Metal forming applications such as welding, extrusion and cutting can all benefit from Syalon 101s and Syalon 050s excellent mechanical and thermal properties and chemical stability.
Welding
In its most simple form a welding operation joins metal pieces together using a pool of molten metal. The first consideration of any welding operation is to create a weld which, as far as possible, has the same properties as the original metal. The join must also be created in such a way that minimum disturbance is caused in the area adjacent to the weld. Such welds are best done at high speed and in such a manner that the molten weld is completely shrouded from the atmosphere during the operation. Welding today encompasses many different techniques and methods, however, speed and protection of the weld are required for all operations.
Welding methods are diverse but they all require the same high standard of material performance. Ceramics in welding must be able to withstand thermal shock at a variety of temperatures. They must have high strength to resist mechanical damage, which is often accidental. They must be resistant to ‘weld spatter’ and the consequent build-up of weld debris. They must also, for many applications, be electrically insulating and stable at high temperatures.
Weld Location Pins
Weld location devices are used in the resistance welding of captive nuts in automotive and commercial vehicle assembly. Syalon 101 weld pins allow precise welding of nuts to sheet metal.
A major European manufacturer used steel pins for the location of nuts in a continuous resistance welding operation. On average, the steel pins lasted for 7,000 operations, that is a working shift, before wear and spatter build-up caused damage to the nut. By using Syalon 101 location pins, over 5 million operations have been completed without wear or damage occurring.
Welding Jigs & Fixtures
In addition to resistance welding, a number of other welding techniques successfully use Syalon 101. These include orbital welding, tungsten inert gas (TIG) welding, metal inert gas (MIG) welding, induction welding and plasma welding.
Orbital welding, often used in aerospace, employs small diameter gas shrouds to weld curved or cylindrical components. Syalon 101 gas shrouds have performed several thousand cycles, giving hundredfold increases over conventional materials.
In the TIG welding of steel tubes in heat exchanger cores, Syalon 101 nozzles have outlasted alumina nozzles by a factor of 10 to one. The confined space in this operation creates severe welding conditions and Syalon 101s thermal shock properties and resistance to weld spatter are the key to the success of this operation.
Syalon 101 nozzles used in a plasma cutting operation had a life at least four times that of alumina and twice that of silicon nitride nozzles and the spatter build–up on the nozzle was easily removed.
Extrusion Dies
Wire drawing, open die extrusion and hydrostatic extrusion, whether performed hot or cold, are all examples of metal flow through converging conical dies. Three independent variables affect the flow of material: the cone angle, the coefficient of friction and the ratio between the original diameter and the extruded diameter. These parameters have a strong influence on the extrusion or drawing force at any particular speed. Other influential variables include lubrication, temperature and the thermal properties of the die itself.
The material properties which make Syalon an excellent candidate for extrusion include hot hardness, high strength, good thermal shock resistance, high rigidity, chemical stability and good frictional properties.
Syalon 101 dies perform extremely well in the extrusion of copper, brass and nimonic alloys, with excellent resistance to wear and thermal shock giving extended die lives. Also, since Syalon materials do not contain a metallic phase, die pick-up can be eliminated, which results in improved continuity of the extrusion process, enhanced surface finish of the product, reduced scrap rates and increased productivity.
Single shot impact extrusion of nimonic components using Syalon 101 dies produced 30,000 components before excessive die wear was noticed. Tool steel dies had to be replaced at 750 components.
A major extruder of brass and copper in the UK has found that using Syalon 101 dies, 250 tons of brass could be extruded compared to 100 tons through conventional dies. For copper, Syalon extruded 75 tons compared to 40 tons for a conventional die.
Cutting Tips
On of the earliest successful applications for Syalon was as a cutting tip or throw away insert. Metal removal generates tremendous heat and even when a coolant is used temperatures of 1000°C at the cutting edge are commonplace. If a cutting tip has poor thermal conductivity, then the heat generated cannot be easily dissipated. The thermal damage is exacerbated by a high coefficient of thermal expansion and exaggerated crater wear develops leading to the rapid destruction of the cutting edge. This thermally induced wear is an important and neglected feature in metal removal.
Most turning operations involve ‘interrupted’ cutting, whether by design or accident. For example, in the turning of a roll of chill-cast iron, the existence of pin holes and local asperities makes the cutting action intermittent. Many cutting operations are by necessity discontinuous and as well as having suitable thermal properties, cutting tools must be tough.
In addition, work pieces are often hard and can be abrasive so the cutting tips should have high hardness values. Finally, the metallurgical properties of the work piece may be such that at the high temperatures generated a chemical reaction takes place between the tool and the work piece. So, chemical stability is also important.
This demanding set of requirements is met by Syalon 050. It is thermally stable up to 1400°C, thermal shock resistant, hard, tough and strong and chemically resistant to corrosion. In use Syalon 050 cutting tips reduced by 75% the machining time for turbine discs for the Rolls Royce RB211 engine.