Perfectly balanced for large-scale production, the solid carbide thread forming solution by LMT Tools provides more efficient, reliable processes for threading on piston rods for cars, with its long tool life.
Both ignition pressure and speed have been increasing in engine development for a number of years. There are not many components that are as directly exposed to these forces as the piston rod which, as a central element, transmits the motion. In view of these requirements, the manufacturers usually rely on high-strength materials. However, this also creates some unique challenges which increases the requirements in production: The strength of the material reduces the life of the tools used - resulting in increased tooling costs and reduced process reliability.
Accurately recommending special tools
In this context the special tools that the experts at LMT Tools match exactly to the application provide new options. This is demonstrated by the use of a solid carbide thread former by an engine manufacturer in Germany. "The customer approached us because the tool life of the HSSE-PM thread formers they used previously for the machining of the M8x1 piston rod thread was too short", explains Michael Rechtziegler, a technical consultant at LMT. "The tool had to be replaced after manufacturing 2,800 threads or 1,400 piston rods." The specialists then developed a new forming tap and matched its solid carbide to the piston rod thread (depth 12 mm, M8x1) and the piston rod material (70MnVS4 + 46MnVS5) as well as the required machining parameters. The cutting speed remained unchanged at 18 m/min. Machining was carried out with minimum quantity lubrication (MQL).
Massive increase in tool life
"This is how we managed to achieve a substantial increase in tool life for forming taps", says Michael Rechtziegler. "With immediate effect the tool now only needs to be replaced after every 32,000 threads, i.e. 16,000 piston rods. The customer benefits from the significant reduction in the costs per piece. At the same time, the quality of the threads with their press-finished flanks is excellent."