When a prominent West Midlands sub-contractor won a new long-term contract to machine con-rods for the yellow-goods industry, it called upon the cutting-tool expertise of Rugby-based Mapal Ltd (
www.mapal.com) to reduce its costs and improve its productivity.
Required to machine more than 15 con-rods every day over a minimum two-year contract term, the company sees efficiency, process reliability and cycle time reductions as critical factors in the project, so it asked for Mapal’s advice about reaming a 40mm-diameter bore.
The latter’s sales manager, Eugene Nugent, said: “The customer involved us at the very start of the process, based on our reputation for automotive tooling solutions and con-rod machining.
“The cast steel con-rods are hardened to 62HRc, which makes them a challenging proposition.
"In addition, the drilling operation leaves between 0.15 and 0.17mm stock allowance for reaming.
"We applied a 40mm-diameter guide-padded reamer, and every bore now has an exceptional surface finish of less than 1.6Ra.”
The success of this reamer led to the opportunity to trial further tools on the con-rods.
Mapal saw that a competitor’s end mill was finish-profiling hardened con-rods in a cycle time of 8min. The eight-flute 16mm-diameter tool was costly, had limited tool life and was not being very productive.
Mr Nugent said: “I ran trials with a 16mm-diameter Optimill Uni end mill and instantly reduced the cost of tooling by 45%, but this changeover was more than just a cost reduction exercise.
"Our Optimill Uni is running at 2,500rev/min with a feed rate of 1,100mm/min on a very difficult material, and the results have delivered a cycle time reduction of 3min per part.
"This is a considerable saving for the customer, and the tool is producing a far superior surface finish.”