C & B Machinery of Livonia, Michigan has improved productivity and flexibility of their double disc non-coplanar connecting rod grinding system first introduced in 2009 for the Chevrolet Volt 1.4L auxiliary engine. The first grinding system produced a stepped connecting rod from a parallel (or coplanar) rod. The 1.4L Chevy Volt connecting rod has a 1.2 mm symmetrically smaller crankshaft end width, and both the pin and crank ends of the rod are ground in one sequence. At the time, the system was considered the most advanced double disc grinder ever produced by C & B.

This latest system, recently shipped to Eston Manufacturing Division of Linamar Corporation, is grinding a 1.8 L connecting rod with a symmetrical reduction of the pin end of 3.8 mm. As before, the challenge was to produce this part from a coplanar connecting rod in one operation. Stock removal from the pin end of the connecting rod is 5 mm and stock removal from the crank end is 1 mm. Previously, this connecting rod required three grinding operations to complete and the crank and pin end were ground on two separate machines.

C & B's application engineers took the challenge to task developing a special tooling package and unique two-stage grinding cycle which first rough grinds the pin end to a stock condition equal to the crank end. It then finish grinds the crank and pin end of the connecting rod simultaneously. Grinding the crank and pin ends at the same time produces much better symmetry between the two. Additionally the grinder easily exceeds Eston's 1.67 Ppk requirements for size, parallel and flatness. The grinding system also includes a post process gaging system with automatic feedback to the grinding wheel infeed servos providing automatic compensation for wheel wear. The gage also inspects step relationship between the crank and pin end faces.

The C & B model DG-2H-30/SA Connecting Rod grinding system has the ability to grind parallel parts, non-coplanar parts, pin end only or crank end only configurations with very simple changeover. This bodes well with today's manufacturing requirements -- lower production rates, better flexibility and a never-ending demand for lower machining costs per piece.  With models utilizing up to 42" diameter grinding wheels, large diesel connecting rods can also be produced in this manner.