Improving traceability of completed engines coming off the line at the Briggs & Stratton Small Engine Facility in Poplar Bluff, MO was a major goal for manufacturing engineering technician Billy DePew. This meant being able to trace a nonconforming part back to the pallet it was produced on, the date of manufacture, and work shift, in order to check other engines of that batch to determine the exact corrective procedure. The Briggs & Stratton facility builds 14,000 units per day of the highly regarded Quantum 4-cycle engine, known for its excellent one-pull starts on power equipment, such as self-propelled lawn mowers.

Working with Balluff engineers, DePew added a Balluff Parallel Passive Inductive ID system to help identify specific engines within their production batch. With this system, engines that did not meet Briggs & Stratton's rigid QA standards could be isolated by a time stamp (date/time of manufacture) that was applied to each block, providing traceability and accountability for work performed by Briggs operators. The ID system helped Briggs and Stratton flag missteps before final engine assembly, and reduce scrap -- increasing throughput and the overall quality of its engine components. (Pictured, Balluff read head relays pallet number to Telesis pin stamper at immediate right, which marks parts with date/time, shift number, and pallet number.)

The Tracking Solution

Working with his Balluff team, DePew determined that a simple Balluff 60R read-only, passive inductive identification system could provide information to help improve quality tracking on the engine line. The Balluff BISC-60R-001-08P ID system installed at Briggs & Stratton consists of a simple parallel, self-contained read head, an 8-bit parallel (8-byte addressable) device resembling a 30 mm inductive proximity sensor. This read head works with 1,023-byte Balluff BISC-12805/L data carriers, one each mounted on the machining pallets. These data carriers are essentially industrial EE-PROMS encapsulated in robust manufacturing-grade Duraplast material. They are capable of withstanding hostile manufacturing environments and rated to -20 to +70 deg C.

The 88 data carriers used in this application have a mounting hole in the center of the tag for easy pallet attachment. Data exchange between the carrier and the read head is noncontact and wear-free. The data and necessary power for the data carrier are inductively coupled and require no battery for operation or data retention, eliminating added cost and the risk of losing data. Precise alignment of the read head and the data carrier is not necessary, since the data carrier can be read "on-the-fly" while moving past the read head.

Installing the System

After the data carriers were mounted on the engine block pallets and the M30 read heads were mounted and aligned, the system was ready for integration into Briggs' existing control system. DePew integrated the Balluff ID system into his Mitsubishi PLC and Telesis workstation with an LCD screen used for visually checking data. All communications in the network are via RS-232.

Small engine blocks are installed on each of 88 production pallets progressing on a conveyor that moves them through 54 machining stations. Cylinder bores are rough-cut, valve guide holes are bored, oil fill holes are cut, breather bores and cam bores are machined, and heads are tapped in sequence at the various stations. At the third machining station, the pallet number is automatically read off the data carrier on the pallet, and that number, plus the date, time, and crew/shift number, is coded by an operator into a pin stamper, which imprints the information on the corresponding engine block. This data is essential in pinpointing any out-of-spec components that must be pulled out of the system. Beyond that, the process provides greater traceability and quality control on the entire engine machining process. (Engine part is shown here with pin-stamped information while still fixtured in pallet.)

Results

With integration of the Balluff Parallel ID system, the Briggs & Stratton Poplar Bluff engine block line achieved a cost-effective method of identifying quality problems. Briggs & Stratton also achieved a system of backtracking components and accounting for work performed by its employees. The system was determined to be efficient, cost-effective, and relatively easy to integrate. The IP67-rated Balluff ID system was also robust enough to withstand rigors typically found in machine tool environments where components are showered with hot chips, coolant, and lubricants.

"The Balluff ID system was simple to install and use," says DePew. "There are no problems with the system and the reads are accurate. We've also received good support from the Balluff organization. We'd like to expand this system into other plant areas, even in a new plant expansion assembly area that's being implemented in 2005."