Not just a lot of hot air! Why robotic grit blasting can generate big savings….
Robotising applications are synonymous with improved productivity and efficiency, but what does that really mean if you’re in the surface preparation and shot peening industry? It’s not unusual to hear reports of higher levels of output, product quality and flexibility amongst the benefits, but where are those real savings? What is the cost to the organisation, and how can those benefits be quantified?
The first and most obvious benefit in moving to a robotic surface preparation solution is a reduction in capital and operating costs, the latter being in the form of direct or overhead costs. Take compressed air consumption as a case in point. Studies suggest that between 10 to 30% of industrial facility energy costs go toward compressed air.
When compared to an automatic machine requiring six to eight nozzles, a robot fitted with a single blast nozzle can achieve an equivalent or superior finish for a fraction of the compressed air consumption. Let’s put that into real numbers. At our warehouse in Adelaide, we’re paying 36.46 cents per KWH for our electricity – some of the most expensive in the world! For arguments sake, let’s say an average compressor uses 7 KWH to generate 1 cubic metre of air per minute, or 0.198 KWH per cubic feet per minute (CFM). In this example, the complex automatic machine uses 8 x 45 CFM nozzles to prepare the part, which is 360 CFM. That’s $26.02 per hour of operation at the price we’re currently paying for electricity. In comparison, a robot fitted with 1 x 75 CFM nozzle would cost just $5.42 per hour to run. If the facility was running 2 x 8 hour shifts, 5 days per week, for 52 weeks a year, the difference for this one application is $22,548.32 versus $108,231.94 – close to a savings of $86,000.00 per annum.
But, that’s not the only direct cost saving – the media consumption used for the blasting is also dramatically reduced because of there is no cross firing of guns. The media used in shot peening varies from application to application, but is generally cast steel, cut-wire, stainless, glass, ceramic or other materials. For this reason, the cost saving on the usage of the shot is very application specific, but what isn’t is the reduction in waste, which can be as much as 30% based on previous applications.
In addition to the compressed air savings and material savings, the ancillary media reclamation system required for one nozzle versus six or eight is much smaller in scale, which flows on to smaller screen classifiers, smaller shape classifiers, and smaller cyclone and dust collectors. The reduction in size and scale of this equipment results in a lower capital investment and a reduction in the required footprint for the application. Further to this is the obvious labour savings associated with robotising the application.
Another benefit of robotising a shot peening application is the improvement seen in the product quality and consistency. Blasting steel serves to clean the substrate and produce an etched surface profile (anchor pattern) when the abrasive strikes the metal. The surface profile improves the ability of a corrosion prevention coating to adhere to the surface, and at the same time, it is designed to generate an even compressive stress pattern, eliminating microscopic defects in the surface of the parts.
Permissible stress levels for various materials are improved through the adoption of this process, increasing the overall life cycle of a product. Because of the nature of a repeatable robotic program, where target distances are maintained, and speed it used to minimise cross fire, a robot has the ability to generate a surface profile that is far more consistent in application measures such as Ra and Rz. Furthermore, the optimal shot impact angle can be maintained and repeated, providing an even residual stress profile across the part that may otherwise have not been achievable with a manual application.
Increased manufacturing uptime is another tangible benefit from robotic shot blasting. Operators in a manual application are required to wear heavy personal protective equipment that can be stifling, and as a result, occupational health and safety laws may dictate that they require significant rest allowances. In comparison, robots can operate around the clock, and also reduce the requirement for constant visual inspection of the part due to their inherent repeatability. This greatly increases the uptime of the cell.
Advances in offline programming capabilities for robot systems have also mitigated the need for excessive downtime between production runs – parts can be simulated offline, and new parts can be brought online without significantly impacting production schedules. The manufacturing uptime is also higher when compared to fixed peening machines, which may need significant downtime between different types of parts for nozzle adjustments and things of the like. The flexibility of running a robotic application means that there is a minimal amount of downtime between product changes, as the industry drives towards smaller batch sizes.
In conclusion, robotic blasting provides an opportunity for manufacturers to reduce their operating expenditure, while improving their product quality and consistency. Manufacturers can look forward to a high cell uptime because of the reduced need for inspection and the ability to program new parts using offline programming tools. Cells can operate night and day, providing the greatest return on investment for your factory, whilst reducing the footprint of the blasting area and the subsequent capital outlay. In the competitive world of blasting, robotic solutions are enabling manufacturing efficiencies that are once again allowing companies to compete with low cost overseas markets. What will you do – innovate, or vanish into thin air?