A Manufacturer of Commercial Explosives Dramatically Reduces Die Changeover, Startup and Shutdown Times
A leading manufacturer of commercial explosives worked with the DPA team to reduce die changeover time for the production of the company’s shock tube lines. The goal: slash approximately 515 hours of unplanned downtime by half by eliminating waste in the die change, startup and shutdown processes and implementing ideas to make each process more efficient.
To address changeover and start-up/shutdown issues in a comprehensive manner, two Kaizen events were scheduled in spring and late summer, with overlapping Kaizen teams working on each event.
The first Kaizen team focused on the die changeovers. DPA senior consultant Mike Beauregard worked with the team to analyze the source of problems on its shock tube extrusion lines.
A video of the changeover revealed that all of the changeover activities were internal to the downtime – this included getting parts from the cleaning room and finding hand tools. However, the video did not capture all time-wasting activities, including the 18 minutes it took an operator to center the extrusion die and the repeated trips to a tool cart during the changeover. The vacuum line and its piping had to be disassembled and then reassembled during the changeover. Valves that the operator needed to turn off were not labeled; the operator fumbled with a few valves before shutting off the one he needed off. Pipe extensions were unsafely used in tightening parts and bolts, actions that could snap bolts off inside the extruder body.
After watching the video and observing the line, the team identified 55 initial improvement ideas; many could be implemented quickly or simulated. These were applied to the process and the team conducted a changeover trial on one of the extrusion lines.
For a trial run to determine time-saving effects, the team converted the preparation from internal to the changeover to external. They created and used One Point Lessons on installing the pencil die and the extrusion die holder retaining ring which saved 14 minutes from the changeover downtime.
The team also:
- Labeled the valves that the operator must use in the changeover.
- Moved the tool cart next to the extruder head during the changeover to eliminate walking time
- Tried the same tool cart positioning with larger operators. Once the approach was found to be acceptable, they marked the location with floor tape.
- Mistake-proofed the shock tube stringing-up process with color-coding and removal of not-needed pullies
- Created new work instructions to accompany the One Point Lessons. These were reviewed with all operators to solicit their feedback; revised and then rolled out with documentation and training.
- Generated seven new ideas from the trial and created an action plan to implement the improvement ideas.
Results and Benefits
After making their recommended improvements in tooling placement, One Point lessons and instrument labeling, the team ran another die changeover trial. This trial took 52 minutes, a savings of 50 minutes or 49% over the changeover’s historical performance. Once additional improvements are made, the team expects to shave an additional 18 minutes off-die changeover times, a net reduction of 65%.
Besides beating their initial goal of a 50% reduction in die change over time, the company now has protocols that improve safety, flexibility, quality of the shock tube products and reduce scrapwork.
Continually Improving the Process: Shut-down and Start-up Waste Reduction
To help it expand upon its successful reduction in die changeover times, DPA returned to the company later that summer for a follow on Kaizen. This event’s goal: Review processes for shutting down and starting up the shock tube lines and reduce downtime by 50%.
Two employees who had participated in the die changeover reduction Kaizen team joined with engineers, supervisors and the plant manager for this event. Existing data showed that starting up the extrusion line took an average of 198 minutes per event, but there was no data on downtime for shutdown events.
The team decided to focus on short-term start-ups and short-term shutdowns. After reviewing videos of both procedures, they went onto the floor and walked through the processes. They discovered that not everyone was using the proper personal protective equipment or the correct tools. The bad workflow created excessive walking (waste of motion). Scrap on the floor posed safety issues. Not all reinstallation of equipment was obvious. In one case, the operator flipped one dam 4 times before getting it into the right position. Many valves specific to start-up and shutdown processes were not marked. Each operator determined how actions would be sequenced; there was no consistency in this process. However, the team did agree that the parts of the set-ups they reviewed in the videos appeared to be typical operator practices.
After watching the video and observing the line, the team initially identified 72 improvement ideas. Among these ideas were:
- Need a remote console near the horizontal extruder head to eliminate walking.
- Work practices need to be standardized.
- Establish best practices for machine speeds and amounts.
- Put work instructions online and make them available at each work station.
- Labeling of sequence for start-up and shutdown at machines.
- Establish purge recipes; return to using standard protocols.
- Replace McGyver solutions with permanent solutions.
- Do other activities in parallel with waiting times.
The team trialed and then critiqued these processes for further improvements. They developed work instructions for the improved processes. To realize additional time savings, they drafted a process for a two-person start-up of the line to be tested at a future date. The team notified Maintenance to make certain repairs. One safety item found in the process was addressed immediately by the team. Other safety items were addressed and put onto the Action Plan along with the other open Improvement ideas.
Results and Benefits of Streamlining Start-Up and Shutdown Processes On The Shock Tube Line
The portion of the start-up that could be trialed took 32 minutes. The team estimated that remaining start-up activities not trialed would take 20 minutes. The resulting 52-minute start-up equals a 73% savings from the average time per start-up event compared with the past year.
After procedures were streamlined and made more consistent, the team measured shutdown times at 24 -34 minutes depending on process add-ons. Adding the new estimated time for the improved start-up process, the team estimated a 12-month payback for the capital goods that will be purchased to further improve the start-up and shutdown. Once due dates are set for open action items, new work instructions are complete and operators are trained consistently over time, process times for both start-up and shutdown will be further reduced.