We attended a complex tube production cycle at TRW; a worldwide operating company that produces suspension arms, tie rods and ball pivots for automobile manufacturers, component suppliers, and their corresponding aftermarket - 60% for cars and 40% for trucks.
As everywhere in the industry the emphasis is on savings, which should be made in the range of materials and time, for instance process simplification or integration of auxiliary materials. An innovative possibility could be to control the measuring process instead of material and time waste. Without using measuring equipment the production needs to bend up to 10 tubes before the part syas within the given tolerance, depending on the complexity of the production. This means that expensive raw material becomes scrap metal. The production of freeform bent tubes without using measuring system is even more complicated, since 150 to 200 specimens will be needed before the tube meets the required tolerance.
The tube production at TRW is extremely demanding, as the tube ends are not straight, but have joints or pivoting connection parts at both ends. TRW recently invested in a measuring are with the specialised tube software TeZetCAD. Now the engineering department is able to read in the parts data without complications and print drawings including the xyz coordinates and bending data format. The possibility of typing erros is eliminated from the outset. The bender operator no longer needs to convert the values of the master part for the bending machine, he can either input them manually or digitally direct from TeZetCAD into the bender.
Mostly the tibes are pushed over the mandrel to start the bender process. 'Uschi,' the new robot, takes a tube from the pile with its arm and grab handle and, moving like a dancer, puts the tube in a jig to control the correct position of the 2 welded ends, continues dancing to work holder on the bender to bend this tube according to the predefined data. One could think that the part is finished. Depending on the material a tube can be a very idiosyncratic part. It cannot be forced to stay in a certain position, sometimes springs back if a bend is too narrow and lengthens the tube for some millimetres, so that the following bends, straights and tude ends are no longer at the predifined coordinates.
Traditionally a 1:1 drawing is used as a visual control of the tolerances. This is no longer neccessary, as the measuring system mesures the bent tube and TeZetCAD calculates the new correction data in relation to the master tube. The person responsible for this point needs a lot of experience with visual control, but in these time the customer wants an excel sheet with precise data in the hundredth range. The digital comparison of the master part to the bent part quickly shows if the deviation stays within the given tolerance or not. If not the software calculates the new bending data. This is not only a considerable time saver but also an appreciable saving of material. The customer realises this fact as price reduction.
The open secret of the user friendly TeZetCAd software is that it was developed from the start from daily practice, and TeZet attaches great importance to staying with this practice. If a worker retires, his special knowledge will be lost for the company. With TeZetCAD people with no previous experience can start, because TeZetCAD is self-explanatory and acts with 'a push of a button.' It runs on Windows XP, 7 and 8.