TPi April 2010

Process steps in radiator manufacturing Surface and weld quality, geometry and dimensions are the characteristics critical to some process steps in radiator manufacturing. Typical process flow in radiator manufacturing is as follows: • Cutting to length • Drilling/punching • Grinding, polishing • Assembly for welding, plug insertion, welding fill-in material application • Welding/brazing (in furnace) • Leakage test • Finishing (polishing) • Electroplating A critical customer requirement: narrow dimensional tolerances to assure conformity for plug installation and welding Welding ina furnace isarecentlydevelopedcontemporary method used in radiator manufacturing. In this process, the four open ends of the hollow sections on the assembled radiator are closed by the insertion of metal plugs, which are welded (or brazed) with the addition of filler metal paste. Conformity of dimensions and geometry of the hollow sections to ensure the convenience of plug installation is a critical requirement. So as to provide this conformity, the variance of dimensions (side length and wall thickness) has to be under control. Six Sigma tools are utilised thoroughly for the purpose of controlling the dimensional variance. So as to fulfil the geometrical and dimensional requirements for tight tolerances, tube geometry and dimensions should be stable. Specialised roll design is another means to ensure this stability.

Future aspects

Multi-generation product planning (MGPP) approach for product development When considering the steel hollow sections to be electroplated as a “product”, a stepwise product development plan may be established as follows:

• MGPP1: Provide cut-to-length tubes to customer (radiator or furniture manufacturers)

• MGPP2: Providesurfacefinishedtubes tocustomer using off-line polishing machinery (after tube mill) • MGPP3: Surface finished tube production (via on-line or in-line polishing) at the tube mill • MGPP4: Tube production using “bright” raw material, suitable for direct chrome plating Other future aspects • Production of high strength tubes suitable for electroplating so as to yield a reduction in the weight of furniture • Usage of stainless steel tubes in radiator manufacturing may become an economically considerable alternative to electroplating carbon steel tubes; thus the current state-of-the-art materials may be substituted at some point • Similarly, hollow sections made of aluminium alloys may become more popular as an alternative to carbon steel in the future • Development of “greener” chemicals in electroplating process – Trivalent bath instead of hexavalent • Development of welding process technology in radiator manufacturing – Carrying out the welding process in specially designed furnaces, which increases productivity as well Future trends for the finishing industry 1. Economic trends (cost of labour and consumables, increase productivity) 2. Regulatory trends (air, wastewater, hazardous, toxic) 3. Technology trends Optimising existing technology • Optimise conventional wet processes to achieve near zero discharge and risk • Improve process monitoring and control systems • Improve energy efficiency • MGPP5: In-line chrome coating of tubes during production at the (exit of) tube mill

Figure 5 : An ideal (normal) measurement distribution for side length of a hollow section

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April 2010 Tube Products International