The Answer: Communication and Advanced Quality Planning
The heat treatment confers resistance to wear, develops excellent mechanical properties and increases the fatigue strength.
The heat treatment, however, is also the source of many problems and potential pitfalls between which an unpredictable amount of distortions and deformations. In addition to the distortion caused by the heat treatment in itself, the residual stresses that are already present and in particular induced by previous operations (such as, for example, the production of steel, forging, mechanical machining and grinding) will be released during this phase and will manifest themselves in the form of a further unpredictable deformation and that the trattamentista can not control.
Achieving all the requirements can turn into a challenge for those who defines all processes of production gear.
Step 1: Allow the trattamentista perform an assessment on the feasibility and on specific requests. Some questions that should be raised is:
The position and orientation of the gears during the heat treatment plays a role of extreme importance for the final result. Long shafts and some gears is preferable to move vertically in order to ensure the best results in terms of deformation and good uniformity of heating and quenching. Signs or bruising may occur as a result of contacts between the teeth or between the teeth and also if the equipment is not guaranteed an adequate separation of the details you do not allow a good flow of the atmosphere and the quenching means. On the other hand gears with larger diameter holes may have better results in terms of cylindricity and circularity when placed resting in baskets instead of hanging. The design and development of tools for fixing and racks for each specific geometry of particular is crucial towards achieving close dimensional tolerances and ensure a good uniformity of the results in an entire charge of gears. Therefore it would be appropriate to design and build the best equipment for every particular.
Step 2: Sampling as Studio Process
The samples are a good idea for the development of a process, as they allow to trattamentista to run tests, measure the results of the process and to finalize all the parameters of heat treatment. It usually takes more samples before running the PPAP; this should not be considered as a cause of delay or loss of time but as a complete view of the process and its variables so that production can proceed smoothly and Cpk capability indices higher once it starts.
Step 3: Run the PPAP: the last step for a good heat treatment process.
For a good PPAP would be appropriate to provide for sampling with bake at full load both in the case of discontinuous furnaces is the case of continuous furnaces, in fact, the execution of samplings of some piece or small parts of an entire charge may not give the same results of the office dedicated. Very often manufacturers gears need sampling with small amounts because it either does not have a great amount of detail available or because they do not want to sacrificing a large number. The danger of the execution of test charges is small and that the oven and the details you can heat with temperature gradients different than when the oven is fully charged.
All these communication tools and design techniques of advanced quality, if used properly, can help technicians that produce gears and treaters to identify and resolve any problems that may occur before production. Treaters as we note that many new projects in the early stages take place without notice, without advance quality planning and no planning in general. In many cases the lack of communication in the early stages of production leads to waste and non-conformity by the manufacturer or by the end user without gearing well know the motives or understand what changes could be made to meet the specifications. Communicate with those who are running daily thermal treatment allows for quick advance quality planning which allow productions more “fluid”, a waste reduction and the elimination of many “headaches by heat treatment”.