We just delivered a new PC based prototype machine with custom software and a touchscreen interface.
We just delivered a new PC based prototype machine with custom software and a touchscreen interface.
With new technologies coming online it seems that machine vision is more accessible than ever. New sensors that incorporate basic vision techniques have the capabilities of systems available ten years ago, at a fraction of the cost.
We integrated these in a turnkey package for one of our customers the other day. By performing the majority of the integration process off-site we were able to deliver it to the customer within a week of their initial request, and they were running within an hour from delivery.
A while back I was looking at a robotic water jet cutting process that needed improvement. The process used two six axis robots and each robot cut half of a part with a high pressure stream of water. We needed to reduce the cycle time and improve the repeatability of the cutting process. By that time in the process about ten engineers had tried to make improvements and each had been able to push the process forward with small incremental improvements. Each of these solutions had two common attributes. The robot was trained to move from point to point, and at each point the robot was told to verify its position. Additionally the robot was told to move at its maximum speed. The solution to reduce the cycle time however was counterintuitive. The first change in the programming involved the elimination of verified positions or points. By doing this the program eliminated a tremendous number of stops in the program. The stops were only milliseconds so they were not initially perceived as relevant. This change also eliminated the jerkiness associated with robots moving at high speed from point to point. The second change reduced the program speed where more precision was required instead of adding points for the robot to follow. The end result were programs that were much faster and more accurate than the original programs. It was common to take a sixty second program and reduce it to thirty seconds!
Takt time has many rewarding attributes when applied properly on the manufacturing floor, however it is important to consider it as one tool in many, relative to Line balancing a production operation.
As Takt time has become more recognized and also more in vogue it has been misapplied in certain situations. Takt time can certainly balance the labor needs on the line and stabilize the production flow as well, but used improperly it can kill a plants overall productivity. Let’s discuss two situations where Takt time is often misapplied.
The first situation involves highly complex processes. When processes become highly complex, the utilization of Takt time to improve overall efficiency may be more harmful than beneficial. How flexible and adjustable is the complex process, and are those adjustments worth the perceived gain in the balancing process? Can the process be documented in enough detail to delineate all the necessary set points to run equally well at multiple speeds? Is there a thorough understanding of the process capabilities at each of these speeds? Only after these questions are answered can changes be made to more complex processes.
The second situation is more common and more important. To understand this situation better let’s take a look from 50,000 feet or a plant management point of view. In general terms the faster you produce a part the less it costs. Also in general terms the faster machines run the higher their capabilities and repeatability’s.
Does your process allow for changeovers utilizing single minute exchange of dies (SMED) and similar techniques? If so can you maximize your throughput, and produce to demand. After defining this best fit for your plant, then apply Takt times for a win-win scenario.
Here is an example for the second situation described above.
Let’s say a plant has a production line with very specialized and expensive equipment. The first priority from a productivity point of view would be to keep that equipment running as fast and as much as would be reasonable considering normal maintenance etc.
Use SMED concepts for quick changeovers to satisfy multiple customers and finally apply Takt times to balance for other opportunities.