A precision manufacturer (think complex curved geometries, micron tolerances, high rpm interacting component parts with sub assembly and final assembly operations) failed with their Lean deployment. They had some physical Lean successes (5S) with sub and final assembly but not with a fully integrated manufacturing scheme and it definitely wasn’t a financial success by any means. The problem, the machining processes were not fundamentally capable.
Business was booming, the backlog was growing, and the plant was on sustained overtime. When it came time to begin the Lean process there wasn’t time or resources to do a value stream map which would have hopefully uncovered the hidden factory. The newly hired Lean practitioners and newly trained Lean associates reasoned that since we’ve always made acceptable product and the marketplace wanted more, they could start the Lean journey from kaizen events in final assembly and work their way back into the production processes by instituting fractional pull systems. The effort stalled at sub-assembly, so the Lean resources kept fine tuning final and sub-assemblies as well as they could while battling inconsistent quality and supplies of manufactured component parts and the organizations involved in making and supplying the components.
Cooperative lines of communication were being dissolved, a separation between the new Lean “outsiders” and the journeyman cadre of Production, Maintenance, Manufacturing Engineering, Tooling, Quality, and Production Control had developed. The journeymen viewed Lean as an assembly nicety that looked good but wasn’t practical in an asset heavy engineered product machining environment. The Lean practitioners were frustrated in their lack of being able to institute a pull system and acquiesced to the belief that precision machining environments like theirs were a different and unique situation since they didn’t have the volume and repetition of automotive products.
Meanwhile, the backlog was growing. The plant was at full capacity and the scrap rate in machining was increasing as was downtime. This definitely was not going unnoticed by upper management and SBTI was given an opportunity. With a narrow focus on scrap reduction we quickly focused on process capability. We began with measurement systems analyses and the re-introduction of control charts. The journeymen were quick to point out that the SPC stuff had been tried many times in the past and they even showed us yellowed forms with a copyright from 1957 for manually calculated control charts. They were proud that they eliminated the need for SPC years ago by instituting adaptive controls within machine tools and between gages and machine tools.
It didn’t take too long to determine that there were gaging and machine tool condition issues that were creating the machining variations. Some coordinate measuring machines were in protected environments and others were not. Some had thermal compensation, some had not. Due to production demands some parts were checked immediately while still warm and others were allowed to cool. When the parts that were gaged in a warm state made their way back to a machining center and were now cool, the coordinates didn’t match what was recorded. Soon we were able to prove that the coordinate measurement machines/processes were not repeatable. We found manual gages with poor R&R’s and that didn’t allow for proper discrimination for the operators when they performed their measurements. We observed well-meaning CNC programmers making changes on the fly to compensate for bad measurements in machines that had encoder issues, worn ways and spindle bearings. The programmers were reprogramming so as to load an axis against another to compensate for the slop in their fit up due to wear in an effort to maintain piece part size and tolerance. Every programmer had their own fix for an encountered situation, and they were encountering a situation with every changeover and measurement audit.
We went through a process of fix the gaging, fix the machine tool, verify capability for key machines. As we went through this process, a preventative maintenance system was developed, statistical process controls re-introduced and maintained, NC programs were brought back to standards, the supply chain calmed down and the conditions for the reintroduction of the Lean system as originally envisioned were created.
In about nine months, shipping records were being set, scrap, overtime and downtime were reduced generating more than $8 Million in annual savings and a Lean continuous improvement process was working.
As a matter of note, all SBTI resources are equally versed in Lean and Six Sigma. It’s all one tool kit! And, we do a lot more, in healthcare, manufacturing and services. Give us a call where we can Listen to your needs.