Automated Honing Creates Consistent Parts

To meet demanding size and surface finish requirements for complex parts, Micron Manufacturing of Lagrange, Ohio, used a single-pass honing/diamond sizing system. However, the company realized that this process was creating inconsistent parts as well as increasing downtime and inspection costs. By adding a fully automated Nagel Eco 40 honing machine from Nagel Precision, the company eliminated its quality issues and achieved consistent uptime.

For more than 20 years, Micron Manufacturing has manufactured high-precision, intricate components and subassemblies for vehicle systems manufacturers. Production volumes range from 200,000 to 4,000,000 parts per year, and sizes range from 3 to 125 mm. The company processes raw materials including barstock, cold-headed blanks and forgings made from carbon and stainless steels.

Micron was initially using a single-pass honing/diamond sizing system to achieve these specifications, but some of the machine's characteristics made this difficult. The system's typical plated-mandrel type tools required manual wear compensation achieved by plastic deformation. All the honing spindles in the diamond sizing machine were driven by a single motor and mounted on a slide. The rotary index table moved the part from station to station, and the part was inspected manually at the end of the cycle. These factors caused Micron to experience numerous problems while producing the fuel injector housing with this process.

Also, the final inspection process could not identify which tools in the various stations were worn. The operator had to measure the bore size in every station individually, and then replace the worn tool. These frequent stoppages, in addition to causing downtime, also had a detrimental effect on tool life. For example, if the tool in the roughing station (the first station) were to wear at a faster rate, the resultant bore would be smaller and other tools downstream had to compensate by trying to take more stock. This caused tools in subsequent stations to wear prematurely.

The post process/final gaging system provides feedback to the automatic wear compensation system within the honing spindle. By gaging every part, bore size can now be monitored on 100 percent of parts and submicron adjustments can be made to compensate for tool wear. The honing tool is dressed on the tool body using a precision grinder at Nagel to ensure that the first part is good to speed tool change.

Mr. Zupan says the Nagel Eco 40 resolved all of the problems associated with the single-pass honing/diamond sizing system and has allowed for smaller tool inventories. The payback for Micron came immediately from quick and reliable tool changes, improved bore quality and consistent uptime, he says. The post process gaging and automatic size compensation feature on the Eco 40 eliminated all size-control-related issues, he says.