Gears and wheel sprockets are low profile components, but that understated physical form belies an innate knack for handling near unendurable loads. Geometrically detailed, these essential mechanical parts are machined from the finest materials. Manufactured, machined, and balanced, the parts are then heat treated so that they can tolerate high loading factors. Flame hardening is the preferred metal-toughening service on this occasion, but what are the advantages of this technique?
Directional Flame Hardening
Tight engineering tolerances manufacture dimensionally accurate single-piece gears and wheel sprockets. Teeth mesh, power is transferred, and torque is governed. A quick application of engineering principles is enough to determine these meshing teeth as the site of all mechanical loading, so this outlying area is where the heat treatment process is required. Subsequently, the hardening flame directs case hardening energy straight to the teeth, the site of known wear. Additionally, dimensional tolerances are maintained here, for the flame hardening process does not distort the geometry of the balanced gear.
Highlighting the Effects of Wear
The guilty culprit in most wear and tear studies is the point where physical contact is made. Gears mostly brush off contact caused wear by using fine lubricants, but these oily substances are mostly there to mitigate frictional influences. Consequently, flame hardening is used to comprehensively reinforce the triangular pitched rim, thus creating a case hardened ring of beveled and pitched gear contacts. Hardened in this manner, the triangular outer rim is now fully capable of enduring the abrasions and impacts that take place when gears dynamically interact.
Targeted Tempering and Highlighted Hardening
There’s a vast range of gear types available on the engineering market. Some products work in tandem with each other, so a quantifiable stress factor is a burden, but it’s manageable. But then there are worm gears and rack and pinion parts, plus a whole range of helical gears. The latter product stretches the meshing interface and adds an angular component to the mix. In order to make these different outer tooth configurations wear-resistant, flame hardening techniques change the fundamental structure of the triangular edges, from each peak to each trough, so that the wear resistance of each heat treated gear wheel is supplemented.
The meshing outer edges of these gears and wheel sprockets represent the harshest focal point in any mechanical power transmission system, so they require protection in the form of a flame hardening heat treatment procedure. Meanwhile, the rest of the wheel, its main body, remains ductile and workable.
High tolerances rule hot and cold precision straightening work. The factory floor is filled with high-tonnage presses and industrial grinding stations, the larger-than-life tools that enable expert material engineers to meet any deadline. But why is a straightening service essential in a heat treatment shop? In order to answer this question, we need to know why treated parts manifest physical deformations.
Quantifying Mechanical Deformations
There’s no way around the fact that some heat treatment work does cause an observable deformation effect. This is due to the stress placed on the alloyed part during its passage through the tempering and quenching process. Machining and cold working stations also introduce distortion zones, but a recovery annealing procedure offsets this undesirable result. Otherwise, a warping component could crack or split while clamped. This abrupt deformation becomes even more likely when complex profiles are part of the part’s design.
Rectifying Warpage by Employing Cold Straightening Processes
If the microcrystalline grain of the metal part hasn’t assumed an overly hardened form, then it can be loaded into a powerful mechanical press and straightened. High tolerance straightening is further refined by passing the part through a grinding machine. The plasticity quotient of the metal’s structure is key here, for a low elasticity limit locks the metal in its twisted form unless further thermal processing is applied. Any attempt to cold straighten a part that’s this hard will likely result in cracking and stress fracturing, thus rendering the part useless.
Using Controlled Thermal Straightening
If cold type precision straightening is voided, a thermal technique is called upon, which makes sense since we’re working under the constraints of a heat treatment facility. Thermal methodologies clamp the part and restore its profile to acceptable tolerances by controlling the direction of the linear-restorative vector, all so that the final part is ready for application. Of course, further annealing may be required to offset the strain introduced by any straightening, but this is an executive decision, one best left to the head engineer.
Linear corrections are as simple as loading the part into a 20-Tonee press until it’s dimensionally stable, but new straightening techniques use proprietary technologies to assure a dead-level profile. These computer-aided scanners use mathematical analysis to correct flaws that are invisible to the eye. Hot and cold precision work is currently meshing the finest attributes of mechanical processing and electronic scanning to create a perfectly repeatable corrective mechanism, one that straightens based on material hardness and any deformations introduced by the heat treatment workflow.