Used Robots in eBay
Why robots end up to sales ad?
Production batch sizes are getting smaller. Number of product variants is increasing. Traditional arena using industrial robots where the products are produced in long series is shrinking. Robots ability to adopt new jobs depends on many things, like programming. Every new job needs a new robot program. More jobs, more programs. Depending on the complexity of a program, the time to create a program might take few minutes, several days or several weeks. Programming time of an arc welding robot welding a complex body frame of a forest harvester will take 60 hours. All this time a robot does not produce a thing.
Company management and especially CFO is looking the economy of robot investment. If a robot stays long periods of time idle, the return on investment (ROI) becomes questionable. Due to programming stoppages the uptime goes down and a robot does not bring the productivity jump to a company for what it was originally invested. The measured utilization rate in small series production can be 30% due to repeated programming stoppages. This might be a shock to management when the investment calculation was based on 90% utilization rate. It soon turns out that human worker will replace a robot. There will be found a new sales ad in eBay under category “used robots”.
This imagined scenario was based on assumption that a robot was programmed by teaching a physical robot on the shop floor, online.
Offline programming for efficiency and economy
CAD-based offline programming doesn’t decrease robot’s uptime as robot programming is done offline with software, not using the actual robot on the shop floor. Delfoi has experienced during 25 years how programming method effects in downtime especially in arc welding or cutting processes.
Production downtime due to programming decreases roughly by ratio one to ten (1/10) when changing from teaching to offline programming. If a robot program by teaching took 40 hours, a robot remained idle also 40 hours. When the same program was done offline, downtime was only 4 hours. This time was spent when test running the program before executing. These are the figures what management likes. He/she might further ask: “do we have to recrute a programmer for offline programming”? No, a modern offline programming software is fast and easy to use. The same robot operator who did the program by teaching can do the job with simulation software offline. And we can take back the sales ad from eBay. Robot’s operating rate will easily go above 90% and also ROI makes sense.
Robot welding for batch size #1
Some industries, like construction steel manufacturers, haven’t invested (much) in welding robots due to low batch sizes. In fact the batch size is often one. Steel structures, like beams, have been welded manually. And when the labor cost is in focus only low labor cost countries could have produced beams economically. When lot size is #1 also a standard offline programming software might become too slow to use. Every time a new product is welded a new welding program has to be ready for execution. Automatic offline programming software has been developed for this purpose.
Companies like Lindab-Astron in Luxembourg has been able to produce cost effectively robot welded beam structures for building industry for several years now. Two large welding robot stations of different robot brands are working without stoppages continuously in two shifts.