromate type, is the latest advance. It is highly corrosion inhibitive in the presence of water. Paints pigmented with this substance may be made with vehicles containing resins and with other vehicles in common use. It has a lowtinting strength. An enlarged bumper guard, made of 1-in. by 6-in, formed steel-plate, has been designed. Fitted over the original smaller bumper plate, the new guard allows the original one to become a structural support in the newer models.
It is easily removable if desired, and is placed soas to protect the trans
mission and steering units. It does not, it is stated, affect the turning radius or manceuVrability of the vehicle.
A method of producing high-quality oil fuel from virgin gas oils, or any other gas oils having a similar make-up, has been patented. The -patent pro-. vides for the conversion of the more simple napthenes into aromatics by a hydro-forming operation, and the solvent extraction of the aromatics from gas oils.
Resistance to Fungi
Cluiing the war some forms of cork engine-gasket were attacked by fungi when exposed in tropical areas, or stored under favourable conditions as regards temjserature and • humidity. Tests have since indicated that untreated resin-bonded cork is far less subject to mildew growth than untreated glueglycerine bonded cork.
Cork gaskets treated with fungicides showed only traces of fungus growth, and the fungicides found satisfactory were (a) 2 per -cent. p-nitrophenol in isopropyl alcohol and fuel oil; and fb) 10 per cent. zinc dimethyldithiocarbonate in an emulsifiable oil containing a cation active product.
An American State Highway department has applied the principle of the magnetic separator to the collection nails and other 'small iron-scrap from roads. • About 1,300 lb. was collected frail a little over 1,500.miles of roads in a single year. The magnet is in the form of a roller mounted on a trailer drawn behind a maintenance lorry at 8 m.p.h.
The 'roller is slowly revOlved by a belt drive from the trailer wheels, and each seetor is demagnetized as it approaches a collecting trough. Iron or steel objects are picked up from loose gravel as well as from pavements.
Safety "Sandwiches " Cellulose nitrate, the first material used in the glass-plastic-glass sandwich of safety glass, has been largely displaced by vinyl-butyral, •which has not the disadvantage of discoloration of cellulose nitrate. I he. main bearings of engine crankshafts are now being checked in three places simultaneously with an air gauge of special design. The possibilities of multiple gauging by air are said to be unlimited.
One instrument simultaneously checks the outside and inside diameters, concentricity, and bore squareness to one face, and a new multiple air-gauge in a cylinder-block production line checks each of eight bore-diameters at four levels, and reveals out-of-roundness.
The painting of broken markings along the centre strips of roar.:s is being done automatically in New York State. A cam-controlled paint gun is used.. The length of the strip can be controlled by a variable-speed drive connected to a wheel running on the roadway. A lorry pushes the stripper, and carries the air compressor arid paint Storage-tank. Fibreglass and brass-coated steel Wire have been shown. by tests to have superior qualities for tyre cord over some other Materials • Power Steering
Hydraulic power-steering, developed origihally for Tank retrievers, is to be used for commercial vehicles. The device consists of a fluid reservoir, engine-driven pump, steering gear, eontrol valve and power cylinder., When the steering wheel is turned by the driver it moves a lever stud through the cam groove to rotate the rocker shaft. The control-valve centring springs are preloaded, so that the hydraulic system is cut in at a given steering-wheel effort, the power cylinder acting directly on the steering-gear lever. If the system fails, the vehicle can still be steered in the normal way.
To test for leaks in vehicle bodies, makers are now sprinkling talcum powder inside door and body joints. The vehicle is then driven past huge wind-producing machines; dispersed talcum indicates a leak.